The primary aim of the study is to establish the range of plasma concentration of free chlorpromazine that would correlate with clinical improvement in psychiatric patients (double blind) and how to achieve this adequate plasma concentration. A. The following aspects in the management of psychiatric patients are under study: 1) Determination of the range of dose of chlorpromazine that would likely produce adequate plasma levels in psychiatric patients. 2) Effect of dosage forms, dosing intervals and multiple drug prescribing on plasma concentration of CPZ. Clinical assessment is by the Brief Psychiatric Rating Scale. Four categories were rated: (1) thinking disorders, (2) depression, (3) paranoid delusions and (4) withdrawal and retardation. Assay of plasma chlorpromazine is by GLC (electron capture detector). Subjects are both acute and chronic psychiatric patients of the Strong Memorial Hospital. B. Mechanism of chlorpromazine interaction with anticholinergics (Artane), lithium, fluphenazine, and stelazine will be studied in rats, using in vivo and in vitro techniques. Assay of drugs will be by GLC atomic absorption spectrometry and by isotopic techniques.