Cyproterone acetate has been prescribed to treat severe hirsutism and
pattern baldness in women of childbearing age; it belongs to the class
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
effect; acts like the female hormone progesterone
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:
- 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
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
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
loss of the 101 hirsute women studied had a satisfactory response
- In another study of 17 women with pattern baldness,
14 of the subjects studied maintain hair growth while on Diane.