Potency Of Pituitary Gonadotropins

THERE ARE 5 different extracts of the anterior lobe of the pituitary in common use which are purported to contain the gonadotropic principle of that gland: prephysin (Chappel), gynantrin (G. D. Searle &Co.), gonadotropic factor (Ayerst, McKenna, and Harrison), ambinon (Roche), prepituitary-G (Italian Drugs Importing Co., Inc.) D'Amour and D'Amour1 have reported that 2 of these (gynantrin and prephycin) contain less than 4% and 25% of the labelled potency respectively. Because of these find' ings, we decided to test all 5 of the above-mentioned products according to the manufacturer's method of standardization, using, however, 10 times the number of units which he gives as required to reach the described end'point. We feel that if a given extract contains less than one-tenth the indicated potency, the active principle is present, if at all, in clinically insignificant amounts. In our assays, the preparation was injected into rats of the age prescribed by the manufacturerand the dose was divided according to the method given in the circular,