How does finasteride help to improve hair growth or stop hair loss?
Finasteride, a synthetic 4-azasteroid compound (it is not a steroid), is a specific inhibitor of steroid Type II 5α-reductase, an intracellular enzyme that converts the androgen testosterone into 5α-dihydrotestosterone (DHT). Finasteride works at the molecular level to halt hair loss and stimulate new hair growth.
While the entire genetic process of male pattern baldness is not completely understood, we do know that DHT shrinks hair follicles, and that when DHT is suppressed, hair follicles continue to thrive. Hair follicles that are sensitive to DHT must be exposed to the hormone for a prolonged period of time in order for the affected follicle to complete the miniaturization process (Miniaturization is the hormone-driven biological process in which hairs shrink in size over time, eventually leaving a bald scalp). Today, with proper intervention this process can be slowed or even stopped if caught earlyenough.
If androgens are present in normal amounts and the gene for hair loss is present, male pattern hair loss will occur.
5-alpha-reductase occurs in two forms identified as Type I and Type II, and that finasteride is effective in inhibition of Type II. Type I of the enzyme predominates in sebaceous glands. Type II occurs most abundantly in hair follicles and prostate tissue. Investigators found that:
- Men with normal to high levels of Type II of the enzyme (and thus normal to high levels of DHT) are more likely to develop MPHL and benign enlargement of the prostate gland;
- Men with low levels of Type II enzyme (and thus low levels of DHT) are less likely to develop MPHL and benign enlargement of the prostate; and thus
Inhibition of Type II 5-alpha-reductase could lower levels of DHT in hair follicles and prostate tissue and decrease the likelihood for development of MPHL and benign prostate enlargement.
Although testosterone is the major circulating androgen, to be maximally active in scalp hair follicles it must first be converted to dihydrotestosterone (DHT) by the enzyme 5α-reductase. The importance of DHT as a causative factor in male pattern hair loss is shown by the absence of MPHL in men with a congenital deficiency of the type 2 5α-reductase enzyme.
Finasteride produces a rapid reduction in serum DHT concentration, reaching 65% suppression within 24 hours of oral dosing with a 1-mg tablet.
Indications and usage
Finasteride is indicated for the treatment of male pattern hair loss in MENONLY. It has been used however as an off-label use in women to treat androgen dependent female pattern hair loss.
Safety and efficacy were demonstrated in men between 18 to 41 years of age with mild to moderate hair loss of the vertex and anterior mid-scalp area Though efficacy in bitemporal recession has not been established it has been our clinical experience that finasteride has beneficial effects in the frontal and temporal areas as well.
Finasteride is not indicated in women
Finasteride is not indicated in children
Oral: 1 milligram tablet. The 1 milligram dose is for treatment of male-pattern hair loss.
It may be administered with or without meals.
The recommended dose of finasteride is one tablet (1 mg) taken once daily.
In general, daily use for six or more months is necessary before benefit is observed. Patients must take Finasteride for one year or longer before its effects in preventing hair loss and re-growing hair can be accurately assessed. Finasteride may take up to a year or more to exert its full effects in both preventing hair loss and in re-growing hair (reversing miniaturization). Continued use is recommended to sustain benefit, which should be re-evaluated periodically. Withdrawal of treatment leads to reversal of effect within 12 months.
Efficacy of finasteride
Large, multi-year studies have shown finasteride to reduce hair loss and/or stimulate hair regrowth in a majority of men treated. In a 5-year study, 65% of men with mild to moderate male-pattern hair loss were found to have a positive result (hair loss reduced and/or hair regrowth stimulated). Finasteride therapy must be continued to maintain a positive result. Physician hair restoration specialists may combine minoxidil and finasteride therapy to achieve an optimal result in selected patients. Medical therapy may be combined with surgical hair restoration to achieve and maintain an optimal result.
Finasteride is most effective in areas of thinning and not effective in completely bald areas. It helps to slow down the progress of hair loss. Patients generally report an improvement in the hair growth by 8 months to a year. A significant number of patients continue using the medication for more than five years and manage to maintain the improved scalp coverage.
As the problem of male pattern hair loss is genetically determined and due to the presence of male hormones, these two factors being constant – the improvements achieved with use of finasteride will stop if the medication is discontinued. After discontinuing finasteride the hair loss gradually returns after 3-6 months to the pre-treatment status. This period is directly linked to the period of usage. So if one has used it for a couple of years the effects will last longer as compared to someone who has used it for a shorter period.
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.
