Intrathecal Morphine 75 mcg Versus 100 mcg for Post-Cesarean Analgesia: A Randomized Double-blind Trial (ITM-CESAREAN)

Efficacy and Safety of Two Doses of Intrathecal Morphine (75 mcg Versus 100mcg) for Postoperative Analgesia After Elective Cesarean Section: A Prospective, Randomized, Double-blind Controlled Trial

This study evaluates the efficacy and safety of two different doses of intrathecal morphine (75 mcg versus 100 mcg) for postoperative analgesia in patients undergoing elective cesarean delivery under spinal anesthesia. Effective postoperative pain control is essential to improve maternal recovery, facilitate early mobilization, and enhance neonatal care. Participants were randomly of assigned to receive either 75 mcg or 100 mcg of intrathecal morphine dose that provides effective analgesia while minimizing adverse effects in the obstetric population.

Study Overview

• Status: Completed
• Conditions: Postoperative Pain; Cesarean Section; Obstetric Anesthesia
• Intervention / Treatment: Drug: Intrathecal Morphine

Detailed Description

This prospective, randomized, double-blind controlled trial was designed to compare the analgesic efficacy and safety of two doses of intrathecal morphine (75 mcg versus 100 mcg) in patients undergoing elective cesarean delivery under spinal anesthesia. A total of 240 ASA physical status II patients schedule for elective cesarean delivery were enrolled and randomly assigned into two parallel groups. Patients received either 75 mcg or 100 mcg of intrathecal morphine as part of a standardized spinal anesthesia technique using local anesthetic. Randomization was performed using a predefined allocation method, and both patients and outcome assessors were blinded to group assignment. Perioperative management was standardized across both groups to minimize confounding variables. Postoperative pain intensity was assessed using the Visual Analog Scale (VAS) at 2, 4, 8, 12 and 24 hours following surgery. The primary outcome was VAS pain score at 24 hours. Secondary outcomes included pain scores at earlier time points, requirement for rescue analgesia, incidence of opioid-related adverse effects (nausea, vomiting, pruritus), and neonatal outcomes assessed by Apgar scores. The objetive of this study was to determinethe optimal intrathecal morphine dose that provides effective postoperative analgesia while minimizing adverse effects in the obstetric population. The study was conducted in accordance with institutional ethical standards and approved by the corresponding ethics committee.

• Study Type: Interventional
• Enrollment (Actual): 240
• Phase: Phase 4

Contacts and Locations

Study Locations

• Venezuela
  • Miranda
    • Caracas, Miranda, Venezuela, 1040
      • Hospital Universitario de Caracas

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Pregnant women scheduled for elective cesarean delivery under spinal anesthesia.
• Age between 18 and 45 years.
• ASA physical status II
• Singleton term pregnancy.
• Ability to provide written informed consent.

Exclusion Criteria:

• Contraindications to spinal anesthesia.
• Known allergy or hypersensitivity to morphine or opioids.
• Chronic opioid use or opioid dependence.
• Significant systemic disease (ASA more or equal to III).
• Pregnancy complications (e.g., preeclampsia, eclampsia).
• Body mass index more than 40 kg/m2.
• Infection at the puncture site.
• Coagulopathy or anticoagulant therapy.
• Refusal to participate.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Intrathecal Morphine 75 mcg; Participants receive a single intrathecal dose of 75 mcg morphine during spinal anesthesia for elective cesarean delivery.	Drug: Intrathecal Morphine; Intrathecal administration of preservative-free morphine sulfate at doses of 75 mcg or 100 mcg as part of spinal anesthesia for elective cesarean delivery. The drug is administered once at the time the spinal anesthesia to provide postoperative analgesia.; Other Names: Morphine sulfate
Experimental: Intrathecal Morphine 100 mcg; Participants receive a single intrathecal dose of 100 mcg morphine during spinal anesthesia for elective cesarean delivery.	Drug: Intrathecal Morphine; Intrathecal administration of preservative-free morphine sulfate at doses of 75 mcg or 100 mcg as part of spinal anesthesia for elective cesarean delivery. The drug is administered once at the time the spinal anesthesia to provide postoperative analgesia.; Other Names: Morphine sulfate

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative pain intensity at 24 hours	Pain intensity will be assessed using the Visual Analog Scale (VAS, 0-10), where 0 indicates no pain and 10 indicates worst imaginable pain. Measurements will be recorded at 2, 4, 8, 12 and 24 hours after surgery. The primary endpoint is the VAS score at 24 hours.	24 hours after cesarean delivery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total opioid consumption within 24 horas	Total supplemental opioid requirement (e.g., tramadol or morphine equivalents) during the first 24 hours postoperatively.	0 - 24 hours after surgery
Incidence of postoperative nausea and vomiting (PONV)	Number of patients experiencing nausea and/or vomiting requiring treatment.	0 - 24 hours after surgery.
Incidence of pruritus	Number of patients reporting clinically significant itching requiring treatment.	0 - 24 hours after surgery.
Time to first rescue analgesia	Time elapsed from spinal anesthesia to first request for additional analgesia.	0 - 24 hours after surgery.
Neonatal outcome	Apgar scores assessed at 1 and 5 minutes after birth	at birth (1 and 5 minutes)

Collaborators and Investigators

• Sponsor: Hospital Universitario de Caracas
• Investigators: Principal Investigator: Joseph a Veraza, Md, Hospital Universitario de Caracas

Publications and helpful links

Helpful Links

• Non-opioid analgesics for chronic postsurgical pain
• Optimal dose of intrathecal morphine for cesarean delivery
• ERAS Society recommendations for cesarean delivery
• Intrathecal morphine dose in total hip surgery

Study record dates

Study Major Dates

• Study Start (Actual): January 7, 2023
• Primary Completion (Actual): June 15, 2024
• Study Completion (Actual): July 17, 2024

Study Registration Dates

• First Submitted: April 1, 2026
• First Submitted That Met QC Criteria: April 1, 2026
• First Posted (Actual): April 8, 2026

Study Record Updates

• Last Update Posted (Actual): April 8, 2026
• Last Update Submitted That Met QC Criteria: April 1, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: spinal anesthesia; postoperative analgesia; cesarean delivery; visual analog scale; intrathecal morphine; opioid side effects
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Postoperative Complications; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain, Postoperative; Heterocyclic Compounds; Heterocyclic Compounds, Fused-Ring; Alkaloids; Polycyclic Aromatic Hydrocarbons; Polycyclic Compounds; Heterocyclic Compounds, 4 or More Rings; Morphinans; Opiate Alkaloids; Heterocyclic Compounds, Bridged-Ring; Phenanthrenes; Morphine Derivatives; Morphine
• Other Study ID Numbers: HUC-ITM-2023-01

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: Individual participant data (IPD) sharing has not yet been determined. Data may be shared upon reasonable request after study completion, subject to institutional approval, ethical considerations, and data protection regulations.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No