Outpatient phenothiazine use and bone marrow depression. A report from the drug epidemiology unit and the Boston collaborative drug surveillance program.

Phenothiazine-induced bone marrow depression (BMD) was evaluated in three separate but complementary data bases: (1) Among 1,048 patients admitted to psychiatric hospitals, there was no evidence of subclinical depression of the white blood cell (WBC) count attributable to phenothiazines used before admission. (2) Among 18,587 medical inpatients, there were 34 patients admitted for BMD in the absence of neoplasia or prior cytotoxic drug therapy; one of the latter reported using chlorpromazine hydrochloride, but it is doubtful whether this drug was the cause of the BMD. (3) Among 24,795 medical, surgical, and gynecological patients surveyed over a ten-month period in 1972, there were four who were admitted for BMD; one of the latter had a reversible leukopenia attributed to trifluoperazine hydrochloride.