Blood dyscrasias induced by psychotropic drugs.

Drugs can cause a variety of blood dyscrasias, e. g., by interfering with hematopoiesis in the bone marrow or damaging mature blood cells by antibodies. Although numerous reports on the risks of adverse hematological effects associated with psychotropic drugs have led to stringent monitoring requirements for some compounds, particularly neuroleptics, it is still difficult to estimate the true prevalence of such risks. Sixteen episodes of thrombocytopenia, 63 of neutropenia, 22 of agranulocytosis, 4 episodes of severe neutro- and thrombocytopenia, and 2 of pancytopenia were documented by the drug safety program in psychiatry AMSP (Arzneimittelsicherheit in der Psychiatrie) in a population of 122,562 patients between 1993 and 2000. All cases were related to the epidemiological data provided for this population and systematically analyzed as regards history of medication, co-medication, and the clinical course. Putative risk rates for the main groups of medications and a number of drugs could be estimated with this database. Most changes in the white blood cell counts, which were rated as probably or definitely drug-induced, were attributed to clozapine (0.18 % of patients exposed), carbamazepine (0.14 %) and perazine (0.09 %). In patients on newer atypical neuroleptics, we documented neutropenia assumed to be probably or definitely drug-related in five patients during treatment with olanzapine and in one case with risperidone. In all five olanzapine-related cases, the drugs were the sole cause of the adverse drug reactions. All surveyed patients who received clozapine showed no difference in age and gender distribution from those who developed hematological changes. Incidences of hematological changes for antidepressants were much lower (about 0.01 %). Although the methodological accuracy of these findings has to be critically discussed these data could be of considerable clinical relevance and should be helpful in making clinical treatment decisions.