Finasteride was approved initially in 1992 as Proscar, a treatment for prostate enlargement, but the sponsor had studied 1 mg of finasteride and demonstrated hair growth in male pattern hair loss. On December 22, 1997, the FDA approved finasteride to treat male pattern hair loss.
Recognized side effects, experienced by around >1% of users, include decreased sex drive and volume of semen. As expected from its short 6-8 hour half-life, in trial studies, side effects ceased after dosage was discontinued. Finasteride is not indicated for use by women.
There are several studies on using finasteride for treatment and prevention of hair loss. In a 5-year study of men with mild to moderate hair loss, 48% of those treated with Propecia (finasteride 1mg) experienced some regrowth of hair, and 42% had no further loss. Average hair count in the treatment group remained above baseline, and showed an increasing difference from hair count in the placebo group, for all five years of the study. Propecia is effective only for as long as it is taken; the hair gained or maintained is lost within 6-12 months of ceasing therapy. In clinical studies, Propecia, like minoxidil, was shown to work on both the crown area and the hairline, but is most successful in the crown area.
Some hair loss patients who use finasteride, in an effort to save money, buy Proscar instead of Propecia, and split the Proscar pills to approximate the Propecia dosage. Doing so is generally considered unadvisable if women of pregnancy age are in the household; this is because finasteride, even in small concentrations, can cause birth defects in a developing male fetus. The birth defects involve the development of male genitalia. Propecia has been shown to be ineffective for treating hair loss in women.
Androgenetic alopecia or male pattern baldness is caused by the effects of the male hormone dihydrotestosterone (DHT) on genetically susceptible hair follicles that are present mainly in the front, top, and crown of the scalp (rather than the back and sides). DHT causes hair loss by shortening the growth, or anagen, phase of the hair cycle, causing miniaturization (decreased size) of the follicles. The effected hair becomes progressively shorter and finer until it eventually disappears.
DHT is formed by the action of the enzyme 5-alpha reductase on testosterone. Finasteride is a drug that works by blocking the enzyme 5-alpha reductase Type II that converts testosterone to dihydrotestosterone (DHT) in the hair follicle. Propecia, the brand name for finasteride, is the only FDA approved oral medication for hair loss. Finasteride causes a significant drop in both scalp and blood levels of DHT and its effect is felt to be related to both of these factors. Finasteride 1-mg/day decreases serum DHT levels by almost 70%. Serum testosterone levels actually increased by 9%, but this are within the range of normal.
Side effects from finasteride at the 1-mg dose are uncommon, but reversible. The one- year drug related side effects were 1.5% greater than in the control group. The data showed that 3.8% of men taking finasteride 1mg experienced some form of sexual dysfunction verses 2.1% in men treated with a placebo. The five-year side effects profile included: decreased libido (0.3%), erectile dysfunction (0.3%), and decreased volume of ejaculate (0.0%).
Most reported cases of sexual dysfunction occurred soon after starting the medication, but there have been reports of sexual dysfunction that have occurred at later points in time. The sexual side effects were reversed in all men who discontinued therapy, and in 58% of those who continued treatment. After the medication was stopped, side effects generally disappeared within a few weeks. When finasteride is discontinued, only the hair that had been gained or preserved by the medication is lost. In effect, the patient returns to the level of balding where he would have been had he never used the drug in the first place. No drug interactions of clinical importance have been identified.
Caution during Pregnancy
The benefits of finasteride will stop if the medication is discontinued. Over the 2-6 months following discontinuation, the hair loss pattern will generally return to the state that it would have been if the medication had never been used.
Propecia and Hair Transplantation
- Propecia works best in the younger patient who may not yet be a candidate for hair transplantation.
- Propecia is less effective in the front part of the scalp, the area where surgical hair restoration can offer the greatest cosmetic improvement.
- Propecia can regrow, or stabilize hair loss, in the back part of the scalp where hair transplantation may not always be indicated.
For those who choose not to take Propecia, or who cannot take it due to its side effects, the surgical hair restoration is just as effective. Medications are not needed for a hair transplant to be successful or the transplanted hair to grow and be permanent, but it minimize shock loss that may be seen after hair transplant surgery.
It is recommended that men aged 50, or over, should inform their regular physicians or urologists that they are taking Propecia (finasteride 1mg). It is also recommended that all men aged 50 or over have a routine annual evaluation for prostate disease, regardless of whether or not Propecia is used and the ones in high risk category have a PSA level before starting Propecia.