Background: Diarrhea is a serious side effect that may prevent the administration of high doses of the antitumor drug Irinotecan (CPT-11).

Purpose: Intensive, high-dose loperamide was used in an attempt to control or downstage CPT-11-induced diarrhea and thus permit the use of higher dose intensities of CPT-11.

Methods: Twenty-three patients with various cancers were treated with doses of CPT-11 ranging from 400 to 600 mg/m2, administered as a 30-minute intravenous infusion every 3 weeks. Starting 8 hours or more after the administration of CPT-11, any episode of diarrhea was treated with 2 mg of loperamide taken every 2 hours. Patients stopped taking loperamide only after a 12-hour diarrhea-free period. If diarrhea was not controlled after 3 consecutive days of nonstop loperamide intake, or if the patient was dehydrated, loperamide was stopped and the patient was hospitalized for intravenous fluids. If blood or mucus were found in the stools at any time during diarrhea, loperamide was stopped and the patient was hospitalized.

Results: Seventeen of 23 patients had diarrhea while on CPT-11 treatment. Eighty-two CPT-11 cycles were administered to these 17 patients, and diarrhea occurred in 49 of these cycles, at a median time-to-onset of 6 days after CPT-11 administration. The loperamide protocol was followed in 46 of the 49 episodes of diarrhea, with 21 capsules of loperamide the median number being taken (range, 5-72). Only one patient was hospitalized for failure to respond to loperamide, and no major toxicity was associated with loperamide use. Fourteen of the 17 patients who experienced diarrhea were rechallenged with CPT-11 three or more times, and seven patients six or more times.

Conclusions: High-dose loperamide controlled diarrhea in patients receiving CPT-11 and allowed administration of higher doses of CPT-11.

Implications: The effectiveness of CPT-11 might be increased by higher dose intensities, which can be made tolerable by control of diarrhea with loperamide.