Effectiveness of metamizol in the management of pain after abdominal surgery: comparison of 1 or 2 g by the intramuscular or intravenous route

In a double-blind, randomized, controlled clinical trial, the onset and duration of the analgesic effect of metamizol (1 or 2 g) either by the intramuscular (i.m.) or intravenous (i.v.) route and diclofenac sodium (75 mg, i.m.) were compared in 235 adult patients with postoperative pain after abdominal surgery. A level of greater than or equal to 50 mm on the 100-mm Visual Analogue Scale (VAS) was required to be included in the study. Patients were randomly allocated to one of the following treatment groups: metamizol 1 g, i.m. (n = 44); metamizol 1 g, i.v. (n = 49); metamizol 2 g, i.m. (n = 42); metamizol 2 g, i.v. (n = 52); and sodium diclofenac 75 mg, i.m. (n = 48). Evaluations were performed at 10, 20, 30 and 60 min. Primary efficacy end-points included pain score in a 100-mm VAS percentage of patients with pain improvement by 50 per cent or more at each evaluation time, pain intensity evaluated by the investigator on a 0-3 scale, and differences in pain intensity. There were no significant differences between metamizol 2 g by the i.m. or i.v. route and the remaining analgesic schedules. All treatment regimens were well tolerated. Diclofenac sodium 75 mg, i.m. induced a significantly greater number of adverse reactions.