Chapter 43 Adverse Effects of Topical Eye Medication in Infants and Children LEONARD APT and WILLIAM L GAFFNEY Table Of Contents |
The ocular and systemic toxicity of topically applied ophthalmic medication
has been a major subject of interest to ophthalmologists. The increased
use of a variety of new eye drop preparations has led to a dramatic
rise in the number of serious cases of systemic toxicity from eye
drops that have been reported to the National Registry of Drug Induced
Ocular Side Effects. In the large number of reports concerning adverse reactions to topical ophthalmic drugs, it is evident that infants and children are particularly prone to toxic reactions.1–10 Many topical ophthalmic drugs frequently used in children are not approved by the Food and Drug Administration (FDA) for the pediatric age group. However, they are commonly prescribed by ophthalmologists for infants and children unless serious side effects specific to the pediatric population have been reported. Since 1999, the FDA has had the authority to request pediatric studies for marketed drugs that are often administered to young patients, and “me-too” drugs must be studied first in adults to establish safety and efficacy profiles.11,12 The numerous isolated case reports and pharmacologic studies of the toxic effects of topical ophthalmic drugs in the pediatric age group are summarized for the practicing ophthalmologist in this updated chapter. Infants and children have increased potential for ocular and systemic drug-induced adverse reactions for several reasons: (1) they may receive an excessive dose owing to difficulty in instilling drops or ointment, particularly if they are uncooperative; (2) administration of a drug may be continued by a parent or nurse who does not recognize early signs of drug toxicity; (3) differences exist between children and adults in their physiologic response to the same drug13,14; (4) drug absorption through the conjunctival epithelium and skin may be more rapid in infants15,16; (5) metabolic enzyme systems are immature, especially in neonates, and may prolong the half-life of drugs17; and (6) the dose relative to blood volume, body weight, and surface area is greater for infants and children (blood in adults dilutes absorbed drug 20 times more than in neonates)5,18,20 This factor of the relationship of the dose to blood volume, body weight, and surface area is particularly important in causing toxicity. If drops only are considered, an approximation can be made of the total dose delivered to the eyes following a routine instillation. The dose per drop of certain topical ocular drugs used in the pediatric age group for examination and therapeutic purposes is listed in Table 1, along with the usual systemic pediatric therapeutic dose and the lethal dose, if known.
Table 1. Administered Dosage of Commonly Used Topical Ophthalmic Drugs
OU,—; SC, subcutaneous; IM intramuscular; IV, intravenous; PO, oral; MLD, mean lethal dose; prn, as required; aGardner, SK: Jules Stein Eye Institute Pharmacology Notes 3(4), 1982. bAmount of drug in drop. The amount of may vary depending on the dropper size used by different manufacturers. If amount is unknown, the average for tested drops (25) is used. cBehrman R, Kliegman RM, Arvin AM (eds); Nelson's Textbook of Pediatrics, pp 2038–2078. 15th ed. Philadelphia, WB Saunders, 1996. dKeys A, Violente A: The cardiocirculatory effects in man of Neo-Synephrine. J Clin Invest 21:1, 1942. eTrue Bev-Lorraine, Dreisbach RH: Dreisbach's Handbook of Poisoning, pp 422, 426, 435. 13th ed. Boca Raton; The Parthenon Publishing Croup, 2001. fGardner Ll! Endocrine and Genetic Diseases of Childhood and Adolescence. 2nd ed. Philadelphia; WB Saunders, 1975.
Relative overdosage of all drugs listed in Table 1 can occur in children, particularly if repeated doses are given. Limited quantitative data on the systemic absorption of drugs after conjunctival instillation indicate that 30% to 80% of a retained topically applied dose enters the general circulation.20 If systemic absorption averages 50% of the instilled medication, the systemic dose can be dangerously large. For example, one drop of 10% phenylephrine (100 mg/mL) instilled into each eye delivers about 7 mg of the drug (see Table 1). Assuming 50% absorption, a child weighing 20 kg receives almost twice the usual parenteral subcutaneous or intramuscular therapeutic dose (2 mg) or nine times the usual parenteral intravenous therapeutic dose (0.4 mg). Similar comparisons can be made for other drugs in Table 1. Topical corticosteroids are frequently instilled into the eye every 2 hours for treatment of uveitis or vernal catarrh in a child. If prednisolone acetate 1% is used, a total of 16 mg of the drug (one drop in each eye every 2 hours for 16 hours) is instilled each day. Assuming that 50% of the administered drug (8 mg) is absorbed, this can be twice the daily pediatric physiologic replacement dose of prednisolone given orally (4–10 mg). Plasma timolol levels have been measured in infants and children receiving topical timolol for glaucoma. Levels ranged from a low of 3.5 ng/mL in a 5-year-old child to a high of 34 ng/mL in a 3-week-old infant, which is far in excess of the usual therapeutic dose of an equivalent amount of propranolol.19 Measures to reduce excessive absorption and toxicity of topical eye medication in pediatric patients have been based on techniques for resisting drainage into the nasolacrimal system or on the use of vehicles and delivery systems that increase topical bioavailability and absorption by the cornea while decreasing total drug concentration in the eye. These measures include the following:
Until medications and delivery systems are available commercially in pediatric doses, the potential remains for administration and absorption of medications in high doses through the ocular route in infants and children. It is thus important to be able to recognize the complex of signs and symptoms associated with toxic reactions to a specific drug, so that the drug may be discontinued and appropriate treatment begun before serious and even fatal consequences ensue. |
SYMPATHOMIMETIC DRUGS |
EPINEPHRINE AND DIPIVEFRIN Epinephrine has been employed topically during various surgical procedures for its vasoconstrictive and mydriatic effects. It must be used with extreme caution on the eye undergoing surgery because rapid absorption of epinephrine from the hyperemic and surgically traumatized conjunctival sac is well established.67,68 In addition, general anesthetic agents such as halothane and cyclopropane sensitize the myocardium to the cardiotoxic effects of systemically absorbed epinephrine.68 Tachycardia and arrhythmias in children following topical use of epinephrine during general anesthesia have been noted by anesthesiologists, many of whom prohibit its use.69 If epinephrine must be used with halothane anesthesia, a concentration of 1:100,000 to 1:200,000 is recommended in children. Concentrations greater than 1:200,000 apparently do not give any additional vasoconstriction.69 A recent study on adults undergoing cataract surgery found a concentration of 1:400,000 safe and effective for mydriasis.70 Dipivalyl epinephrine (dipivefrin [Propine]) is a prodrug of epinephrine that penetrates the cornea about 17 times better than epinephrine.71 It is converted to epinephrine in the eye and has the same effect as epinephrine, but with fewer local and systemic side effects. Epinephrine and dipivefrin have a systemic absorption of 55% to 65% of the ocularly applied dose in rabbits.72 This potential for high systemic absorption can lead to sympathomimetic effects such as excessive sweating, pallor, faintness, occipital headaches, hypertension, palpitations, tachycardia, and cardiac arrhythmias, particularly in patients with preexisting cardiac disease,67,73,74 and premature infants and neonates.8 The administration of epinephrine by subcutaneous injection in patients taking propranolol can lead to a marked hypertensive episode followed shortly by bradycardia progressing to cardiac arrest or hypertensive stroke.75 Epinephrine should therefore be used with great caution in a patient taking propranolol. Local side effects of epinephrine and dipivefrin include irritation, foreign body sensation, brow ache, blurred vision, adrenochrome deposits in the conjunctiva and cornea, corneal edema, allergic blepharoconjunctivitis, reactive hyperemia, giant follicles of the tarsal and bulbar conjunctiva, shrinkage of the conjunctiva with symblepharon, and nasolacrimal duct obstruction.76–81 The association of epinephrine and dipivefrin with cystoid macular edema in adults has not been reported in children, although safety of these drugs in children has not been fully tested.8 The use of epinephrine and dipivefrin has largely been replaced by the newer adrenergic agonists apraclonidine and brominidine for the treatment of glaucoma in adults. These selective adrenergic agonists have significant side effects in infants and children (see section on alpha-2 selective antagonists). HYDROXYAMPHETAMINE Similar in chemical structure to epinephrine, hydroxyamphetamine (Paredrine) produces mydriasis with little, if any, effect on accommodation.82 It is a weaker mydriatic than phenylephrine in infants and children,6 but equivalent to 2.5% phenylephrine in young adults. Paredrine is not currently available.83 Hydroxyamphetamine 1% has been combined with tropicamide 0.25% commercially (Paremyd), producing a more pronounced mydriatic effect than either hydroxyamphetamine 1% or tropicamide 0.5% alone.84 Topical instillation of hydroxyamphetamine can produce increased blood pressure, and significant cardiac events have been reported after systemic administration, although a causal relationship is unproven.85 PHENYLEPHRINE Phenylephrine is a powerful local and systemic vasoconstrictor and mydriatic that has been widely used in the pediatric age group since its introduction by Heath in 1936.86 Initially it was believed to have a wide margin of safety with