Atropine for the treatment of biliary tract pain: a double-blind, placebo-controlled trial.

Abstract

To compare the efficacy of IM atropine with placebo for the treatment of pain caused by biliary tract disease. Prospective randomized, double-blind, crossover study. Emergency departments of a university medical center and affiliated county hospital. Fifty-five adults with biliary tract disease. Subjects were randomized to receive either 0.6 mg (0.5 mL) IM atropine or normal saline placebo in a double-blinded manner. If pain relief with the initial injection was inadequate, patients received the alternate injection. Pain was assessed by visual analog scale (0 to 100 mm) before the initial injection and 30 to 40 minutes after each subsequent injection. Relief of pain was complete after the initial injection in four of 28 (14%) who received atropine and four of 27 (15%) who received normal saline (P = .956). For subjects who received both injections, atropine and placebo resulted in similar pain relief (-12.0 mm versus -16.0 mm; P = .316). There also was no difference in pain relief between atropine and placebo for the subset of patients with biliary colic receiving both injections (-15.2 mm versus -17.0 mm; P = .658). This study had more than 80% power to detect a 7.5-mm difference in pain relief between atropine and placebo in all patients with biliary tract disease and a 12.5-mm difference in those with biliary colic. Atropine is no better than placebo in the treatment of biliary tract pain.