In US phase I trials, single doses of up to 345 mg/m2 of irinotecan injection were administered to patients with various cancers. Single doses up to 750 mg/m2 of irinotecan have been given in non US trials. The adverse events in these patients were similar to those reported with the recommended dosage and regimen. There is no known antidote for overdosage. Maximum supportive care should be instituted to prevent dehydration due to diarrhea and to treat any infectious complications.