In vitro and in vivo enhancement of vincristine antitumor activity on B16 melanoma cells by calcium antagonist flunarizine.

Flunarizine, a calcium antagonist commonly employed in therapy for vascular diseases, enhances the in vitro and in vivo antitumor activity of vincristine on B16 melanoma cells. In the presence of flunarizine higher intracellular levels of vincristine were observed in vitro and for a longer time. B16 melanoma bearing mice treated with both the drugs presented a median survival time that was significantly longer than that of the controls. The possible mechanism of the enhancement is herein discussed.