A Randomized Trial Evaluating the Synergistic Effect of Parenteral Diclofenac and Paracetamol for Pain Management in Adult Males With Acute Limb Injury.

Introduction: In the emergency department (ED), commonly used analgesics for pain management are nonsteroidal anti-inflammatory drugs (NSAIDs), paracetamol, and opioids. The aim of this clinical trial was to evaluate the effectiveness of intravenous (IV) or oral (PO) paracetamol, combined with intramuscular (IM) diclofenac, in patients with acute limb injuries. Methods: This study utilized a double-blind, randomized controlled design to evaluate three different treatment groups. The trial included healthy adult males aged 18-65 years, who arrived at the ED with acute limb injuries, and an initial pain score of at least 5 on the Numerical Rating Scale (NRS). Participants were randomly assigned in equal numbers to one of three groups: one group received IM diclofenac (75 mg/3 mL), along with oral paracetamol (1000 mg); the second group was given IM diclofenac plus IV paracetamol (1000 mg in 100 mL); and the third group received IM diclofenac (75 mg/3 mL), accompanied by a placebo. The main goal of the study was to compare the average pain reduction among the three groups at 30 min after treatment (t30). Results: A total of 162 participants were recruited between October 2022 and February 2023. Pain levels were assessed at baseline (t0) and continued to be monitored up to 90 min after medication was administered (t90). The average reduction in pain scores for each group was as follows: diclofenac plus oral paracetamol resulted in a mean decrease of 2.5 ± 0.03, diclofenac plus IV paracetamol had a mean reduction of 2.6 ± 0.03, and diclofenac with placebo showed a mean decrease of 2.2 ± 0.04. These results indicate there was no statistically significant difference in pain relief among the three groups. Additionally, none of the groups required rescue pain medication, and no adverse events were reported in any group. Conclusion: The results demonstrate that the three treatment groups achieved similar levels of pain relief within the observed timeframe, offering no significant advantage in terms of speed or extent of pain reduction. Nonetheless, additional studies are warranted to explore the potential synergistic effects of combining paracetamol with NSAIDs via various administration routes, as well as to assess possible adverse events, and the necessity for supplemental analgesia.