regorafenib + warfarin + omeprazole + midazolam

This is a **combination of four drugs**: regorafenib, warfarin, omeprazole, and midazolam. - **Regorafenib** is an oral small molecule multikinase inhibitor primarily used for the treatment of refractory metastatic colorectal cancer and gastrointestinal stromal tumors (GIST). It inhibits multiple protein kinases involved in tumor angiogenesis, oncogenesis, and the tumor microenvironment, including VEGFR, PDGFR, FGFR, KIT, RET, and RAF kinases[2][10]. - **Warfarin** is an oral anticoagulant that inhibits vitamin K epoxide reductase, blocking the synthesis of vitamin K-dependent clotting factors (II, VII, IX, X) and proteins C and S, reducing blood clot formation. - **Omeprazole** is an oral proton pump inhibitor that reduces gastric acid secretion by irreversibly inhibiting the H+/K+-ATPase enzyme in gastric parietal cells. It is predominantly metabolized by CYP2C19 and to a lesser extent by CYP3A4[6][9]. - **Midazolam** is a benzodiazepine, used primarily for sedation, anxiolysis, and anesthesia. It acts as a positive allosteric modulator of the GABAA receptor and is metabolized by CYP3A4[6][3]. This combination is not available as a commercial product, and its use would generally be for **drug-drug interaction studies**, especially for evaluating the effects on cytochrome P450 enzymes (CYP2C19 and CYP3A4)[3][6].