AHR-6646: a new, long-acting neuroleptic

1. AHR-6646 blocked d-amphetamine lethality in mice under aggregated conditions when the pretreatment interval was between one hour and seven days. 2. Conditioned avoidance responding in mice and cats was suppressed by AHR-6646 in doses that did not impair escape behavior. The duration of this effect was markedly prolonged. 3. AHR-6646 produced catalepsy in rats. The onset of this effect was delayed and the duration was prolonged when compared with that of chlorpromazine. 4. Apomorphine-induced pivoting in mice with unilateral lesions of the caudate nucleus was suppressed by AHR-6646. 5. AHR-6646 was a potent antiemetic agent in dogs, with a delayed onset and prolonged duration of action.

Assessment of the neuroleptic potential of some novel benzamide, butyrophenone, phenothiazine and indole derivatives

A series of experimental models were used to determine the activity spectra of potential neuroleptic agents on extrapyramidal and/or mesolimbic dopamine systems: catalepsy induction by the drug alone or in the presence of the acetylcholine-like agent, RS86 [spiro-(N'-methylpiperidyl-4′)-N-ethyl succinamide hydrogen fumarate], or α-methyl-p-tyrosine (α-MT), stereotypy antagonism (amphetamine) and hyperactivity antagonism (intra-accumbens and intrastriatal dopamine). Antiemetic potential was also considered. Whilst classical neuroleptics were active in all test situations, other neuroleptics including benzamide, phenothiazine, butyrophenone and indole derivatives exhibited novel activity spectra: clozapine failed to interact with α-MT, metoclopramide failed to antagonize a mesolimbic hyperactivity or interact with the acetylcholine-like agent. Other benzamide derivatives, clebopride, AHR6092, sultopride and tiapride also failed to interact with RS86, but whilst clebopride was active in all other test situations, AHR6092 was inactive in all but the antiemetic test, sultopride was only weakly cataleptogenic and tiapride only antagonized stereotypy and hyperactivity from the striatum. AHR6839, AHR6134, AHR6645, AHR6505B and AHR1709 were generally inactive in the catalepsy tests but exerted dopamine antagonistic potential in other test procedures. The antagonistic ability of AHR1709 was only revealed in the tests where dopamine function was specifically raised in the nucleus accumbens and caudate-putamen by intracerebral dopamine injections. Data are discussed in terms of a dissociation of drug effects on different cerebral dopamine systems.

(1-(3-(Phenothiazin-10-yl)propyl)-4-piperidinyl)phenylmethanones, a novel class of long-acting neuroleptic agents

In previous studies the phenyl-4-piperidinylmethanone moiety was shown to be a neuroleptic pharmacophore. A short series of [1-[3-(phenothiazin-10-yl)propyl]-4-piperidinyl]phenylmethanones was prepared and tested for neuroleptic activity using the blockade of d-amphetamine lethality in aggregated mice and suppression of conditioned avoidance behavior as the end points. Most compounds were shown to be potent neuroleptic agents and two were found to possess a long duration of action.

Species-dependent effects of fenfluramine on the central nervous system

The cortical effects of fenfluramine and a metabolite, norfenfluramine, were studied in rabbits and cats. The parent compound produced slow waves in the e.e.g. which were compatible with sedation in cats. Norfenfluramine also produced slow waves and apparent sedation in cats, but neither compound produced marked changes in the cortical waves of rabbits. When cortical waves in both species were slowed with pentobarbitone, fenfluramine increased the frequency of the waves in rabbits but did not alter the frequency in cats. Both fenfluramine and the metabolite blocked cortical after-discharges in both species. There is no apparent explanation for the differences in the action of the two drugs in the two species.