Finasteride and hair transplantation (combined therapy)
It is equally important to understand that each modality (surgical, non-surgical and camouflage) of treatment will address a different aspect of the hair loss. When we look at a patient of PHL – there are two issues that need to be dealt with – the progressive nature of the hair loss with and the deficit created by receding hair line/baldness. Both these aspects will have different treatments. Hair transplantation involves transferring follicles from the permanent zone of the scalp to the areas of baldness. Hair transplantation will provide permanent follicles where there were none or relatively reduced. But it has no impact on the progress of hair loss in the other areas of scalp. So hair transplantation does not solve the problem completely. On the other hand when we use Minoxidil and/or finasteride the spectrum of response ranges from keeping the hair loss stabilized to actual regrowth. But both these medications will work only in areas of thinning. They do not have any effect on totally bald areas. So again the problem is not completely solved.
But if we were to combine both the forms of treatment we could be able to achieve more than using the individual treatments.
Managing MPHL requires the hair transplant surgeon to arrest the hair loss and also restore the bald area partly or completely, depending on the grade of hair loss. For the purpose of arresting the progress of hair loss only two medical treatments, Minoxidil and finasteride, are of proven benefit in male balding. Both are also approved by US FDA for treatment in males. Both drugs primarily stop the progress of hair loss but also stimulate some regrowth of hair in some men and hence are better regarded as preventative treatments. Neither will regrow hair on completely bald scalp and continued treatment is necessary to maintain the response. Both drugs have a good safety record, a consideration of paramount importance when treating hair growth disorders.
But it must be remembered that Minoxidil or Finasteride are not needed to support or maintain the transplanted hair. They help in preventing further hair loss.
Adverse effects of Finasteride
Finasteride has been in use since its approval by the US FDA in December 1997 for use in male pattern hair loss. And since then millions of patients have benefitted from finasteride with no side effects at all, or minimal and reversible side effects.
Side effects from finasteride at the 1-mg dose are uncommon. The data from the clinical trial using oral finasteride 1mg for one year revealed that 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. Most reported cases of sexual dysfunction occurred soon after starting the medication, but there have been reports of sexual dysfunction that have occurred atlater points in time. The sexual side effects were reversed in those who discontinued therapy, and in 58% of those who continued treatment. After the medication was stopped, side effects generally disappeared within a few weeks. There have been anecdotal reports where side effects have persisted after discontinuation oftherapy. This had been referred to as “Post-finasteride syndrome.”
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 baldingwhere he would have been had he never used the drug in the first place. No drug interactions of clinical importance have been identified.
In the clinical studies with finasteride, the incidences for breast tenderness and enlargement, hypersensitivity reactions, and testicular pain in finasteride-treated patients were not different from those in patients treated with placebo.
In a paper published in2009 it was revealed that the analysis of the role of androgens in male sexual function and evidences from large population based long term placebo controlled studies using validated questionnaire and objective method for assessing sexual function, suggested no substantial evidence of erectile dysfunction in men receiving finasteride.
Our experience of using finasteride in male patients with pattern hair loss
The incidence of adverse effects with finasteride in our practice is much less than that reported in clinical trials. In patients who reported sexual adverse effects, sexual dysfunction occurred soon after starting the medication, rarely we had patients who reported sexual dysfunction that occurred at later points in time. We have usually seen reversal of these adverse effects within a few weeks of discontinuing the finasteride. In some patients the side effects were resolved even after continuing the treatment. Recently, several anecdotal reports in the media and health-related literature have described a number of younger men with androgenetic alopecia who claim to have experienced persistent sexual side effects following the use and subsequent discontinuation of finasteride. This had been referred to as “Post-finasteride syndrome.”
Post-Finasteride Syndrome (PFS)
Post Finasteride Syndrome (PFS) is the term applied to reports of significant sexual, neurological and physical side effects, such as erectile dysfunction, depression, clouded thinking “brain fog,” penile numbness, penile shrinkage, and loss of libido, that persist in men who have taken and then discontinued finasteride.
Although persistent sexual side effects associated with finasteride have been publicized in the lay press, controlled clinical data show a low incidence of sexual side effects that resolve on cessation of treatment. Several large population-based long-term placebo-controlled studies have demonstrated no clear evidence of the negative effect of 5-alpha reductase inhibitor on erectile function. Erectile dysfunction has also been reported to be a nocebo effect.
Studies in progress are trying to better understand the incidence, cause and risk factors of PFS.
Studies in progress are trying to better understand the incidence, cause and risk factors of PFS.
On April 11, 2012, the U.S. Food and Drug Administration (FDA) announced changes to the professional labels forfinasteride 1 mg (Propecia) and finasteride 5 mg(Proscar) to expand the list of sexual adverse events reported to FDA as some of these events have been reported to continue after the drug is no longerbeing used (note that erectile dysfunction after stopping use of these drugs was added as a known event in 2011). The new label changes include:
- A revision to the finasteride 1 mg label to include libido disorders, ejaculation disorders, and orgasm disorders that continued after discontinuation of the drug.
- A revision to the finasteride 5 mg label to include decreased libido that continued after discontinuation of the drug.
- A revision to both the finasteride 1 mg and 5 mg labels to include a description of reports of male infertility and/or poor semen quality that normalized or improved after drug discontinuation.