topical use,87 and it rapidly became a standard drug in all age groups for mydriasis prior to examination of the fundus. Before 1972, the reports of systemic reactions to phenylephrine were few. Schepens, in 1951, noted that the drug used topically in eyes undergoing retinal detachment surgery “may cause unpleasant systemic reactions such as nervousness, pounding of the heart, violent headaches, nausea, and vomiting.”88 Over the years, with widespread use, numerous case reports and research studies demonstrated that topical phenylephrine in 10% concentration had a potent and dangerous systemic hypertensive and cardiotoxic effect in patients in high-risk categories, such as the young and the elderly. A 3-month-old infant who received three drops of 10% phenylephrine in one eye at the conclusion of cataract surgery had a prompt increase in blood pressure to 230 mm Hg that returned to a normal level gradually over the next 2 hours.89 The same report described two elderly patients who had similar sharp and sudden increases in systolic blood pressure following the ocular application of 10% phenylephrine either preoperatively or immediately postoperatively. Other workers described an adult whose blood pressure rose to 270/170 mm Hg after administration of three drops of phenylephrine in one eye.90 Vaughan reported that an 8-year-old boy, while undergoing strabismus surgery, received four to five drops of 10% phenylephrine to control conjunctival bleeding.68 Almost immediately, the patient's blood pressure rose from 100/60 to 190/120 mm Hg, and he developed ventricular arrhythmias. He reverted to normotension and normal sinus rhythm after lidocaine was given intravenously. Because phenylephrine is solely an alpha-adrenergic receptor stimulator, it has no direct cardiotoxic effect; however, its hypertensive action can initiate reflex vagal stimulation, which can then induce serious ventricular arrhythmias. A definitive study of the dangers of the use of 10% phenylephrine in infants was done by Borromeo-McGrail and associates.91 They compared the hypertensive effect of 10% and 2.5% phenylephrine in healthy low-birth-weight neonates. Systolic and diastolic blood increases of 20% to 40%, lasting up to 1 hour, were found consistently in the group of infants who received one drop of 10% phenylephrine; 2.5% phenylephrine did not cause blood pressure elevation in any of the infants tested. The authors concluded that the hypertensive effect of the 10% concentration could be especially dangerous in the infant with intracranial bleeding or with a left-to-right shunt, or even in the normal low-birth-weight infant, because of an increased potential for intracranial hemorrhage. Caution is advised in infants with cardiac anomalies as well. In a premature infant with a ventricular septal defect, 10% phenylephrine caused acute hypertension and pulmonary edema.92 It has been shown that 10% phenylephrrine in both aqueous and viscous forms causes blanching of the skin of the eyelids, increased systolic and diastolic blood pressure, and inadequate papillary dilatation in neonates.93 In summary, although no case of death or permanent morbidity has been reported in children from 10% phenylephrine, the drug has significant and dangerous cardiovascular effects in newborns and infants. Because of these effects, and because phenylephrine produces inadequate mydriasis in newborns, 10% phenylephrine should not be used in infants and should be employed in the older pediatric age group cautiously and only when strong active dilatation of the pupil is required. The 2.5% solution of phenylephrine has been widely used in pediatrics because it has been believed to produce fewer cardiovascular toxic effects from systemic absorption than the10% solution. However, although some past studies have shown no significant effect of 2.5% phenylephrine on systemic blood pressure in neonates,93–97 the current data in the National Registry of Drug-Induced Side Effects indicates that 2.5%, like 10%, phenylephrine can have serious cardiovascular effects in infants, the aged, insulin-dependent diabetics, and patients with high blood pressure or cardiovascular disease.98 The low-birth-weight (<1600 g) infant is particularly at risk for elevated systolic blood pressure, and mean systolic blood pressure elevations of 20% to more than 50% have been reported.99–102 Because of these findings, it is recommended that 2.5% phenylephrine not be used for routine mydriasis during the first 6 weeks of life in premature infants or in any infant with cardiovascular disease.103 Cycloplegics alone (either cyclopentolate 0.5% for infants younger than 8 months of age, and 1% thereafter, or tropicamide 1%) or phenylephrine 1% in combination with cyclopentolate 0.2% (Cyclomydril) or phenylephrine 1% in combination with tropicamide 0.5%.96,104–106 Phenylephrine frequently has been substituted for epinephrine at surgery to control bleeding because it produces fewer cardiac effects.87 Systemic absorption, however, is enhanced in the eye undergoing surgery, and in large doses phenylephrine, like epinephrine, can cause serious cardiac arrhythmias and pulmonary edema in patients receiving general anesthesia.68,107–109 In addition, atropinization enhances the pressor effects of phenylephrine, which may lead to hypertension, tachycardia, and cardiac arrhythmias.98 For these reasons, 10% phenylephrine should never be used topically on the eye having surgery. If phenylephrine is used, a concentration of 1:50,000 produces satisfactory vasoconstriction.70 Phenylephrine should be avoided preoperatively and intraoperatively in patients taking tricyclic or monoamine oxidase inhibitor antidepressants, β-adrenergic blockers, reserpine, or guanethidine because potentiation of the pressor effects of phenylephrine may result.98,110 The proprietary collyria used to produce vasoconstriction in minor eye irritations contain 0.12% to 0.2% phenylephrine, and they have not been implicated in the production of systemic hypertension in any age group. Local reactions to topical ocular phenylephrine include transient pain, headache and brow ache, blurred vision, release of pigment into the aqueous with transient elevation of intraocular pressure, lacrimation, reactive hyperemia, transient keratitis, rebound miosis, and severe allergic dermatoconjunctivitis.10,111 Dapiprazole (Rev-Eyes) is an alpha-1-adrenergic inhibitor that reverses mydriasis produced by phenylephrine, and to a lesser extent, tropicamide. Safety of this drug in children has not been established. The high incidence of conjunctival hyperemia (greater than 80% of patients), burning and stinging (about 50% of patients), and a weak effect on reversal of accommodation paralysis in the pediatric age group make this drug of little practical clinical usefulness in young patients.112 |
ANTICHOLINERGIC (PARASYMPATHOLYTIC) DRUGS | ||||||||||||||||||||||||||||||||||||
ATROPINE Since the introduction of atropine in 1833, many cases of systemic toxicity have been reported after conjunctival instillation of the drug.113–127 These cases include six deaths in children, all of whom were younger than 3 years of age.124–128 Two mechanisms appear operative in cases of atropine poisoning. First, in some children a definite idiosyncratic response occurs, consisting of acute systemic toxicity and even death after the instillation of only one or two drops in each eye (a total dose of 1 to 2 mg of a 1% solution).126,127 Increased susceptibility to atropine has been reported for infants,6,13 blond children, children with spastic paralysis or brain damage,6,121 children with akinetic seizures,129 and children with Down syndrome.130–132 The eyes of patients with Down syndrome, compared with normal controls, dilate more rapidly and mydriasis lasts longer after instillation of atropine eye drops.130 Harris and Goodman demonstrated a twofold increased sensitivity to the vagolytic action of atropine in Down syndrome patients.132 Atropine should be administered with great caution to these sensitive persons. The second mechanism of atropine toxicity is overdosage following multiple instillations of the drug, often when early toxic symptoms are not recognized. Relative overdosage of atropine can occur easily via the conjunctival route in the pediatric age group. Frequently in the past, atropine eye drops were instilled in young strabismic children as part of a 3-day routine for cycloplegic retinoscopy (one drop in each eye three times a day for 3 days prior to the next office visit), during which time a total of at least 9 mg of 1% atropine was administered. Although not all of the drug is retained and absorbed, this amount is close to the average fatal dose of 10 mg for infants and 10 to 20 mg for children.126,133 Death has been reported from a dose as low as 1.6 mg in a 2-year-old boy.127 Atropine appears rapidly in the blood after ocular instillation (as rapidly as intramuscular atropine),134 and because children have a low atropine clearance compared with adults, repeated instillation may lead to accumulation of the drug and may increase the potential for overdosage and toxicity.123,135 Because of toxicity concerns, it may be prudent to consider abandoning the traditional 3-day atropine regimen for cycloplegic refraction in young pediatric patients. Refractive values in children 90 minutes after two drops of 0.5% atropine (in children less than 2 and a half years of age) or 1.0% atropine (in children older than 2 and a half years) have shown to be equal to the usual 3-day administration in 80% to 90% of cases.136 Systemic atropine toxicity results from peripheral blockade of postganglionic parasympathetic fibers and from subsequent depression of certain cortical and medullary centers. The signs and symptoms of systemic atropine poisoning given in Table 2 may appear within a few minutes to a few hours after instillation. Peripheral signs and symptoms generally occur at lower doses and usually are of little consequence. Central nervous system (CNS) toxicity, however, is most serious and can result in stupor or coma lasting up to 5 days or even in death. In general, the clinical picture of systemic atropine toxicity is the same in older children and adults. Infants and young children have fewer symptoms of CNS excitation and are more likely to show CNS depression with drowsiness and coma.118,121 Hyperpyrexia may reach alarming levels in infants (109°F [41.1°C] or greater), and abdominal distention usually is pronounced.8 It is not surprising that the combination of high fever, rash, tachycardia, and delirium in patients with systemic atropine toxicity has been confused in the past with the symptoms of scarlet fever.118 Atropine readily crosses the placenta and is excreted in breast milk in small amounts; therefore, neonates and breast-feeding infants of mothers treated with ocular atropine are at risk.8
