Limited benefit of atropine as premedication for colonoscopy

A prospective double-blind trial was performed comparing atropine (0.5 mg) by slow intravenous administration to placebo as premedication for colonoscopy, to assess the possible beneficial effects of this vagolytic agent on the performance and safety of the procedure. A total of 77 patients was randomly assigned to receive atropine (38 patients) or placebo (39 patients) before colonoscopy in conjunction with our standard initial medications for conscious sedation (meperidine, 0.4 mg/kg and midazolam, 0.03 mg/kg). Total procedure time was 31 min for the atropine group and 35 min for the placebo group (p greater than 0.05), and there was no overall difference in the total amount of intra-procedural medications required. No statistically significant differences were observed relative to the number or severity of vagal episodes, and neither the endoscopist nor the patients noted any differences in the ease or tolerance of the procedure (p greater than 0.05). Although these results fail to demonstrate a significant benefit of atropine when given routinely as premedication for colonoscopy, this study does not rule out the potential usefulness of atropine in counteracting vagal episodes when they occur.