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Consider age, weight when using diagnostic, therapeutic agents in children
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When infants and children are examined in the optometric office, a number of considerations must be made before using diagnostic drugs and prescribing pharmaceutical agents. Because the blood volume of children is relatively small due to their low body weight, medications have a greater potential to cause systemic toxicity than when used in adults. In addition, the pathogens that commonly cause pediatric ocular infection differ from those most frequently responsible for adult disease. In this article, I’ll review these issues and offer suggestions on prescribing for children in a safe and effective manner.
| Guidelines for Prescribing Pharmaceutical Agents to Children | |
|---|---|
| Age | Dosage |
| Younger than 2 years | half the adult dose |
| 2 to 3 years | two-thirds the adult dose |
| 3 to 12 years | 90% to 95% of the regular adult dose (no titration for practical purposes) |
| 12 years and older | Full adult dose |
After drops are instilled in the eye, they pass from the lacrimal system into the nasopharyngeal mucosa and are subsequently absorbed systemically. A child’s low body weight and related smaller blood volume result in increased plasma levels of drugs compared to adults. The higher plasma drug levels place children at increased risk for serious systemic side effects.
To minimize the likelihood of adverse effects, the guidelines in the accompanying chart have been set forth for prescribing for children (Walson PD, Getschman S, Koren G. Principles of drug prescribing in infants and children. A practical guide. Drugs. 1993;462:281-288.).
Nasolacrimal occlusion should be attempted, although the technique is often difficult to perform in uncooperative children. Eyelid closure for 1 minute after drop instillation is also an effective means of decreasing systemic absorption. In addition, although the risk of serious systemic side effects is remote when diagnostic agents are used as recommended, consideration should be made for routinely dilating children with strictly 0.5% tropicamide or a combination agent, such as Cyclomydril (cyclopentolate 0.2%/phenylephrine 1%, Alcon) or Paremyd (hydroxyamphetamine 1%/tropicamide 0.25%). Paremyd will be available from Akorn (Buffalo Grove, Ill.) upon Food and Drug Administration approval.
Common conditions in children
Otitis media and pharyngitis are frequently implicated in pathogen migration to the eye and its surrounding structures and may result in pediatric eye diseases, such as conjunctivitis, keratitis, preseptal cellulitis and dacryocystitis. The most common pathogens causing eye diseases in children are (in descending order) Hemophilus influenzae (most common cause of acute bacterial conjunctivitis in children younger than 6 years), adenovirus, Streptococcus pneumoniae and others, including Staphylococcus aureus, Staphylococcus epidermidis, Corynebacterium and Moraxella.
Initial evaluation of the pediatric patient should include questioning and observation regarding extraocular findings, such as fever, headache, malaise, sore throat, cough, earache, stiff neck and nasal discharge. Eye cultures should be attempted in cases of suspected bacterial disease. Children should be weighed prior to prescribing systemic medication (to ultimately determine proper dosage) for conditions such as Hemophilus-confirmed conjunctivitis and preseptal cellulitis. Pediatric or specialty referral is indicated when co-existing conditions, such as otitis media, pharyngitis, epiglottitis, pneumonia, sinusitis or meningitis, are suspected.
Common pediatric medications
Some of the ophthalmic and systemic medications most commonly used to treat conditions of the eye and adjacent structures in children include:
Polytrim ophthalmic solution (polymyxin B sulfate/trimethoprim, Allergan) — Indicated for use in children 2 months of age and older, this antibiotic combines trimethoprim (folic acid inhibitor) with polymyxin B (increases permeability of the bacterial cell membrane) to provide a broad spectrum of activity against the most common causes of acute bacterial conjunctivitis in children, such as H. influenzae, Staphylococcus and Streptococcus.
Ocuflox ophthalmic solution (ofloxacin 0.3%, Allergan) and Ciloxan ophthalmic solution and ointment (ciprofloxacin 0.3%, Alcon) — These fluoroquinolones inhibit DNA gyrase, a bacterial enzyme necessary for the synthesis and supercoiling of bacterial DNA to provide broad-spectrum bactericidal activity. Ocuflox and Ciloxan solutions are indicated for use in children 1 year of age and older, while Ciloxan ointment is approved for those 2 years of age.
Erythromycin 0.5% ophthalmic ointment — This macrolide antibiotic inhibits protein synthesis of bacteria by binding to their 50s ribosomal unit. Approved for use in all age groups, its primary uses are prophylaxis of ophthalmia neonatorum and in postsensitivity studies demonstrating its effectiveness in individual cases. Because of its limited spectrum of antimicrobial activity, it is not indicated for use against H. influenzae nor ocular disease of unknown cause.
Ceclor (cefaclor, Eli Lilly) — A second-generation cephalosporin, cefaclor is a broad-spectrum agent that inhibits bacterial cell wall development. It may be used in infants and children at least 1 month of age and is the drug of choice for Hemophilus ocular and respiratory tract infections. Dosages are typically 20 to 40 mg/kg/day, and fewer than 16% of penicillin-sensitive patients display similar sensitivity to Ceclor.
Biaxin (clarithromycin, Abbott Laboratories) — This semi-synthetic macrolide antibiotic of the erythromycin family is considered to be the second-best medication for treating H. influenzae infection. It is also effective against both Staphylococcus and Streptococcus. Available in both 125 mg/5 mL and 250 mg/5 mL liquid dose form, it is prescribed at a dosage of 7.5 mg/kg every 12 hours (total of 15 mg/kg/day) up to a weight of 75 lb (33 kg).
Pediazole (erythromycin ethylsuccinate/sulfisoxazole, Ross Laboratories) — Approved for children 2 months of age, this oral suspension combines erythromycin 200 mg/5 cc and sulfisoxazole 600 mg/5 cc. Effective against Hemophilus, it is prescribed according to the child’s weight in four daily divided doses totaling 50 mg/kg/day of erythromycin and 150 mg/kg/day of sulfisoxazole.
Zithromax (azithromycin, Pfizer) — Another member of the erythromycin family, this drug is effective against the most common ocular pathogens (including Hemophilus), and the oral suspension is approved for children 6 months of age. The oral suspension comes in 100 and 200 mg/5 cc liquid dosage form and is prescribed as a single dose of 10 mg/kg (not to exceed 500 mg/day) on the first day, followed by daily single doses of 5 mg/kg (not to exceed 250 mg/day) for days 2 through 5. Zithromax is also the preferred choice for chlamydial infection in children.
Augmentin (amoxicillin/clavulanate, SmithKline Beecham) — This semisynthetic penicillin and lactamase inhibitor combination provides broad antimicrobial coverage and is the drug of choice for treating Streptococcus and Staphylococcus infection. Augmentin is available in oral suspension, chewable tablet and tablet forms. Suspensions (dosages adjusted according to weight for children weighing less than 88 lb) are approved for all age groups, while chewable tablets are only approved for children weighing 40 kg (88 lb) or more.
For Your Information:
- Michael J. Trad, OD, may be contacted at Medical Arts Center, 1620 Sauk Road, Dixon, IL 61021; (815) 288-7711; fax: (815) 288-5077. Dr. Trad has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.