Ambrisentan and bosentan are both endothelin receptor antagonists (ERAs) used primarily to treat pulmonary arterial hypertension (PAH), but they differ in selectivity, dosing, side effects, and drug interactions. Here’s a side-by-side comparison to break it down:
🧬 Mechanism of Action
- Ambrisentan: Selective endothelin-A (ETA) receptor antagonist
- Blocks vasoconstriction but preserves vasodilation effects via endothelin-B (ETB) receptors.
- Bosentan: Dual ETA and ETB receptor antagonist
- Blocks both vasoconstriction and ETB-mediated vasodilation/clearance of endothelin.
💊 Indication
Both are used for:
- Pulmonary Arterial Hypertension (PAH)
- WHO Group 1
- Improves exercise capacity, delays disease progression
📈 Dosing
- Ambrisentan: Once daily (typically 5–10 mg)
- Bosentan: Twice daily (typically 62.5 mg twice daily for 4 weeks, then 125 mg twice daily)
🧪 Liver Toxicity
- Ambrisentan: Lower risk of liver enzyme elevation
- Less frequent liver monitoring needed
- Bosentan: Higher risk of hepatotoxicity
- Requires monthly liver function tests (LFTs)
🚼 Pregnancy
- Both are teratogenic (Category X) – strict REMS (Risk Evaluation and Mitigation Strategy) programs apply
🤝 Drug Interactions
- Bosentan: Strong CYP3A4 inducer – interacts with many drugs (e.g., warfarin, hormonal contraceptives)
- Ambrisentan: Fewer drug interactions; metabolized mainly via glucuronidation
🧍♂️ Side Effects
- Common to both: Peripheral edema, nasal congestion, headache, anemia
- Bosentan: More likely to cause elevated liver enzymes
- Ambrisentan: More selective, generally better tolerated
Ambrisentan and bosentan are both endothelin receptor antagonists (ERAs) used primarily to treat pulmonary arterial hypertension (PAH), but they differ in selectivity, dosing, side effects, and drug interactions. Here’s a side-by-side comparison to break it down:
🧬 Mechanism of Action
- Ambrisentan: Selective endothelin-A (ETA) receptor antagonist
- Blocks vasoconstriction but preserves vasodilation effects via endothelin-B (ETB) receptors.
- Bosentan: Dual ETA and ETB receptor antagonist
- Blocks both vasoconstriction and ETB-mediated vasodilation/clearance of endothelin.
💊 Indication
Both are used for:
- Pulmonary Arterial Hypertension (PAH)
- WHO Group 1
- Improves exercise capacity, delays disease progression
📈 Dosing
- Ambrisentan: Once daily (typically 5–10 mg)
- Bosentan: Twice daily (typically 62.5 mg twice daily for 4 weeks, then 125 mg twice daily)
🧪 Liver Toxicity
- Ambrisentan: Lower risk of liver enzyme elevation
- Less frequent liver monitoring needed
- Bosentan: Higher risk of hepatotoxicity
- Requires monthly liver function tests (LFTs)
🚼 Pregnancy
- Both are teratogenic (Category X) – strict REMS (Risk Evaluation and Mitigation Strategy) programs apply
🤝 Drug Interactions
- Bosentan: Strong CYP3A4 inducer – interacts with many drugs (e.g., warfarin, hormonal contraceptives)
- Ambrisentan: Fewer drug interactions; metabolized mainly via glucuronidation
🧍♂️ Side Effects
- Common to both: Peripheral edema, nasal congestion, headache, anemia
- Bosentan: More likely to cause elevated liver enzymes
- Ambrisentan: More selective, generally better tolerated
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