What is Finasteride?

Aug.01, 2018 Finasteride

Short facts about Alopecia and Finasteride

A person loses normally about 100 hairs every day.
Alopecia refers to hair loss from any part of the body for any reason.
Androgenetic alopecia is commonly called male or female pattern baldness.
The hair follicles affected by androgenetic alopecia are permanently damaged and any hair loss as a result is irreversible.
Dihydrotestosterone (DHT) is the main hormone responsible for androgenetic alopecia.
Dihydrotestosterone (DHT) causes scalp hair loss by inducing a change in the hair follicles on the scalp.
Finasteride belongs to type II ‘5-alpha reductase inhibitors.
Finasteride has no effect on womens hair loss.
Finasteride 1 mg is indicated in the treatment of male pattern hair loss.
Finasteride 5 mg is indicated in the treatment and control of benign prostatic hyperplasia.

Hair growth phases

The anagen phase is also called the growth phase and it lasts for 3 to 5 years. During the anagen phase, the cells in the root of the hair are dividing rapidly. The newly formed hair pushed the hair that has stopped growing or is no longer in the anagen phase, up to the follicle. In this phase, hair grows about 1 cm every 28 days. Hair length is influenced by the duration of the growth phase.

Catagen phase is known as the involutional phase and it appears immediately after the end of the anagen phase. It lasts 2 to 3 weeks.

Telogen phase is the resting and shedding period of the hair cycle and it usually lasts 3 to 4 months. At the end of this period, older hairs that have finished their life will fall out and newer hairs will begin to grow.

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Androgenetic alopecia

Androgenetic alopecia is the most common hair loss disorder and it affects both men and women. It is characterized by progressive hair loss, usually in a pattern distribution. The disease can begin at any age starting with puberty and the frequency increases with age.

The incidence of androgenetic alopecia is generally considered to be greater in males than females. 80% of Caucasian men and 42% of women have signs of androgenetic alopecia.

Androgenetic alopecia is characterized by progressive shortening of the anagen phase of the hair cycle, prolongation of the post-exogen phase of telogen and miniaturization of the hair follicle in predisposed men and women. ⁸

Which are the signs and symptoms?

Androgenetic alopecia affects men earlier, and more commonly than women.

Signs of androgenetic alopecia are the following:

Gradual onset;
Increased hair shedding;
Transition in the involved areas from large, thick, pigmented terminal hairs to thinner, shorter, indeterminate hairs and finally to short, wispy, non-pigmented vellus hairs;
The final result can be an area of total denudation; this area varies from patient to patient and is usually most marked at the vertex

Differences between male and female pattern baldness

Men affected by androgenetic alopecia present a gradual recession of the frontal hairline early in the process and gradual thinning in the temporal areas.

In case of women with androgenetic alopecia, hair generally is lost diffusely over the crown. Hair is gradually thinning, but there is no evidence of a marked area of baldness. Androgenetic alopecia in women rarely leads to total baldness.

Does the heredity influence androgenetic alopecia?

Yes, androgenetic alopecia is familial. Twin studies have identified heredity as representing about 80% of the predisposition to baldness.

The polymorphism of the androgen receptor gene (AR) was first identified to be associated with androgenetic alopecia and was subsequently confirmed by many other researchers in different cohorts of patients. Researchers have discovered that men affected by Kennedy disease, a familial neuromuscular disorder associated with a functional alteration of the androgen receptor, have a reduced risk of developing androgenetic alopecia.

The role of androgens in androgenetic alopecia

Androgens, hormones synthesized from cholesterol, are present in both sexes, but with higher concentration in men. In men, androgens are synthesized in the testes as testosterone, dihydrotestosterone (DHT) or androsterone, while in women, they are synthesized in the ovaries as dihydrotestosterone (DHT) or in the adrenal cortex as testosterone or dehydroepiandrosterone (DHEA).

Androgens receptors have a significant impact on the development and function of the sebaceous glands, and the functioning of the pilosebaceous unit.

High levels of sex hormones (hyperandrogenism) are the consequence of the excessive production of endogenous hormones by dysregulation of the hypothalamic-pituitary-adrenal cortex, polycystic ovary syndrome (PCOS) or by hormonally-active tumours. In men, increased androgen levels lead to androgenetic alopecia. Women affected by hyperandrogenism present the following signs and symptoms: formation of a male body type, change in voice tone, the appearance of the male pattern hair, impaired fertility, clitoromegaly, breast atrophy and androgenetic alopecia.

History of 5 alpha-reductase-inhibitors in the management of androgenetic alopecia

Pharmaceutical 5α-reductase inhibitors were initially developed for the treatment of benign prostatic hyperplasia. On the market, there were available two drugs inhibiting 5 alpha-reductase, finasteride and dutasteride. Finasteride was registered in Europe in 1992, while dutasteride was registered in 2003.

