Side Effects of Bosentan
Bosentan, an endothelin receptor antagonist, has several important side effects including hepatotoxicity, anemia, fluid retention, and potential teratogenic effects that require careful monitoring and management. 1, 2
Major Side Effects
Hepatotoxicity
- Increases in hepatic aminotransferases occur in approximately 10% of patients treated with bosentan 1, 2
- Liver enzyme elevations are dose-dependent and reversible after dose reduction or discontinuation 3
- Monthly liver function tests are required by both FDA and European regulatory agencies 1, 2
- Severe hepatotoxicity is rare but can occur even after long periods of uneventful therapy 4
Hematologic Effects
- Anemia is a common side effect that is typically mild 3
- Regular monitoring of hemoglobin/hematocrit is recommended every 3 months 1, 3
- Reductions in hemoglobin levels have been consistently observed across clinical trials 2, 5
Fluid Retention and Edema
- Lower limb edema is frequently reported in patients taking bosentan 3
- Fluid retention can occur and may be more problematic in patients with pre-existing heart failure 5
Reproductive Effects
- Bosentan is potentially teratogenic and contraindicated in pregnancy 1, 3
- The drug may decrease the efficacy of hormonal contraceptive methods 3
- Barrier contraception is recommended for women of childbearing age 1, 3
- Concerns exist about potential testicular atrophy and male infertility 1, 3
- Young males considering future conception should be counseled about this possibility 1
Other Side Effects
Cardiovascular Effects
- Hypotension can occur due to vasodilatory effects 6, 7
- Dizziness may result, particularly in elderly patients or those with pre-existing cardiovascular conditions 6
- Bosentan reduces both pulmonary and systemic vascular resistance, which can lead to systemic hypotension 7
Gastrointestinal Effects
- Nausea is reported in approximately 31% of patients 8
- Headache (43%) and fatigue (34%) are also commonly reported 8, 9
Drug Interactions
- Bosentan induces CYP3A4 and CYP2C9, potentially reducing the efficacy of medications metabolized by these enzymes 9
- Significant interactions with warfarin, cyclosporine, and glibenclamide have been reported 9
- Concomitant use with cyclosporine is contraindicated 9
- Concomitant use with glibenclamide is not recommended due to increased risk of aminotransferase elevations 9
Monitoring Requirements
- Monthly liver function tests throughout treatment 1, 3
- Hemoglobin/hematocrit checks every 3 months 1
- Pregnancy testing in women of childbearing potential 3
- Careful monitoring for signs of fluid retention and edema 3
- Assessment for symptoms of liver injury (jaundice, fatigue, right upper quadrant pain) 4