What are the concentrations of Cortisporin (neomycin, polymyxin B, hydrocortisone) and the recommended number of drops and dosing frequency for an adult with otitis externa?

Cortisporin Dosing for Acute Otitis Externa

For adults with acute otitis externa, use Cortisporin (neomycin/polymyxin B/hydrocortisone) otic suspension: 5 drops into the affected ear 3-4 times daily for 7-10 days (maximum 10 days). 1

Specific Concentrations

The Cortisporin otic suspension contains:

• Neomycin sulfate 0.35%
• Polymyxin B 10,000 IU/mL
• Hydrocortisone 1.0%

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Dosing by Age

Adults

• 5 drops into affected ear
• 3-4 times daily
• Duration: 7-10 days (do not exceed 10 days)

Pediatric Patients

• 4 drops into affected ear (smaller ear canal capacity)
• 3-4 times daily
• Duration: 7-10 days (do not exceed 10 days)

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Administration Technique

The proper technique is critical for drug delivery:

• Patient lies with affected ear upward
• Instill the prescribed number of drops to fill the ear canal
• Maintain this position for 5 minutes to allow penetration
• Gentle to-and-fro movement of the ear or pressing the tragus in/out helps drops penetrate
• Wipe off excess after rising

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Alternative Wick Method

If drops cannot easily enter the canal due to severe edema:

• Insert cotton wick into canal
• Saturate wick with suspension
• Keep moist by adding drops every 4 hours
• Replace wick at least once every 24 hours

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Treatment Duration and Expectations

Patients should use drops for at least 7 days, even if symptoms improve sooner, to prevent relapse. Most patients experience relief within 48-72 hours and have minimal symptoms by day 7. If symptoms persist beyond 7 days, continue drops and notify physician, with maximum total treatment of 14 days. 3

Important Clinical Considerations

Contraindications and Cautions

• Do not use if tympanic membrane is perforated - neomycin is potentially ototoxic when it enters the middle ear 2
• Neomycin causes contact dermatitis in 13-30% of patients with chronic otitis externa 2
• If patient tastes the drops, suspect tympanic membrane perforation 3

Why This Formulation Works

The combination provides:

• Broad antimicrobial coverage against Pseudomonas aeruginosa (20-60% of cases) and Staphylococcus aureus (10-70% of cases) 2
• Hydrocortisone reduces inflammation, edema, and pain
• Topical delivery achieves concentrations 100-1000 times higher than systemic antibiotics (3000 µg/mL with 0.3% solution) 2

Common Pitfall

Do not prescribe oral antibiotics unless infection extends beyond the ear canal - they are ineffective for uncomplicated acute otitis externa and promote resistance. 2 Topical therapy alone is superior and sufficient. 4

Pain Management

Prescribe analgesics (oral NSAIDs or acetaminophen) for the first 2-3 days while drops take effect - pain relief is especially important early in treatment. 2, 3