Absorption of Estradiol and its Esters from Subcutaneously Implanted Tablets in the Guinea Pig.

Abstract

Deanesly and Parkes made use of their ingenious method of subcutaneously implanted tablets to study the question of the rate of hormone absorption. Emmensl has recently communicated important results on the comparative rate of absorption of estrogens and androgens and their esters in the rat.In the course of our work on the fibromatogenic action of a prolonged treatment with estrogens in the guinea pig, we have applied the method of Deanesly and Parkes with most satisfactory results2 In this way, we also became interested in the rate of absorption of different hormones. In the present paper, we shall give the results obtained in 52 female guinea pigs with 3 estrogens: free estradiol, dipropionate of estradiol and 17-caprylate of estradiol. Our results (Table I ) which confirm those of Emmens, present new relevant details and render it possible to compare the rate of absorption in two different species.The range of weight of the disc-shaped tablets, or their fragments, was the same in all 3 groups, and range of surface was very likely the same. This is important because absorption is related to the surface. There was considerable scattering of percentage of absorption in each of these three groups (fifth row of Table I and Fig. l ) , but it is remarkable that the range of scattering of percentage of absorption coincided with the range of weight of tablets in the respective group (fourth row of Table I, figures in parentheses). The smaller or the thinner a tablet, the greater the surface in relation to the weight and the greater also the percentage of absorption.The average absorption of estradiol was 20% in 73 days, or 0.28% per day (sixth row of Table I). The caprylate tablets lost 6.1 % in 74 days or 0.08% per day.