A Phase 4 interventional study of Ondansetron and Placebo (0.9% Sodium Chloride) in Hypotension, Spinal Anesthesia and Cesarean Section, sponsored by Saglik Bilimleri Universitesi Gazi Yasargil Training and Research Hospital. Completed at 1 site in Turkey (Türkiye). Open to female participants aged 18 Years to 45 Years. Per ClinicalTrials.gov, last updated 2026-10-21.
Sponsored by Saglik Bilimleri Universitesi Gazi Yasargil Training and Research Hospital · Phase 4, Interventional, and Prevention
Spinal anesthesia is the preferred technique for elective cesarean section, but it frequently causes maternal hypotension due to sympathetic blockade and the Bezold-Jarisch reflex, which can threaten both mother and baby. Ondansetron, a serotonin 5-HT3 receptor antagonist commonly used to prevent nausea and vomiting, may attenuate this reflex.
The purpose of this prospective, randomized, controlled, single-blind study is to evaluate whether a single prophylactic intravenous dose of ondansetron (4 mg) given before spinal anesthesia reduces the incidence of hypotension in women undergoing elective cesarean section. Vasopressor (ephedrine) requirement, heart rate, postspinal shivering, intraoperative nausea and vomiting, and newborn Apgar scores are also compared between the ondansetron and control (saline) groups.
Design: Prospective, randomized, controlled, single-blind (participant), parallel-group, single-center trial conducted in the operating rooms of University of Health Sciences Gazi Yasargil Training and Research Hospital, Diyarbakir, Turkey.
Participants: Term pregnant women aged 18-45 years, ASA physical status II, with a singleton pregnancy, scheduled for elective cesarean section under spinal anesthesia.
Randomization: Eligible participants are allocated 1:1 by computer-generated simple randomization to the ondansetron group or the control group. The study solutions are identical in appearance, so participants are unaware of their group allocation.
Interventions: Ten minutes before spinal anesthesia, the ondansetron group receives 4 mg ondansetron in 100 mL of 0.9% sodium chloride warmed to 37°C as an intravenous infusion; the control group receives 100 mL of 0.9% sodium chloride warmed to 37°C under the same conditions.
Anesthesia protocol: Operating room temperature is maintained at 20±2°C. Spinal anesthesia is performed in the sitting position at the L4-L5 interspace with a 26G sharp-tip spinal needle using 0.5% hyperbaric bupivacaine, dosed according to the patient's height and weight. Simultaneously with spinal anesthesia, 20 mL/kg crystalloid (Ringer's lactate or 0.9% sodium chloride) is given as a rapid co-load infusion. Patients are positioned supine with approximately 15° left lateral tilt. After delivery, oxytocin is given as a 3 IU IV bolus followed by a 3 IU/hour infusion. The highest sensory block level is assessed by pin-prick.
Hemodynamic management: Hypotension is defined as a mean arterial pressure (MAP) below 65 mmHg or a decrease of 20% or more from baseline at any measurement time. Hypotension is treated with 10 mg IV ephedrine, repeated as needed. Bradycardia (heart rate below 50 beats/min) with hypotension is treated with 0.5 mg IV atropine. Intraoperative nausea or vomiting is treated with 4 mg IV ondansetron as a rescue antiemetic regardless of group.
Monitoring: Systolic, diastolic and mean arterial pressure, heart rate and SpO2 are recorded at baseline (before spinal anesthesia), at 3, 6, 9, 12, 15, 20, 25, 30 and 35 minutes after spinal anesthesia, and postoperatively. Nausea-vomiting episodes, postspinal shivering (Crossley and Mahajan five-point scale; grade 2 or higher considered clinically significant), total ephedrine and atropine use, sensory and motor block levels, and 1- and 5-minute Apgar scores are recorded.
Withdrawal criteria: Need for intraoperative sedation, conversion to general anesthesia due to failed spinal anesthesia, serious drug reactions, other technical failures (including prolonged surgery), data loss, or participant withdrawal.
Sample size: Power analysis (G*Power; alpha 0.05, power 80%) indicated a minimum of 47 participants per group (94 in total); allowing for dropouts, 102 participants were planned.
