Chronic diarrhea due to surreptitious use of bisacodyl: case reports and methods for detection.

Surreptitious abuse of laxatives is a common cause of severe chronic diarrhea. Standard laboratory screening studies of urine and stool specimens may identify phenolphthalein, diuretics, and magnesium-containing agents. An assay for bisacodyl, a commonly used over-the-counter laxative, however, is not included in routine screening tests. Herein we describe two patients with chronic watery diarrhea of large volume; analysis of stool and urine samples revealed that surreptitious use of bisacodyl was the cause. In one patient, nonspecific inflammatory changes of the colonic mucosa were noted on biopsy, and fecal leukocytes were detected in both patients. In a prospective study of eight patients who received bisacodyl as part of a preparation for colonoscopy, we analyzed serial urine samples for bisacodyl diphenol during a 48-hour period. This metabolite was found in seven of eight hydrolyzed urine samples obtained 12 hours after oral administration of bisacodyl but not in samples obtained 24 and 48 hours after ingestion of the laxative. We recommend that urinalysis and, in some cases, stool analysis for bisacodyl should be considered in the diagnostic assessment for surreptitious use of laxatives.

Improved chromatography of cyclosporine.

A fast liquid chromatographic procedure for the measurement of whole-blood cyclosporine concentration is described. A sample preparation using solid-phase extraction requires 5.5 min of technical effort per sample. Chromatographic development is complete in 6 min. The results of this procedure correlate with those of a previously validated procedure. The slope of the correlation equation is 1.04, the gamma-intercept is -17, and the correlation coefficient is 0.99. Reproducibility of the procedure at midtherapeutic concentration is 5.5%, and sensitivity is 25 ng/ml. No chemical interference was observed from 33 drugs commonly co-administered during immunosuppression.