Table 2. Signs and Symptoms of SystemicAtropine Toxicity
Physostigmine salicylate (Antilirium) is an effective antidote for systemic atropine toxicity.137,138 Physostigmine reverses atropinization by inhibiting cholinesterase so that acetylcholine accumulates at the neuroreceptor site. After subcutaneous, intramuscular, or intravenous administration, physostigmine salicylate readily enters the CNS and within minutes reverses all central and peripheral anticholinergic effects. Limited trials have indicated that it is safe for use in children.138 The recommended dose for children as young as 1 year of age is 0.5 mg given slowly intravenously over 2 to 3 minutes or 1 mg/M2 given subcutaneously or intramuscularly, repeated every 5 minutes if toxic effects persist until a maximum dose of 2 mg is reached137,138 In adolescents and adults, the dose is 1 to 2 mg given slowly intravenously over 2 to 3 minutes or 1 to 2 mg given subcutaneously or intramuscularly, with a second dose of 1 to 2 mg in 10 to 20 minutes if toxic effects persist. One to 4 mg may then be given every 30 to 60 minutes until symptoms subside. An alternative dosage schedule for physostigmine salicylate is 0.02 to 0.03 mg/kg up to 2 mg intravenously, intramuscularly, or subcutaneously. The dose may be repeated in 15 minutes, then every 2 hours as needed. Other supportive measures for treating atropine toxicity include hospitalization in a dark, quiet room, high fluid intake, measures to control fever, artificial respiration and catheterization as needed, and sedation with short-acting barbiturates, chloral hydrate, or morphine (in small doses). Despite the risk of intoxication in infants and children when atropine is instilled in the eye, atropine is widely used for cycloplegic refractions and in the treatment of amblyopia. A recent randomized National Eye Institute–sponsored trial of atropine 1%, one drop daily, versus patching for the treatment of moderate amblyopia in children, found that atropine was as effective as patching in visual results for the 3- to 7-old age group and had a clear advantage in parent and patient compliance. Adverse effects of atropine in the study were local and minimal.139 Used cautiously in patients at risk and employing measures to control overdosage, atropine can be used safely and effectively. Refer to Table 3 for the authors' protocol for atropine and other cycloplegic agent usage in cycloplegic refractions.
Table 3. Choice of Cycloplegic Agent for Infants and Children
aNot commercially available. The pharmacy at the UCLA Health Sciences left makes the preparation for us because it is no longer available commercially.
Local adverse reactions from atropine and other cycloplegic mydriatics (e.g., scopolamine, homatropine, cyclopentolate, tropicamide) include increased intraocular pressure (rare in pediatric patients), transient stinging, allergic reactions of the eyelid and conjunctiva, follicular conjunctivitis, hyperemia, edema, photophobia, and eczematous dermatitis. Some cycloplegic mydriatic products contain sulfites that may cause allergic reactions (e.g., hives, itching, wheezing, anaphylaxis) in susceptible persons, especially those known to have allergic disorders such as asthma and atopic dermatitis. HOMATROPINE Homatropine is a weaker cycloplegic agent than atropine and is less reliable than similar drugs for cycloplegic refractions in children. Systemic toxic reactions following ocular instillation are similar to those for atropine (see Table 2). Walsh and Hoyt128 stated that untoward reactions are milder with homatropine than with atropine, but Hoefnagel did not find this so in his study.120 He reported five cases of anticholinergic toxicity in children following the instillation of 2% homatropine drops. CNS signs and symptoms, including ataxia and visual hallucinations, were striking in each of these cases, and although one patient recovered in 6 hours, another had persistent visual hallucinations for 5 days. Three more recent cases of anticholinergic delirium have been reported due to topical ocular homatropine solution.141,142 One fatality has been reported due to homatropine hypersensitivity in a 7-month old infant with atypical Down syndrome.128 Febrile reactions have been observed in severely retarded children in whom homatropine has been used.128 There appears to be a relation between these reactions and high environmental temperatures and humidity.142 Like atropine, homatropine should be used with great caution in children with Down syndrome or brain damage. Physostigmine reverses the systemic anticholinergic effects of homatropine.137,138 SCOPOLAMINE Systemic anticholinergic toxicity after ocular use of scopolamine (Hyoscine) in children has been reported infrequently, and no death attributable to ocular scopolamine has been reported. German authors have described toxic reactions associated with the use of scopolamine ointment143,144 and with 1% drops.145 Another report found acute systemic toxicity in three African children and four African adults following the administration of 1% scopolamine eye drops in each eye.146 Confusion, disorientation, hallucination, spasticity of extremities, vomiting, and urinary incontinence lasted for several hours and then spontaneously resolved. Acute toxic psychosis with recovery within 24 hours has been described in children after the ocular use of 0.2% scopolamine.147,148 The rapid absorption of ocularly applied scopolamine may explain its occasional systemic anticholinergic side effects.149 Adverse reactions with the use of commercially available 0.25% solution in the United States have been rare. Scopolamine is an effective cycloplegic substitute for children with known hypersensitivity to atropine (although some cross-reactivity occurs). The cycloplegic strengths of 1% atropine sulfate and 0.25% scopolamine are similar, although the duration of scopolamine cycloplegia is much shorter.150 Physostigmine promptly reverses the central and peripheral toxicity of scopolamine.137,138 CYCLOPENTOLATE Introduced in the early 1950s, cyclopentolate hydrochloride (Cyclogyl) has been used to treat both cycloplegia and mydriasis primarily in children older than 1 year of age. Systemic toxicity induced by the ocular administration of cyclopentolate is similar to that produced by atropine, except that cerebellar dysfunction and visual and tactile hallucinations are more constant and striking features of cyclopentolate toxicity. This is not surprising, becausecyclopentolate is structurally similar to atropine but contains a dimethylated side group (–N–[CH3]2) also found in some tranquilizers and hallucinogenic drugs. Seizures and acute psychosis induced by cyclopentolate are especially prominent in children151–160 and the elderly.161–163 The psychosis is characterized by disorientation, dysarthria, ataxia, hallucinations, and retrograde amnesia. This seems to indicate that CNS immaturity or aging is necessary for its potent psychotomimetic action to become manifest.155 Additionally, ocularly instilled cyclopentolate is rapidly absorbed in adults and children.164–166 The peripheral signs and symptoms of cyclopentolate toxicity are variable and frequently are absent. Gastrointestinal toxicity consisting of ileus or gastroenteritis has been observed with cyclopentolate concentrations of 0.5% or greater in preterm infants, due to reduced gastric acid secretion and volume.156,157 Gastrointestinal effects can be minimized by delaying feeding until after the application of eye drops and ocular examination have been performed.168 Toxic reactions to cyclopentolate are dose dependent and are more likely to occur with the 2% solution than with repeated doses of 1% solution. Toxic reactions in children and adolescents are much less common with the 1% compared with the 2% solution.153 Systemic adverse reactions are rarely encountered with the use of the 0.5% concentration in children. Cyclopentolate 0.5% solution has been used for both mydriasis and cycloplegia in infants and children. For newborns, a safer drug is cyclopentolate 0.2% concentration in combination with 1% phenylephrine (Cyclomydril). A 1% solution of cyclopentolate may be used for refraction in older infants and children if the irides are highly pigmented. The 1% solution is close to atropine in cycloplegic effectiveness (in white children, only .34 D less hypermetropia was found with cyclopentolate-induced cycloplegia than with atropine-induced cycloplegia).169 There are few, if any, indications for use of the 2% solution in the pediatric age group. Cycloplegia protocol recommendations are summarized in Table 3. The onset of cyclopentolate toxicity occurs within 20 to 30 minutes of drug instillation, and although usually transient (subsiding in 4 to 6 hours), the symptoms can last 12 to 24 hours. The treatment of systemic cyclopentolate poisoning is the same as for atropine137,138 Kothery and coworkers found that cyclopentolate inhibits cholinesterase in vitro.170 Accordingly, the authors advise using succinylcholine in weak doses for patients undergoing general anesthesia who have been treated with cyclopentolate within the past several weeks, or avoiding the use of succinylcholine