Abstract
Phenylethanolamine (a-phenyl-b-aminoethanol) is related chemically to tyramine, epinephrine and ephedrine According to the recent work of Alles 1 its circulatory stimulant efficiency would be higher than that of ephedrine. In view of this and because its general pharmacological action have not been previously studied it was thought desirable to make a survey of its possibilities. The product used was synthesized as the sulphate by Gr. Gordon A. Alles of the Clinic of Dr. George Piness, Los Angeles, who generously donated a large quantity to the laboratory. The method of synthesis eliminated contamination with its position isomer (b-phenyl-b-aminoethanol). The product consisted of white glistening crystals; was freely soluble in water, and had a melting point of 239-240°C.
The toxicity of phenylethanolamine is relatively low, the minimal fatal dose intravenously in white rats is about 0.14 gm. per kilo, which is the same as that of ephedrine reported by Chen. 2 This tendency to low toxicity agrees with the results of Alles 1 on guinea pigs and rabbits. Doses of 1 to 5 mg. per kilo intravenously in anesthetized dogs, cats and rabbits promptly raised the blood pressure from 25 to 103%, and accelerated the pulse to 42%, the effects persisting about 10 minutes, and hence qualitatively resembling tyramine. There seemed to be less cardiac depression with phenylethanolamine than with ephedrine. During the blood pressure rise the pupils dilated, while the hind leg and intestine usually were passively dilated, but occasionally were constricted. In cats, the pressor action was not reversed by ergot, but was abolished by cocaine during sensitization to epinephrine, resembling the actions of tyramine 3 and ephedrine. 4
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