Losartan K: Rifampicin & fluconazole; K-sparing diuretics, K supplements or K-containing salt substitutes. Hydrochlorothiazide: Alcohol, barbiturates or narcotics; antidiabetic drugs (oral agents & insulin); other antihypertensive drugs; cholestyramine & colestipol resins; corticosteroids, ACTH; pressor amines (eg, adrenaline).