Effectiveness and tolerability of amidotrizoate for the treatment of constipation resistant to laxatives in advanced cancer patients.

Constipation is a common problem for advanced cancer patients, and is generally inadequately treated. The aim of this study was to prospectively evaluate the effectiveness and tolerability of amidotrizoate (AM) in patients unresponsive to current laxatives. A consecutive sample of advanced cancer patients was surveyed. Inclusion criteria were no bowel movements for three days despite receiving regular doses of senna or lactulose. AM 50 mL was administered orally; the dose could be repeated the day after, based on clinical judgment and/or patients' preference. Age, sex, primary tumor, previous abdominal surgery, chemotherapy and radiotherapy performed in the previous month, and the use of opioids were recorded. Nausea, the presence of early satiety, and fluid and food intake also were measured. Time to first bowel movement was recorded, and adverse effects attributable to AM. Ninety-nine patients were surveyed (36 women/63 men). The mean age was 65.7 years (SD±12.2) and the mean Karnofsky score was 46.8 (SD±9.4). Patients had no bowel movement for a mean of four days (SD±1.8, range 3-15 days). A total of 80.8% of patients were receiving opioids in doses of mean daily oral morphine equivalents of 164 mg (SD±235). After AM administration (mean 9.9±6.5 hours), 44.4% of patients had a bowel movement within 24 hours. This effect was associated with significant improvement of other symptoms and was independent of age (P=0.513), gender (P=0.090), Karnofsky status (P=0.979), days of constipation (P=0.198), concomitant chemotherapy (P=0.098) or radiotherapy (P=0.414), the use of opioids (P=0.361), opioid doses (P=0.420), and primary tumor (P=0.231). The treatment was more effective in patients who had previous abdominal surgery (HR=3.33). AM was found to be an easy and inexpensive breakthrough medication to induce a bowel movement in about 45% of advanced cancer patients not responsive to common laxatives, with limited and acceptable adverse effects.