cholestyramine + irinotecan + levofloxacin

This is a combination regimen consisting of three drugs: - **Cholestyramine** is a bile acid sequestrant primarily used to lower cholesterol and manage pruritus associated with partial biliary obstruction. In this context, it is used off-label to bind bile acids in the gut, potentially reducing gastrointestinal toxicity. - **Irinotecan** is a topoisomerase I inhibitor chemotherapy agent widely used in the treatment of metastatic colorectal cancer. Its main dose-limiting toxicity is delayed-onset diarrhea, which can be severe. - **Levofloxacin** is a broad-spectrum fluoroquinolone antibiotic that targets bacterial DNA gyrase and topoisomerase IV, inhibiting bacterial replication. It may help prevent or treat infections secondary to chemotherapy-induced mucosal injury. The combination of cholestyramine and levofloxacin has been studied as prophylaxis for irinotecan-induced delayed diarrhea in patients with metastatic colorectal cancer receiving second-line irinotecan therapy. The rationale involves cholestyramine binding toxic metabolites (such as SN-38) in the gut and levofloxacin reducing beta-glucuronidase-producing bacteria that reactivate these metabolites, thereby decreasing mucosal damage and incidence/severity of diarrhea[1][2][3].