Systemic cyproterone acetate is a popular treatment for female pattern baldness in Europe

Male and female pattern hair loss information
 Systemic cyproterone acetate treatment of female pattern baldness

Cyproterone acetate belongs to the class of hormone inhibitors and has been prescribed to treat severe hirsutism in woman of childbearing age and also androgenetic alopecia in women. Every woman normally produces a certain amount of androgen, which is necessary for axillary and pubic hair formation and maintenance.

Cyproterone acetate is an anti-androgen and blocks the normal activity of androgen by suppressing the actions of testosterone (and its metabolite dihydrotestosterone) on tissues. The term antiandrogen, as defined by Dorfman, implies prevention of expression of androgen activity at target sites and does not include other mechanisms of decreasing androgen action, such as a decrease in production of androgens, interference with androgen metabolism, or change in androgen plasma protein binding. However, Cyproterone acetate exerts its effects by blocking the binding of dihydrotestosterone (DHT) to its receptors.

Cyproterone acetate is available in Europe, Asia and Canada, but not in the US. Oral cyproterone acetate is poorly absorbed (5 to 30 percent), with maximum plasma levels achieved in a few hours. 58 percent of the drug is excreted via bile and 30 percent via urine.

Pharmacological action

Cyproterone acetate has three effects:

  • Antiandrogenic effect (i.e. it inhibits the action of androgens)
  • Progestational effect (i.e., it acts like the female hormone progesterone)
  • Antigonadotropic effect (reducing the growth /function of the gonads)

As Cyproterone acetate suppresses production of estrogen by its antigonadotrophic effect, as a rule, estrogens are given along with cyproterone acetate. This ensures that the woman receiving Cyproterone acetate has regular menstrual periods and proper levels of the sex hormone-binding globulin. Although it is possible for the drug to stop further hair loss and trigger re-growth of hair within about a year, it needs to be used on an ongoing basis in order to maintain re-growth and eliminate hair loss.

Administration and dosage

When Cyproterone acetate is given in combination with estrogen and delivered in a reverse sequential regimen, it is termed as cyclical antiandrogen therapy (CAT). The dose of this regimen is 100 mg cyproterone acetate on days 5 to 15 and 50 µg ethinyl estradiol on days 5 to 25 of the menstrual cycle. A low-dose combined formulation of 2 mg cyproterone acetate and 50 µg ethinyl estradiol given on days 5 to 25 is also utilized in patients with mild acne or hirsutism or for maintenance doses following CAT in the same conditions. It is common practice to use Diane/Dianette (brand names of drugs that contain 2 mg CPA in combination with 35 mg ethynil estradiol) in CAT.

Side effects of cyclical antiandrogen therapy

Cyproterone acetate is potentially damaging to the liver (hepatotoxic) and liver function tests should be performed periodically. Women of childbearing potential must never get pregnant while taking Cyproterone. Fetal malformations (damage) can occur in patients on cyproterone; therefore the drug must be prescribed in conjunction with the contraceptive pill. Potential side effects of CAT are somewhat similar to those seen with intake of oral contraceptive pills and include:

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

Additional side effects of cyclical antiandrogen therapy in patients with androgenetic alopecia

Significant decrease in levels of serum vitamin B12 and increase in total iron-binding capacity (without change in serum iron) after 6 months of commencement of cyproterone acetate/ethinyl estradiol therapy has been reported in non-vegetarian females with pattern hair loss. In a trial of cyclical treatment with cyproterone acetate in women with serum ferritin levels above and below 40 µg / L (10 subjects in each group) hair densities increased by about 15% in the high ferritin group after 1 year of treatment whereas the low ferritin group failed to respond. Serum ferritin is an indirect measure of the body's iron stores, typically expressed in µg /L, or micrograms of iron per liter of blood.

Clinical trials

There is evidence that Cyproterone acetate slows the process of hair loss but this has not been thoroughly investigated in large-scale well-controlled studies of cyproterone acetate use in female pattern hair loss.

  • One study compared 29 women with female pattern hair loss treated with CAT with 20 women without specific treatment. 18 of the 29 patients treated with CAT subjectively improved, and 24 of 29 had objective improvement including decreased shedding, increased diameter of hairs, and/or decreased telogen counts in affected areas. In the other group, 7 of the 20 patients without therapy also subjectively improved, but no reference was made to an objective improvement in these patients.
  • Two reports of less than 11 women in each group showed decreased shedding and/or an increased density of non-vellus hair with CAT.
  • In one series, 40 percent of women with female pattern hair loss treated with CAT showed improvement.
  • The results with the lower doses of cyproterone acetate in Diane have apparently been less dramatic than with CAT. However, in one study of 101 hirsute women, 85 percent of those with concomitant pattern hair loss had a satisfactory response to Diane.
  • In another study, 14 of 17 women with androgenetic alopecia had maintenance of hair growth while on Diane.