Serum antibodies against desipramine as a possible cause for thrombocytopenia.

I N RECENT YEARS more and more drugs have become implicated as causes of thrombocytopenia. In many instances correlations were made from clinical reports, and occasionally in vitro methods have demonstrated the presence of antibodies specific for a certain drug.1’2 In the present paper two cases were studied in which in vitro methods suggested that thrombocytopenia was induced by desipramine (Pertofrane#{174}). The drug manufacturers have received reports on the occurrence of purpura in one patient taking desipramine and in 23 taking imipramine (Tofranil#{174}).3 The two drugs are considered together because imipramine is metabolized in vivo to desipramine, and owes its pharmacologic activities to this demethylated metabolite.4 Platelet counts were done in 10 of the 23 patients who developed purpura while taking imipramine. Thrombocytopenia was noted in eight. No additional studies were done on these patients. To our knowledge, thrombocytopenia has not been proved to be associated with the