Acetaminophen vs Placebo for Postoperative Analgesia After Abdominal Surgery

NCT07720791 | Not Yet Recruiting Phase 4 DMC

• 1 other identifier: Study Aceta
• Study Type: interventional
• Target: 1,504
• Locations: 0 countries
• Sites: N/A

Brief Summary

This study investigates whether oral acetaminophen, when added to standard pain management, reduces opioid use and pain after major abdominal surgery, compared to a placebo (inactive pill). Patients undergoing planned abdominal surgery under general anesthesia will be randomly assigned to receive either acetaminophen or a placebo tablet before surgery and every 6 hours afterward for 48 hours, in addition to their usual pain medication. Researchers will measure how much opioid pain medication patients need, how much pain they report, and how satisfied they are with their pain control during the first two days after surgery. The goal is to determine whether oral acetaminophen provides a genuine benefit beyond placebo in reducing opioid use while maintaining adequate pain control.

Conditions

Pain, Postoperative

Outcome Measures

Primary Outcomes (2)

• Total Postoperative Opioid Consumption

  Cumulative opioid consumption during the first 48 postoperative hours, expressed as intravenous morphine milligram equivalents (MME). Tramadol consumption will be converted using a potency equivalence factor of 0.15 relative to morphine.

  48 hours after surgery

• Average Postoperative Pain Score

  Average postoperative pain intensity assessed using a 0-10 Visual Analog Scale (VAS), with 0 indicating no pain and 10 indicating the worst pain. Pain will be assessed every 30 minutes during the first 2 hours in the recovery area, then approximately every 6 hours thereafter until 48 hours postoperatively.

  48 hours after surgery

Secondary Outcomes (1)

• Patient Satisfaction with Postoperative Pain Management

  24 and 48 hours after surgery

Other Outcomes (1)

• Composite Opioid-Related Symptom Distress

  48 hours after surgery

Study Arms (2)

Acetaminophen

ACTIVE COMPARATOR

Arm 1: Acetaminophen (Arm Type: Experimental) Participants will receive oral acetaminophen 1000 mg, administered 30 minutes before surgery and every 6 hours postoperatively for 48 hours.

Drug: Acetaminophen

Placebo

PLACEBO COMPARATOR

Participants will receive a matching placebo tablet, administered 30 minutes before surgery and every 6 hours postoperatively for 48 hours.

Drug: Acetaminophen

Interventions

Acetaminophen DRUG

Intervention 1: Acetaminophen (Type: Drug) Oral acetaminophen 1000 mg tablet, administered 30 minutes before surgery and every 6 hours postoperatively until 48 hours after surgery. Other Name(s): Paracetamol Intervention 2: Placebo (Type: Other / Drug) Oral placebo tablet, visually identical to the acetaminophen tablet, administered on the same schedule (30 minutes before surgery and every 6 hours postoperatively until 48 hours after surgery).

Also known as: Placebo

Acetaminophen; Placebo

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Written informed consent
• Age ≥ 18 years
• ASA physical status I, II, or III
• Scheduled for elective non-cardiac abdominal surgery with expected surgery duration ≥ 2 h-hours
• General anesthesia
• Planned hospital stay of at least 48 hours

You may not qualify if:

• Pregnant or nursing (breastfeeding) women
• Neurologic deficit or chronic pain disease
• Planned use of regional anesthesia techniques for postoperative pain
• Emergency surgery

Sponsors & Collaborators

• Konya City Hospital: lead
• Erzurum Regional Training & Research Hospital: collaborator

MeSH Terms

Conditions

Pain, Postoperative

Interventions

Acetaminophen

Condition Hierarchy (Ancestors)

Postoperative Complications; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Pain; Neurologic Manifestations; Signs and Symptoms

Intervention Hierarchy (Ancestors)

Acetanilides; Anilides; Amides; Organic Chemicals; Aniline Compounds; Amines

Central Study Contacts

Yasin Tire

CONTACT

+905055367970; dryasintire@hotmail.com

Ayşenur Dostbil

CONTACT

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, OUTCOMES ASSESSOR
• Masking Details: This is a triple-blind study. Participants, care providers, and outcomes assessors are all blinded to treatment allocation. Acetaminophen and placebo tablets are identical in appearance, packaging, and administration schedule, making them indistinguishable to anyone involved in clinical care or outcome assessment. Treatment allocation is generated and maintained by the randomization system (REDCap) and is known only to personnel responsible for randomization and drug dispensing, who have no role in patient care, pain assessment, or outcome evaluation. The blinded outcomes assessor independently records pain scores and opioid consumption data, with no knowledge of group assignment.
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assoc. Prof. Dr. Yasin Tire

Model Details: Participants will be randomized in a 1:1 ratio using a web-based randomization system (REDCap) with random-sized blocks to one of two parallel arms: oral acetaminophen 1000 mg or matching placebo tablet. The first dose will be administered 30 minutes before surgery, with repeat dosing every 6 hours for 48 hours postoperatively. Both groups will receive an identical standardized multimodal analgesic protocol, including intraoperative fentanyl, intraoperative/postoperative tramadol, and patient-controlled and per-request rescue analgesia. The two groups will be followed concurrently over the same 48-hour postoperative period, with no crossover between arms.

Study Record Dates

• First Submitted: June 27, 2026
• First Posted: July 22, 2026
• Study Start: July 15, 2026
• Primary Completion (Estimated): July 15, 2027
• Study Completion (Estimated): August 1, 2027
• Last Updated: July 22, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will not share