Polymyxin B Ear Drop Dosing for 49-Pound Child
For a 49-pound (22 kg) child with otitis externa, use 3 drops of polymyxin B-neomycin-hydrocortisone otic suspension four times daily for 7-10 days. 1
Dosing Specifics
The FDA-approved formulation contains polymyxin B sulfate 10,000 units per mL combined with neomycin sulfate and hydrocortisone 1. The standard pediatric dose is:
- 3 drops in the affected ear(s) four times daily
- Duration: 7-10 days maximum 1
Weight-based calculations are not used for otic (ear) preparations—the dose is the same regardless of whether the child weighs 20 or 50 pounds.
Administration Instructions
- Shake the suspension well before each use 1
- Avoid contaminating the dropper tip 1
- The patient should lie with the affected ear upward and remain in this position for several minutes after instillation to allow penetration
Critical Safety Considerations
Treatment should not exceed 10 days 1. Prolonged use increases risk of:
- Fungal superinfection from antibiotic overuse
- Ototoxicity from neomycin (though topical otic use carries lower risk than systemic administration)
Discontinue immediately if sensitization or irritation occurs and contact the prescribing physician 1.
Important Caveats
The polymyxin B dosing information in the provided evidence primarily addresses intravenous formulations for systemic multidrug-resistant infections 2, 3, 4, 2, 3. These IV dosing guidelines (1.5-3 mg/kg/day for polymyxin B or complex colistin dosing) are completely irrelevant to otic preparations and should never be applied to ear drops.
For otitis externa specifically, clinical trial data demonstrates that once-daily ofloxacin otic solution provides equivalent efficacy to four-times-daily polymyxin B-neomycin-hydrocortisone with potentially better safety profile (no ototoxicity risk from neomycin) 5. However, when polymyxin B otic suspension is selected, the standard four-times-daily regimen remains appropriate.