ABSORPTION OF STEROIDS FROM SUBCUTANEOUSLY IMPLANTED TABLETS OF THE PURE HORMONE AND OF THE HORMONE MIXED WITH CHOLESTEROL

Abstract

THE comparative rate of absorption of steroid hormones and their esters from subcutaneously implanted tablets has been studied by different observers (1–5). Lipschutz and Vargas (6) have calculated absorption per square millimeter of the tablet. Most important work on the laws governing absorption from tablets has been done by Folley and his associates (7–10). Tablets prepared by mixing cholesterol with various substances have been in use for a long time (11–13), and great diminution of the absorption rate has been found (12–14). The degree of this diminution and the laws to which it is subject have apparently not been under discussion so far; but the following statements can be made. Whereas cholesterol is not absorbed from tablets of pure cholesterol (15) it is absorbed from hormone-cholesterol tablets; this is shown by the fact that the concentration of the steroid hormone in the hormone-cholesterol tablet does not diminish as it should if absorption is selective (14, 16). One must then suppose that some change in the physical condition of cholesterol is effected through the contact with the steroid hormone. It can be shown that something similar occurs also with the steroid hormone, but in the opposite direction. When using tablets containing 60 per cent of cholesterol and 40 per cent of progesterone, one would suppose that absorption of progesterone would drop two and one-half times compared to tablets of pure progesterone, should absorption per square millimeter remain unchanged. This is not the case. Absorption of progesterone from tablets containing 40 per cent of this steroid drops much more; absorption is about 25 micrograms or less per square millimeter (13) instead of more than 200 to 300 micrograms from similar tablets of pure progesterone, i.e., absorption drops probably ten times instead of two and one-half times. In other words, absorption of progesterone per square millimeter of this steroid diminishes greatly when the steroid is mixed with cholesterol.