May increase antihypertensive effects w/ other antihypertensive agents. Do not use w/ K-sparing diuretics, K supplements & other agents that increase K blood levels. Caution when used w/ lithium, muscle relaxants, NSAIDs, oral antidiabetics, baclofen, antipsychotics, antidepressants, allopurinol, cytostatics, immunosuppressants, systemic glucocorticoids, procainamide, amifostine, cimetidine, ranitidine, digoxin, anticonvulsants, rifampicin & antifungals.