Abstract
Aim: Breast cancer is the most common cancer among Arab women and also around the world. Chronic cardiotoxicity and multidrug resistance are potential limiting factors of doxorubicin (DOX), a known anthracycline antibiotic. Materials & methods: DOX cytotoxicity was evaluated by the sulforhodamine method. DOX cellular uptake, detection of P-glycoprotein activity and the photomicrograph of MCF-7 cells were also determined. Results: Diltiazem (DIL) treatment improved DOX cytotoxic activity and increased the cellular uptake of DOX significantly and aggregation of rhodamine 123, reflecting inhibition of P-glycoprotein pump. Cytopathological investigation of MCF-7 cells revealed marked cytotoxic activity of DOX in the presence of DIL. Conclusion: DIL treatment enhanced DOX cytotoxic effect and reduced multidrug resistance, which increased the drug accumulation intracellularly.