Efficacy of Prophylactic Ondansetron in Preventing Post-Spinal Hypotension during Cesarean Delivery: A Prospective Randomized Controlled Trial

Background: Post-spinal hypotension represents the most frequent complication of obstetric anesthesia, with an incidence of 60%–80% in parturients. This complication primarily results from sympathetic blockade induced by local anesthetics, leading to vasodilation and decreased venous return. Ondansetron, a selective 5-HT3 receptor antagonist, shows promising preventive potential by blocking the serotonergic mechanisms involved in hypotension. Objective: To evaluate the efficacy and safety of prophylactic ondansetron in preventing post-spinal hypotension during elective cesarean deliveries, comparing two different dosages of ondansetron. Methods: This prospective, randomized, double-blind, placebo-controlled study included 150 ASA I-II parturients scheduled for cesarean delivery under spinal anesthesia. Patients were randomized into three groups: Group A (ondansetron 8 mg, n = 50), Group B (ondansetron 4 mg, n = 50), and Group C (placebo, n = 50). Intravenous administration 15 minutes before spinal anesthesia. Primary endpoints: Incidence of hypotension, bradycardia, nausea-vomiting, and ephedrine consumption. Results: Ondansetron demonstrated significant efficacy in preventing post-spinal hypotension in the present study. The incidence of hypotension was significantly reduced in the ondansetron groups: 22% (Group A) and 20% (Group B) vs. 96% (Group C) (p