IN VIVO STUDY OF THE ACTION MECHANISM OF THE RAPITALAM PHARMACEUTICAL SUBSTANCE

The aim is to study the action mechanisms of the Rapitalam pharmaceutical substance using Parkinsonian syndrome models.

Materials and methods. Various effects of a new pharmacological substance, N-chlorophenylmethyl-dihydro-methoxy-methylphenyl-oxopyridazine carboxamide (Rapitalam), were studied in male laboratory mice and rats. During the experiment, the various models of the Parkinsonian syndrome were reproduced: the simulation of the Parkinsonian syndrome by administering 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP) neurotoxin, the simulation of haloperidol-induced catalepsy, the simulation of apomorphine-induced stereotypy and the simulation of oxotremorine-induced tremor followed by tests. The following tests were carried out in order to determine the Rapitalam efficacy with regard to symptoms manifested after the MPTP administration in animals: the open field test, the rotarod performance test, as well as the evaluation of the grip strength and the degree of rigidity using the stride length. When simulating the haloperidol-induced catalepsy, a horizontal bar test was performed. After the administration of apomorphine, the severity of stereotypy was assessed in scores. A simulation of oxotremorine-induced tremor in rats was used to study the cholinergic link. After the administration of oxotremorine, the severity of tremor was assessed against the background of administration of the test compounds.

Results. During the analysis of the data obtained in the open field and rotarod tests as well as the stride length and the grip force when simulating the Parkinsonian syndrome by introducing MPTP, no intergroup statistical differences were found. Thus, the tested Rapitalam substance in doses of 2 mg/kg, 6 mg/kg and 20 mg/kg and the Levodopa reference drug at a dose of 60 mg/kg had no effect on the indices of motor activity and motor coordination in mice when administered orally for 10 days. Rapitalam in doses of 1 mg/kg, 3 mg/kg and 10 mg/kg as well as the Levodopa reference drug at a dose of 50 mg/kg, did not affect the severity of haloperidol-induced catalepsy and apomorphine-induced stereotypy in rats. Under the administration of oxotremorine to laboratory animals, a statistically significant decrease in the severity of tremor was observed during the Rapitalam administration in doses of 3 mg/kg and 10 mg/kg.

Conclusion. Rapitalam is established to have no effect on motor impairment due to dopaminergic mechanisms. The tested substance is characterized by a pronounced cholinoblocking effect at doses of 3 mg/kg and 10 mg/kg.

Conflict of interest: the author declares no conflict of interest.