Should I take ambrisentan (Endothelin receptor antagonist) before surgery?

Management of Ambrisentan (Endothelin Receptor Antagonist) Before Surgery

Ambrisentan should be discontinued before surgery, with the last dose given 2-3 days prior to the procedure to minimize the risk of perioperative hypotension. 1

Perioperative Management of Ambrisentan

Rationale for Discontinuation

• Endothelin receptor antagonists like ambrisentan can cause significant hypotension during anesthesia induction
• Similar to angiotensin receptor blockers (ARBs), these medications affect vascular tone and can lead to refractory hypotension during surgery 2

Timing of Discontinuation

Based on pharmacokinetic properties and clinical evidence:

• For minor procedures with low bleeding risk:

  • Last dose: 2 days before surgery
  • This allows approximately 4-5 half-lives to elapse (ambrisentan half-life is 7-8 hours)

• For major procedures with high bleeding risk:

  • Last dose: 3 days before surgery
  • This provides additional time for drug clearance and minimizes risk of hemodynamic instability

Special Considerations

• Renal function impact:
  • Normal or mild impairment: 2 days before surgery
  • Moderate impairment: 3 days before surgery
  • Severe impairment: Consider 4 days before surgery

Perioperative Hemodynamic Concerns

Research has shown that patients who continue endothelin receptor antagonists and similar vasodilatory medications before surgery experience:

• More frequent episodes of hypotension
• Longer duration of hypotensive episodes
• Increased need for vasopressor support 2

The 2014 ACC/AHA guidelines on perioperative cardiovascular evaluation provide similar recommendations for ARBs, which have comparable hemodynamic effects to endothelin receptor antagonists:

• "Continuation of ACE inhibitors or ARBs is reasonable perioperatively" (Class IIa, Level of Evidence B) 1
• "If ACE inhibitors or ARBs are held before surgery, it is reasonable to restart as soon as clinically feasible postoperatively" (Class IIa, Level of Evidence C) 1

Postoperative Resumption

• Resume ambrisentan once hemodynamic stability is achieved, typically 24-48 hours after surgery
• Consider the following factors before resuming:
  • Hemodynamic stability
  • Adequate oral intake
  • Absence of significant postoperative complications
  • Normal renal function

Monitoring Recommendations

• Monitor blood pressure closely during anesthesia induction and throughout the perioperative period
• Have vasopressors readily available to treat potential hypotension
• Consider more intensive hemodynamic monitoring for high-risk patients

Common Pitfalls to Avoid

1. Continuing ambrisentan on the day of surgery - this significantly increases the risk of refractory hypotension during anesthesia induction
2. Restarting too early postoperatively - wait until hemodynamic stability is confirmed
3. Failing to communicate the medication management plan with the entire perioperative team

Remember that the management of ambrisentan should be discussed with the entire perioperative team, including the surgeon, anesthesiologist, and other specialists involved in the patient's care.