Prolonged Neuroleptic Effect of α‐Flupenthixol Decanoate in Oil

The duration and intensity of the neuroleptic effect of α‐flupenthixol decanoate in viscoleo® have been compared with that of α‐flupenthixol, 2 HCl in aqueous solution and α‐flupenthixol base in viscoleo® in a number of animal experimental models. Incorporation of α‐flupenthixol base in oil led to a prolongation of the neuroleptic effect (apomorphine antagonism in dogs, inhibition of conditioned avoidance in rats and mice) as compared to the duration of the effect of α‐flupenthixol, 2 HCl in aqueous solution. In both cases marked sedation was observed. In contrast, there was no sedation after α‐flupenthixol decanoate in oil, but a slower, smoother onset and a much longer duration of neuroleptic effect resulted. In rats the cataleptic effect and the apomorphine antagonistic effect of α‐flupenthixol decanoate in oil were of much shorter duration than the inhibitory effect on conditioned avoidance response. In mice a slight potentiation of barbiturate anaesthesia could be demonstrated 1‐6 hrs after high doses of α‐flupenthixol decanoate in oil. The clinical advantages of the depot preparation are discussed.