TRANQUILLIZING AND HYPOTENSIVE ACTIVITIES OF TWELVE PHENOTHIAZINES

Twelve phenothiazine derivatives have been compared in relation to their central sedative, tranquillizing and hypotensive activities. The ED50's of the compounds to suppress the conditioned response, unconditioned response and forced locomotor activity were determined. Suppressions of the conditioned and unconditioned responses were taken as criteria for tranquillizing and central sedative activities respectively. The "tranquillizing ratio" (ED50 for unconditioned response/ED50 for conditioned response) was used as the criterion of tranquillizing activity in relation to sedative activity and for purposes of comparison this ratio was assigned a value of unity for chlorpromazine. Perphenazine was the most potent drug in suppressing the conditioned and unconditioned responses whereas fluopromazine had the maximal "tranquillizing index" activity. Six compounds had great, three moderate and three mild hypotensive activity when doses of 1 mg/kg were injected intravenously into dogs. The relationship of the chemical structure to the central sedative activity is discussed.

THE EFFECT OF SOME PHENOTHIAZINE TRANQUILLIZERS ON THE OESTROUS CYCLE OF ALBINO MICE

The effects of reserpine and of nine phenothiazine compounds on the oestrous cycle of albino mice were tested. With the exception of promethazine (which is not a tranquillizer) all the phenothiazine compounds and reserpine prolonged the oestrous cycle. The mechanism by which these tranquillizers interfere with the oestrous cycle is discussed.

STUDIES ON THE HYPERGLYCAEMIA INDUCED BY CHLORPROMAZINE IN RATS

Chlorpromazine induces in rats a marked and long-lasting hyperglycaemia which (a) is more marked at low than high room temperatures, (b) is inhibited by phentolamine but not by dibenamine, and (c) is prevented by adrenalectomy, by removal of the adrenal medullae and by treatment of the rats with reserpine. Other experimental results suggest that there is a correlation between the hyperglycaemia and the hypothermia induced by chlorpromazine and by its congeners. The hyperglycaemia seems to be the result of at least two factors: an activation of the adrenergic mechanisms and an impaired peripheral utilization of glucose.

ANTI-EMETIC ACTIVITY OF PHENOTHIAZINES IN RELATION TO THEIR CHEMICAL STRUCTURE

Twelve phenothiazine derivatives have been studied for anti-emetic potency in dogs against emesis induced by apomorphine. The PD(50)s of all the compounds were determined and the activities compared with chlorpromazine hydrochloride as standard. Thioproperazine methanesulphonate was 300 times more active than chlorpromazine hydrochloride and twice as active as perphenazine sodium citrate. The anti-emetic activity of the compounds has been correlated with their chemical structure.