For a patient with otitis externa, what dose of Cortisporin (neomycin + polymyxin B + hydrocortisone) otic suspension should be given?

Cortisporin Dosing for Otitis Externa

For otitis externa with an intact tympanic membrane, prescribe Cortisporin (neomycin/polymyxin B/hydrocortisone) otic suspension: 4 drops in the affected ear 3-4 times daily for adults, and 3 drops 3-4 times daily for children, for a minimum of 7 days. 1

Specific Dosing Instructions

Adult Dosing

• 5 drops into the affected ear 3-4 times daily when using the calibrated dropper 1
• Alternative formulations may specify 4 drops 2

Pediatric Dosing

• 4 drops into the affected ear 3-4 times daily (using calibrated dropper) 1
• Some formulations suggest 3 drops due to smaller ear canal capacity 2

Duration of Therapy

• Minimum 7 days, even if symptoms improve earlier 3, 4
• Maximum 10 days total treatment 1
• If symptoms persist beyond 7 days, continue drops until symptoms resolve for a maximum of 7 additional days (14 days total) 3, 4

Critical Administration Technique

The patient must follow these steps to ensure drug delivery 3, 4:

• Lie with affected ear upward
• Instill the prescribed number of drops to fill the ear canal
• Remain in this position for 5 minutes (use a timer) 2, 1
• Gently move the ear or press the tragus in/out to facilitate penetration 3, 4
• Have someone else administer drops if possible 3, 4

When to Use a Wick

Place a wick if the ear canal is edematous and preventing drop entry or if the tympanic membrane cannot be visualized 3. The wick should be:

• Made of compressed cellulose (preferred) or ribbon gauze 3
• Saturated with the suspension every 4 hours 2, 1
• Replaced at least once every 24 hours 2, 1
• Removed once edema subsides (may occur within 24 hours to a few days) 3

Critical Caveat: Tympanic Membrane Status

Do NOT use Cortisporin if there is a known or suspected tympanic membrane perforation or tympanostomy tube 3. Neomycin and polymyxin B are ototoxic agents that can cause severe hearing loss with prolonged or repetitive administration through a non-intact tympanic membrane 3. In these cases, prescribe a non-ototoxic fluoroquinolone preparation instead.

Expected Clinical Response

• Most patients improve within 48-72 hours 3, 4
• Minimal or no symptoms by 7 days 3, 4
• If no improvement by 48-72 hours, reassess for drug delivery issues, compliance, or alternative diagnosis 3

Additional Management Points

Systemic antibiotics are NOT indicated for uncomplicated otitis externa 3. Topical therapy alone is highly effective, delivering antibiotic concentrations 100-1000 times higher than systemic therapy can achieve 3.

Pain management is essential in the first 48-72 hours while drops take effect 3, 4. Prescribe appropriate oral analgesics; do NOT use anesthetic ear drops as they can mask treatment failure 3, 4.

Water precautions: Instruct patients to keep the ear dry, use earplugs with petroleum jelly when showering, and avoid swimming during treatment 3, 4.

Common Pitfall: Neomycin Allergy

Neomycin causes contact sensitivity in 13-30% of patients with chronic otitis externa 3. If the patient develops worsening erythema, pruritus, or persistent otorrhea despite treatment, suspect allergic contact dermatitis and switch to a non-neomycin containing preparation (fluoroquinolone) 3.