Androgens

Androgens

The therapeutically useful androgens are synthetic derivatives of naturally occurring testosterone. They include:

·                 fluoxymesterone

·                 testolactone

·                 testosterone enanthate

·                 testosterone propionate.

Pharmacokinetics

The pharmacokinetic properties of therapeutic androgens resem-ble those of naturally occurring testosterone.

Absorption

The oral androgens—fluoxymesterone and testolactone—are well absorbed. The parenteral ones—testosterone enanthate and testosterone propionate—are designed specifically for slow ab-sorption after I.M. injection.

Distribution, metabolism, and excretion

Androgens are well distributed throughout the body, metabolized extensively in the liver, and excreted in urine.

Checking the suspension

The duration of the parenteral forms is longer because the oil sus-pension is absorbed slowly. Parenteral androgens are adminis-tered one to three times per week.

Pharmacodynamics

Androgens probably act by one or more mechanisms. They may reduce the number of prolactin receptors or may bind competi-tively to those that are available.

Keeping its sister hormone in check

Androgens may inhibit estrogen synthesis or competitively bind at estrogen receptors. These actions prevent estrogen from affect-ing estrogen-sensitive tumors.

Pharmacotherapeutics

Androgens are indicated for the palliative treatment of advanced breast cancer, particularly in postmenopausal women with bone metastasis.

Drug interactions

Androgens may alter dose requirement in patients receiving in-sulin, oral antidiabetic drugs, or oral anticoagulants. Taking them with drugs that are toxic to the liver increases the risk of liver tox-icity. (See Adverse reactions to androgens.)