Is telmisartan the same as losartan?

The most often prescribed ARBs are telmisartan and losartan. Both drugs are ARBs. However, they are different. According to the World Health Organization, Losartan is an essential drug. Telmisartan is an ARB that selectively inhibits the angiotensin II receptor. It has a partial peroxisome proliferator-activated receptor-gamma (PPAR-g) agonistic activity. PPAR-g belongs to the nuclear hormone receptor superfamily. Inhibition by losartan is transient and readily reversible, while that of telmisartan is insurmountable, which causes prolonged and irreversible inhibition of angiotensin 1 (AT1)[1].

The analysis indicated that the Telmisartan group had fewer side effects than losartan. Both drugs are ARBs. However, studies have shown that telmisartan shows a more selective affinity for AT1. This could be the reason for less adverse effects in telmisartan-treated patients[2]. On the other hand, losartan is a prodrug that needs to be metabolized in the liver to become active. Therefore, it has a slower onset of action compared to telmisartan. An additional advantage of telmisartan is its prolonged action due to a longer half-life. Besides this, telmisartan has PPAR-g activity, which is responsible for its other cardiovascular protective effects.

References

[1] Kusum Kumari. “Blood pressure-lowering effect of telmisartan compared to losartan among mild to moderate essential hypertensive adult subjects: A meta-analysis.” Journal of Family Medicine and Primary Care 11 10 (2022): 6227–6235.

[2] George Bakris . “Telmisartan is more effective than losartan in reducing proteinuria in patients with diabetic nephropathy.” Kidney international 74 3 (2008): Pages 364-369.