Zaart 50 mg contains losartan which is used in the treatment of high blood pressure. Decreasing high blood pressure lowers the risk of heart attack and stroke. Zaart 50 Tablet is an angiotensin receptor blocker (ARB). It relaxes the blood vessel by blocking the action of a chemical that usually makes blood vessels tighter. This lowers the blood pressure allowing the blood to flow more smoothly to different organs and the heart to pump more efficiently.