gentamicin sulfate + hydrocortisone acetate: clinical use

Prescribing considerations

• Confirm that the condition affects the external ear or an appropriate post-operative mastoid cavity and matches a licensed indication.
• Examine the tympanic membrane before prescribing; do not use if its integrity cannot be assured.
• Consider alternative therapy with known susceptible mitochondrial mutations or a maternal history of aminoglycoside-associated deafness.
• Consider increased absorption and toxicity with damaged skin, open wounds or larger treated areas.

Contraindications and cautions

• Hypersensitivity to gentamicin, hydrocortisone acetate, related aminoglycosides or an excipient.
• Myasthenia gravis.
• Known or suspected perforation of the tympanic membrane.

Monitoring

• Review clinical response, persistent infection, superinfection, irritation and contact sensitisation.
• Assess new hearing impairment, tinnitus, vertigo or balance disturbance promptly.
• Monitor for systemic corticosteroid effects if strong CYP3A inhibitors are unavoidable; infants may be more vulnerable to adrenal suppression.
• Assess visual symptoms and consider ophthalmology referral for blurred vision or other disturbances.

Clinical pharmacology

Gentamicin is a bactericidal aminoglycoside that inhibits bacterial protein synthesis at the 30S ribosomal subunit. Hydrocortisone acetate provides local glucocorticoid anti-inflammatory and immunosuppressive activity and is absorbed more slowly than hydrocortisone, producing a more prolonged local action.

Formulation and product differences

• A sterile aqueous ear-drop preparation containing suspended active ingredients and benzalkonium chloride as a preservative.
• Intended for auricular use; it may also be applied using a medicated wick in the external ear or mastoid cavity.
• Benzalkonium chloride may irritate the skin. Discard the bottle four weeks after opening.