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.