Preparation and pharmacological activity of 2-(4'R')benzyl-5R-benzimidazoles. Analgesic activity and effect on conditioned avoidance response

Several derivatives of 2-benzylbenzimidazole (dibazole) bearing substituents on positions 5 and 4' were prepared and tested, together with dibazole, for their activity on the acquisition of a conditioned avoidance response and for analgesic activity. Chlorpromazine and acetylsalicylic acid were used as standards. Analgesic activity was found for all these compounds, most of which proved more active than A.S.A. As regards the acquisition of a C.A.R., the 5-chloroderivatives exhibit a strong inhibitory activity, that for compound (VIII) is equal to that of chloropromazine, while dibazole and the 5-trifluormethylderivatives stimulate the acquisition.