Pharmacology of cis(Z)-clopenthixol decanoate, a depot neuroleptic

The duration and intensity of the neuroleptic effect of cis(Z)-clopenthixol decanoate in Viscoleo have been compared with those of cis(Z)-clopenthixol, 2 HCl in aqueous solution in a number of animal experimental models. Cis(Z)-clopenthixol, 2 HCl had a strong, but short-lasting neuroleptic effect (apomorphine antagonistic effect in dogs, inhibition of conditioned avoidance response in rats) which was accompanied by marked sedation. In contrast, cis(Z)-clopenthixol decanoate in oil had an effect which was slower in onset, but of much longer duration and only the highest doses caused a slight sedation. In rats catalepsy could be induced in some animals by high doses of cis(Z)-clopenthixol decanoate whereas cis(Z)-clopenthixol, 2 HCl at all the doses tested caused catalepsy in all animals. In mice only high doses of cis(Z)-clopenthixol decanoate in oil caused reduction of spontaneous motor activity and potentiation of barbiturate anaesthesia. The results are discussed with special reference to the clinical use of the depot preparation.