Irbesartan is metabolized by CYP 2C9, and weak inhibitory potential of this CYP enzyme is observed in vitro. No clinically significant effects on CYP is expected or observed in clinical studies.

Angiotensin II receptor antagonist.

Irbesartan is used in the treatment of essential hypertension. It is administered orally.

According to in vitro studies irbesartan is primarily metabolized by CYP 2C9, whilst CYP 3A4 has only negligible effect. It has a half-life of 11-15 hours (SPC). In an in vitro study irbesartan was found to have potential for inhibition of CYP 2C9. Irbesartan was also found to be a modest and most likely clinically insignificant inhibitor of CYP 1A2 and 3A4 (Taavitsainen 2000). In another in vitro study, irbesartan was found to be an inhibitor of CYP2C9, but the authors conclude that such inhibition is unlikely to be clinically relevant due to the low free plasma concentration obtained at therapeutic doses (Kamiyama 2007). According to the Sanofi product monograph irbesartan does not inhibit or induce CYP 3A4 (Product monograph Avapro). In vivo studies has shown that irbesartan does not interact with the pharmacokinetics of simvastatin (CYP 3A4 substrate) and warfarin/ tolbutamide (CYP 2C9 substrates) (Marino 2001, Yang 2016).

Uneventful use reported in 10 patients with acute porphyria.