Clopimozide (R 29 764), a new highly potent and orally long-acting neuroleptic of the diphenylbutylpiperidine series.

Clopimozide (R 29 764), 5-chloro-1-(4-[4,4-bis(p-fluorophenyl)butyl]-4-piperidyl)-2-benzimidazolinone, is a new member of the potent and long-acting series of diphenylbutylpiperidine neuroleptics of which pimozide is the prototype, In animals the pharmacological profile of R 29 764 resembles that of typical neuroleptic compounds. R29 764 is very potent by oral route and has an extremely long duration of action. The onset of action of clopimozide is relatively fast, it is already very potent after 4 h and, in the procedures described, reaches its peak effect 24 h after administration. In spite of the high potency and long duration of action clopimozide is relatively atoxic. The safety margin, calculated as the ratio between the acute LD50 value and the lowest ED50 value is larger than or equal to 15.000 in rats and greater than 7.250 in dogs. Qualitatively, R 29 764 is more closely related to haloperidol, pimozide and penfluridol than to chlorpromazine. The side effect liability is expected to be very low, when hypotensive, autonomic and undesirable neurological side effects are concerned.