Does premedication with either intravenous or oral hyoscyamine facilitate colonoscopy?

Background: Several studies have assessed the utility of hyoscyamine in facilitating colonoscopy, with conflicting results. These studies have been relatively small and none has compared intravenous (IV) to oral (PO) hyoscyamine. Aim: To determine the effects of premedication with intravenous IV or PO hyoscyamine on pertinent outcomes in elective colonoscopy. Methods: The study was a randomized, double-blinded, placebo controlled trial in which patients were assigned to one of three arms: IV hyoscyamine (0.25 mg), PO hyoscamine (0.25 mg), or placebo, administered 20-40 minutes prior to the procedure. Patients between the ages of 18-75 presenting for elective colonoscopy were included. Exclusion criteria were glaucoma, unstable cardiovascular status, pregnancy, chronic use of anticholinergic drugs, and surgical alterations of the colon. Demographic data included age, sex, prior abdominal surgeries, prior colonoscopies, and a history of diabetes or a functional bowel disorder. A pre-procedure assessment of patient anxiety levels using 1-10 visual analog scales (VAS) was performed. Primary outcome measures included: insertion time to cecum, amount of sedation used, amount and type of pathology visualized, and patient assessment of pain (1-10 VAS). Secondary outcome measures included: physician assessment of spasm (1-10 VAS), physician assessment of pain (1-10 VAS), and total procedure time. Results: One hundred and thirty-three patients were enrolled in the trial. There were no significant differences between the groups with regard to age, gender, past abdominal surgeries, or history of functional bowel disorder. Bivariate analysis showed no difference between the three groups with regard to time to cecum (14.5 min, 16.2 min, and 14.4 min, for IV, PO, and placebo, respectively, p=0.66), patient assessment of pain (3.9, 3.9, and 3.7 on 1-10 VAS for IV, PO, and placebo, respectively, p=0.90), or any other primary or secondary outcome variable. A multi-variate analysis controlling for endoscopist identity, pre-procedure anxiety, and amount of sedation also failed to demonstrate any differences between the groups. High pre-procedure anxiety levels, and female gender were predictive of a longer time to cecum, higher patient assessment of pain, and higher medication needs (p < 0.05 for all). Conclusions: This randomized, double-blinded placebo-controlled trial demonstrated no efficacy of either IV or PO hyoscyamine as a pre-medication for elective colonoscopy. Investigational drug for this study was provided by Schwarz Pharma, Inc.