completely. A local or generalized allergic-type response to cyclopentolate consisting of an urticarial rash has been described in children.171–173 No treatment is necessary except antihistamines. Severe anaphylactic reactions are rare and are treated with epinephrine, steroids, and antihistamines according to standard anaphylactic treatment protocols. TROPICAMIDE Tropicamide (Mydriacyl) is a rapid-acting mydriatic with mild and transient cycloplegic action. Tropicamide 0.5% or 1% eye drops combined with phenylephrine 2.5% eye drops, given either separately 5 minutes apart or combined in one drop, produces wide papillary dilation for indirect ophthalmoscopy in infants and children. Down syndrome mydriatic response is three times greater in comparison with healthy patients.174 Milder found 1% tropicamide a relatively inadequate cycloplegic drug compared with 1% cyclopentolate.175 One study found tropicamide equal to cyclopentolate in measuring the refractive error of low to moderate hyperopia in school-aged children176 Although two studies report no adverse reactions with the use of 1% tropicamide,177,178 serious CNS disturbances have been observed on rare occasions.85 The low affinity for muscarinic receptors in plasma after conjunctival instillation explains the low incidence of serious systemic side effects of tropicamide drops.180 There are many protocols for cycloplegic refraction that are individualistic and heterogeneous. Based on the authors' review of the literature and clinical experience, Table 3 has been formulated to guide clinicians in the proper selection of cycloplegic agents in the different age groups. When cyclopentolate is used, tropicamide 0.5% can be added in infants up to 3 months of age and 1% thereafter, to enhance the cycloplegic effect. Phenylephrine drops can enhance mydriasis for ophthalmoscopy. The use of a topical anesthetic drop prior to administration of cyclopentolate (and of other drops) can result in a more comfortable and atraumatic cycloplegia in children.181 |
CHOLINERGIC (PARASYMPATHOMIMETIC) DRUGS | ||||||||||||||||
PILOCARPINE Pilocarpine has limited therapeutic use in infants and children, but occasionally it is employed in the treatment of congential or juvenile glaucoma. Pilogel (Pilopine HS Gel) may be better tolerated by children, as the increase in myopia produced occurs primarily during sleep. Pilocarpine is a direct-acting miotic with effect on the muscarinic (parasympathomimetic) receptors in the eye. The drug is rapidly absorbed into the systemic circulation after ocular instillation.182 Systemic toxicity after repeated instillation of pilocarpine, evidenced by salivation, lacrimation, rhinorrhea, sweating, nausea, vomiting, diarrhea, muscle tremor, muscle weakness, ataxia, and confusion, is uncommon.183,184 Since pilocarpine also may produce bronchospasm, a typical asthmatic attack may be precipitated in susceptible patients. Toxicity may be treated with systemic administration of parenteral atropine, which antagonizes the muscarinic effects.182 Newborns of mothers taking topical pilocarpine may have hyperthermia, hyperemia, diaphoresis, restlessness, and seizures.185 Because this symptom complex may be mistaken for neonatal meningitis and cause needless therapy, it is important that the ophthalmologist inform the pediatrician and obstetrician that the mother is using pilocarpine eye drops. Pilocarpine infrequently produces iris cysts in children186 and has no consistent cataractogenic effect in children. There have been reports received by the National Registry of Drug Induced Ocular Side Effects of peripheral, white, subepithelial corneal deposits and iritis with pilocarpine use. Other local ocular reactions include burning and smarting, conjunctival and ciliary congestion, ocular pain, eyelid twitching, accommodative myopia, lacrimal canalicular obstruction, and allergic blepharoconjunctivitis.187 CARBECHOL Carbechol is similar in action to pilocarpine but has a longer duration of action and more frequent systemic toxicity. Like pilocarpine, it should be used with caution in children with bronchial asthma. Systemic toxic reactions are treated in the same manner as for pilocarpine.182 PHYSOSTIGMINE Physostigmine (Eserine) is an indirect-acting miotic. The drug inhibits the enzyme cholinesterase and thus enhances the effects of acetylcholine. A short-lived, reversible depression of blood cholinesterase has been observed in children following the topical use of physostigmine.183 Physostigmine is rapidly absorbed from the nasal mucosa after conjunctival instillation and may result in systemic toxicity similar to that of acetylcholine. An effective antagonist to physostigmine toxicity is atropine sulfate given parenterally. Physostigmine salicylate by injection is the standard antidote for anticholinergic drug toxicity.137,138 ECHOTHIPHATE AND ISOFLUROPHATE Echothiophate iodide (phospholine iodide) and isoflurophate (Floropryl, DFP) are indirect-acting miotics that cause a prolonged and irreversible inactivation of cholinesterase. They commonly are referred to by the misnomer “strong miotics.” These anticholinesterase inhibitors are not really strong but have a long duration of action, and their action makes the pupillary sphincter highly sensitive to a lower concentration of cholinergic drugs. These miotics are used in children mainly to identify or treat the accommodative component of esotropia. Occasionally they are used to treat developmental glaucoma and parasitic infestations of the eyelids. Isoflurophate is no longer available commercially, and echothiophate 0.125% is in short supply and presently only available on a limited basis from Merck Pharmaceuticals. Echothiophate iodide aqueous solution can be readily absorbed into the general circulation, lowering the blood cholinesterase level and producing systemic toxicity. No consistent relationship exists, however, between symptoms of toxicity and blood cholinesterase levels. Immediate systemic reactions from echothiophate iodide are rare188 Clinical evidence of generalized toxicity may not appear for weeks to months after beginning therapy, and because systemic toxicity may mimic other illnesses, the relationship between anticholinesterase therapy and toxic symptoms may go unrecognized.188 Children generally tolerate the anticholinesterase agents better than adults do, and they suffer fewer ocular and systemic toxic effects189 The ocular toxic effects of the anticholinesterase agents in children have been reviewed by several authors,1,3 and include the following: Ciliary spasm (headache, pain in eye and brow, transient myopia) Ciliary spasm, hyperemia, and iritis are of little consequence in children and disappear after 5 to 10 days of continuous treatment. Chronic irreversible miosis has been reported in a 15-month-old girl who received echothiophate daily for 9 months. Two years later, her pupils were still 2 mm in normal light.190 Young infants may be more susceptible to this effect because of an immature iris dilator muscle. Angle-closure glaucoma is a rare occurrence.191 The association of retinal detachment and anticholinesterase agents in adults is controversial; no instances of retinal detachment have been reported in children receiving ocular anticholinesterases.192 Intraepithelial cysts of the iris have been associated with the use of most miotics, but they are seen most often in conjunction with the prolonged and intense miosis produced by echothiophate iodide and isoflurophate.185,193,194 These large brown cysts appear either along or behind the pupillary margin of the iris and are secondary to an accumulation of fluid between the epithelial layers of the iris. The incidence of miotic cysts may be reduced by the use of lower dosage strengths of the miotic or by less frequent instillation. Occasionally the miotic must be discontinued. In some cases, the cysts may persist for up to 10 weeks after the miotic is stopped.193 Phenylephrine in combination with echothiophate iodide or isoflurophate reduces pupillary cyst formation and does not impair the effect of the miotic.194 Iris cysts may attain such size in children that in combination with a miosis they totally occlude the pupil. In one instance, a mistaken diagnosis of malignant melanoma led to enucleation of a child's eye.195 In this case, several iris cysts nearly occluded the pupil and, since they did not transilluminate well because of iris pigment, they were mistaken for a melanoma. Histologic study showed the “tumor” to consist of intraepithelial cystic spaces extending beyond the pupillary margin. Lenticular opacities occur rarely in children receiving anticholinesterase miotics. These begin as anterior subcapsular opacities, and later posterior subcapsular opacities and nuclear sclerosis can develop. The opacities require 10 to 18 months to appear and are related to total dosage.196 Older children are more commonly affected. Although the cataracts may seem reversible and resolve on cessation of the miotic,197 they often redevelop.196 Systemic anticholinesterase poisoning is unusual in children, and the toxic effects that do occur are milder and of shorter duration than those experienced by adults198 Children at highest risk are those with asthma, Down syndrome, myasthenia gravis, epilepsy, and gastrointestinal disturbance.8 Children with Down syndrome can develop excitement, crying, restlessness, tremors, and uncontrollable behavior. The signs and symptoms of systemic anticholinesterase toxicity are summarized in Table 4. An additional toxic effect has been noted but has not received widespread attention. A “miotic URI” consisting of persistent mild rhinorrhea, lacrimation, and upper respiratory congestion can occur and frequently may be missed. A number of children using strong miotics have undergone repeated laboratory tests, radiography, and drug therapy for a “chronic resistant cold or allergy” because this association between localized parasympathetic stimulation of the glands of the upper respiratory tract and anticholinesterase agents was overlooked.189
