Generality
Finasteride is an FDA approved drug for the treatment of hair loss and, more specifically, androgenetic alopecia.
The FDA approved the use of finasteride for the treatment of androgenetic alopecia back in 1997. The many years since that date are a further guarantee on the excellent tolerability of the drug, at least in the short term.
Unfortunately, however, this drug is not always used appropriately. In fact, in the world of "sport" finasteride is used to limit the side effects linked to the administration of some anabolic steroids for doping purposes.
Hair loss
What is androgenetic alopecia?
The adjective "androgenetic" suggests a close link between this form of alopecia and two factors: androgens ( andro ) on one side and a certain genetic predisposition on the other. For this reason, subjects castrated before puberty will never need to resort to finasteride or minoxidil to counteract hair loss .
This assumption also explains why the incidence of androgenetic alopecia is clearly lower in the female population than in the male population.
The influence of genetic factors is more complicated. In this regard we limit ourselves to mentioning that the progressive thinning of the hair, caused by the miniaturization of hair follicles in response to androgens, depends not only on the plasma concentration of these hormones, but also on the sensitivity of the follicles to their action. At this level, in fact, we can find more or less marked concentrations of an enzyme, called 5-α-reductase (in particular isoform II), which converts the hormone testosterone into dihydrotestosterone. The expression of this enzyme is much higher in the male than in the female, and in both sexes it prevails in the frontal region compared to the occipital one. In addition to promoting hair loss, the excess of dihydrotestosterone stimulates the growth of body hair, the enlargement of the prostate and the sebaceous secretion of the skin (oily skin, acne and seborrhea).
Action mechanism
How can finasteride counteract hair loss?
As mentioned, in androgenetic alopecia, the main responsible for the miniaturization of hair follicles - hence, hair loss - is dihydrotestosterone.
Finasteride is able to counteract thinning hair by acting on the synthesis of this hormone.
More in detail, finasteride is able to selectively inhibit the enzyme 5-α-reductase type II, preventing the conversion of testosterone into dihydrotestosterone at the tissue level.
As said, this action is particularly useful in the presence of androgenetic alopecia and, at higher dosages, in the treatment of hirsutism and benign prostatic hypertrophy (of which we will not deal in this article).
By decreasing the levels of DHT (dihydrotestosterone), finasteride can prevent the follicles from shrinking and induce the miniaturized ones to produce hair with terminal characteristics rather than fleece. In this way it prevents further hair loss and promotes regrowth. A big advantage of finasteride lies in its ability to selectively inhibit the synthesis of dihydrotestosterone starting from testosterone, without thereby preventing the physiological effect of this typically male hormone in tissues. To put it in medical terms, finasteride has no antiandrogenic or androgenic effects and is also devoid of estrogenic, anti-estrogenic or progestin activity. The intake of finasteride has no impact on the circulating levels of cortisol, thyroid stimulating hormone and thyroxine; it also does not modify the ratio between HDL and LDL cholesterol, and does not show significant interactions with the hypothalamic-pituitary-gonadal axis. Circulating levels of testosterone may even increase (about 15%) due to the lack of tissue conversion to dihydrotestosterone.
Doses and method of use
To combat hair loss, finasteride must be taken orally, then systemically. Generally, the drug is formulated in the form of tablets that must be swallowed whole.
Among the various pharmaceutical products based on finasteride we recall the registered trademarks Proscar and Propecia, in which the active principle is found, respectively, in concentrations of 5 and 1 mg. The latter is the dosage indicated in the treatment of androgenetic baldness (one tablet per day).
Since finasteride is able to hinder hair loss without affecting the normal activity of testosterone, its use in the treatment of androgenetic alopecia is widespread and appreciated.
Not surprisingly, therefore, after having tried without much success the variegated paraphernalia of cosmetic treatments and functional supplements, many men resort to finasteride under the advice of their dermatologist. In fact, most doctors believe that systemic finasteride is the most effective intervention in the treatment of androgenetic alopecia today.
The recommended doses are 1 mg / day; the drug is well tolerated and it is not necessary to undergo blood and / or instrumental tests if it is taken before the age of 40. After this age, the dermatologist generally prescribes a series of tests to investigate prostate health, such as the prostate specific antigen (PSA) assay, rectal exploration, urinary jet force measurement and suprapubic ultrasound.
Effectiveness and Results
The results obtained thanks to the treatment based on finasteride are generally good and, in most cases, satisfactory for patients.
One year after the start of treatment, about 50% of men between the ages of 18 and 41 experience a fall arrest, while the remaining percentage also appreciates a certain regrowth. Only in a very small number of cases (around 1%) does the drug prove ineffective or should it be suspended due to the appearance of significant side effects.
Unlike minoxidil (lotion or foam), finasteride has been shown to be more effective in promoting regrowth and stopping the fall in the frontal area than in the vertex. Moreover, finasteride has better therapeutic effects thanks to the more targeted mode of action and better bio-availability (for minoxidil systemic administration is not feasible due to the marked hypotensive effect).
In women, finasteride seems less effective than men, particularly in the post-menopausal period, when hair loss is mainly attributable to the drop in estrogen. In fertile age, in the event of pregnancy, the possible teratogenic effects on a male fetus are striking, configuring the framework of a hermaphroditism. Therefore, finasteride should not be taken by women of childbearing age.
However, it is important to point out that the results obtained with the use of this drug can be appreciated only after some time.
Despite a reduction in serum DHT concentration of more than 65% within 24 hours of taking a single 1 mg tablet, the efficacy of finasteride is not immediate. In fact, to obtain significant clinical effects it must be taken for at least three months; however, it is advisable to continue the intake for at least twelve months before evaluating the results achieved. Another important detail is that the benefits obtained can be maintained only by continuing the therapy for indefinite times.
Side effects
What are the side effects caused by finasteride?
Generally, the use of finasteride against hair loss is a well tolerated treatment, but it requires decidedly prolonged intake times, from a minimum of three months, up to a year or more.
The need to prolong the administration of the drug for periods of time so long - and sometimes undefined - can cause fears among users about the possible side effects of such a therapeutic approach.
Thanks to the particular pharmacological action, the undesirable effects of finasteride are generally absent or in any case limited. The most important is given by the teratogenic action (in the male fetus, anomalies may occur in the external genitals, even at extremely low doses), which imposes the absolute prohibition of using finasteride in the presence of a planned or ongoing pregnancy. During this period it is also necessary to refrain from handling broken or crumbled finasteride tablets, since the active ingredient can also be absorbed through the skin.
In humans, in a small percentage of cases (less than 1%), finasteride can have an inhibitory effect on the sexual area, such as reduced libido, erectile dysfunction and reduced volume of the ejaculate.
In patients with predisposing factors, such as obesity or varicocele, finasteride could also alter spermatogenesis, while in some subjects very rare cases of unilateral gynecomastia have been described.
The link between the intake of finasteride and prostate cancer is still unclear, due to conflicting publications concerning a possible protective effect, neutral or predisposing (now considered unlikely compared to the past).
The side effects of finasteride are however very rare and often transitory, with spontaneous regression to the continuation of the therapy (most cases) or to its interruption (totality of the subjects).
