Olanzapine for Postoperative Nausea and Vomiting: Clinical Evidence and Guidelines

Introduction to Olanzapine's Mechanism and Efficacy

The American Society of Anesthesiologists recommends considering olanzapine as an add-on to standard prophylaxis for high-risk surgical patients, given its broad-spectrum antagonism of multiple neurotransmitter receptors, providing a multimodal antiemetic effect through a single agent, with standard first-line agents (ondansetron, dexamethasone) each providing approximately 25% relative risk reduction when used individually, with combination therapy improving efficacy 1, 2

The World Journal of Emergency Surgery suggests that olanzapine's multi-receptor antagonism provides broader coverage than single-mechanism agents, potentially explaining its superior efficacy in high-risk patients who fail standard dual prophylaxis, with a single preoperative dose of olanzapine 10 mg combined with dexamethasone and ondansetron reducing PONV incidence from 63% to 26% in the first 24 hours postoperatively (RR 0.40, 95% CI 0.21-0.79, p=0.008) 1
The ERAS Society guidelines, as reported in the World Journal of Emergency Surgery, recommend ondansetron plus dexamethasone as first-line dual therapy, but suggest reserving olanzapine for high-risk patients (≥3 Apfel risk factors) who have failed or are predicted to fail standard dual prophylaxis, rather than using it as routine first-line therapy, with olanzapine 10 mg added to standard dual prophylaxis (dexamethasone plus ondansetron) reducing postdischarge nausea and vomiting from 38% to 14% (RR 0.37, 95% CI 0.20-0.72, p=0.003) 3, 4