Increased plasma lithium. Increased risk of ventricular arrhythmias w/ Torsade de pointes-inducing drugs eg, class IA & III antiarrhythmics, some antipsychotics (eg, phenothiazines, benzamides, butyrophenones, pimozide), bepridil, cisapride, diphemanil, erythromycin IV, halofantrine, mizolastine, pentamidine, sparfloxacin, moxifloxacin, vincamine IV, methadone, astemizole, terfenadine. Reduced antihypertensive effect w/ systemic NSAIDs eg, COX-2 selective inhibitors, high-dose ASA (≥3 g daily). Risk of sudden hypotension &/or acute renal failure w/ ACE inhibitors. Increased risk of hypokalaemia w/ IV amphotericin B, systemic gluco- & mineralocorticoids, tetracosactide, stimulant laxatives. Increased antihypertensive effect w/ baclofen. Hypokalaemia &/or hypomagnesaemia predisposed to digitalis toxicity w/ digitalis prep. Increased incidence of hypersensitivity reactions to allopurinol. Hypo- or hyperkalaemia w/ K-sparing diuretics eg, amiloride, spirinolactone, triamterene. Increased risk of metformin-induced lactic acidosis. Increased risk of acute renal failure w/ iodinated contrast media (large doses). Increased antihypertensive effect & risk of orthostatic hypotension w/ imipramine-like antidepressants, neuroleptics. Decreased urinary Ca elimination. Increased plasma creatinine w/ ciclosporin, tacrolimus. Decreased antihypertensive effect w/ corticosteroids, systemic tetracosactide.