What is the appropriate dosage and administration of neomycin‑polymyxin B (plus hydrocortisone) ear drops for a 9‑month‑old infant with bilateral ear infection and intact tympanic membranes?

Neomycin-Polymyxin-Hydrocortisone Ear Drops Dosage for 9-Month-Old Infant with Bilateral Ear Infection

Critical First Question: Does This Infant Have Tympanostomy Tubes?

If this is acute otitis media (middle ear infection) with tympanostomy tubes and tube otorrhea, use topical antibiotic ear drops as first-line therapy. 1 If this is acute otitis media WITHOUT tubes (intact tympanic membranes), do NOT use ear drops—systemic antibiotics are required instead, as topical drops cannot penetrate an intact tympanic membrane to reach the middle ear space. 2

The question states "bilateral ear infection" but does not specify whether tubes are present or if the tympanic membranes are intact. This distinction is absolutely critical because:

• Acute otitis externa (outer ear canal infection) is treated with topical ear drops 2
• Acute otitis media with tubes (middle ear infection draining through tubes) is treated with topical ear drops 1
• Acute otitis media without tubes (middle ear infection with intact membranes) requires oral antibiotics, NOT ear drops 2

Dosing for Neomycin-Polymyxin B-Hydrocortisone (If Appropriate)

For a 9-month-old infant, instill 3 drops into each affected ear 3-4 times daily for up to 10 consecutive days maximum. 3

Administration Technique

• Position the infant lying down with the affected ear facing upward 3
• Instill 3 drops (not 4 drops, which is the adult dose—infants require fewer drops due to smaller ear canal capacity) 3
• Keep the infant in this position for 5 minutes to allow penetration of drops into the ear canal 3
• Gently pump the tragus (the cartilage flap in front of the ear) several times after instillation to facilitate drug delivery 2
• Repeat for the opposite ear 3
• Clean any visible discharge from the ear canal opening before administering drops by gently blotting with sterile cotton or using an infant nasal aspirator 1

Important Safety Considerations and Caveats

Ototoxicity Risk with Non-Intact Tympanic Membranes

Neomycin-polymyxin B-hydrocortisone should NEVER be used if there is any possibility of tympanic membrane perforation or if membrane integrity cannot be confirmed. 2 These aminoglycoside-containing drops are potentially ototoxic when they contact the middle ear space 2. However, when used appropriately with intact membranes or through patent tympanostomy tubes for short durations (≤10 days), decades of clinical experience and DPOAE testing studies show no significant ototoxicity risk 4.

Contact Dermatitis Risk

• Neomycin causes contact dermatitis in 5-15% of patients with prolonged use 5
• Hydrocortisone can cause contact sensitivity in 13-30% of patients 5
• Limit therapy to a single 10-day course maximum to prevent fungal external otitis and allergic reactions 1, 3
• If symptoms worsen despite treatment, consider neomycin allergy and switch to a fluoroquinolone preparation 5

When This Preparation Is NOT Appropriate

Do not use neomycin-polymyxin B-hydrocortisone if:

• Tympanic membrane integrity is uncertain or known to be perforated (without tubes)—use only non-ototoxic fluoroquinolones like ciprofloxacin-dexamethasone instead 5
• This is acute otitis media WITHOUT tympanostomy tubes—topical drops cannot penetrate intact membranes to reach the middle ear infection 2
• There is extension of infection beyond the ear canal (cellulitis of pinna, adjacent skin, or systemic signs)—systemic antibiotics are required 2, 1
• The infant is immunocompromised—systemic antibiotics should be added 5

Superior Alternative: Ciprofloxacin-Dexamethasone

Ciprofloxacin-dexamethasone (Ciprodex) is clinically and microbiologically superior to neomycin-polymyxin B-hydrocortisone, with higher cure rates (90.9% vs 83.9%) and better microbiologic eradication (94.7% vs 86.0%), plus it has no ototoxicity risk and requires only twice-daily dosing. 6 For a 9-month-old, the dose would be 4 drops twice daily for 7 days 1.

The advantages of ciprofloxacin-dexamethasone over neomycin-polymyxin B-hydrocortisone include:

• No ototoxicity risk—safe even with non-intact membranes 2, 5
• Better pathogen coverage including Pseudomonas aeruginosa, which is common in tube otorrhea 1
• Twice-daily dosing versus 3-4 times daily, improving adherence 6
• No neomycin allergy risk 5
• Statistically superior clinical outcomes 6

When to Add or Switch to Systemic Antibiotics

Consider oral antibiotics if:

• Otorrhea persists or worsens after 48-72 hours of appropriate topical therapy 1
• Cellulitis of the pinna or adjacent skin develops 1
• Concurrent bacterial infection elsewhere (e.g., concurrent acute otitis media in the contralateral ear without tubes) 1
• Signs of severe infection (fever, significant pain, systemic symptoms) 1
• The infant is immunocompromised 1
• Administration of ear drops is not feasible (uncooperative infant, lack of caregiver assistance) 1

Approximately 4-8% of children treated with topical therapy require oral antibiotic rescue 1.

Ensuring Adequate Drug Delivery

Have an assistant (parent/caregiver) administer the drops rather than attempting self-administration, as adherence increases significantly with assisted administration—only 40% of patients who self-medicate do so appropriately. 2 For a 9-month-old infant, caregiver administration is obviously required.

If the ear canal is obstructed with debris or edema, the clinician may need to perform aural toilet (gentle suction or irrigation with body-temperature saline) to ensure drops can reach the site of infection 2. In severe cases with canal edema, a wick may need to be placed 2.