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.

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).

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

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).

Beginning at the time of article publication, with no end date.

Data and code will be publicly available with no access restrictions via GitHub.

Study drugs were prepared in identical 100 mL 0.9% saline bags by personnel not otherwise involved in the study and delivered unlabelled to the responsible anaesthesiologist, ensuring blinding of both the investigator and the patient.