Table 4. Signs and Symptoms of Anticholinesterase Toxicity
The systemic absorption of anticholinesterase agents may be enhanced in patients with fistulizing devices (e.g., Jones tube) inserted after lacrimal surgery for dacryostenosis.200 The development of adverse systemic effects can also be accelerated in patients receiving anticholinesterases who are exposed to organophosphate pesticides because these pesticides are also cholinesterase inhibitors.196,201 Although systemic toxicity secondary to topical anticholinesterase use is uncommon in children, the ophthalmologist should be familiar with treatment of this complication. The fatal dose of echothiophate iodide and isoflurophate is 10 mg given topically133 Havener states that a child could easily die of the systemic toxic effects associated with ingestion of a 5-ml bottle of anticholinesterase eye drops.202 The classic antidote for anticholinesterase poisoning has been atropine, which can be given intravenously or intramuscularly at an initial dosage of 0.05 mg/kg up to 2 to 5 mg. The intravenous dose can be repeated every 5 minutes, and the intramuscular dose every 15 minutes, until the signs and symptoms of parasympathomimetic overdosage disappear. Additional doses should be given to maintain atropinization for 24 to 48.205 The cholinesterase activator pralidoxime (Protopam, PAM) has been found to be an effective antidote used in conjunction with atropine for anticholinesterase toxicity.203–205 Pralidoxine is ineffective topically due to poor corneal penetration but is effective after subconjunctival injection (0.1 – 0.2 ml 5% aqueous solution) for reversal of ocular side effects.202 The systemic effects of the anticholinesterase drugs may be counteracted by giving pralidoxime as a 5% solution slowly intravenously over about 30 minutes every 8 to 12 hours in a dosage of 25 to 50 mg/kg up to a maximum of 1 g in older children.205 Patients with depressed levels of blood cholinesterase due to anticholinesterase therapy may suffer prolonged respiratory paralysis, and even death, if the depolarizing muscle relaxant succinylcholine is used to aid endotracheal intubation during the initiation of general anesthesia.198 If the anesthesiologist is informed of the potential problem, he may substitute a nondepolarizing agent that does not require cholinesterase for its breakdown. Preferably, anticholinesterase agents should not be used for at least 6 weeks prior to an elective surgical procedure requiring general anesthesia. Whenever possible, a blood cholinesterase level determination should be obtained when any topical anticholinesterase therapy has been used, to be sure that the level is in the safe range. |
STEROIDAL ANTI-INFLAMMATORY DRUGS |
Corticosteroids instilled in the eye in high doses or on a long-term
basis can have serious ocular and systemic adverse effects in the
pediatric age group. It is now well demonstrated that topical (and
systemic) corticosteroids produce glaucoma, simulating either
congenital or juvenile glaucoma in genetically predisposed children.206 At least ten cases have been reported of ocular corticosteroid-induced
glaucoma simulating or complicating congenital glaucoma in infants.207–210 These infants had in common chronic nasolacrimal duct obstruction for
which they received long-term topical corticosteroid therapy, usually
in combination with an antibiotic. Abnormalities of the anterior
chamber angle structures in some patients indicated that infants with
these abnormalities may be more susceptible to the pressure-elevating
effects of corticosteroids. Kass and associates have emphasized
that the use of corticosteroids has no rationale in the therapy for
dacryostenosis.207 Cases of glaucoma simulating congenital glaucoma in infants receiving
systemic corticosteroids have been reported.211,212 At least nine cases are known of glaucoma simulating juvenile or developmental
open-angle glaucoma secondary to prolonged administration
of topical ocular corticosteroids.213–217 Several patients developed advanced visual field loss and glaucoma so
resistant to therapy that a filtering procedure was required to control
intraocular pressure214,217 The tragedy for some of these young patients is that they were receiving
treatment for minor ocular irritations, such as chronic redness secondary
to contact lens wear or chronic blepharitis. Topical ocular corticosteroids are frequently used routinely after strabismus surgery. One survey found that more than 90% of strabismus surgeons gave corticosteroid drops to young patients after strabismus surgery.218 This common practice is disturbing in the light of recent studies in children that show a marked dose-dependent ocular hypertensive response to 0.1% dexamethasone after strabismus surgery in all childhood age groups.219–222 This response is more severe and more rapid than that reported in adults, with as many as 56% of studied children showing a high response in most cases within 8 days of instituting treatment.222 This hypertensive effect was also seen in a young rabbit model.223 Because it is difficult to monitor intraocular pressure in young children, the routine use of topical dexamethasone or prednisolone in children after strabismus surgery should be avoided if possible. Acceptable alternatives shown to have comparable anti-inflammatory action with much less hypertensive effect are fluorometholone 0.1% (FML),219,220 rimexolone 1% (Vexol),224,225 diclofenac 1% (Voltaren),226–228 and loteprednol etabonate (Alrex 0.2%, Lotemax 0.5%).229–233 These anti-inflammatory agents have not been thoroughly studied in the pediatric age group, but they appear to be safe to use in infants and children for postoperative inflammation and the long-term treatment of ocular inflammatory diseases such as uveitis and giant papillary conjunctivitis (vernal keratoconjunctivitis). Since 1960, when Black and associates first reported the induction of posterior subcapsular cataracts (PSCs) by systemic corticosteroids in patients with rheumatoid arthritis,234 considerable evidence has accumulated linking PSCs with long-term systemic corticosteroid therapy in adults.206 PSCs are seen following as little as 4 months of topical steroid use.206 Topical ophthalmic corticosteroids have been incriminated similarly in adults.206 Only a few reports have dealt with this problem in children. One study found PSCs in 8 of 15 children receiving systemic corticosteroids for more than 2 years,235 and another study added eight more cases of systemic corticosteroid-induced cataracts.236 In a report by Burde and Becker, two older adolescents with redness due to contact lens wear developed PSCs and severe glaucoma following the use of topical prednisolone daily for 2 years in one case and topical dexamethasone or prednisolone twice daily for 4 years in the other.4 The paucity of reports of PSCs in infants and children attributable to long-term topical corticosteroid use may in part be due to difficulty in examining this age group with the slit lamp to discover subtle or minimal lens changes. The proven induction of lens opacities in adults receiving systemic and ocular corticosteroids for periods of months and the occurrence of PSCs in children on chronic systemic corticosteroid therapy make it obligatory to perform slit-lamp examinations periodically in each child who is receiving long-term systemic or ocular corticosteroid therapy. No correlation has been found between PSCs and total corticosteroid dose, weekly dose, duration of dose, or age of patient. The most important etiologic factor seems to be individual susceptibility to the side effects of corticosteroids.237 Systemic absorption of topically applied ophthalmic corticosteroid preparations has not been quantified, but significant absorption is implied by several research and case studies. Volunteers receiving 0.01% dexamethasone topically to the eye showed a reduction in urinary excretion of 17-hydroxycorticosteroids and a reduction in endogenous cortisol production.238,239 Adrenal atrophy, chronic pyelonephritis, weight change, and fetal malformations have been described in rabbits receiving corticosteroid eye drops.240,241 Nursall described a patient who demonstrated allergic symptomatology and a reproducible decrease in circulating eosinophils each time she was given corticosteroid eye drops242 Two cases of induced Cushing's syndrome (one fatal) in children receiving dexamethasone eye drops have been reported.243,244 Both patients received eight drops per day of 0.1% dexamethasone, equivalent to 0.4 mg. When this quantity is compared with the daily oral physiologic replacement dose of dexamethasone for these two children, aged 8 months and 2 and a half years (approximately 0.4 mg/day and 0.6 mg/day, respectively), the potential for partial adrenal suppression is evident, especially with long-term use of corticosteroids. The older child, in a case reported by Romano and associates, received, in addition to dexamethasone eye drops, periocular injections of triamcinolone, 0.5 ml (20 mg), on several occasions during therapy.244 This child died after 4 months of corticosteroid therapy for a corneal homograft rejection. Postmortem examination confirmed the diagnosis of Cushing's syndrome with adrenal suppression and atrophy. Two infants with periocular hemangiomas treated with a 1-ml intralesional injection of a 50:50 mixture of triamcinolone acetonide (Kenolog-40, 40 mg/mL) and betamethasone phosphate/acetate (Celestone Soluspan, 6 mg/mL) promptly developed adrenal suppression, as evidenced by depression of their serum cortisol and adrenocorticotropic hormone levels. The hormone levels and the growth and weight rates in one of the infants remained depressed for 5 months post injection.245 Topical corticosteroids tend to decrease resistance to bacterial, viral (especially herpes simplex), and fungal infections. Other adverse local reactions include mydriasis, epithelial punctuate keratitis, delayed corneal and scleral healing, corneal and scleralmalacia, tear-film instability, uveitis, crystalline keratopathy, orbital fat atrophy, limitation of ocular movement, and occasional allergic reactions.34 |
