PHARMACOKINETICS OF VINBLASTINE-LOADED PLATELETS UTILIZED IN THE TREATMENT OF PLATELET-PHAGOCYTIZING TUMORS

  • 1 January 1980
    • journal article
    • research article
    • Vol. 64  (12) , 1227-1233
Abstract
Vinblastine-loaded platelets (VLP) were successfully used in the treatment of idiopathic thrombocytopenic purpura. Three patients with platelet-phagocytizing tumors and thrombocytopenia were treated with VLP. Patient 1 has sustained a response for 11 mo. Patient 2 was not evaluable for response because of early death. Patient 3 had a brief partial response. Vinblastine levels were measured by radioimmunoassay in the platelet-rich plasma, platelet-poor plasma and serum. The pharmacokinetic data obtained on the patients suggest the following; the amount of vinblastine bound to platelets in vivo is a function of the platelet-poor plasma vinblastine level and the platelet count; VLP will probably not have any therapeutic advantage, compared with i.v. vinblastine alone in patients with normal platelet counts; it appears that delivery of vinblastine was tumor-specific, since the bone marrow serum vinblastine level in patient 2, obtained when the marrow was replaced by tumor cells, was 2.5-fold higher than a simultaneous peripheral blood serum vinblastine level after VLP. Additional studies with VLP appear warranted in patients with platelet-phagocytizing tumors resulting in thrombocytopenia.

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