Welireg Drug Interactions

Effects of Other Drugs on WELIREG: UGT2B17 or CYP2C19 Inhibitors: Co-administration of WELIREG with inhibitors of UGT2B17 or CYP2C19 increases plasma exposure of belzutifan [see Pharmacology: Pharmacokinetics and Pharmacogenomics under Actions], which may increase the incidence and severity of adverse reactions of WELIREG. Monitor for anemia and hypoxia and reduce the dosage of WELIREG as recommended [see Dosage Modifications for Adverse Reactions under Dosage & Administration; Anemia and Hypoxia under Precautions; Adverse Reactions].
Effect of WELIREG on Other Drugs: Sensitive CYP3A4 Substrates: Co-administration of WELIREG with CYP3A4 substrates decreases concentrations of CYP3A substrates [see Pharmacology: Pharmacokinetics under Actions], 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 [see Pharmacology: Pharmacokinetics under Actions]. Avoid co-administration of WELIREG with sensitive CYP3A4 substrates, for which minimal decrease in concentration may lead to therapeutic failures of the substrate. If co-administration cannot be avoided, increase the sensitive CYP3A4 substrate dosage in accordance with its Prescribing Information.
Hormonal Contraceptives: Co-administration of WELIREG with hormonal contraceptives may lead to contraceptive failure or an increase in breakthrough bleeding [see Pharmacology: Pharmacokinetics under Actions; Females and Males of Reproductive Potential under Use in Pregnancy & Lactation].