SOME PHARMACOLOGICAL PROPERTIES OF ACEPROMAZINE:ITS POTENTIATING ACTION AND ITS EFFECT ON THE RELEASE OF THE TRANSMITTER FROM THE POST-GANGLIONIC SYMPATHETIC NERVE FIBRES

(1) The analgesic potency of acepromazine in a dose of 0.5 mg/kg was somewhat inferior to that of morphine (2mg/kg). By combining these two drugs, the analgesic effect was summated and the duration of action was prolonged. (2) After intracerebral injection, acepromazine produced more prominent tranquilizing and hypothermic effects than those elicited by hypodermic administration. It could also potentiate the hypothermic action of chloral hydrate and antipyrin. (3) Acepromazine, applied locally or injected subcutaneously, produced definite surface anaesthesia in rabbit's cornea and potentiated the anaesthetic action of procaine. (4) The vasopressor response to 5 γ/kg of adrenaline in the anaesthetized cats was reduced by 2.5 γ/kg of acepromazine and reversed by 5 γ/kg of the antagonist. The contraction of the nictitating membrane due to preganglionic sympathetic stimulation and injection of adrenaline was reduced by the larger dose. (5) When the periarterial nerves of Finkleman's preparation were stimulated, the motor activity of the isolated rabbit's ileum was decreased and the tone was reduced. This inhibitory response to the nerve stimulation was potentiated by acepromazine and chlorpromazine in the concentrations of 1:1,000,000-4:1,000,000. It is concluded that acepromazine and chlorpromazine do not interfere, with the release of noradrenaline from the post-ganglionic sympathetic nerve endings.