Despite the fact that clear causal links between finasteride (Propecia and Proscar) and sexual adverse events have NOT been established, the cases suggest abroader range of adverse effects than previously reported in patients taking these drugs.
Only a small percentage of men using these drugs have experienced a sexual adverse event. During treatment with finasteride 1 mg, 3.8% of men had reported one ormore adverse sexual experiences as compared to 2.1% men who did not receive finasteride 1 mg (received placebo). This represents a 1.7% difference.
For finasteride 1 mg, the FDA’s Agency’s Adverse Events Reporting System (AERS) database between 1998 and 2011 found 59 cases of reported sexual dysfunction that lasted for at least three months following discontinuation of finasteride 1 mg, and included erectile dysfunction, decreased libido, problems with ejaculation and orgasm disorders.
The FDA has not established a cause and effect relationship between finasteride and the sexual adverse events that continued after stopping drug use. TheFDA believes that finasteride remains a safe and effective drug for its approved indications. Healthcare professionals and patients should consider this new label information when deciding the best treatment option.
Finasteride and Fertility
Finasteride may decrease fertility in some men. The effects may be due to changes in the composition of ejaculate and/or a reduction in sperm count. The effects appear to be reversible on discontinuing the medication.
Finasteride – Effects on Breast Tissue
Adverse reactions related to the breast, including breast tenderness or breast enlargement (gynecomastia), occurred in 0.4% of men taking finasteride 1-mg, but this was no greater than in the control group. In a large study published in the Journal of Urology in 2013, the authors reported: “The lack of an association in our study suggests breast cancer development should not influence prescribing of 5ARI therapy.”
Other Adverse Reactions
Other, uncommon side effects, included hypersensitivity reactions including rash, pruritus (itching), urticaria (hives), swelling of the lips and face, testicular pain, mood changes (including depression) and cognitive changes (sometimes referred to as “brain fog”).
Finasteride and Prostate Cancer
The results of an 18-year, 18,000 patient study published 8-14-2013 in the New England Journal of Medicine, showed that taking finasteride 5mg a day does not increase the likelihood of death from prostate cancer. Early results from the same study had suggested that finasteride might increase the risk of developing higher grade tumors; however, follow-up results from the long-term study show that men taking the drug do not have an increased risk.
Additionally, the results of the study show that taking finasteride actually decreases the likelihood of a diagnosis of prostate cancer in men by 30% and a diagnosisof “low-grade” cancer in men by 43%. By shrinking the healthy prostate tissue, finasteride decreases the chances of a false positive result in PSA screening testsand can avoid unnecessary surgery.
Caution during Pregnancy
Women should not handle crushed or broken finasteride 1 mg tablets when they are pregnant, or may potentially be pregnant, because of the possibilities of absorption of finasteride and the subsequent potential risk to a male fetus. Finasteride 1 mg tablets are coated and will prevent contact with the active ingredient during normal handling, provided that the tablets have not been broken or crushed. Exposure of pregnant women to semen from men treated with PROPECIA has notbeen shown to pose any risk to the fetus.
Patients taking finasteride should not donate blood as this blood may potentially be given to pregnant women.
There are no scientific studies that prove that increasing the dose will have any additional beneficial effects on hair loss. There are published data demonstrating that 5 mg is no better than 1 mg in controlled clinical trials. In practice, however, doctors may increase the dose when someone has been on the same dose of medication for 3-5 years and then stops responding (begins to lose hair after being stable). It has been our experience that increasing the dose may enable the medication to continue to be effective. It is important to understand that increasing the dose is an off-label use of this medication. It may increase the incidence of adverse reactions. When increasing the dose, we generally use generic finasteride 5mg that is taken whole or broken into parts (see Caution during Pregnancy).
Effects on PSA
Finasteride causes a decrease in serum PSA (prostate specific antigen) by approximately 50% in normal men. Since PSA levels are used to screen for prostate enlargement and prostate cancer, it is important that your personal physician is aware that you are taking finasteride 1mg so that he/she may take this into account when interpreting your PSA results.
Prostate Cancer Screening
The American Cancer Society and the American Urological Association recommend the following screening ages:
- Age 50 for men who are at average risk of prostate cancer and are expected to live at least 10 more years.
- Age 45 for men at high risk of developing prostate cancer: African American men and men who have a first-degree relative (father, brother, or son) diagnosed with prostate cancer younger than age 65.
- Age 40 for men at even higher risk (those with several first-degree relatives who had prostate cancer at an early age).
- Regardless of age, yearly screening for PSA level if 2.5ng/ml or higher, and every 2 years for less than 2.5ng/ml.
An evaluation should include a rectal examination, a PSA, and other tests that your examining physician feels are appropriate. The above are general guidelines recommended men regardless of whether they use finasteride or not. Specific recommendations for each patient should be based upon the judgment of his own physician.