Lederle, F.A., Busch, D.L., Mattox, K.M., West, M.J., & Aske, D.M. (1990). Cost-effective treatment of constipation in the elderly: A randomized double-blind comparison of sorbitol and lactulose. American Journal of Medicine, 89, 597–601.
To evaluate the use of sorbitol as an inexpensive alternative to lactulose for treating constipation in older adults.
Lactulose and 70% sorbitol (0–60 ml daily) were given for four weeks. During the treatment period, patients were instructed to begin taking 30 ml of the study laxative at bedtime, thereafter adjusting the dose as needed from 0–60 ml. Patients were instructed to maintain high dietary fiber and avoid sources of free fructose such as apples and pears.
The length of the wash-in and washout periods was based on previous studies, which showed up to three to four days are required for lactulose to take effect and the carryover effect after cessation of lactulose is about six to seven days. The study began with a two-week lead-in period, during which patients received lactulose in a single-blind fashion. This was followed sequentially by washout period A (two weeks), treatment period A (four weeks), washout period B (two weeks), and treatment period B (four weeks). The purpose of the lead-in period was to ensure (a) the patient tolerated lactulose, (b) the patient understood how to fill out the diary, and (c) the conditions preceding the two treatment periods were similar. At the end of washout period A, patients were randomly assigned to receive one of the two study laxatives in treatment period A, with the other laxative being used in treatment period B.
The primary endpoints of the study were average number of bowel movements per week and the average number of days per week on which bowel movements occurred.
This was a randomized, double-blind, crossover study.
The results supported the hypothesis that sorbitol and lactulose have no clinically or statistically significant difference in laxative effect. Sorbitol can be recommended as a cost-effective alternative to lactulose for the treatment of constipation in older men.