Indication

Bacterial skin infections

Adult dose

Adult: Topical: Cream: Apply 3 times/day. Powder: Apply 2-4 times/day.

Child dose

Topical: Cream: Apply 3 times/day. Powder: Apply 2-4 times/day.

Contraindication

Hypersensitivity to aminoglycosides. Pre-existing nerve deafness. Neonates and infants <2 yr.

Mode of action

Neomycin, an aminoglyoside with antimicrobial spectrum similar to gentamicin, binds to the 30S subunits of the bacterial ribosome, inhibiting protein synthesis and thereby disrupting DNA synthesis. It is active against many gram-negative aerobes and against some strains of staphylococci. Bacitracin, on the other hand, inhibits bacterial cell wall synthesis and is active against many gram-positive bacteria (e.g. staphylococci, streptococci, corynebacteria and clostridia) and some gram-negative species (e.g. Neisseria and Haemophilus influenzae). They are often found in combinations in topical preparations as broad spectrum antibacterial agents.

Precaution

Avoid application in large quantities and prolonged use. Pregnancy and lactation. Liver and renal impairment.

Side effect

>10% Allergic contact dermatitis (60%)

Interaction

Bacitracin Zinc: Increased risk of nephrotoxicity when used with other nephrotoxic drugs. May enhance the action of neuromuscular-blocking agents. Neomycin Sulphate: Additive nephrotoxic and neurotoxic effect w/ other aminoglycosides (e.g. paromomycin), bacitracin, cisplatin, vancomycin, amphotericin B, polymyxin B, colistin and viomycin. Enhanced toxicity w/ potent diuretics (e.g. ethacrynic acid, furosemide). May impair the absorption of other drugs (e.g. phenoxymethylpenicillin, digoxin, methotrexate and some vit). May reduce the efficacy of OCs. May enhance the effect of acarbose. May enhance the effect of non-depolarising muscle relaxants. May antagonise the parasympathomimetic effect of neostigmine and pyridostigmine. May increase the risk of hypocalcaemia in patients receiving bisphosphonates. May alter INR when given w/ anticoagulants. May inactivate oral typhoid vaccine.