ENHANCEMENT OF CYTOTOXICITY OF DOXORUBICIN BY VERAPAMIL IN THE HEPATIC-ARTERY INFUSION FOR LIVER-TUMORS IN RATS

Background. The calcium channel blocker has been demonstrated to be ef fective in the accumulation and retention of chemotherapeutic agents i n tumor cells. Methods. The effect of verapamil on cytotoxicity of dox orubicin was investigated in a hepatic artery infusion (HAI) for liver tumors of Walker 256 carcinosarcoma in rats. Doxorubicin was infused by way of a hepatic artery by a bolus injection intra-arterially (IA) (1 mg/kg) and a continuous infusion intra-arterially (CIA) (6 mg/kg/da y for 6 days). Results. Doxorubicin increased 90% and 66% in tumor tis sue following HAI of verapamil by a bolus and continuous infusion (P < 0.05), respectively. However, no enhancement of the accumulation of d oxorubicin in the tumor tissue was found in an intravenous administrat ion of verapamil. The CIA infusion of verapamil with doxorubicin inhib ited the tumor growth by 73% in comparison with doxorubicin only (P < 0.05). Verapamil administered intravenously (IV) could not induce this inhibitory effect. The CIA administration of verapamil reduced the se rum concentration by 45% (P < 0.001) in comparison with the CIV route. Furthermore, the administration of verapamil did not increase the acc umulation of doxorubicin in the normal liver and heart tissues. No enh ancement of bone marrow suppression and hepatic biochemical influence by doxorubicin was revealed by the concomitant use of verapamil. Concl usions. The continuous HAI of verapamil remarkably enhanced the cytoto xicity of HAI with doxorubicin for the treatment of hepatic tumor with out aggravating the side effects induced by doxorubicin.