ANTI-INFECTIVE DRUGS |
SULFONAMIDES Serious allergic reactions leading to death from Stevens-Johnson syndrome or aplastic anemia have occurred in children receiving systemic sulfonamides.246,247 Three cases of Stevens-Johnson syndrome, one in an 8-year-old boy, have occurred following ocular sulfonamide use.248–250 For this reason, topical sulfonamide eye drops should be used prudently and only after a careful medical history regarding exposure to sulfonamides and specifically any record of reactions to these drugs. Sulfonamide ointments used to treat marginal blepharitis have led to local photosensitization that caused circumscribed sunburn of the lid margin. Erroneous diagnoses of allergy to the drug have been made.251 True allergic dermatoconjunctivitis occurs occasionally. CHLORAMPHENICOL Topical ocular chloramphenicol is widely used throughout the world in the treatment of superficial ocular infections because of its broad spectrum of activity, infrequent local irritative and hypersensitive reactions, and low cost. Its use in the United States has declined markedly since the report published by Fraunfelder et al in 1982 of two fatal cases of aplastic anemia attributable to chloramphenicol eyedrops.252 By 1993, the National Registry of Drug-Induced Ocular Side Effects listed 23 patients with blood dyscrasias, including seven published cases possibly due to topical ocular chloramphenicol.253 The current Physicians Desk Reference emphasizes that ocular chloramphenicol be used for eye infections only if no alternative exists.254 The association of aplastic anemia and systemic administration of chloramphenicol in adults is well established255 The cause-and-effect relationship between topical ocular chloramphenicol and aplastic anemia is not clearly proven by current reports, and the data has been reviewed by several authors.256–259 The risk of aplastic anemia with ocular chloramphenicol may be the same as the risk of aplastic anemia after oral administration of chloramphenicol: approximately 1 in 30,000 to 1 in 50,000 courses of therapy.256 Chloramphenicol has two effects on bone marrow. First, there is a dose-related hematopoetic toxicity with systemic and rarely topical use. The toxic effect on bone marrow usually is reversible with cessation of the drug. Secondly, there are the rare cases of idiosyncratic aplastic anemia, usually with prolonged (months to years) or frequent intermittent (over months to years) use of ocular chloramphenicol. This effect is not dose related and appears to occur only in genetically predisposed individuals. Although serum levels do not reach detectable levels after short-term ocular treatment with chloramphenicol in children,262 some systemic absorption may occur and precipitate an idiosyncratic aplastic anemia.231,262 The potential danger of chloramphenicaol merits judicious use of this drug in children. It should be avoided in any young patient with a genetic predisposition to hematologic disorders (a careful personal and family history of blood dyscrasia is important), those requiring long-term treatment, and patients for whom there are suitable alternatives. Appropriate substitute drugs for superficial ocular infections include polymyxin in combination with bacitracin (Polysporin) or trimethoprim (Polytrim), or one of the fluoroquinilone antibiotics alone. In one European study, Ciprofloxacin in a 0.3% solution was found to be safe and as effective as 0.5% chloramphenicol solution in the treatment of conjunctivitis and blepharitis.263 AMINOGLYCOSIDES The aminoglycosides can produce allergic contact and toxic conjunctivitis in all age groups with neomycin the major sensitizer. Cross-allergenicity does occur.264 Allergic contact dermatoconjunctivitis is a cell-mediated reaction (type IV hypersensitivity) caused by sensitization through previous exposure to the drug. The cutaneous changes are those of acute eczema with significant itching. The conjunctiva typically has a papillary reaction initially more apparent in the inferior conjunctiva with a mucoid discharge. A report of five newborns with orbital irritant contact dermatitis caused by gentamicin ointment used in newborn preventive therapy may have been due to the preservative in gentamicin, paraben.265 Gentamicin and tobramycin have broad gram-negative coverage, but corneal epithelial toxicity and inhibition of wound healing are common with continued use. Tobramycin has been found to be equally effective (90%) as ciprofloxacin in treating childhood bacterial conjunctivitis.266 Resistance to gentamicin and tobramycin is increasing annually. Erythromycin has been an effective treatment for gram-positive organisms and ophthalmia neonatorium prophylaxis. No current available treatment, however, offers complete protection against neonatal chlamydial infection267 One study found povidine-iodine 2.5% solution an effective antibacterial agent on the conjunctiva of newborns that caused less toxicity than silver nitrate. Erythromycin was found ineffective in this same study.268 Absorption of aminoglycosides after ocular use appears to be insufficient to cause toxic systemic effects.269 FLUOROQUINILONES Since their introduction in 1990, the ocular fluoroquinilone antibiotics have demonstrated a broad spectrum of activity with low toxicity. They have found wide acceptance for the treatment of superficial ocular infections in infants and children. These drugs inhibit DNA synthesis by binding to two specific enzymes: DNAsyrase and topoisomerase IV, both of which are required for DNA replication. Third-generation fluoroquinilone antibiotics—ofloxacin, ciprofloxacin, levofloxacin, and norfloxacin—have proved effective against gram-negative organisms, but gram-positive coverage has been variable and resistance to some organisms is emerging. Fourth-generation fluoroquinilones currently in development—gatifloxacin and moxifloxacin—may be more effective against Staphylococcus aureus and other organisms currently resistant to the third-generation drugs. The safety profile of this class of antibiotics is excellent. White crystalline precipitates are seen in the cornea epithelium with intense treatment for corneal ulcers. These precipitates cause no harm. A single case of idiosyncratic acute psychosis after the use of ciprofloxacin for a severe conjunctivitis in a 27-year-old woman has been reported.270 ANTI-VIRAL AGENTS Idoxuridine (Herplex), an antiviral drug used for treatment of herpetic eye infections, frequently causes contact dermatoconjunctivitis and chronic follicular conjunctivitis.271 Use of idoxuridine has been replaced by newer, more effective agents, but contact dermatitis has also been reported in patients using trifluridine (Viroptic).271 Punctal stenosis and occlusion, conjunctival scarring, and delayed wound healing can occur from both agents. Systemic reactions are unlikely, as there were no untoward effects from the ingestion of an entire 7.5-cc bottle.71 |
ANTI-ALLERGY DRUGS |
DECONGESTANTS These drugs have a good safety record but can be irritating, causing stinging, burning, and tearing. They can initiate rebound conjunctival hyperemia, follicular or papillary conjunctivitis, and allergic dermatoconjunctivitis.272,273 Systemic side effects are infrequent because of the low concentrations required for ocular decongestion. These drugs, however, are adrenergic agonists, and caution is advised concerning use in infants and children, as they can cause a marked decrease in body temperature.9 Systemic absorption of imidazole decongestants, such as naphazoline, through accidental or intentional poisoning, can cause CNS and respiratory depression, bradycardia, and hypotension.274 PROPRIETARY ANTIHISTAMINES Limited data is available for children, but the effectiveness and adverse reaction profile for this group of allergy medications is similar to that seen in adults. Levocabastine (Livostin) has been found equal or superior to cromoglycate in treating seasonal allergic conjunctivitis275,276 and vernal keratoconjunctivitis.277,278 It is well tolerated with minimal nasal and ocular adverse irritant reactions. Emadastine (Emadine), another H1-antagonist, has been studied in pediatric patients and was superior to levocabastine in relieving the itching of seasonal allergic conjunctivitis.279,280 MAST CELL STABILIZERS AND MAST CELL STABILIZER/ANTIHISTAMINE COMBINATIONS Cromoglycate (Cromolyn) was the first mast-cell stabilizing drug and is useful in treating vernal and atopic keratoconjunctivitis when used alone or in combination with other drugs. It causes transient stinging, burning, hyperemia, and watering on ocular instillation.281 Contact dermatitis is a well-known side effect.282 Absorption into the eye and systemic circulation is poor.283 Lodoxamide (Alomide) is a mast-cell stabilizer that has been well studied in children. It is a safe and effective treatment for allergic conjunctivitis276,284 and vernal keratoconjunctivitis.283,285,286 Its clinical effectiveness is superior to that of levocabastine and cromoglycolate. All of the mast-cell stabilizer/antihistamine drugs are useful in treating seasonal allergic conjunctivitis and vernal keratoconjunctivitis. Adverse effects are few, with 15% of patients reporting headache and rhinitis, and less than 5% burning and stinging. Azelastine (Optivar) eye drops are effective and well tolerated for the treatment of seasonal allergic conjunctivitis in young children.287,288 Nedocromil (Alocril) was studied in children with vernal keratoconjunctivitis and demonstrated excellent efficacy exceeding that of cromoglycate.285 Olopatadine (Patanol) is the most effective conjunctival mast-cell inhibitor for topical use in the conjunctiva and offers the advantage of immediate effect and relative comfort upon instillation. |
NON-STEROIDAL ANTI-INFLAMMATORY DRUGS |
These ocular drugs may relieve the signs and symptoms of seasonal allergic
