The effects of fluphenazine decanoate injection and chlorpromazine on symptom severity and learning in outpatient schizophrenics

Abstract

Twenty-five schizophrenics being treated at an outpatient clinic were assigned to one of two treatment conditions. One treatment group received from 150 to 800 mg of chlorpromazine daily; patients in the other condition received injections of fluphenazine decanoate ranging from 25 to 100 mg at bi-weekly intervals. Subjects remained on the experimental regimes for six weeks during which they completed a series of personality inventories and were rated in psychiatric interviews. After the full period on study drugs, subjects completed tasks designed to assess their ability to learn in both impersonal and social contexts. Both treatment groups demonstrated significant symptom diminution over the course of the experimental trials, these changes being apparent on virtually every measure. Treatments did not affect symptom levels differently. Only on measures of learning could treatment differences be identified. Fluphenazine subjects performed significantly better than those receiving chlorpromazine on all major indices of task learning. Fluphenazine patients also demonstrated significantly greater control or consistency in the interpersonal task. These differences were not entirely unexpected given the greater sedative effects of chlorpromazine. Implications for the chemotherapy of schizophrenia are considered.