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Telmisartan, sold under the brand name Micardis among others, is a medication used to treat high blood pressure and heart failure. It is an angiotensin II receptor blocker and works by blocking the effects of angiotensin II.
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Telmisartan was patented in 1991 and came into medical use in 1999. It is available as a generic medication. In 2023, it was the 184th most commonly prescribed medication in the United States, with more than 2million prescriptions. It is available in combination with hydrochlorothiazide as telmisartan/hydrochlorothiazide; with cilnidipine as telmisartan/cilnidipine; and with amlodipine as telmisartan/amlodipine.
Medical uses
Telmisartan is used to treat high blood pressure, heart failure, and diabetic kidney disease.
Contraindications
Telmisartan is contraindicated during pregnancy.
Pharmacology
Mechanism of action
Telmisartan is an angiotensin II receptor blocker that shows high affinity for the angiotensin II receptor type 1 (AT<sub>1</sub>), with a binding affinity 3000 times greater for AT<sub>1</sub> than AT<sub>2</sub>.
In addition to blocking the renin–angiotensin system, telmisartan acts as a partial agonist of peroxisome proliferator-activated receptor gamma (PPAR-γ), a central regulator of insulin and glucose metabolism. It is believed that telmisartan's dual mode of action may provide protective benefits against the vascular and renal damage caused by diabetes and cardiovascular disease (CVD). The kidney-protecting activity of telmisartan is attributed to both angiotensin II antagonism and improved endothelial function from PPAR-γ. Telmisartan activates PPAR-δ receptors in several tissues. In mice, this results in effects such as enhanced endurance. However, telmisartan does not improve the walking performance (6-minute walk distance) in people with lower extremity peripheral artery disease.
Telmisartan activates PPAR-α in vitro. Telmisartan inhibits CYP2J2.
Pharmacokinetics
The substance is quickly but to varying degrees absorbed from the gut. The average bioavailability is about 50% (42–100%). Food intake has no clinically relevant influence on the kinetics of telmisartan. Plasma protein binding is over 99.5%, mainly to albumin and alpha-1-acid glycoprotein. and the largest volume of distribution among ARBs (500 liters). Less than 3% of telmisartan is inactivated by glucuronidation in the liver, and over 97% is eliminated in unchanged form via bile and faeces.
Telmisartan does not cause rapid cancer growth like the PPAR-δ agonist GW 501516, but whether it causes a change in cancer rates is disputed. Short-term use is not associated with an increased incidence of cancer over other ARB drugs, according to a large 2016 analysis of UK patients. A 2022 meta-analysis finds that a longer duration of taking ARBs (including telmisartan) is associated with an increase in cancer rates. Patients who have taken an ARB for more than 3 years appears 11% more likely to develop cancer. A 2023 large-scale study on Lebanese patients finds that taking ARBs reduces the incidence of cancer, with greater effects on those who have taken the drug for a long time. A 2021 Korean study and a 2012 Japanese study finds similar results.