conjunctivitis and may help some cases of vernal and atopic keratoconjunctivitis, but
response and effectiveness is variable. Ketorolac (Acular) has
been the most useful in adults. Corneal complications, including
superficial punctuate keratitis, erosions, sterile ulcers, and
corneal melts and perforations, have been associated with all
of the ocular non-steroidal anti-inflammatory drugs, primarily
generic diclofenac, but also proprietary diclofenac (Voltaren), and
ketorolac (Acular).289,290 Predisposing risk factors are concurrent use of topical steroids and superficial
punctuate keratitis in the postoperative period.289 Allergies and hypersensitivity reactions are reported with all of these
drugs. Transient burning, stinging, and hyperemia are side effects.291 Non-steroidal anti-inflammatory drugs should be used with caution in the pediatric age group. Closely monitor patients and limit use to short-term treatment. In general, these drugs should be avoided in treating ocular allergy because there are other, safer drugs such as the proprietary antihistamines and mast-cell stabilizers. If an anti-inflammatory effect is desired, a better alternative is a site-active steroid. CORTICOSTEROIDS Because of the side effects of potent steroids, they should be used only if an allergic condition is refractive to other treatment. If steroids are required, therapy should be initiated with milder or site-active steroids that have a good safety profile, such as fluoromethalone, rimexalone, or loteprednol. When the initial insult is past, a mast-cell stabilizer or mast-cell stabilizer/antihistamine combination may be substituted. There is very little pediatric data on steroidal treatment of allergic eye disease. Several studies on lotepradnol (Alrex 0.2%, Lotemax, 0.5%) have found that it produces a rapid clinical response with a low incidence of side effects (including a low and transient elevation of intraocular pressure in some patients) in giant papillary conjunctivitis,231–233 and seasonal allergic conjunctivitis.292–294 Lotepradnol is a the only true soft steroid in the ophthalmic world. The drug is metabolized soon after making its way into the eye and has less likelihood of causing cataracts and glaucoma. The 0.2% solution is the weaker formulation of the two available and hence is the one approved for ocular allergies. CYCLOPSORINE A Cyclosporine A is a potent immunosuppressive agent used to treat severe, resistant ligneous conjunctivitis and atopic and vernal keratoconjunctivitis in children295–301 It is useful as a steroid-sparing drug and is relatively safe, although not always well tolerated due to side effects, including stinging, lid rash, and superficial punctate keratitis. A commercial topical cyclosporine A (Restasis) has just received FDA approval. No measurable drug blood levels or renal toxicity have been found in long-term treatment of adult patients with ocular cyclosporine A.297 MITOMYCIN-C Mitomycin-C can be considered for patients with severe vernal keratoconjunctivitis refractive to conventional treatment. Akpek and associates302 studied 26 patients, including older children, with severe vernal keratoconjunctivitis. Used in low-dose, short-term therapy, mitomycin-C was effective with no adverse effects of treatment. Long-term studies are lacking. |
ANTIGLAUCOMA DRUGS |
There are no commercially available antiglaucoma medications for use in
pediatric patients. Efficacy and safety have not been established in
children. Ophthalmologists frequently use antiglaucoma eye drops as “off-label” treatment to avoid surgery. The carbonic
anhydrase inhibitors and the prostaglandin analogs have shown an excellent
safety and efficacy record in limited studies in the pediatric age
group. The other available antiglaucoma drugs may have a select role
in severe pediatric glaucoma, but their use requires expedient recognition
of potentially serious adverse side effects in the pediatric age
group. BETA-ADRENERGIC ANTAGONISTS Timolol maleate was introduced to clinical usage in 1978 as the first beta-blocker for the treatment of glaucoma. A wide range of adverse reactions led to the development of second-generation beta-blockers that had similar adverse effects, but in varying frequency and severity. In general, these anti-hypertensive drugs have been well tolerated by older children, but the reduced blood volume and immature metabolic systems in young children and infants pose a significant risk of adverse systemic side effects. Timolol Timolol maleate (Timoptic), timolol maleate gel (Timoptic-XE), and timolol hemihydrate (Betimol) are non-cardioselective (beta 1 and beta 2) beta-blockers that have been a useful adjunct to the treatment of severe pediatric glaucomas. Timolol is rapidly absorbed after ocular application in adults303 and potentially can reach blood levels high enough to produce toxic effects known to follow the systemic administration of beta-adrenergic blocking agents. Blood levels ranging from 3.5 ng/mL (5-year-old child) to 34 ng/mL (3-week-old infant) have been measured in a group of small children 2 to 6 hours after instillation of timolol eyedrops.19 This exceeds the equivalent beta-blocker levels achieved with oral or parenteral treatment of systemic pediatric cardiovascular disorders.304 In addition, the beta-blockers have a longer half-life in children—two to six times that in adults.305 The literature suggests that neonates and infants are most at risk for systemic bronchopulmonary toxic effects. Apnea has been possibly associated with timolol in infants in several reports.19,306–308 Bronchospasm with precipitation of asthmatic attacks in predisposed children is well known.307–309 Other adverse effects in childhood glaucoma patients include arrthymias and bradycardia, depression and other mood alterations, and light-headedness.310–312 The clinician is urged to be aware of potential drug interactions of ophthalmic beta-adrenergic antangonists with systemic medications.313 Local adverse side effects of the beta-blockers include stinging, burning, dryness, nasolacrimal duct obstruction, conjunctival hyperemia, superficial punctuate keratitis, corneal anesthesia (adults only), allergic blepharoconjunctivitis, and anterior uveitis (rare).305,314 In general, timolol seems to be well tolerated in older children, but caution is advised particularly in infants. Other antiglaucoma drugs are recommended in infants and those children with a history of asthma, allergic rhinitis, lung disease (including cystic fibrosis), cardiac disease, and labile diabetes mellitus. A complete medical consultation including electrocardiography should precede initiation of treatment. In healthy children, the lowest concentration and dosage possible of timolol should be used. The gel-forming sustained-release form of the drug (Timoptic-XE) used once a day is preferred. Passo and associates have recommended that all pediatric patients be observed for 2 hours in the office after the initial drops are instilled before the eye drop is prescribed for home use.19 The anesthesiologist should be alerted if general anesthesia is required for a child taking timolol eye drops because the risk of cardiovascular failure and sustained hypotension is increased. Beta-adrenergic blockers are generally safe during pregnancy and without neonatal side effects.315,316 It has been recommended, however, that timolol be avoided during the first trimester and be discontinued a few days before delivery to reduce possible complications from beta-blockade in the neonate.185 Since breast milk timolol levels (5.6 ng/ml) have been measured to be six times higher than plasma levels (0.93 ng/mL) in nursing mothers on timolol treatment, infants born to nursing mothers using timolol should be observed for signs of beta-blockade.317 Levobunolol Levobunolol (Betagan) is another non-cardioselective (beta 1 and beta 2) beta-adrenergic antagonist that has demonstrated fewer cardiovascular effects than timolol in adults.318 Therefore, it may be a better choice than timolol for children. Levobunolol has been safely used in pediatric patients after pupilloplasty with neodymium:YAG laser.319 Caution is advised, because the larger drop size (50 μL) of levobunolol compared with that of timolol (35 μL) means that more drug is delivered with each instillation.320 Once-daily use is suggested in children. Metipranolol No side effects have been reported for children, but the observed serious side effects in adults, including reported loss of pressure control (tachyphylaxis) make metipranolol (Optipranolol) an unsuitable choice for treating pediatric glaucomas.8 Like timolol, metipranolol has been used to treat progressive myopia in children with unproven and controversial results.321,322 Carteolol Carteolol (Ocupress) is a non-cardioselective (beta 1 and beta 2) beta-adrenergic antagonist with intrinsic sympathomimetic activity (ISA). Ocular instillation produces less discomfort than with the other beta-blockers.8 Side effects are similar to those of timolol, but fewer systemic adverse side effects have generally been encountered.323 Betoxolol Betoxolol (Betoptic) is a cardioselective beta 1 adrenoreceptor antagonist with weak beta-2 blocking capability. Because of this, betoxolol has fewer bronchopulmonary and cardiac effects and might be a better alternative for treating pediatric glaucomas.324 However, there is no data to substantiate this. Significant stinging upon ocular instillation in 30% to 40% of patients has been observed. As with all members of this class of drugs, contact dermatitis can occur with some cross-sensitivity and reactivity among the drugs.325 CARBONIC ANHYDRASE INHIBITORS Dorzolamide (Trusopt) is useful in pediatric glaucoma, although its long-term safety is not established. One study of six children with glaucoma who were previously treated with oral acetazolamide were treated effectively with dorzolamide with no adverse reactions.326 Local side effects include stinging, burning, blurred vision, superficial punctuate