The syndrome of inappropriate ADH secretion secondary to vinblastine-bleomycin therapy

A clinical picture compatible with the syndrome of inappropriate ADH (antidiuretic hormone) secretion was observed in two patients receiving vinblastine-bleomycin chemotherapy. The mechanism by which this response is brought about is unclear. Penetration of Vinka alkaloids into CSF of humans is poor in the absence of extensive meningeal involvement, and hence an indirect method of action by a reduction in the osmotic threshold for vasopressin release has been suggested. By administering vinblastine on days 1 and 4 (instead of days 1 and 2, as suggested in the high-response regimen consisting of vinblastine, bleomycin, and cis-platinum) we have found better bone marrow tolerance and have not noticed the inappropriate ADH syndrome.