Losartan K: Increased AUC w/ cimetidine. Reduced AUC w/ phenobarb. Decreased levels w/ rifampicin & fluconazole. Increased serum K w/ K-sparing diuretics (eg, spironolactone, triamterene, amiloride), K supplements or K-containing salt substitutes. Hydrochlorothiazide: Potentiation of orthostatic hypotension w/ alcohol, barbiturates or narcotics. Insulin & oral antidiabetic agents. Impaired absorption w/ cholestyramine & colestipol resins. Intensified electrolyte depletion particularly hypokalemia w/ corticosteroids, ACTH. Possible decreased response to pressor amines (eg, adrenaline). Potential increased responsiveness to nondepolarizing skeletal muscle relaxants (eg, tubocurarine). Reduced renal clearance & increased risk of lithium toxicity. Diuretic, natriuretic & antihypertensive effects may be reduced by NSAIDs.