Pentazocine, a Kappa-Opioid Agonist, Is Better Than Diclofenac for Analgesia in Acute Pancreatitis: A Randomised Controlled Trial

Abstract

Background: The ideal analgesic is not known for patients with acute pancreatitis (AP). Concerns have been raised about serious adverse effects of opioid analgesics increasing the severity of AP. We hypothesized that non-steroidal anti-inflammatory drugs (NSAIDs) might be better analgesics due to their anti-inflammatory effect. Our objective was to compare pentazocine, an opioid, and diclofenac, an NSAID for adequate analgesia in patients with AP. Methods: In a double-blind randomised controlled trial, patients with AP were randomised to either intravenous Diclofenac 75 mg or Pentazocine 30 mg. Fentanyl was given as a rescue analgesic through a patient controlled analgesia pump. Primary outcome was pain relief measured objectively by the dose of fentanyl required as rescue analgesic, pain-free period, and numbers of good and bad demands of fentanyl. Secondary outcome was adverse events. Findings: Fifty patients were randomised: 24 to pentazocine group and 26 to diclofenac group. Baseline characteristics were comparable between the groups. Pentazocine was found to be better than diclofenac in terms of significantly lower dose of rescue analgesic (fentanyl) required [126 μg (range 0-960 μg) vs. 225·5 μg (range 0-810 μg); p = 0·028], and longer pain-free period (31·1±8·2 hours vs. 27·9±6·6 hours, p=0·047). The number of good and bad demands was lower in the pentazocine compared with diclofenac group [11·5 (range 0-92) vs. 16 (range 0-85), p=0·098] although not statistically significant. Adverse events were similar between the groups. Interpretation: Pentazocine, a kappa opioid receptor agonist, was significantly better than Diclofenac for pain relief in AP. Clinical Trial Number: (Trial registration number: CTRI/2016/09/007326) Funding Statement: The authors state: None, and It was an investigator initiated study. Declaration of Interests: None of the authors have any conflict of interest. Ethics Approval Statement: The study was approved by the institutional ethics committee (IECPG 69/27·11·2015). An informed written consent was taken from the participants.