Telmisartan (Micardis): Angiotensin II receptor blocker tablets approved for cardiovascular risk reduction for patients unable to take an ACE inhibitor

Telmisartan angiotensin II receptor blocker (ARB) tablets 80 mg have been approved for reduction of the risk of myocardial infarction, stroke, or death from cardiovascular causes in patients aged 55 years or older at high risk of developing major cardiovascular events who are unable to take angiotensin-converting enzyme (ACE) inhibitors. Some studies estimate that up to 20% of patients taking an ACE inhibitor experience side effects, usually cough, suggesting that some patients might be less likely to take this medication as prescribed.

Efficacy. The ONTARGET Trial Program, which combined two multi-center international outcome trials (ONTARGET and TRANSCEND), was the first trial of its size to compare the efficacy of telmisartan, an ARB, with ramipril, an ACE inhibitor, in reducing major cardiovascular events. The ONTARGET Trial Program also investigated the potential cardiovascular risk reduction effect of telmisartan versus placebo on top of standard therapy (ie, anti-hypertensives, anti-platelets, statins) in patients who cannot tolerate an ACE inhibitor but are at high risk of major cardiovascular events. Results of these studies support that telmisartan is more effective than placebo in a high-risk population who are unable to take ACE inhibitors. The results of ONTARGET were presented at the American College of Cardiology annual meeting and published in the New England Journal of Medicine in March 2008, and the results of the TRANSCEND trial were presented at the European Society of Cardiology annual meeting and published in The Lancet in August 2008. Because studies with telmisartan did not exclude that it may not preserve a meaningful fraction of the effect of the ACE inhibitor to which it was compared, consider using the ACE inhibitor first, per product labeling.

Safety. When pregnancy is detected, telmisartan tablets should be discontinued as soon as possible. In patients with an activated renin-angiotensin system, such as volume- and/or salt-depleted patients, symptomatic hypotension may occur after initiation of therapy with telmisartan tablets. This condition should be corrected prior to administration of telmisartan tablets, or treatment should start under close medical supervision. As the majority of telmisartan is eliminated by biliary excretion, patients with biliary obstructive disorders or hepatic insufficiency can be expected to have reduced clearance. Telmisartan tablets should be used with caution in these patients. In patients whose renal function may depend on the activity of the renin-angiotensin-aldosterone system (eg, patients with severe congestive heart failure), treatment with ACE inhibitors and ARBs has been associated with oliguria and/or progressive azotemia and (rarely) with acute renal failure and/or death. Similar results may be anticipated in patients treated with telmisartan tablets. In studies of ACE-inhibitors in patients with renal artery stenosis, increases in serum creatinine or blood urea nitrogen were observed. An effect similar to that seen with ACE inhibitors should be anticipated with telmisartan tablets.