Which agent is commonly associated with transient diarrhea in chemotherapy?

• A. Vincristine
• B. Paclitaxel
• C. Irinotecan
• D. Topotecan

Answer: (C)

Transient diarrhea is a short-lived, early diarrheal response that can occur soon after chemotherapy infusion. Irinotecan is the classic drug linked to this pattern. It’s a topoisomerase I inhibitor that is converted to the active metabolite SN-38, which irritates the intestinal lining and drives secretory diarrhea. The initial, acute diarrhea is cholinergic in nature, arising within about a day of treatment, and often responds to anticholinergic measures like atropine, with rapid improvement. There can also be a later diarrheal phase from mucosal injury, but the immediate, transient form is what this drug is most known for. The other agents listed have different toxicity profiles: vincristine commonly causes constipation and neuropathy; paclitaxel mainly causes neuropathy and myelosuppression; topotecan can cause diarrhea but is not as characteristically associated with this transient pattern as irinotecan.