Additive effect w/ other neurotoxic and/or nephrotoxic drugs including cephalosporins, methicillin, amphotericin B, ciclosporin, cisplatin, potent diuretics (e.g. ethacrynic acid, furosemide) and neuromuscular blocking agents (e.g. succinylcholine, tubocurarine). May potentiate the effect of anticoagulants (e.g. warfarin, phenindione). May antagonise the effect of neostigmine and pyridostigmine. Increased risk of hypocalcaemia w/ bisphosphonates. Increased risk of neuromuscular blockade w/ botulinum toxin. Indometacin may increase the plasma concentration of gentamicin in neonates.