keratopathy, headache, and bitter taste.327 Corneal edema has been reported in patients with borderline endothelial function.328 Systemic side effects are minimal compared with oral use of the carbonic anhydrase inhibitors. Brinzolamide (Azopt) and the combination drug of dorzolamide and timolol (Cosopt) have similar adverse side effects as dorzolamide.329 ALPHA-2 SELECTIVE ANTAGONISTS Apraclonidine After a few doses of apraclonidine (1 % Iopidine solution) used to suppress acute intraocular pressure spikes after laser treatments, side effects including hypotension, bradycardia, arrhythmia, and somnolence have been observed and reported to the National Registry of Drug Induced Ocular Side Effects, but have not been proven.10 Chronic use of 0.5% Iopidine solution seems to have minimal effects on respiratory and cardiovascular systems, and these effects are rarely a cause for discontinuing the drug in adults.30 With prolonged use of apraclonidine, there is a high incidence of allergic reactions of either a direct toxic or hypersensitivity nature (20%–50%).331 The high incidence of local side effects and the frequently observed tachyphylaxis seen in one half of patients after 3 months use make this drug undesirable in the chronic treatment of pediatric glaucoma. Brimonidine After its introduction in 1996, brimonidine 0.2% solution (Alphagan) was found to be effective as monotherapy and as adjunctive treatment in adult open-angle glaucoma. Recently the preservative benzalkonium chloride was replaced by Purite (Alphagan P). This led to an increase in pH, which improved absorption, allowing use of a lower concentration of brimonidine (0.15% versus 0.2%) and improving its safety profile.32,333 Brimonidine differs from clonidine by a chemical alteration that decreases its ability to cross the blood-brain barrier. In young children, however, the immaturity of this barrier may allow more access to the CNS. There have been numerous case reports of single pill ingestion of clonidine causing bradycardia, hypotension, apnea, and coma in young children.334 Reports of bradycardia, hypotension, hypothermia, lethargy, and apnea in infants after brimonidine eye drop instillation335,336 and CNS depression in children337 make this drug unsuitable for treating pediatric glaucoma. PROSTAGLANDIN ANALOGS The prostaglandin analogs are the newest group of antiglaucoma medications, and use to-date has been thoroughly reviewed.338,339 Latanoprost (Xalatan), unoprostone (Rescula), bimatoprost (Lumigan), and travopost (Travatan) show an excellent safety profile. Pressure-lowering efficacy in adult open-angle glaucoma has been superior to that of the beta-blockers. However, only 20% of pediatric patients show a significant reduction in intraocular pressure in studies on children. Local side effects have been notable but have not led to cessation of treatment in most cases. Conjunctival hyperemia is usually tolerable, although a study of patients with Sturge-Weber syndrome and glaucoma found a 23% incidence of significant conjunctival hyperemia, causing one patient to stop therapy.340 A permanent darkening of iris color, especially in patients with nonhomogeneous eye color, has been observed in 5% to 20% of patients after several months of therapy. There is a report in the literature of this increase in iris pigment in a 1-year-old patient after 5 months of treatment341 This color change does not seem to have any adverse ocular consequences. Other local side effects include a reversible increase in eyelid skin pigment,342 hypertrichosis, superficial punctuate keratopathy, corneal erosions, pseudodendrites, initiation or reactivation of herpes simplex keratitis,343 and contact dermatitis.344 All of the manufacturer's product information for the prostaglandin analogs suggest that they be used with caution in patients with active uveitis, in aphakic patients, in pseudophakic patients with a torn posterior capsule, and in patients with known risk factors for macular edema. Cystoid macular edema has been reported during treatment in these susceptible patients. Studies on latanoprost indicate some systemic absorption after topical instillation, but the drug does not cross the blood-brain barrier,345 and its metabolites are rapidly eliminated, with a systemic half-life of 17 minutes.346 This suggests a margin of safety in children. No serious systemic side effects were reported with latanoprost therapy of pediatric glaucoma in three studies.340,347,348 There is one report in the literature of a child with aniridia and glaucoma who developed heavy sweat secretion 1 to 2 hours after instillation of latanoprost.349 Systemic side effects in adults have infrequently included fatigue, dizziness, asthma, angina, nausea and vomiting, nasal congestion, and headache.339 |
TOPICAL ANESTHETICS |
Local anesthetics instilled in the eye in small amounts do not usually
cause toxicity. Significant side effects usually have been secondary to
use of cocaine, anesthetics in high doses, long-term anesthesia
abuse, or nerve-block anesthesia. However, topical anesthetics
are rapidly absorbed, and blood levels rise almost as fast as after
intravenous administration.350 Adverse systemic reactions can occur with more serious consequences in
young children.8 Seizures351,352 and bradycardia352 have been described after topical ocular anesthetic use. The major local side effect of topical ocular anesthesia is corneal epithelial toxicity, which is most pronounced with cocaine. Significant epithelial desquamation is unusual in children and more characteristic of elderly patients. Local allergic reactions are rare and are mainly observed with the ester group of anesthetics used for eye drops. Since there is no cross-sensitivity between classes of local anesthetics, another anesthetic can be substituted.354 Unfortunately, no topical anesthetic with an amide linkage ( i.e., benoxinate) is available in the United State except in combination with fluorescein sodium for applanation tonometry. Systemic hypersensitivity reactions after ocular anesthetic use are extremely rare and no life-threatening episodes have been reported in the literature.85 Clinicians should be alerted , however, to an increased susceptibility in infants and children with drug allergies or asthma.85 Signs of a systemic reaction include angioneurotic edema, urticaria, bronchospasm, hypotension, and joint pain.85 COCAINE Cocaine has the greatest potential for systemic toxicity in children. The 4% solution is used rarely for topical anesthesia, but in most cases, other safer, synthetic local anesthetics are preferable. The 10% and higher solutions should be avoided completely. Systemic toxicity can develop from as little as 20 mg (10 drops of 4% solution).354 It is recommended that a dosage of 3mg/kg body weight not be exceeded. Potential systemic toxic side effects include hypertension, tachycardia, arrhythmia, headache, excitement, dilated pupils, nausea and vomiting, abdominal pain, delirium, and seizures.85 Propranolol can reverse the cardiovascular toxicity.355 PROPARACAINE HYDROCHLORIDE Proparacaine 0.5% solution is a widely used topical anesthetic agent with few side effects, possibly because of its poor penetration of the conjunctiva and cornea.356 However, there is one report of seizures following the use of proparacaine eye drops.352 Proparacaine is popular for pediatric use because it has minimum sting after ocular administration. As a result, it can be used prior to the instillation of other more uncomfortable eye drops (eg., cycloplegics) to aid in an atraumatic examination.181 TETRACAINE Tetracaine 0.5% solution is available in sterile minums for use in the operating room. It produces a degree of anesthesia similar to proparacaine and has a similar speed of onset and duration of effect.85 It penetrates the conjunctiva and cornea better than proparacaine,356 and overdosage with toxicity can result if more than 1.5 mg/kg of body weight is administered.357 Because of stinging and burning upon ocular instillation, tetracaine is less desirable than proparacaine as a topical anesthetic for alert children. Local allergic reactions and corneal epithelial toxicity are similar to those for proparacaine. |
PRESERVATIVES |
The most common preservatives in ophthalmic preparations are benzalkonium
chloride (BAC), chlorobutanol, ethylenediaminetetraacetic
acid (EDTA), sodium perborate, and stabilized oxychloro complex (SOC). Long-term use of preserved eye drops can
have significant ocular cytotoxic effects, especially with multiple prescribed
drugs358 and use of more than twelve drops per day.71 Of the various preservatives, BAC has been implicated most often in local toxic and hypersensitivity reactions. Many eye drops contain BAC, and some of the toxic and allergic reactions attributable to the main therapeutic agent are probably secondary to the BAC preservative. Cytotoxicity has been demonstrated for BAC in cell culture as well as in animal and human studies. Chronic use of BAC-preserved eye drops can cause an unstable tear film and reduced tear secretion,359–361 conjunctival metaplasia and inflammation,359,360 corneal epithelial and endothelial toxicity,362 inhibition of corneal healing,362 trabecular inflammation,360 and allergic reactions.362,363 The use of thimerasol as a preservative in medicated eye drops and contact lens solutions has been largely discontinued owing to the high rate of allergic hypersensitivity reactions. Blepharoconjunctivitis with corneal infiltrates occurred in up to 25% of contact lens wearers using a thimerasol-preserved contact lens storage and rinsing solution. For pediatric use, preservative-free eye drops are preferred because they create less burning upon instillation, have reduced foreign body sensation and dry eye sensation, and produce less tearing than preserved eye drops.364 Unfortunately, except for non-preserved artificial tears, preservative-free eye drops are unavailable and impractical because of the need for antimicrobial protection in multi-dose topical solutions. |