Evaluation and comparison of the preventive effect of intravenous dexmedetomidine and meperidine on the intensity and incidence of postoperative pain following cesarean section under spinal anesthesia
Design
A phase III randomized, triple‑blind, parallel‑group clinical trial including 120 patients. Randomization was performed in blocks of 15 using the random.org website.
Settings and conduct
This randomized, triple-blind clinical trial is conducted at Shahid Beheshti Hospital of Isfahan. After obtaining written informed consent, eligible patients undergo spinal anesthesia. The participants are then randomly assigned to one of three groups to receive the designated intravenous drug. The study drugs are prepared by the anesthesiologist in identical and coded syringes. Following delivery, pain intensity, side effects, and patient satisfaction are assessed for up to eight hours.
Participants/Inclusion and exclusion criteria
Women aged 18 to 45 years with ASA class II status who are admitted to Shahid Beheshti Hospital of Isfahan for elective cesarean section under spinal anesthesia will be included in the study. Exclusion criteria consist of cardiovascular, pulmonary, renal, hepatic, or psychiatric diseases; diabetes or thyroid disorders; body temperature outside the range of 36.5–37.5 °C; history of alcohol or substance abuse; use of vasodilator medications; or the need for intraoperative blood transfusion. Patients experiencing spinal anesthesia failure or any unexpected complications during the procedure will be excluded from the study.
Intervention groups
1.Dexmedetomidine group: 10 µg of IV dexmedetomidine
2.Meperidine group: 10 mg of IV meperidine
3.Control group: 10 mL of IV normal saline
Main outcome variables
Pain intensity; need for additional analgesics; adverse events (hypotension, bradycardia, nausea/vomiting); patient satisfaction level.
General information
Reason for update
Acronym
IRCT registration information
IRCT registration number:IRCT20240221061070N8
Registration date:2025-11-18, 1404/08/27
Registration timing:prospective
Last update:2025-11-18, 1404/08/27
Update count:0
Registration date
2025-11-18, 1404/08/27
Registrant information
Name
Milad Masaeli
Name of organization / entity
Country
Iran (Islamic Republic of)
Phone
+98 913 106 6709
Email address
drmilmas@med.mui.ac.ir
Recruitment status
Recruitment complete
Funding source
Expected recruitment start date
2025-11-22, 1404/09/01
Expected recruitment end date
2026-02-20, 1404/12/01
Actual recruitment start date
empty
Actual recruitment end date
empty
Trial completion date
empty
Scientific title
Comparative study of the preventive effect of intravenous meperidine and intravenous dexmedetomidine on analgesia after cesarean section
Public title
Effect of Meperidine and Dexmedetomidine on Post‑Cesarean Analgesia
Purpose
Prevention
Inclusion/Exclusion criteria
Inclusion criteria:
Pregnant women classified as ASA II
Age range between 18 and 45 years
Candidates for elective cesarean section under spinal anesthesia
Written informed consent to participate in the study
No known allergy to the study medications (meperidine or dexmedetomidine)
Exclusion criteria:
Known cardiac, pulmonary, hepatic, or renal disease
Psychiatric disorders, diabetes mellitus, or thyroid dysfunction
Body temperature at operating room admission < 36.5 °C or > 37.5 °C
History of alcohol or substance abuse
Use of vasodilator medications
Requirement of intraoperative blood transfusion
Age
From 18 years old to 45 years old
Gender
Female
Phase
Bioequivalence
Groups that have been masked
Participant
Care provider
Investigator
Outcome assessor
Data analyser
Data and Safety Monitoring Board
Sample size
Target sample size:
120
Randomization (investigator's opinion)
Randomized
Randomization description
Participants are randomly assigned to one of three groups (meperidine, dexmedetomidine, or placebo) using block randomization (blocks of 15) generated through random.org. Allocation concealment is maintained through sealed opaque envelopes prepared by an independent statistician. The study is triple‑blind (investigator, participants, and outcome assessor).
Blinding (investigator's opinion)
Triple blinded
Blinding description
This clinical trial is conducted under a triple‑blind design to ensure unbiased assessment of outcomes.
The study drugs (meperidine, dexmedetomidine, and normal saline) are prepared by an anesthesiologist not involved in data collection, using identical, coded syringes labeled A, B, and C.
Only the anesthesiologist and the randomization coordinator know the allocation code until data analysis is completed.
The principal investigator, participants, clinical caregivers, outcome assessor (VAS), and data analyst are all blinded to group assignment.
At the end of the study, the randomization codes are disclosed by an independent statistician for final data analysis.
Placebo
Used
Assignment
Parallel
Other design features
Secondary Ids
empty
Ethics committees
1
Ethics committee
Name of ethics committee
Research Ethics Committees of School of Medicine - Isfahan University of Medical Sciences
Street address
Al-Zahra Hospital, Daneshgah Street.
City
Isfahan
Province
Isfehan
Postal code
8174673461
Approval date
2025-10-05, 1404/07/13
Ethics committee reference number
IR.ARI.MUI.REC.1404.175
Health conditions studied
1
Description of health condition studied
Post‑Cesarean Pain (Postoperative Pain after Cesarean Section)
ICD-10 code
G89.18
ICD-10 code description
Other acute postprocedural pain
Primary outcomes
1
Description
Postoperative pain intensity after cesarean section
Timepoint
At baseline (0 hour), 2 hours, 4 hours, 6 hours, and 8 hours after surgery
Method of measurement
The primary variable (postoperative pain intensity) will be measured using the Visual Analogue Scale for pain assessment. This scale consists of a 10‑centimeter horizontal line with “no pain” marked at one end (score 0) and “the worst pain imaginable” at the other end (score 10). At each predefined postoperative time point (0, 2, 4, 6, and 8 hours after the cesarean section), the patient will indicate the intensity of pain by marking a point on the line corresponding to their perceived pain level. The score is obtained by measuring the distance in centimeters from the “no pain” anchor to the patient’s mark. Before surgery, all participants will be instructed on how to use the scale to ensure a consistent and valid understanding of pain rating across subjects.