I Cost-Effective Treatment of Constipation in the Elderly: A Randomized Double-Blind Comparison of Sorbitol and Lactulose FRANKA. LEDERLE,M.D., DAVIDL. BUSCH, B.S., KIMBERLY M. MATTOX,PHARM.D.,MELISSA J. WEST, M.D., DONNA M. ASKE, R.N., M.S., Minneapolis, Minnesota PURPOSE: The purpose of this study was to evaluate the use of sorbitol as an inexpensive al- ternative to lactulose for treating constipation in the elderly. PATIENTS AND METHODS:T h i r t y men aged 65 to 86 with chronic constipation were studied in a randomized, double-blind, cross-over trial in which lactulose and 70% sorbitol (0 to 60 mL daily) were each given for 4 weeks preceded by a 2-week washout period. RESULTS: The average number of bowel move- ments per week was 6.71 with sorbitol and 7.02 with lactulose (95% confidence interval of the difference: -0.43 to 1.06), and the average num- ber of days per week with bowel movements was 5.23 with sorbitol and 5.31 with lactulose (95% confidence interval of the difference: -0.32 to 0.48). Eleven patients stated a preference for sorbitol, 12 for lactulose, and seven had no pref- erence. On a visual analogue scale measuring se- verity of constipation (0 to 100 mm), the average score for sorbitol was 35.6 mm versus 37.1 mm for lactulose (95% confidence interval of the dif- ference: -6.4 to 9.3). The sorbitol and lactulose treatment periods were also similar in percent of bowel movements recorded as "normal," fre- quency and severity of symptoms such as bloat- ing, cramping, and excessive flatulence, and overall health status as assessed by a previously validated five-category questionnaire. There were no significant differences between sorbitol and lactulose in any outcome measured except nausea, which was increased with lactulose (p <0.05). From the Department of Medicine (FAL, MJW), Pharmacy Service (DLB, KMM), Department of Nursing (DMA), Minneapolis Veterans Affairs Medical Center, University of Minnesota, Minneapolis, Minnesota. This work was presented at the Annual Meeting of the Society of General Internal Medicine, May 3, 1990, Washington, D.C. Requests for reprints should be addressed to Frank A. Lederle, M.D., Division of General Internal Medicine (Ill-O), Department of Medicine, Min- neapolis Veterans Affairs Medical Center, One Veterans Drive, Minneapolis, Minnesota 55417. Manuscript submitted April 20, I990, and accepted in revised form July 23, 1990. CONCLUSION: These results support the hypoth- esis that sorbitol and lactulose have no clinically significant differences in laxative effect. Sorbi- tol can be recommended as a cost-effective al- ternative to lactulose for the treatment of con- stipation in the elderly. C onstipation is the most common chronic diges- tive complaint in the United States, accounting for 2.5 million physician visits each year [1]. The prevalence of constipation increases markedly after age 65 [2], and treatment can be especially difficult in older patients [3]. Although satisfactory results are achieved in most older patients with constipa- tion by increasing dietary fiber and fluids or by adding a bulk-forming agent such as psyllium, a clinically important subgroup requires additional laxative therapy. Treating these patients is difficult because most laxatives have a potentiaI for serious adverse effects, which renders them unsuitable for long-term use [4]. An exception is lactulose, which has been shown in several studies to be safe and effective for treating constipation in the elderly [5- 7]. Lactulose is a nonabsorbable disaccharide and acts as an osmotic laxative. Its only common ad- verse effects are bloating, flatulence, and diarrhea. Lactulose is often recommended for the treatment of chronic constipation in the elderly and has been called the drug of choice [5,6,8]. The practical value of lactulose has been limited by its high cost, how- ever, and its use has been discouraged for this rea- son [4,9]. Sorbitol is another nonabsorbable sugar with an osmotic laxative effect, and it is much less expen- sive than lactulose. The cost to the pharmacist for a 960-mL bottle of sorbitol is $4.85, compared with $30 to $50 for lactulose, despite the availability of generic products [10]. In current literature and practice, sorbitol is usually considered only for spe- cialized uses such as counteracting the constipating effect of potassium-binding resins, rather than for general use in constipation [11,12]. Because sorbitol November 1990 The American Journal of Medicine Volume 89 597