A Comparison of the Efficacy of Metoclopramide and Ondansetron in Reducing Nausea and Vomiting during Spinal Anesthesia for Elective Cesarean Section

Determining the Effectiveness of Metoclopramide and Ondansetron in Reducing Nausea and Vomiting During Spinal Anesthesia in Elective Cesarean Section

This study is a randomized, double‑blind, parallel‑group, phase 3 clinical trial. One hundred elective cesarean patients will be enrolled and allocated into two groups using the Excel RAND function. The intervention is administered 5 minutes before spinal anesthesia, and both participants and outcome assessors are blinded to group allocation.

This randomized double-blind trial at Kosar Hospital compares metoclopramide and ondansetron for reducing nausea and vomiting during spinal anesthesia. Patients receive one of the drugs 5 minutes before anesthesia. Spinal anesthesia is standardized. Both patients and the outcome assessor are blinded, with drugs prepared in identical syringes by an independent provider.

Inclusion criteria: women aged 18–40 years, informed consent, singleton pregnancy undergoing elective cesarean section, and ASA physical status I–II. Exclusion criteria: withdrawal of consent, known hypersensitivity to metoclopramide or ondansetron (or their components), and occurrence of drug-related adverse effects.

The intervention includes two groups: Metoclopramide group (M): Patients receive 10 mg of intravenous metoclopramide. Ondansetron group (O): Patients receive 4 mg of intravenous ondansetron. In both groups, the study drug will be diluted with normal saline to an equal volume (5 mL) and administered as a slow intravenous injection 5 minutes before spinal anesthesia. The timing, injection volume, administration rate, anesthesia protocol, and pre‑anesthetic care will be identical in both groups. The selected doses and timing are based on previous studies and commonly used protocols.

nausea and vomiting

Participants will be randomized using block randomization with fixed block sizes of four. The random allocation sequence will be generated by computer software, and within each block, patients will be randomly assigned to either Group A or Group B. To prevent selection bias, allocation concealment will be ensured using the SNOSE method (Sequentially Numbered, Opaque, Sealed Envelopes). The random sequence will be placed inside opaque, sequentially numbered, sealed envelopes, which will be opened only after participant enrollment.

To maintain blinding, both medications (metoclopramide and ondansetron) are clear, colorless injectable solutions and are indistinguishable in appearance, volume, and method of administration. The medications will be prepared by an independent person in identical unlabelled syringes and coded as A/B. Therefore, both participants and outcome assessors will remain unaware of the allocated intervention, ensuring effective blinding at both participant and assessor levels.