Finasteride (Propecia)

• Finasteride (Fintrid/Proscar/Propecia)
• Finasteride in sport
• Effects on PSA
• Long-term benefits and risks
• Propecia and hair transplantation
• Proscar – important information about pregnancy
• Dutasteride

Finasteride (Fintrid/Proscar/Propecia)

Finasteride is an oral medication which blocks the conversion of testosterone to dihydrotestosterone (DHT), the form of the hormone that causes male pattern baldness. It is marketed in the US as Propecia but this is not available in Ireland.  Here we often use a generic form of the medication called Fintrid (or Proscar) 5mg.  Finasteride inhibits the action of the type II 5-alpha reductase enzyme that is present in higher concentration in and around the hair follicles of balding men with androgenetic alopecia. After two years, results showed that 83% of the men taking Finasteride either kept their hair or grew more. Seventeen percent continued to lose hair while taking the medication.

The medication causes a significant drop in both scalp and blood levels of DHT. Its effectiveness is thought to be related to both of these factors. In patients taking Finasteride 1-mg/day, serum DHT levels decreased by 68.4%. Serum testosterone levels actually increased by 9.1% but remained within the normal range.

Finasteride was originally developed for use in prostate enlargement in men over 50. This medication, in a 5-mg per day dose, is available under the name Proscar.

Many men are concerned about reported sexual side effects with the drug. In truth, the side effect of lower libido was noted in only 1.8% of the men taking the drug in clinical trials, versus 1.3% on a placebo. Further, this side effect always went away in men who stopped taking Propecia, and also disappeared in most men who continued taking Propecia.

Most reported cases of sexual dysfunction occurred soon after the medication was begun. The sexual side effects were reversible in all men who discontinued therapy and in 58% of those who chose to continue treatment. When the medication was stopped, side effects generally went away within weeks, but occasionally took longer.

It is important to remember that when Finasteride (or Minoxidil) is discontinued, you only lose the hair that was gained or preserved by the medication, not more. In effect, you return to the level of balding where you would have been had you never used the drugs in the first place.

Back to top

Finasteride in sport

The World Anti-Doping Agency (WADA) removed Finasteride from its list of banned substances in October 2008.  It had previously been added as it was believed that Finasteride could be used to mask the use of steroids and other drugs.  This is no longer believed to the case and you can read more about WADA and its decision here.  We would however still advise you to consult your sport's governing body before taking Finasteride.

Back to top

Effects on PSA

Finasteride causes an approximate 1/3 decrease in serum PSA (prostate specific antigen) in normal men (from 0.78ng/ml to 0.52 ng/ml). It may also blunt the rise of PSA levels in patients with prostate enlargement and in patients who have developed prostate cancer.

Since PSA is used as a screening test for the development of prostate cancer there is a concern that the use of Propecia may interfere with the detection of this disease. It is important that your family doctor is aware that you are taking Finasteride so that he can take into account any effects that finasteride may have on your PSA. It is possible that the long term use of Propecia may actually decrease the incidence of prostate disease, but this has not yet been confirmed in scientific studies. A recent study suggested a possible 25% reduction in prostate cancer.

Back to top

Long-term benefits and risks

The effects of finasteride are confined to areas of the scalp that are thinning, but where there is still some hair present. It does not seem to grow hair in areas that are completely bald. Therefore, the major benefit of Finasteride seems to be in its ability to slow down or stop hair loss, or regrow hair in parts of the scalp that are thin. The long-term ability of Finasteride to maintain one's hair is unknown. Results generally peak around one year and then are stable in the second year or decrease very slightly.

Back to top

Propecia and hair transplantation

Propecia (Finasteride) has been shown to be a useful addition to surgical hair restoration for a number of reasons. 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 crown where hair transplantation may not always be indicated.

If Propecia is shown to be safe and effective in the long-term, it will allow the hair restoration surgeon the ability of creating more density in the cosmetically most important areas (such as the front part of the scalp), thus keeping donor reserves for future hair loss in other areas.

Now an estimated 1 million men in the United States take Propecia daily. Most men taking Propecia experienced an increase in hair count, a decrease in hair loss, and an improvement in appearance. It is important to have realistic expectations, as results take time. If you are not willing to commit yourself to taking Finasteride for at least twelve months, it's probably not worth starting. Secondly, Finasteride must be taken on an ongoing basis to maintain the benefit.

The manufacturer states that any hair grown or maintained by Propecia will be lost within twelve months if the patient stops taking the medication. Further, men who are already very bald are less likely to benefit from Propecia, because the hair follicles may not be salvageable. Men who have early thinning in the back and top have a better chance to see some benefit, but as noted above, only for as long as they continue taking the medication.

Back to top

Proscar – important information about pregnancy

As outlined above, the type II 5-á Reductase inhibitor Finasteride in Proscar and Propecia works by inhibiting the conversion of testosterone to dihydrotestosterone. This makes this chemical extremely useful in treating male pattern baldness. However, because of this ability to affect testosterone, exposure to finasteride could have the potential to cause abnormalities in the sexual organs of male foetuses. 

For this reason, women should not take or handle Proscar or Propecia tablets when they are or may become pregnant.  Therefore, although Proscar tablets are specially coated to prevent any contact with the active ingredients, women are advised not to handle tablets, especially broken or crushed tables, as there is a potential for Finasteride to be absorbed through the skin and into the bloodstream. 

Questions have been raised as to whether women who are pregnant or trying to conceive are at any risk if their partner is taking Proscar or Propecia. To date, animal studies on pregnant monkeys using intravenous doses as high as 800ng/day (which is up to 120 times the highest estimated exposure of women to Finasteride from the semen of men taking 5mg/day) resulted in no abnormalities at. However, for peace of mind, to prevent even this tiny theoretical risk, men who are concerned can either stop taking the drug or use condoms to prevent any possible Finasteride exposure during pregnancy.

Further information on Finasteride (Propecia) is available from the manufacturers, Merck Sharp and Dohme, or from the electronic medicines compendium.

Back to top

Dutasteride

Dutasteride, a second-generation 5 alpha-reductase inhibitor, is the first medicine to inhibit both the type 1 and type 2 enzymes responsible for the conversion of testosterone to DHT (dihydrotestosterone), the primary cause of prostate growth. Dutasteride's dual inhibition decreases levels of DHT by 90 percent at two weeks and 93 percent at two years. To date it has not been approved for the treatment of male pattern baldness.

A study by Elise Olsen et al. published in the Journal of the American Academy of Dermatology demonstrated that dutasteride increased scalp hair growth and the results from Dutasteride 2.5mg were superior to the results from Finasteride 5mg at 12 and 24 weeks.  The study included over four hundred male subjects over 24 weeks and compared the results achieved by 0.05mg, 0.1mg, 0.5mg and 2.5mg Dutasteride, 5mg Finasteride, and placebo tablets daily.  For further information, please see the Journal of the American Academy of Dermatology Vol 55 Issue 6, Pages 1014-1023 December 2006.

Back to top