Telmisartan (Micardis)

Detailed overview

Telmisartan blocks the type 1 receptor for angiotensin II. Angiotensin II is a potent vasoconstrictor that also stimulates aldosterone secretion; blocking the receptor produces vasodilation and sodium excretion, thereby lowering blood pressure. That is the shared mechanism of the class. Two things, however, are specific to telmisartan. The first is pharmacokinetics: its half-life is about 24 hours, the longest among angiotensin receptor blockers. The practical consequence is that blood-pressure control persists to the end of the dosing interval and a missed tablet does not immediately upset it. The second is partial PPAR-gamma agonist activity, discussed in the Ernsberger 2007 review: this nuclear receptor is the target of glitazone antidiabetics, and telmisartan partially activates it. The Imenshahidi 2024 review derives from this the favourable effects on components of the metabolic syndrome, chiefly insulin sensitivity and the lipid profile. The backbone of the clinical evidence is ONTARGET, which in 2008 randomised more than 25,000 high-cardiovascular-risk patients to telmisartan, ramipril or both. Telmisartan was not inferior to ramipril and caused less cough and angioedema. The trial's most important lesson, though, concerns the third arm: dual blockade brought no added benefit while causing more hypotension, syncope and renal impairment. That finding still shapes clinical practice, and the Tobe 2011 renal subanalysis confirmed it.