The behavioral pharmacology of butaclamol hydrochloride (AY-23,028), a new potent neuroleptic drug.

Butaclamol hydrochloride (AY-23,028) is a member of a new chemical class for which antipsychotic activity in humans has recently been demonstrated. The compound antagonized amphetamine-induced stereotyped behavior in rats, amphetamine toxicity in aggregated mice and apomorphine-induced emesis in dogs. It depressed both discriminated avoidance and continuous lever-pressing behavior in rats and inhibited ambulation and rearing in the open field. At higher doses, AY-23,028 induced catalepsy. Adrenergic blocking activity, measured by the antagonism of epinephrine-induced mortality, was weak. These pharmacological actions are characteristic of neuroleptic drugs. In the dose range where the aforementioned effects were observed AY-23,028 did not antagonize either the tetrabenazine-induced ptosis or the tremorine syndrome and did not cause either hypothermia or ataxia. The potency and onset of action of AY-23,028 were comparable to those of fluphenazine but AY-23,028 was of longer duration. The results are discussed in relation to current concepts of neuroleptic mechanisms.