Prophylactic Ondansetron for Preventing Spinal Anesthesia-Induced Hypotension in Elective Cesarean Section

NCT07886151 | Completed Phase 4

• 2 other identifiers: 34176196
• Study Type: interventional
• Target: 96
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Hypotension; Cesarean Section; Spinal Anesthesia

Keywords

Ondansetron; Spinal anesthesia-induced hypotension; Bezold-Jarisch reflex; Shivering; Ephedrine; Obstetric anesthesia

Outcome Measures

Primary Outcomes (1)

• 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.

  From intrathecal injection until the end of surgery (up to 60 minutes)

Secondary Outcomes (6)

• Total Ephedrine Consumption

  From intrathecal injection until the end of surgery (up to 60 minutes)

• Mean Arterial Pressure Over Time

  Baseline and 3, 6, 9, 12, 15, 20, 25, 30 and 35 minutes after spinal anesthesia, and postoperatively

• Heart Rate and Incidence of Bradycardia

  Baseline and 3, 6, 9, 12, 15, 20, 25, 30 and 35 minutes after spinal anesthesia, and postoperatively

• Incidence of Postspinal Shivering

  From intrathecal injection until the end of surgery (up to 60 minutes)

• Incidence of Intraoperative Nausea and Vomiting

  From intrathecal injection until the end of surgery (up to 60 minutes)

Study Arms (2)

Ondansetron Group

EXPERIMENTAL

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

Control Group

PLACEBO COMPARATOR

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)

Interventions

Ondansetron DRUG

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.

Ondansetron Group

Placebo (0.9% Sodium Chloride) DRUG

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.

Control Group

Eligibility Criteria

• Age: 18 Years - 45 Years
• Gender Eligibility Details: Only pregnant women scheduled for elective cesarean section are eligible.
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• Age 18-45 years
• Term pregnancy
• Singleton pregnancy
• Scheduled for elective cesarean section
• American Society of Anesthesiologists (ASA) physical status II
• Accepting spinal anesthesia as the anesthetic technique
• Written informed consent

You may not qualify if:

• Emergency cesarean section
• ASA physical status III or higher
• Allergy to ondansetron or other 5-HT3 receptor antagonists
• Multiple pregnancy
• Preeclampsia, eclampsia or HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome
• Active smoking
• Pre-existing serious cardiac disease or history of QT prolongation
• Need for intraoperative sedation or conversion to general anesthesia
• Surgery lasting longer than one hour

Sponsors & Collaborators

• Saglik Bilimleri Universitesi Gazi Yasargil Training and Research Hospital: lead

Study Sites (1)

Saglik Bilimleri Universitesi Gazi Yasargil Training and Research Hospital

Diyarbakır, 21070, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Hypotension

Interventions

Ondansetron; Sodium Chloride

Condition Hierarchy (Ancestors)

Vascular Diseases; Cardiovascular Diseases

Intervention Hierarchy (Ancestors)

Imidazoles; Azoles; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds; Carbazoles; Indoles; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Heterocyclic Compounds, 3-Ring; Chlorides; Hydrochloric Acid; Chlorine Compounds; Inorganic Chemicals; Sodium Compounds

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Masking Details: Single-blind: the ondansetron and control solutions (100 mL 0.9% sodium chloride, warmed to 37°C) are identical in appearance, so participants are unaware of their group allocation.
• Purpose: PREVENTION
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Resident Physician, Department of Anesthesiology and Reanimation

Model Details: Participants are randomized 1:1 to receive either prophylactic intravenous ondansetron or an equal volume of 0.9% sodium chloride (control) 10 minutes before spinal anesthesia.

Study Record Dates

• First Submitted: October 14, 2026
• First Posted: October 21, 2026
• Study Start: February 2, 2026
• Primary Completion: July 10, 2026
• Study Completion: July 10, 2026
• Last Updated: October 21, 2026

Record last verified: 2026-10

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)