The
antipsychotic properties of
dilept, a new
drug representing substituted
dipeptide based on a beta-rotational structure of the main metabolite of endogenous
neuroleptic NT8-13, have been studied using the test for prestimulus inhibition (PSI) of the acoustic startle reflex in rats. It is established that
dilept eliminates the PSI deficiency caused by the introduction of a noncompetitive
NMDA receptor blocker
ketamine, which is evidence for pronounced
neuroleptic properties of the
drug. Effective doses of
dilept for intraperitoneal administration were 1.6, 3.2, and 6.4 mg/kg, the maximum
antipsychotic effect being produced at 1.6 mg/kg.
Dilept also prevented the PSI deficiency upon peroral administration in rats. In this case, the
drug administration per os in the form of a tabletization mixture with poly(vinyl
pyrrolidone) and
lactose was more effective compared to a mixture of the parent substance with Tween-80, which can be explained by the favorable effect of additives on the bioavailability of
dilept. The maximum
antipsychotic effect of
dilept upon
oral administration was observed for a dose of 16 mg/kg. The ability of
dilept to eliminate the PSI deficiency in the acoustic startle reflex test on the model of
glutamate-negative
psychosis in rats can be considered as a prognostic sign for the
drug efficiency with respect to the negative and
cognitive symptoms of
schizophrenia and
autism manifestations. The antidopamine activity of
dilept allows us also to predict the
drug efficiency with respect to the positive manifestations of
schizophrenia.