Losartan, administered for 12 days, did not affect the pharmacokinetics or pharmacodynamics of a single dose of Warfarin. Losartan did not affect the pharmacokinetics of oral or intravenous Digoxin. Coadministration of Losartan and Cimetidine led to an increase of about 18% in AUC of Losartan but did not affect the pharmacokinetics of its active metabolite. Coadministration of Losartan and Phenobarbital led to a reduction of about 20% in the AUC of Losartan and that of its active metabolite. Hydrochlorothiazide when administered concurrently may interact with drugs like alcohol, barbiturates, or narcotics. Antidiabetic drugs (oral agents and insulin) require dosage adjustment. Lithium should not generally be given with diuretics. In some patients, the administration of NSAIDs can reduce the diuretic, natriuretic, and antihypertensive effects of loop, potassium-sparing and thiazide diuretics.