Precautions and Contraindications
Neomycin sulfate should be administered with caution to patients with otitis externa complicated by chronic otitis media or by a perforated tympanic membrane because of possible absorption of the drug leading to ototoxicity. Ototoxicity, nephrotoxicity, and neuromuscular blockade have occurred following topical application of neomycin, especially in patients undergoing peritoneal instillation, irrigation of wounds or surgical sites, or those receiving treatment for skin ulcers, granulating wounds, burns, or extensive areas of denuded skin. Following systemic absorption of neomycin, toxicity is most likely to occur in patients with renal impairment. The possibility of cumulative toxicity should be considered when neomycin is applied topically in combination with systemic aminoglycoside therapy. Patients using ophthalmic preparations containing neomycin sulfate should be advised to consult a physician if ocular pain, redness, swelling, or irritation worsens or persists. Patients also should be advised to seek their physician's advice immediately regarding the continued use of ophthalmic preparations containing neomycin sulfate if an intercurrent ocular condition (e.g., trauma, infection) occurs.
Because benzalkonium chloride may be absorbed by soft contact lenses, patients receiving ophthalmic preparations that contain this preservative should be advised to wait at least 15 minutes after instillation of the ophthalmic preparation before they insert their contact lenses.
Topical corticosteroids, when used in combination with neomycin, may mask the clinical signs of bacterial, fungal, or viral infections, or may suppress hypersensitivity reactions to the antibiotic or other ingredients in the formulations. The possibility of corticosteroid-induced adverse ocular effects, including increased intraocular pressure, glaucoma, delayed wound healing, and cataract formation, also must be considered. When neomycin is used in fixed combination with a corticosteroid, other cautions, precautions, and contraindications associated with EENT corticosteroids also must be considered in addition to those associated with the anti-infective. In addition, such fixed combinations are contraindicated following uncomplicated removal of a corneal foreign body.
The use of neomycin may result in overgrowth of nonsusceptible organisms including fungi. If superinfection occurs during neomycin therapy, the drug should be discontinued and appropriate therapy instituted.
Although some ophthalmic ointment vehicles used in the past were reported to retard corneal wound healing, currently used ophthalmic ointment vehicles do not appear to slow the rate of corneal wound healing; in addition, ointments may provide a protective effect if the cornea is exposed. However, the manufacturers caution that ophthalmic ointments have retarded corneal healing.
Some commercially available otic formulations of neomycin sulfate contain sulfites that can cause allergic-type reactions, including anaphylaxis and life-threatening or less severe asthmatic episodes, in certain susceptible individuals. The overall prevalence of sulfite sensitivity in the general population is unknown but probably low; such sensitivity appears to occur more frequently in asthmatic than in nonasthmatic individuals.
Neomycin ophthalmic and otic preparations are contraindicated in patients who are hypersensitive to the drug or any ingredients in the formulations. Cross-allergenicity among the aminoglycosides has been demonstrated, and the possibility that patients who become sensitized to topical neomycin also may be sensitive to other topical and/or systemic aminoglycosides should be considered.