Neuroleptic drug-induced changes in platelet levels

Abstract

The results of a prospective study on the incidence of thrombocytopenia in matched psychiatric inpatients receiving different antipsychotics are reported. Patients were receiving haloperidol (N = 159), chlorpromazine (N = 164), fluphenazine decanoate (N = 152), or no drug therapy (control, N = 102). The groups did not differ statistically in respect to the incidence of thrombocytopenia, mean platelet levels, age, chlorpromazine equivalent dosages, or duration of drug therapy (p greater than 0.05). The two phenothiazine-treated groups had significantly higher numbers of patients with low-normal platelet levels when compared to both the haloperidol and control groups (p less than 0.05). Also, a nonsignificant trend was noted for increased incidence of thrombocytopenia among the phenothiazine groups compared with the haloperidol and control groups. Upon retrospective analysis of preneuroleptic treatment platelet levels, significant decreases in platelet values were observed with the phenothiazine-treated patients (p less than 0.001), but not with haloperidol (p greater than 0.05). The results indicate that neuroleptic drug-induced thrombocytopenia is rare but may be more common with phenothiazine antipsychotics.