Kozelsky, T.F., Meyers, G.E., Sloan, J.A., Shanahan, T.G., Dick, S.J., Moore, R.L., … North Central Cancer Treatment Group. (2003). Phase III double-blind study of glutamine versus placebo for the prevention of acute diarrhea in patients receiving pelvic radiation therapy. Journal of Clinical Oncology, 21(9), 1669–1674.
The study design was based on a goal of 120 patients, so that the two-sided, 0.05-level Wilcoxon rank sum would have a power of 97.5% to detect an improvement in diarrhea severity. After stratification, patients were randomly assigned to the experimental group (4 grams of glutamine twice per day for 7 days per week during radiation and for 2 weeks thereafter) or an identically appearing placebo (glycine) for the same time period.
This was a two-arm, placebo-controlled, randomized clinical trial.
The primary measure of treatment efficacy was diarrhea levels, which were evaluated using a bowel function questionnaire that was derived from previous studies on radiation therapy and bowel functioning. Participants completed the questionnaire weekly for 4 weeks, then at 12- and 24-month follow-up intervals. Toxicity was measured using National Cancer Institute (NCI) Common Terminology Toxicity Criteria for Adverse Events: Diarrhea.
No significant differences were found in incidence of diarrhea (p = 0.99), stools per day, maximum stools per day, antidiarrheal agent used, or use of loperamide.