II. Indications

  1. Pumonary Arterial Hypertension
    1. Bosentan (Tracleer)
    2. Ambrisentan (Letairis)
    3. Macitentan (Opsumit)
    4. Sitaxsentan
  2. Hypertension (fourth-line, refractory)
    1. Aprocitentan
  3. Cancer (e.g. Prostate Cancer, Colorectal Cancer, experimental)
    1. Endothelins inhibition may decrease tumor growth, progression, and Angiogenesis

III. Mechanism

  1. Endothelin is a vasonstrictor and Aldosterone mediator
  2. Endothelin Receptor Antagonists inhibit endothelin activity, resulting in vasodilation

IV. Dosing: Pulmonary Hypertension

  1. Bosentan (Tracleer)
    1. Start 62.5 mg orally twice daily (may increase to 125 mg twice daily)
  2. Ambrisentan (Letairis)
    1. Start 5 mg daily (may increase to 10 mg daily)
  3. Macitentan (Opsumit)
    1. Start 10 mg orally daily
  4. Sitaxsentan

V. Drug Interactions

  1. Oral Contraceptives (OCP)
    1. May reduce OCP efficacy
  2. Warfarin
    1. Increased INR

VI. Adverse Effects

VII. Safety

  1. FDA pregnancy category X
  2. Monitoring
    1. Liver Function Testing monthly (hepatotoxicity risk)

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