How does oral hormone replacement therapy work?
Given-To-Fly asked:
I have always been wondering since hormones are proteins and proteins are ripped into smaller sequences of amino acids in the stomach, how does a hormone orally ingested increases it’s level in the bloodstream?
I have always been wondering since hormones are proteins and proteins are ripped into smaller sequences of amino acids in the stomach, how does a hormone orally ingested increases it’s level in the bloodstream?
01 June 2009, 12:52 am
Pharmacokinetics: Animal studies have shown that T 4 is only partially absorbed from the gastrointestinal tract. The degree of absorption is dependent on the vehicle used for its administration and by the character of the intestinal contents, the intestinal flora, including plasma protein, soluble dietary factors, all of which bind thyroid and thereby make it unavailable for diffusion. Only 41% is absorbed when given in a gelatin capsule as opposed to a 74 percent absorption when given with an albumin carrier.
Depending on other factors, absorption has varied from 48 to 79% of the administered dose.
Fasting increases absorption. Malabsorption syndromes, as well as dietary factors (children’s soybean formula, concomitant use of anionic exchange resins such as cholestyramine), cause excessive fecal loss. T 3 is almost totally absorbed, (95% in 4 hours). The hormones contained in the natural preparations are absorbed in a manner similar to the synthetic hormones.
More than 99% of circulating hormones are bound to serum proteins, including thyroid-binding globulin (TB g), thyroid-binding prealbumin (TBPA), and albumin (TB a), whose capacities and affinities vary for the hormones. The higher affinity of levothyroxine (T 4) for both TB g and TBPA as compared to triiodothyronine (T 3) partially explains the higher serum levels and longer half-life of the former hormone. Both protein-bound hormones exist in reverse equilibrium with minute amounts of free hormone, the latter accounting for the