Which agent commonly causes transient early diarrhea?

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

Answer: (C)

Early transient diarrhea is most characteristic of irinotecan. After administration, a rapid, secretory diarrhea can occur within about 24 hours due to a cholinergic surge from the drug, and this early diarrhea is usually short-lived and often responsive to atropine given to prevent or treat the symptom. This pattern is distinct from the other drugs listed: vincristine mainly causes neurotoxicity and constipation, paclitaxel can cause GI upset but not the classic early-onset, transient diarrhea, and topotecan does cause diarrhea but the well-known early, transient type is specifically associated with irinotecan. Remembering this biphasic diarrhea pattern helps you identify irinotecan and guides management (anticholinergic for the early phase, loperamide and supportive care for late-phase diarrhea).