Adverse reactions of Belzutifan

1 Effects of Other Drugs on Belzutifan  

UGT2B17 or CYP2C19 Inhibitors  

Coadministration of Belzutifan with inhibitors of UGT2B17 or CYP2C19 increases plasma exposure of  belzutifan, which may increase the incidence and severity of  adverse reactions of Belzutifan. Monitor for anemia and hypoxia and reduce the dosage of Belzutifan as  recommended.

2 Effect of Belzutifan on Other Drugs  

Sensitive CYP3A4 Substrates  

Coadministration of Belzutifan with CYP3A4 substrates decreases concentrations of CYP3A substrates, which may reduce the efficacy of these substrates. The magnitude of  this decrease may be more pronounced in patients who are dual UGT2B17 and CYP2C19 poor  metabolizers . Avoid coadministration of Belzutifan with sensitive  CYP3A4 substrates, for which minimal decrease in concentration may lead to therapeutic failures of the  substrate. If coadministration cannot be avoided, increase the sensitive CYP3A4 substrate dosage in  accordance with its Prescribing Information.

Hormonal Contraceptives  Coadministration of Belzutifan with hormonal contraceptives may lead to contraceptive failure or an  increase in breakthrough bleeding.

FDA，2021.08