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Belzutifan

Also known as: Welireg

Hypoxia-inducible Factor InhibitorHypoxia-inducible Factor 2 alpha InhibitorsCytochrome P450 3A4 Inducers

Route: Oral

2 interactions on record⛔ Black Box Warning

Belzutifan has 2 known drug interactions based on U.S. FDA drug labeling data. 1 are classified as major interactions requiring close medical supervision. Notable interactions include combinations with Oral Contraceptives, Mao Inhibitors. Patients taking Belzutifan should inform their healthcare provider of all current medications — including over-the-counter drugs and supplements — to avoid potentially harmful combinations. Data sourced from OpenFDA and the NIH National Library of Medicine.

Total: 2
Major: 1
Moderate: 1

Major (1)

Belzutifan + Oral Contraceptives— Coadministration may lead to contraceptive failure or increase in breakthrough bleeding.

Moderate (1)

Belzutifan + Mao Inhibitors— Coadministration increases belzutifan exposure. Monitor for anemia and hypoxia; reduce belzutifan dosage as recommended.

Belzutifan + Oral Contraceptives⚠️Major

Coadministration may lead to contraceptive failure or increase in breakthrough bleeding.

Belzutifan + Mao Inhibitors🟡Moderate

Coadministration increases belzutifan exposure. Monitor for anemia and hypoxia; reduce belzutifan dosage as recommended.

⛔ FDA Black Box Warning

WARNING: EMBRYO-FETAL TOXICITY Exposure to WELIREG during pregnancy can cause embryo-fetal harm. Verify pregnancy status prior to the initiation of WELIREG. Advise patients of these risks and the need for effective non-hormonal contraception. WELIREG can render some hormonal contraceptives ineffective [see Warnings and Precautions (5.3) , Drug Interactions (7.2) , Use in Specific Populations (8.1 , 8.3) ]. WARNING: EMBRYO-FETAL TOXICITY See full prescribing information for complete boxed warning. Exposure to WELIREG during pregnancy can cause embryo-fetal harm. Verify pregnancy status prior to the initiation of WELIREG. Advise patients of these risks and the need for effective non-hormonal contraception. WELIREG can render some hormonal contraceptives ineffective. ( 5.3 , 7.2 , 8.1 , 8.3 )

Contraindications

4 CONTRAINDICATIONS None. None. ( 4 )

Pregnancy & Breastfeeding

8.1 Pregnancy Risk Summary Based on findings in animal studies, WELIREG can cause fetal harm when administered to a pregnant woman. There are no available data on the use of WELIREG in pregnant women to inform the drug-associated risk. In an animal reproduction study, oral administration of belzutifan to pregnant rats during the period of organogenesis caused embryo-fetal lethality, reduced fetal body weight, and fetal skeletal malformations at maternal exposures ≥0.2 times the human exposure (AUC) at the recommended dose of 120 mg daily ( see Data ). Advise pregnant women and females of reproductive potential of the potential risk to a fetus. The background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2–4% and 15–20%, respectively. Data Animal Data In a pilot embryo-fetal development study, pregnant rats received oral doses of 6, 60, or 200 mg/kg/day of belzutifan during the period of organogenesis. Belzutifan caused embryo-fetal lethality at doses ≥60 mg/kg/day (approximately 1 time the human exposure at the recommended dose based on AUC). Reduced fetal body weights, fetal rib malformations, and reduced skeletal ossification occurred at doses of 6 and 60 mg/kg/day (approximately ≥0.2 times the human exposure at the recommended dose based on AUC).

Data sourced from U.S. FDA drug labeling via openFDA and the NIH National Library of Medicine, supplemented with a small number of well-established interactions from curated clinical references. For informational purposes only. Always consult your pharmacist or physician.