Cyproterone acetate has been prescribed to treat severe hirsutism and pattern baldness in women of childbearing age; it belongs to the class of hormone inhibitors.

All women are genetically program to produce a certain amount of androgen that is necessary for axillary and pubic hair formation and maintenance. Anti-androgen cyproterone acetate blocks by suppressing the action of testosterone and its metabolites, dihydrotestosterone, on tissues. Dorfman defines anti-androgen to imply prevention of expression of androgen activity at target sites and does not include other mechanisms of decreasing androgen action, such as a decrease in the production of androgens, interference with androgen metabolism, or change in androgen plasma protein binding. Cyproterone acetate blocks the binding of dihydrotestosterone (DHT) to its receptors.

Oral cyproterone is not available in US; it’s only available in Europe, Asia and Canada. The percent absorption of oral cyproterone in the body is only 5 to 30 percent, with maximum plasma levels achieved after few hours of ingestion. Fifty eight percent (58%) of the drug is excreted through the bile and 30 percent via urine.

Cyproterone Pharmacological Action

The three effects of cyproterone acetate:

• Anti-androgenic effect; inhibits the action of androgens
• Progestational effect; acts like the female hormone progesterone
• Ani-gonadotropic effect; reducing the growth/function of the gonads

Cyproterone acetate suppresses manufacture of estrogen by its anti-gonadotrophic effect, thus as a rule, estrogens are given along with cyproterone acetate. This is imperative so that women receiving cyproterone acetate has regular menstrual periods and proper levels of the sex-hormone-binding globulin. If used in an on going basis, the cyproterone acetate can possibly stop further hair loss and trigger re-growth of hair within a year, continued use is needed to maintain re-growth and eliminate hair loss.

Cyproterone Administration and Dosage

Cyclical anti-androgen therapy (CAT) is the term when cyproterone acetate is given in combination with estrogen and delivered in a reverse sequential regimen. During a woman’s 5 to 15 days menstrual cycle, the regimen requires giving 100 mg cyproterone acetate and 50µg ethinyl estradiol on the 5 to 25 days of the menstrual cycle. A low-dose combination of 2 mg cyproterone acetate and 50µg ethinyl estradiol is given on the days 5 to 25 is given to patients with mild acne or hirsutism or for maintenance doses following CAT in the same conditions. The Dianne/Dianette (brand names of drugs that contain 2 mg CPA in combination with 35 mg ethynil estradiol) is commonly used in the CAT.

Adverse Effects of Cyclical Anti-Androgen Therapy

Women under CAT should be tested periodically with liver damage as cyproterone acetate is potentially damaging to the liver (hepatotoxic). It is also imperative to women of childbearing age to never get pregnant while taking cyproterone; the drug has the potential to cause fetal malformations (damage). Therefore, the drug must be prescribed in conjunction with a contraceptive pill. The potential side effects of CAT that are somewhat similar to those observed in the intake of oral contraceptive pills include:

• Nausea
• Headache
• Asthenia; lack of body strength
• Increased weight
• Decreased libido
• Breast discomfort and depression have also been reported in more than 5 percent of cases treated with CAT

Side effects of CAT therapy in patients with pattern baldness

There has been a significant decrease in levels of serum vitamin B12 and increase in total iron-binding capacity (without change in serum iron) after six months of commencement cyproterone acetate/ethinyl estradiol therapy among non-vegetarian women with female pattern hair loss. A cyclical treatment trial with cyproterone acetate was conducted in 20 women with 10 subjects in serum ferritin levels above 40µg/L and 10 subjects in serum ferritin levels below 40µg/L. After 1 year of treatment, the high ferritin group reported hair densities increased by about 15% while the low ferritin group failed to respond. Serum ferritin serves as an indirect measure of the body’s stored iron; it’s typically expressed in micrograms of iron per liter of blood.

Cyproterone Acetate Clinical Trials

Although there is evidence that cyproterone acetate slows the process of hair loss, however, there has not been a large-scale, well-controlled thorough investigation of cyproterone acetate in female pattern hair loss.

• A study compared 29 women with female pattern hair loss treated with CAT to 20 women without specific treatment. The study showed 18 of the 29 patients treated CAT subjectively improved, and 24 of them had objective improvement including decreased shedding, increased hair diameter, and decreased telogen counts in affected areas. On the other hand, 7 of the 20 patients without therapy also showed subjective improvement, however, no reference was made to an objective improvement in these patients.
• 11 women in each group showed decreased shedding and an increased density of non-vellus hair with CAT.
• 40 percent of women with female pattern hair loss treated with CAT showed improvement, according to a series.
• Compared with CAT, the lower doses of cyproterone in Diane was apparently less dramatic. However, 85 percent of those with concomitant pattern hair loss of the 101 hirsute women studied had a satisfactory response to Diane.
• In another study of 17 women with pattern baldness, 14 of the subjects studied maintain hair growth while on Diane.