[ Action of low doses of vincristine, lidocaine and verapamil on DNA replication in vitro].

: Lidocaine and Verapamil at pharmacological doses which for single drug are not cytotoxic, when used together in vitro, inhibit DNA replication in PHA-stimulated lymphocytes but not in Jurkat cell (T-ALL line) cultures. At the same concentration the two drugs used in association with very low doses of Vincristine are cytotoxic to PHA-stimulated lymphocytes and Jurkat cells. Cytotoxic action of Doxorubicin is not increased by Lidocaine or by Verapamil or by an association of the two drugs. Changes in calcium ion concentration in the medium did not show any significant effect. These results suggest that Lidocaine and Verapamil have a common mechanism of action and have a toxic action on the same cell structure of Vincristine; furthermore the cytotoxic action of Vincristine is considerably increased. These in vitro effects could be tested in animal models.