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Baldness Biology
 Male pattern baldness overview
 Female pattern baldness overview
 Male pattern baldness presentation
 Female baldness presentation
 Hair fiber in pattern baldness
 Hair follicles in pattern baldness
 Androgen hormones in men
 Androgen hormones in women
 Androgen receptors in baldness
 5 alpha reductase in baldness
 Inflammation in baldness
 Genetics in pattern baldness
 Diseases associated with baldness
 Pattern baldness in children
 
Baldness Treatments
 Minoxidil for pattern baldness
 Minoxidil for female baldness
 Minoxidil for male baldness
 Finasteride for male baldness
 Finasteride for female baldness
 Tretinoin for pattern baldness
 Diazoxide for pattern baldness
 Ketoconazole for pattern baldness
 Antiandrogens for pattern baldness
 Contraceptives for female baldness
 Spironolactone for female baldness
 Flutamide for female baldness
 Cyproterone acetate for baldness
 

The assumption that anti-androgen can be feasibly used to halt or even reverse male pattern baldness resulted from observing castrated men. Hamilton observed that castration prevented further progression of male pattern hair loss among eunuchs; furthermore, the hair loss in eunuchs resulting from induced exogenous testosterone halted when testosterone treatment was discontinued. Anti-androgen therapy for androgen-induced baldness is a relatively new concept, and only a topical anti-androgen would be plausible in men.

Anti-androgens are compounds (usually synthetic pharmaceuticals) that stops or interferes with the normal action of androgens at cellular receptor sites. There are two types of anti-androgen:

  • Steroidal anti-androgens
  • Non-steroidal anti-androgens

Anti-androgen drugs may be systemic or topical. Systemic anti-androgens are currently only specified for women suffering from pattern baldness, as it reduces circulating testosterone and may hamper normal male sexual functioning. Topical anti-androgens can be applied directly to the skin and are generally preferred by men.

Anti-androgen’s mechanism of action

The perception on the mechanism of action of anti-androgens is it prevents the Dihydrotestosterone (DHT) from binding to the androgen receptor. Being weak agonists, Anti-androgens compete less well than endogenous hormones and dissociate rapidly from the androgen receptor, or potent agonists, which form a complex bond with the receptor molecule and dissociate slowly. The weak agonists are the true antagonists of the endogenous and exogenous androgens that rely only on a continuous supply of the compound to achieve full inhibition.

Non-steroid Cyoctol

Non-steroid anti-androgen cyoctol displays neither the estrogen (female hormone estrogen) production nor progestogenic (female hormone progesterone) production activity, acting by competitively binding to the androgen receptors thus preventing dihydrotestosterone from binding and effectively inhibiting the stimulatory effects of androgens. Cyoctol is completely metabolized in the skin after topical application and it competitively inhibits DHT receptor. During the American Academy of Dermatology presentation in 1989, the use of cyoctol has been reported in only one; however, the dropout rate of that study was greater than 50% thus the definitive results was ruled out.

Topical Progesterone Treatment

Progesterone is a compound that has high structural similarity to testosterone, and can therefore use the enzyme 5a-Reductase, and can bind to the androgen receptor. Some synthetic progesterone naturally has estrogenic as well as androgenic effects. Progesterone has affinity to the androgen receptor that allows it to act as androgen or anti-androgen; it also binds to its own intracellular transcription receptor.

Aside from the inhibiting effect of progesterone to the androgen receptor binding, it also inhibits the enzyme 5a-Reductase responsible for the metabolism of testosterone to DHT. Compared to testosterone, however, the DHT binds the androgen receptor with five times the tenacity of testosterone and is more potent in its ability to cause downstream activation. Another inhibitory effect of progesterone is towards the formation of the 5ametabolites from androstenedione. Most tissues such as the skin rapidly metabolize progesterone to relatively nonandrogenic substances. In women, one milliliter of a 2 percent solution applied topically twice daily appears to be well tolerated, but higher doses lead to menstrual irregularities.

Although it has not been tested thoroughly in clinical studies, topical progesterone has been utilized widely. To ascertain the efficacy of the compound, a study using topical progesterone has been undertaken for 10 to 48 months in 12 men in the age group 18 to 39-year old with male pattern baldness. However, the results were not that promising because none of the subjects grew hair: 6 of them developed further thinning, and the other 6 had the same hair density.

However, 14 patients treated with 15 mL of a 0.5percent topical 11a-hydroxyprogesterone applied twice daily to the scalp for 2.4 to 4 years documented a “positive” response.

Another study on 1% 11a-hydroxyprogesterone lotions in 18 young men for 12-month period found that the 11a-hydroxyprogesterone treated group had increased numbers of anagen hairs in the treated scalp, and 9 of 10 had improvement. In the controls, however, there was a decrease in anagen hairs and worsening hair loss in 7 of the 8 subjects.

Topical Estrogen Treatment

Estrogens, as indirect anti-androgens, lead to a decrease in the bioactive free testosterone by increasing the production of sex hormone binding globulin (SHBG). Synthesized by the liver, SHBG is a glycoprotein most important for androgen binding in which in the plasma, the more potent androgens and estradiol are bound with different binding affinities. An increased activity of 5a-Reductase – the enzyme responsible for the metabolism of testosterone to DHT, and an increased testosterone level causes SHBG synthesis to decrease. On the other hand, estrogen increases the Sex Hormone Binding Globulin (SHBG) and thus decreasing further the amount of free testosterone.

There have been no extensive clinical trials regarding the use or topical estrogen preparation in subjects with pattern baldness; however, there has been one double-blind, controlled 6-month trial to topical 0.025% 17a-estradiol conducted with 15 men and women who had pattern alopecia. The trial showed that a significant reduction in the percentage of telogen hairs along with stabilization of the hair loss. However, the absorption of topical estrogen can lead to decreased libido in men even if more than 70 percent of a topically applied preparation is metabolized to weak non-androgenic by-products.

 
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