Analgesic Equivalence of NSAIDs and Tramadol in Acute Postoperative Pain Following Minimally Invasive Surgery

Analgesic Equivalence of NSAIDs and a Weak Opioid in Acute Postoperative Pain Following Minimally Invasive Surgery Under Balanced General Anaesthesia: A Pilot Randomised Controlled Trial

This pilot randomised controlled trial compared the analgesic equivalence of three intravenous premedication regimens - tramadol 150 mg, ketorolac 60 mg, and diclofenac 150 mg - in adult patients undergoing elective minimally invasive surgery under balanced general anaesthesia. The primary outcome was postoperative pain intensity measured using the Numerical Rating Scale (NRS 0-10) at recovery room arrival and at 30, 60, and 90 minutes thereafter.

Study Overview

• Status: Completed
• Conditions: Postoperative Pain; Acute Pain
• Intervention / Treatment: Drug: Tramadol; Drug: Ketorolac; Drug: Diclofenac

Detailed Description

Acute postoperative pain remains inadequately managed in a substantial proportion of surgical patients, with particular challenges in resource-limited settings where access to potent opioids is restricted. Cross-class equianalgesic data comparing NSAIDs with weak opioids are scarce. This single-centre, double-blind, parallel-group pilot RCT was conducted at Hospital Regional "General Ignacio Zaragoza," ISSSTE, Mexico City. Thirty adult patients (ASA I-II, age 18-55 years, BMI 18.5-34.99 kg/m²) scheduled for elective laparoscopic surgery were randomised equally to receive tramadol 150 mg IV, ketorolac 60 mg IV, or diclofenac 150 mg IV, administered 45 minutes before skin incision. All patients received standardised balanced general anaesthesia. Pain was assessed using the NRS and Verbal Rating Scale (VRS) at five time points. Rescue analgesia (morphine 3 mg IV) was available on request. The trial was initially registered with the ISSSTE institutional research registry (RPI #403-2024).

• Study Type: Interventional
• Enrollment (Actual): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Mexico
  • Mexico City
    • Mexico City, Mexico City, Mexico, 09360
      • Hospital Regional "General Ignacio Zaragoza," ISSSTE

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Age 18-55 years
• ASA physical status I or II
• Body mass index 18.5-34.99 kg/m²
• Scheduled for elective minimally invasive surgery under balanced general anaesthesia
• Pre-surgical pain NRS = 0 and VRS = "absence" at baseline assessment

Exclusion Criteria:

• Pregnancy
• Known hypersensitivity to any study drug (tramadol, ketorolac, or diclofenac)
• Pre-existing acute pain with NRS ≥ 4 or VRS ≥ "moderate" before surgery
• Chronic pain with current analgesic use
• Withdrawal of consent before premedication administration
• Surgical duration exceeding 180 minutes
• Conversion from laparoscopic to open surgical approach
• Hypersensitivity reaction during study drug administration
• Haemodynamic shock of any aetiology during the perioperative period
• Requirement for postoperative mechanical ventilation due to anaesthetic-surgical complications

Study Plan

How is the study designed?

Design Details

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

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: TRAM; Participants received tramadol 150 mg IV in 100 mL 0.9% saline, administered 45 minutes before skin incision as a single premedication dose, under double-blind conditions.	Drug: Tramadol; Tramadol 150 mg IV, single dose, administered in 100 mL 0.9% saline 45 minutes before skin incision.
Active Comparator: KETO; Participants received ketorolac 60 mg IV in 100 mL 0.9% saline, administered 45 minutes before skin incision as a single premedication dose, under double-blind conditions.	Drug: Ketorolac; Ketorolac 60 mg IV, single dose, administered in 100 mL 0.9% saline 45 minutes before skin incision.
Active Comparator: DICLO; Participants received diclofenac 150 mg IV in 100 mL 0.9% saline, administered 45 minutes before skin incision as a single premedication dose, under double-blind conditions.	Drug: Diclofenac; Diclofenac 150 mg IV, single dose, administered in 100 mL 0.9% saline 45 minutes before skin incision.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative pain intensity	Pain intensity assessed using the Numerical Rating Scale (NRS, 0-10; 0 = no pain, 10 = worst imaginable pain). Between-group comparisons performed at each time point using Kruskal-Wallis tests with Dunn post-hoc correction.	At recovery room arrival (Time_0), and at 30 (Time_1), 60 (Time_2), and 90 (Time_3) minutes after recovery room arrival.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Categorical pain intensity by Verbal Rating Scale (VRS)	Pain category assessed using a four-point Verbal Rating Scale (0 = absence, 1 = low, 2 = moderate, 3 = severe). Between-group differences assessed using Pearson's chi-squared test with Cramér's V as effect size.	At recovery room arrival (Time_0), and at 30 (Time_1), 60 (Time_2), and 90 (Time_3) minutes after recovery room arrival.
Rescue morphine consumption	Number of rescue analgesic doses and total morphine consumed (mg IV) per group. Rescue analgesia (morphine 3 mg IV) was administered on patient request or clinical indication.	At 30 (Time_1), 60 (Time_2), and 90 (Time_3) minutes after recovery room arrival.
Incidence of hypersensitivity reactions	Hypersensitivity reactions of any grade classified according to Müller criteria (Grade I-IV). Managed per institutional protocol (hydrocortisone 100 mg IV; adrenaline 0.5 mg IM for anaphylaxis).	Throughout the 90-minute observation period

Collaborators and Investigators

• Sponsor: ISSSTE Hospital Regional "Gral. Ignacio Zaragoza"

Study record dates

Study Major Dates

• Study Start (Actual): June 20, 2024
• Primary Completion (Actual): July 23, 2024
• Study Completion (Actual): July 26, 2024

Study Registration Dates

• First Submitted: March 20, 2026
• First Submitted That Met QC Criteria: March 25, 2026
• First Posted (Actual): March 30, 2026

Study Record Updates

• Last Update Posted (Actual): May 15, 2026
• Last Update Submitted That Met QC Criteria: May 12, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Acute pain; Postoperative pain; Diclofenac; Ketorolac; Pilot; Tramadol; NSAIDs; RTC
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Postoperative Complications; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain, Postoperative; Acute Pain; Organic Chemicals; Heterocyclic Compounds; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Lipids; Carboxylic Acids; Amines; Indomethacin; Indoles; Alcohols; Acids, Carbocyclic; Phenylacetates; Cyclohexanols; Hexanols; Fatty Alcohols; Dimethylamines; Methylamines; Ketorolac; Tramadol; Diclofenac
• Other Study ID Numbers: ISSSTE RPI #403-2024

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual participant data underlying the results reported in this article, along with the full analysis code, will be made available following article publication via the corresponding author's public GitHub repository (https://github.com/phabel-LD).
• IPD Sharing Time Frame: Beginning at the time of article publication, with no end date.
• IPD Sharing Access Criteria: Data and code will be publicly available with no access restrictions via GitHub.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; ANALYTIC_CODE; CSR

Drug and device information, study documents

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