Efficacy and Tolerance of Metamizole versus Morphine for Acute Pancreatitis Pain

Background/Aims: Morphine has been contraindicated for pain treatment in acute pancreatitis because of its presumed opioid-induced sphincter of Oddi dysfunction. However, scientific evidence supporting a deleterious influence on the clinical course is absent. This pilot study was undertaken to evaluate the efficacy and adverse events of metamizole versus morphine in acute pancreatitis. Methods: 16 patients with acute pancreatitis were randomized to receive 10 mg/ 4 h s.c. (n = 8) morphine or 2 g/8 h i.v. (n = 8) metamizole. Pain scores were recorded every 4 h during 48 h after admission by a Visual Analogue Scale. Pethidine was additionally administered as a rescue therapy. Results: 75% of patients achieved pain relief in the metamizole group versus 37.5% in the morphine group within 24 h of hospitalization (6/8 vs. 3/8; p: n.s.).The mean time to achieve pain relief was shorter in the metamizole group (10 ± 6.6 vs. 17 ± 18.3 h; p: n.s.). At the end of the study, 75% of patients achieved pain relief in the metamizole group versus 50% in the morphine group. Three patients in each group needed pethidine: 2 out of 3 achieved pain control in the metamizole group vs. 0 out of 3 in the morphine group. Conclusions: Intravenous metamizole shows a non-significant association with a quicker pain relief than morphine s.c. in acute pancreatitis. A larger randomized controlled trial should be desirable to confirm this result.