The comparison of the effects of DL-308, a potential new neuroleptic agent, and thioridazine on some psychological and physiological functions in healthy volunteers.

Eight healthy male volunteers participated in four experimental sessions in which they ingested either DL-308 (10 mg), DL-308 (20 mg), thioridazine (50 mg) or placebo. Drugs were allocated to subjects and sessions in a double-blind fashion according to a balanced cross-over design. Both DL-308 and thioridazine displayed sedative properties, as indicated by the sedated appearance of the subjects, by a decrease in subjectively rated alertness and by an impairment of performance on psychomotor tests. DL-308 appeared to be a more potent sedative than thioridazine. DL-308 (10 mg) caused an increase in subjectivey rated sweating and objectively measured heart rate, suggesting a sympathomimetic property for the drug. DL-308, similarly to thioridazine, had effects consistent with an alpha-adrenolytic action; both drugs caused miosis, hypotension and a decrease in salivation. The decrease in salivation may also be consistent with an anticholinergic effect. When equisedative doses of the two drugs were compared, DL-308 had a much smaller influence on autonomic functions than thioridazine. DL-308 had a faster time-course of action than thioridazine. Peak effects were attained 1-3 h post-drug and the effects almost completely dissipated within 5 h. DL-308, similarly to thioridazine, had little effect on the motor system, as indicated by conventional clinical neurological examination.