Effectiveness of Diclofenac Sodium Suppository in Reduction of Pain and Dosage of Fentanyl in Patients Undergoing Colonoscopy: A Randomized Clinical Trial

Background and purpose: Opioid analgesics cause bradycardia and respiratory depression.  The aim of this study was to investigate the efficacy of diclofenac suppository on pain and dose reduction of injectable fentanyl in patients undergoing colonoscopy. Materials and methods: In a clinical trial, 500 patients undergoing colonoscopy were randomly divided into two groups to receive either diclofenac or glycerin (placebo) administered 30 min before colonoscopy. Five minutes before colonoscopy, fentanyl (50 μg/iv) was administered, and then, if pain persisted during colonoscopy, fentanyl 50 μg was administered as a rescue. Baseline demographic and clinical data and other information, including cecal arrival time, patients’ and gastroenterologist’s satisfaction, pain intensity based on visual analogue scale (VAS), rescue dose of fentanyl, frequency of hypotension and apnea were compared between the two groups. Results: The groups were similar in age, sex, and baseline clinical parameters (P> 0.05). Cecal arrival time was shorter in the group that received diclofenac (10.59±3.8 min) than the placebo group (12.41±2.5 min) (P= 0.035). Mean pain score was found to be lower in diclofenac group (3.2±54.2) than the placebo group (5.10±2.8) (P <0.0001). Frequency of fentanyl administration in diclofenac group (6%) was lower than that in placebo group (24.8%) (P <0.0001). Frequency of hypotension and apnea events were observed to be lower in the group that received diclofenac (P< 0.05). Conclusion: In this study, diclofenac suppository had positive effects on reducing the pain intensity, the dose of fentanyl, and side effects, therefore, it is recommended in colonoscopy analgesia protocols.   (Clinical Trials Registry Number: IRCT2016092629976N1)