What precautions should be taken with bosentan and pregnancy?

Why Bosentan Is Dangerous in Pregnancy

Bosentan, sold as Tracleer, causes serious birth defects and fetal harm. It is pregnancy category X, meaning the risks outweigh any benefits, and it should not be used by pregnant women or those planning pregnancy.[1][2]

Key Precautions for Women of Childbearing Potential

• Monthly Pregnancy Testing: Women must have a negative pregnancy test before starting bosentan and monthly thereafter. Use serum or urine tests with sensitivity to detect 25 mIU/mL hCG.[1]
  
• Two Contraception Methods: Require use of two effective birth control methods (e.g., hormonal plus barrier) starting one month before treatment, during therapy, and for one month after stopping. Tubal sterilization counts as one method.[1][2]
  
• No Use During Pregnancy: Discontinue immediately if pregnancy occurs. Report to the manufacturer and FDA.[1]
  
• REMS Program Enrollment: Mandatory under the Tracleer Risk Evaluation and Mitigation Strategy (REMS). Prescribers, pharmacies, and patients must register; only certified prescribers can prescribe it.[2]
  
  

Recommendations for Men Taking Bosentan

Semen contains bosentan, which may harm a fetus if a partner becomes pregnant. Men must use condoms with female partners of childbearing potential during treatment and for 3 months after the last dose.[1]

What If Pregnancy Occurs Anyway

Stop bosentan right away. Enroll in the Tracleer Pregnancy Surveillance Program to report outcomes. Fetal risks include teratogenic effects like skull and limb defects, based on animal studies and human case reports.[1][2]

Drug Interactions Affecting Contraception

Bosentan induces CYP3A4, reducing effectiveness of hormonal contraceptives like pills, patches, or rings. Do not rely on them alone; always combine with a barrier method.[1]

Sources
[1]: Tracleer Prescribing Information (FDA)
[2]: REMS@FDA - Tracleer