OBSERVER-BLIND STUDY WITH METAMIZOLE VERSUS TRAMADOL AND BUTYLSCOPOLAMINE IN ACUTE BILIARY COLIC PAIN

To investigate the combined analgesic and spasmolytic effect of metami zole (dipyrone, Novalgin(R), CAS 68-89-3) this drug was compared with an opioid analgesic (tramadol) and a pure spasmolytic drug (butylscopo lamine). In a multicentre, observer-blind, parallel-group study conduc ted in five German centres 74 patients suffering from ''severe'' or '' excruciating'' colic pain caused by a calculus in the bile duct were r andomized to receive intravenously 2.5 g metamizole (25 patients), 100 mg tramadol (25 patients), or 20 mg butylscopolamine (24 patients). T he three treatment groups were homogeneous for age, sex, height, weigh t and baseline pain intensity. Metamizole was significantly more effec tive in reducing pain than tramadol and butylscopolamine for the prima ry endpoint, pain intensity on a visual analogue scale (VAS) when eval uated as the area under the curve (AUC) from baseline to onset of anal gesic action (p < 0. 05) and the sum of pain in tensity differences (S PID) for the observation period of 2 h (p < 0. 005). The mean time unt il the onset of analgesic action occured was shortest (p < 0.005) for metamizole (10.9 +/- 5.8 min) compared with tramadol (15.8 +/- 11.7 mi n) and butylscopolamine (25.6 +/- 24.3 min). Metamizole was also more effective for the secondary efficacy endpoint, pain intensity on a 5-p oint ordinal scale. In the patient's overall assessment of treatment e fficacy at the end of the trial, metamizole was rated as the most effe ctive drug (p < 0. 005). Fewer patients in the metamizole (3) and the tramadol (1) groups than in the butylscopolamine group (8) needed a se cond injection of the ''rescue'' medication (p < 0.05). Adverse events were reported in 3 patients each in the metamizole group (burning at the site of injection, mild blood pressure reduction) and the butylsco polamine group (nausea, dry mouth), and in 9 patients in the tramadol group (nausea, vomiting). The superior efficacy of dipyrone for acute biliary colic pain may be attributed to its combined analgesic and spa smolytic effect. ''Distinct '' pain relief as assessed on a VA S is an appropriate method of determining the onset of analgesic action in th e colic pain model.