Enhanced digitalis glycoside toxicity, nephrotoxicity of cephalosporin & NSAIDs, ototoxicity of aminoglycoside & other ototoxic drugs. Increased risk of arrhythmias w/ astemizol, terfenadine, halofantrine, pimozide & sotalol. Enhanced neuromuscular-blocking action of atracurium. Enhanced K-depleting effect by corticosteroids, corticotrophin, salbutamol, carbenoxolone, amphotericin B, reboxetine. Enhanced effect of other antihypertensives. Antagonized antihypertensive effect by corticosteroids, NSAIDs or carbenoxolone. Enhanced orthostatic hypotension by alcohol, barbiturates or opioids. Increased allopurinol & tetracycline toxicity. Toxic blood conc of lithium. Symptomatic hyponatraemia w/ hydrochlorothiazide & carbamazepine.