Effects of aspirin and prostaglandin E2 on secondary phase aggregation responses of schizophrenic patients treated with chlorpromazine.

We investigated the effects of oral aspirin 900 mg upon the platelet aggregation responses to 5-hydroxytryptamine, dopamine or N-dimethyl dopamine in schizophrenic patients chronically treated with chlorpromazine. Most subjects showed enchanced aggregation responses (that is appearance of secondary phase aggregation) to these agents prior to aspirin administration. When aggregation was re-tested 23.5 h after aspirin the secondary phase of the enhanced aggregation responses was abolished. Addition of 0.14-0.3 mumol/l prostaglandin E2 15 s after inducing aggregation partially restored the secondary phase. The observed secondary phase of aggregation may be due to increased prostaglandin synthesis or release.