neomisin

Neomycin, sometimes spelled neomysin, is an aminoglycoside antibiotic produced by the fermentation of Streptomyces fradiae. It binds to the 30S ribosomal subunit, causing misreading of mRNA and inhibition of protein synthesis, and is bactericidal.

Systemic use is limited by toxicity, so neomycin is mainly used topically for skin, ocular, and otic infections or in oral formulations for bowel decontamination prior to gastrointestinal procedures. In combination products such as neomycin–polymyxin B–bacitracin, it provides broad topical coverage.

Its activity is primarily against many Gram-negative bacteria; activity against most Gram-positive cocci and anaerobes is limited. Neomycin has poor systemic absorption when taken orally, which makes topical and local applications preferred, but systemic exposure can occur with prolonged use or damaged mucosa.

Adverse effects include nephrotoxicity and ototoxicity (cochlear and vestibular), with increased risk when used systemically or with other nephrotoxic or ototoxic drugs. Neuromuscular blockade and hypersensitivity reactions are possible but less common. Because of these risks, use is carefully weighed against benefits, and monitoring is advised for patients at higher risk.

Regulatory and usage considerations vary by country. In pregnancy, breastfeeding, and in patients with kidney impairment, neomycin-containing products are typically used with caution. Resistance can develop with prolonged exposure, so neomycin is generally reserved for specific indications and short courses when possible.