Neomycin

Neomycin was discovered in 1949 by the microbiologist Selman Waksman and his student Hubert Lechevalier. It is produced naturally by the bacterium Streptomyces fradiae.
Neomycin is an aminoglycoside antibiotic that is found in many topical medications such as creams, ointments and eyedrops.

Formula C23H46N6O13 Mol. mass 614.644 g/mol
Half life 2 to 3 hours

Drug Uses
Neomycin is overwhelmingly used as a topical preparation. It can also be given orally, where it is usually combined with other antibiotics. Neomycin is not absorbed from the gastrointestinal tract, and has been used as a preventative measure for hepatic encephalopathy and hypercholesterolemia. By killing bacteria in the intestinal tract, it keeps ammonia levels low and prevents hepatic encephalopathy, especially prior to GI surgery. It has also been used to treat small intestinal bacterial overgrowth. It is not given intravenously, as neomycin is extremely nephrotoxic (causes kidney damage), especially compared to other aminoglycosides. The exception to this, is when it is included in some vaccines as a preservative, but in very small quantities -typically 0.025 mg per dose.
Neomycin is now also used in certain cell culture applications.

Drug Spectrum
Similar to other aminoglycosides, neomycin has excellent activity against Gram negative bacteria, and has partial activity against Gram positive bacteria. It is relatively toxic to humans, and many people have allergic reactions to it. See: Hypersensitivity. Physicians sometimes recommend using antibiotic ointments wihout neomycin, such as Polysporin.