Pharmacokinetics of Testosterone (Androgen)
| Home | | Pharmacology |Chapter: Essential pharmacology : Androgens and Drugs for Erectile Dysfunction
Testosterone is inactive orally due to high first pass metabolism in liver. The duration of action after i.m. injection is also very short,
PHARMACOKINETICS
Testosterone is inactive orally due to high first pass metabolism in liver. The duration of action after i.m. injection is also very short, therefore, slowly absorbed esters of testosterone are used by this route—are hydrolysed to the active free form. Testosterone in circulation is 98% bound to sex hormone binding globulin (SHBG) and to albumin.
The
major metabolic products of testosterone are androsterone and etiocholanolone
which are excreted in urine, mostly as conjugates with
glucuronic
acid and sulfate. Small quantities of estradiol are also produced from testosterone
by aromatization of A ring in extraglandular tissues (liver, fat,
hypothalamus). Plasma t½ of testosterone is 10–20 min.
Methyltestosterone
and fluoxymesterone are metabolized slowly and have a longer duration of
action. Estrogens are not produced from fluoxymesterone and
dihydrotestosterone.
Related Topics