Statistical analysis: Group comparisons are performed using Welch's t-test, Mann-Whitney U test, Pearson chi-square or Fisher's exact test as appropriate; changes in MAP over time are analyzed with repeated-measures ANOVA. A p value \< 0.05 is considered statistically significant.
1,021 studies on the registry are indexed under Hypotension; 172 are open to participants now.
This study's enrollment of 96 is above the median of 80 across 686 interventional studies indexed under Hypotension.
Browse Hypotension studies →Saglik Bilimleri Universitesi Gazi Yasargil Training and Research Hospital is the lead sponsor of 58 studies on the registry; 24 are open to participants now.
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Participants receive 4 mg intravenous ondansetron in 100 mL of warmed (37°C) 0.9% sodium chloride, infused starting 10 minutes before spinal anesthesia with 0.5% hyperbaric bupivacaine, plus 20 mL/kg crystalloid co-load.
Drug: Ondansetron
Participants receive 100 mL of warmed (37°C) 0.9% sodium chloride, identical in appearance, infused starting 10 minutes before spinal anesthesia with 0.5% hyperbaric bupivacaine, plus 20 mL/kg crystalloid co-load.
Drug: Placebo (0.9% Sodium Chloride)
A single dose of 4 mg ondansetron diluted in 100 mL of 0.9% sodium chloride warmed to 37°C, administered as an intravenous infusion starting 10 minutes before spinal anesthesia.
100 mL of 0.9% sodium chloride warmed to 37°C, identical in appearance to the study solution, administered as an intravenous infusion starting 10 minutes before spinal anesthesia.
Incidence of Spinal Anesthesia-Induced Hypotension
Percentage of participants who develop hypotension, defined as a mean arterial pressure (MAP) below 65 mmHg or a decrease of 20% or more from baseline MAP at any measurement time after spinal anesthesia. MAP is recorded at baseline and at 3, 6, 9, 12, 15, 20, 25, 30 and 35 minutes after spinal anesthesia.
Time frame: From intrathecal injection until the end of surgery (up to 60 minutes)
Total Ephedrine Consumption
Total dose (mg) of intravenous ephedrine administered to treat hypotension (10 mg boluses, repeated as needed).
Time frame: From intrathecal injection until the end of surgery (up to 60 minutes)
Mean Arterial Pressure Over Time
Mean arterial pressure (mmHg) measured non-invasively at baseline (before spinal anesthesia) and at 3, 6, 9, 12, 15, 20, 25, 30 and 35 minutes after spinal anesthesia, and postoperatively.
Time frame: Baseline and 3, 6, 9, 12, 15, 20, 25, 30 and 35 minutes after spinal anesthesia, and postoperatively
Heart Rate and Incidence of Bradycardia
Heart rate (beats/min) at the same time points as blood pressure; bradycardia is defined as heart rate below 50 beats/min, and the number of participants requiring 0.5 mg IV atropine is recorded.
Time frame: Baseline and 3, 6, 9, 12, 15, 20, 25, 30 and 35 minutes after spinal anesthesia, and postoperatively
Incidence of Postspinal Shivering
Percentage of participants with clinically significant shivering, defined as grade 2 or higher on the five-point Crossley and Mahajan shivering scale.
Time frame: From intrathecal injection until the end of surgery (up to 60 minutes)
Incidence of Intraoperative Nausea and Vomiting
Percentage of participants experiencing at least one episode of nausea or vomiting during surgery.
Time frame: From intrathecal injection until the end of surgery (up to 60 minutes)
Neonatal Apgar Scores
Apgar scores of the newborn at 1 and 5 minutes after delivery (scale 0-10; higher scores indicate better neonatal condition).
Time frame: 1 and 5 minutes after delivery
Plan to share: No — Individual participant data will not be shared publicly; anonymized data may be made available by the investigators upon reasonable request.
No publications or documents are linked to this record.
Ran from Feb 2026 to primary completion in Jul 2026, 5 months.
Of 69 non-industry phase 4 interventional studies under Hypotension, half reached primary completion within 12 months of starting (the median), counting those still running; a quarter within 5 and three quarters within 23. This study's 5 months is below that.
Counting every sponsor, half of 76 studies reached it within 12 months; a quarter within 5 and three quarters within 23.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is completed, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Ondansetron
Saglik Bilimleri Universitesi Gazi Yasargil Training and Research Hospital