Acetic acid glacial + dexamethasone + neomycin: clinical use

Prescribing considerations

• Confirm otitis externa and exclude chronic otitis media or another persistent diagnosis.
• Establish that the tympanic membrane is intact and no tympanostomy tube is present.
• Reassess worsening or non-improving symptoms; consider obstruction, sensitisation, resistant bacteria, fungal infection or an alternative diagnosis.
• Avoid prolonged exposure because corticosteroids can mask infection and neomycin can promote sensitisation or resistant organisms.
• Use particular caution in young children, renal or hepatic impairment, damaged canal skin, and known or suspected mitochondrial disease associated with aminoglycoside ototoxicity.

Contraindications and cautions

• Hypersensitivity to dexamethasone, neomycin sulfate, acetic acid or an excipient.
• Known or suspected perforated tympanic membrane.
• Tympanostomy tube or grommet in situ.
• Children under 2 years.

Monitoring

• Clinical response and spread beyond the ear canal.
• Local irritation, rash, dermatitis or increasing itch.
• New hearing loss, tinnitus or vestibular symptoms.
• Visual disturbance associated with corticosteroid exposure.
• With prolonged paediatric exposure, consider theoretical systemic steroid absorption and aminoglycoside toxicity.

Clinical pharmacology

Neomycin is a broad-spectrum aminoglycoside antibacterial, dexamethasone is a topical glucocorticoid and acetic acid lowers local pH to assist bacterial control. The preparation acts predominantly locally in the external auditory meatus.

Formulation and product differences

• Milky, non-pressurised oil-in-water ear-spray emulsion supplied in an amber glass bottle.
• Contains methyl and propyl hydroxybenzoates, which may cause delayed allergic reactions, and stearyl alcohol, which may cause contact dermatitis.
• Keep the opened bottle upright in its carton, protect it from freezing and discard it after one month.