Candesartan is an angiotensin receptor blocker used mainly for the treatment of high blood pressure and congestive heart failure. Candesartan has a very low maintenance dose. The metabolism for the drug is unique as it is a cascading prodrug. Candesartan has good bioavailibility and is more potent among the AT-1 receptor antagonists. It was patented in 1990 and approved for medical use in 1997. Medical uses Hypertension As with other angiotensin II receptor antagonists, candesartan is indicated for the treatment of hypertension. Candesartan has an additive antihypertensive effect when combined with a diuretic, such as chlorthalidone. It is available in a fixed-combination formulation with a low dose of the thiazide diuretic hydrochlorothiazide. Candesartan/hydrochlorothiazide combination preparations are marketed under various trade names including Atacand Plus, Hytacand, Blopress Plus, Advantec and Ratacand Plus. Congestive heart failure Angiotensin receptor blockers such as candesartan and valsartan have been demonstrated in randomised controlled trials to reduce heart failure hospitalisations and cardiovascular deaths for chronic heart failure patients with reduced left ventricular ejection fraction (LVEF ≤40%) and are intolerant to angiotensin-converting enzyme inhibitors. Prehypertension In a four-year randomized controlled trial, candesartan was compared to placebo to see whether it could prevent or postpone the development of full-blown hypertension in people with so-called prehypertension. During the first two years of the trial, half of participants were given candesartan while the other half received placebo; candesartan reduced the risk of developing hypertension by nearly two-thirds during this period. In the last two years of the study, all participants were switched to placebo. By the end of the study, candesartan had significantly reduced the risk of hypertension, by more than 15%. Serious adverse effects were more common among participants receiving placebo than in those given candesartan. Prevention of atrial fibrillation Results from a meta-analysis completed in 2005 demonstrated a reduction in atrial fibrillation in patients with systolic left ventricular dysfunction treated with candesartan, another angiotensin receptor blocker or an angiotensin converting enzyme inhibitor. Evidence for the use of candesartan specifically is also supported by an analysis of the CHARM study which demonstrated a reduction in atrial fibrillation in patients with systolic left ventricular dysfunction. While these studies have demonstrated a potential additional benefit for candesartan when used in patients with systolic left ventricular dysfunction, additional studies are required to further elucidate the role of candesartan in the prevention of atrial fibrillation in other population groups. Diabetic retinopathy Use of