II. Indications
- Pumonary Arterial Hypertension
- Bosentan (Tracleer)
- Ambrisentan (Letairis)
- Macitentan (Opsumit)
- Sitaxsentan
- Hypertension (fourth-line, refractory)
- Cancer (e.g. Prostate Cancer, Colorectal Cancer, experimental)
- Endothelins inhibition may decrease tumor growth, progression, and Angiogenesis
III. Mechanism
- Endothelin is a vasonstrictor and Aldosterone mediator
- Endothelin Receptor Antagonists inhibit endothelin activity, resulting in vasodilation
IV. Dosing: Pulmonary Hypertension
- Bosentan (Tracleer)
- Start 62.5 mg orally twice daily (may increase to 125 mg twice daily)
- Ambrisentan (Letairis)
- Start 5 mg daily (may increase to 10 mg daily)
- Macitentan (Opsumit)
- Start 10 mg orally daily
- Sitaxsentan
V. Drug Interactions
-
Oral Contraceptives (OCP)
- May reduce OCP efficacy
-
Warfarin
- Increased INR
VI. Adverse Effects
- Peripheral Edema
- Flushing
- Headache
- Liver Function Test abnormalities
VII. Safety
- FDA pregnancy category X
- Monitoring
- Liver Function Testing monthly (hepatotoxicity risk)