Pharmacological studies on 3-[gamma-(p-fluorobenzoyl)propyl]-2,3,4,4a,5,6-hexahydro-1-(H)-pyrazino ]1,2-a] quinoline hydrochloride (compound 69/183). Part III: Assessment of tranquillising activity.

The tranquillising activity of 3-[gamma-(p-fluorobenzoyl)propyl]-2,3,4,4a,5,6-hexahydro-1-(H)-pyrazino [1, 2-a]quinoline hydrochloride (centpyraquin), a new adrenergic neurone blocking antihypertensive agent, has been evaluated in various laboratory animals. The compound has a calming effect in mice, rats, cats and monkeys. In low doses it reduces the spontaneous motor activity followed in progressively higher doses by hypothermia, ptosis and catalepsy and a taming effect in monkeys and cats. It potentiates pentobarbitone-, hexobarbitone- and ethanol-induced sleep and antagonises amphetamine induced toxicity in mice. It, however, fails to antagonise morphine induced mania and hyperactivity in cats. It blocks conditioned avoidance response in rats at a much lower dose (ED50 = 2.73 mg/kg) than the unconditioned response (ED50 = 10,9 mg/kg). In cats centpyraquin increases the voltage and slows the frequency of cortical EEG discharges. Centpyraquin has the profile of activity of a neuroleptic on the central nervous system.