Can finasteride be continued perioperatively without any modification to the anesthetic plan for general, regional, or monitored anesthesia care?

Finasteride and Anesthesia

Finasteride can be safely continued perioperatively without any modification to the anesthetic plan for general, regional, or monitored anesthesia care. No evidence exists demonstrating clinically significant interactions between finasteride and anesthetic agents or techniques.

Pharmacologic Rationale for Continuation

Finasteride's mechanism of action does not interfere with anesthetic management. The drug is a specific competitive inhibitor of 5α-reductase that converts testosterone to dihydrotestosterone, with no binding affinity for androgen receptors and no androgenic, antiandrogenic, or other steroid hormone-related properties that would affect cardiovascular or respiratory physiology during anesthesia 1.

Key Pharmacokinetic Properties Supporting Perioperative Safety

• Finasteride has a terminal elimination half-life of 4.7-7.1 hours, with steady-state achieved through slow accumulation over multiple doses 2.
• The drug undergoes extensive hepatic metabolism to essentially inactive metabolites eliminated through bile and urine, with no clinically significant accumulation even in renal dysfunction 2.
• No drug interactions of clinical importance have been reported with finasteride, including in large-scale studies of over 3,000 patients 3.

Anesthetic Technique Selection

The choice of anesthetic technique (general, regional, or monitored anesthesia care) should be based on surgical and patient factors rather than finasteride use, as the ACC/AHA guidelines explicitly state that the choice of anesthetic technique is best left to the discretion of the anesthesia care team 4.

General Anesthesia Considerations

• Volatile anesthetic agents (sevoflurane, desflurane, isoflurane) can be used without concern for finasteride interaction 4, 5.
• Opioid-based anesthetics are compatible with finasteride therapy 4.
• No modification to standard hemodynamic monitoring or intraoperative management is required for patients taking finasteride 4.

Regional Anesthesia Considerations

• Neuraxial techniques (epidural, spinal) are safe in patients on finasteride, as the drug does not affect coagulation parameters 4, 5, 6.
• Standard anticoagulation screening applies (platelet count ≥70,000 × 10⁹/L for insertion, INR ≤1.4 if on warfarin) without additional restrictions from finasteride 6.
• Finasteride does not alter the risk-benefit calculation for regional versus general anesthesia in procedures where either technique is appropriate 4, 5.

Monitored Anesthesia Care

• Finasteride does not contraindicate monitored anesthesia care when appropriate for the surgical procedure 4, 7.
• The standard caveat applies that inadequate local anesthesia with monitored anesthesia care can increase myocardial ischemia risk, but this is unrelated to finasteride use 4, 7.

Cardiovascular Safety Profile

Finasteride has no clinically significant cardiovascular effects that would alter perioperative risk stratification. In the 4-year PLESS trial of 3,040 men, no significant differences were found between placebo and finasteride-treated patients in the incidence of cardiovascular adverse events in either younger (45-64 years) or older (≥65 years) cohorts 3.

• The drug does not affect cardiac contractility, afterload, or preload 2.
• No special intraoperative hemodynamic monitoring is required beyond what the surgical procedure and patient comorbidities dictate 4.
• Standard ACC/AHA recommendations to maintain mean arterial pressure >60 mmHg and avoid decreases >20% from baseline apply equally to patients on finasteride 5, 7.

Common Pitfalls to Avoid

• Do not discontinue finasteride perioperatively based on unfounded concerns about drug interactions—no evidence supports this practice 2, 1, 3.
• Do not attribute perioperative depression or anxiety solely to anesthesia in patients on chronic finasteride, as these are known adverse effects of the drug itself that may be present preoperatively 8, 9.
• Do not confuse finasteride's neuroactive steroid effects with anesthetic sensitivity—while finasteride decreases α-reduced neurosteroids and increases 5β-reduced metabolites that modulate GABA receptors, this does not translate to clinically significant alterations in anesthetic requirements 8.

Practical Management Algorithm

1. Continue finasteride through the perioperative period without dose adjustment 2, 3.
2. Select anesthetic technique based on surgical requirements, patient comorbidities, and institutional expertise—not on finasteride use 4, 5.
3. Apply standard monitoring protocols without modification for finasteride 4.
4. Resume finasteride postoperatively as soon as oral intake is tolerated, as the drug's long half-life and slow accumulation pattern make brief interruptions clinically insignificant 2.