Observer-blind study with metamizole versus tramadol and butylscopolamine in acute biliary colic pain

To investigate the combined analgesic and spasmolytic effect of metamizole (dipyrone, Novalgin, CAS 68-89-3) this drug was compared with an opioid analgesic (tramadol) and a pure spasmolytic drug (butylscopolamine). In a multicentre, observer-blind, parallel-group study conducted in five German centres 74 patients suffering from "severe" or "excruciating" colic pain caused by a calculus in the bile duct were randomized to receive intravenously 2.5 g metamizole (25 patients), 100 mg tramadol (25 patients), or 20 mg butylscopolamine (24 patients). The three treatment groups were homogeneous for age, sex, height, weight and baseline pain intensity. Metamizole was significantly more effective in reducing pain than tramadol and butylscopolamine for the primary endpoint, pain intensity on a visual analogue scale (VAS) when evaluated as the area under the curve (AUC) from baseline to onset of analgesic action (p < 0.05) and the sum of pain intensity differences (SPID) for the observation period of 2 h (p < 0.005). The mean time until the onset of analgesic action occurred was shortest (p < 0.005) for metamizole (10.9 +/- 5.8 min) compared with tramadol (15.8 +/- 11.7 min) and butylscopolamine (25.6 +/- 24.3 min). Metamizole was also more effective for the secondary efficacy endpoint, pain intensity on a 5-point ordinal scale. In the patient's overall assessment of treatment efficacy at the end of the trial, metamizole was rated as the most effective drug (p < 0.005). Fewer patients in the metamizole (3) and the tramadol (1) groups than in the butylscopolamine group (8) needed a second injection of the "rescue" medication (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)