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Indications and Dosage
Topical/Cutaneous
Bacterial skin infections Adult: As cream containing 3300 units/g of neomycin and 250 units/g of bacitracin zinc: Apply a thin layer up to 3 times daily. As powder containing 5000 units/g of neomycin and 250 units/g of bacitracin zinc: Apply 2-4 times daily.
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Contraindications
Hypersensitivity to aminoglycosides. Pre-existing nerve deafness. Neonates and infants <2 yr.
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Special Precautions
Neuromuscular disorders, hearing impaired, extensive skin damage. Avoid application in large quantities and prolonged use. Do not use if tympanic membrane is perforated. Pregnancy and lactation. Liver and renal impairment.
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Adverse Reactions
Hypersensitivity reactions. Possibility of ototoxicity and nephrotoxicity if used in large quantities or on large areas for prolonged use.
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Overdosage
Symptoms: Nephrotoxicity and ototoxicity may occur if significant amounts are absorbed systemically. Management: Discontinue the product and monitor patient's hearing acuity, renal, neuromuscular function and serum concentrations of neomycin and bacitracin. Haemodialysis may be useful in reducing neomycin levels.
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Drug Interactions
Additive toxicity with neurotoxic, ototoxic or nephrotoxic drugs. Increased neuromuscular blockade and possibly respiratory depression with neuromuscular blocking agents if significant amount of neomycin is absorbed systemically.
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Action
Description:
Mechanism 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. Pharmacokinetics: Absorption: Neomycin: Poorly absorbed from GI tract. Absorption may occur from peritoneum, respiratory tract, bladder, wounds and inflamed skin; increased when mucosa is damaged or inflamed. Bacitracin: Poorly absorbed from the GI tract or from intact or denuded skin, wounds or mucous membranes. Distribution: Bacitracin: Diffuses into pleural and ascitic fluids. Excretion: Neomycin: 97% of oral dose excreted unchanged in faeces; absorbed neomycin excreted by kidneys in active form; half life: 2-3 hr. Bacitracin: 10-40% of injected dose excreted slowly by kidney and appears in urine within 24 hr. |
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MIMS Class
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