May increase toxicity of drugs inducing QT interval prolongation syndrome eg, amisulpride, atomoxetine, pimozide, sotalol, sertindole. Increased risk of hypokalaemia w/ β2
sympathomimetics (large doses), theophylline, corticosteroids, liquorice, carbenoxolone, laxatives (prolonged use), reboxetine, or amphotericin. May attenuate effect of antidiabetics & pressor amines. Effect may be reduced w/ probenecid & methotrexate. May decrease renal elimination of probenecid & methotrexate. Increased toxic effects of digoxin & other digitalis glycosides. May increase cardiac toxicity of anti-arrhythmic drugs (eg, amiodarone, disopyramide, flecainide, quinidine & sotalol) & may antagonise effects of lidocaine & mexiletine. Possible marked fall in BP & renal function deterioration w/ ACE inhibitors or angiotensin II receptor antagonists. May increase serum lithium levels. Avoid concomitant use w/ risperidone in elderly w/ dementia. Certain NSAIDs (including indomethacin, ketorolac, acetylsalicylic acid) may decrease effectiveness & may cause acute renal failure in cases of preexisting hypovolaemia or dehydration. May increase salicylate toxicity. May potentiate nephrotoxicity & ototoxicity of aminoglycosides & other ototoxic drugs. Increased risk of ototoxicity w/ vancomycin or polymyxins (colistin). Renal function impairment may develop w/ high doses of certain cephalosporins eg, cephaloridine. Risk of ototoxicity w/ cisplatin. Increased risk of gouty arthritis w/ ciclosporin. Effectiveness may be decreased w/ phenytoin. May increase risk of hyponatraemia w/ carbamazepine. May cause Na retention & increased risk of developing hypokalaemia w/ corticosteroids. Bolus doses may induce flushing, sweating, tachycardia & BP variations w/ chloral hydrate/triclofos. May affect response to neuromuscular blocking agents.