Two years after the registration of finasteride for the treatment of benign prostatic hyperplasia, appeared the first publications concerning the efficacy of finasteride in androgenetic alopecia in male patients. During clinical trials performed on men with prostate problems, the investigators observed a strange side effect: hair growth. The drug was registered in the United States in 1993 and in Europe in 1994 for treatment of mild to moderate androgenetic alopecia in men.

In December 1997, US. Food and Drug Administration approved finasteride under the name of Propecia (finasteride 1 mg) for the treatment of androgenetic alopecia in men.

How does finasteride work?

The hair-raising success of finasteride is due to its ability to specifically inhibit an enzyme called 5-alpha reductase. This enzyme has the role to convert the testosterone into its active form dihydrotestosterone (DHT). 5-alpha reductase exists as two isoforms. Type I 5-alpha-reductase is mainly found in the sebaceous glands and the epidermis but is also present in sweat glands, hair follicles, endothelial cells and Schwann cells in the myelin sheaths of nerves. Type II 5-alpha-reductase is mainly located in the hair follicle.

Finasteride is a competitive and specific inhibitor of type II 5-alpha-reductase. Finasteride has no affinity for the androgen receptor and has no androgenic, anti-androgenic, oestrogenic, anti-oestrogenic, or progestational effects. Inhibition of this enzyme blocks the peripheral conversion of testosterone to dihydrotestosterone, resulting in significant decreases in serum and tissue dihydrotestosterone concentrations.

In men with male pattern hair loss, the balding scalp contains miniaturised hair follicles and increased amounts of dihydrotestosterone. Administration of finasteride decreases scalp and serum dihydrotestosterone concentrations in these men. Men with a genetic deficiency of type II 5α-reductase do not suffer from male pattern hair loss. Finasteride inhibits a process responsible for miniaturisation of the scalp hair follicles, which can lead to a reversal of the balding process.

Placebo-controlled studies shown that after 1-2 years of treatment with finasteride, hair count is increased, and the effect is sustained after 5 years of therapy

Pharmacokinetics of finasteride

Oral bioavailability of finasteride is approximately 80% compared with an intravenous interference dose. Food does not influence oral bioavailability. Maximum plasma concentration of finasteride is reached approximately two hours after administration and the absorption is complete after 6 to 8 hours.

In blood, finasteride protein binding is approximately 93%.

Finasteride is metabolized via cytochrome P450 3A4 system to two metabolites. The metabolites were found to possess only a small fraction of the 5-alpha-reductase inhibitory activity of finasteride.

The elimination rate of finasteride decreases somewhat with age. Mean terminal half-life is

approximately 5-6 hours in men 18-60 years of age and 8 hours in elderly men (more than 70 years of age)

These findings are of no clinical significance and hence, a reduction in dosage in the elderly is not warranted.

Safety profile of Finasteride

Like any other drug, finasteride can cause side effects, although not everybody gets them. Some of the side effects are temporary and disappeared when treatment is stopped.

The following adverse reactions have been identified during post-approval use of Propecia, they are reported voluntarily from a population of uncertain size and it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure:

Hypersensitivity Reaction: hypersensitivity reactions such as rash, pruritus, urticaria, and angioedema (including swelling of the lips, tongue, throat, and face);
Reproductive System: sexual dysfunction that continued after discontinuation of treatment, including erectile dysfunction, libido disorders, ejaculation disorders, and orgasm disorders; male infertility and/or poor seminal quality (normalization or improvement of seminal quality has been reported after discontinuation of finasteride); testicular pain.
Neoplasms: male breast cancer;
Breast disorders: breast tenderness and enlargement;
Nervous System/Psychiatric: depression

Stop taking the drug and talk to your doctor if you experience:

Symptoms of an allergic reaction: swelling of your lips, face, tongue and throat; difficulty swallowing; lumps under your skin (hives) and breathing difficulties.
Depression (feeling of severe sadness and unworthiness).

You should promptly report to your doctor any changes in your breast tissue such as lumps, pain, enlargement or nipple discharge as these may be signs of a serious condition, such as breast cancer.

Uncommon side effects (may affect up to 1 in 100 people) are the following:

incapacity to have an erection (impotence)
have less desire for having sex
problems with ejaculation, for example, a decrease in the amount of semen released during sex. This decrease in the amount of semen does not appear to affect normal sexual function

Side effects with unknown frequency include:

breast tenderness and enlargement
testicular pain
infertility
palpitations (heart is beating too hard or too fast)
increased hepatic enzymes
persistent difficulty having an erection after discontinuation of treatment
persistent decrease in sex drive after discontinuation of treatment
persistent problems with ejaculation after discontinuation of treatment
male infertility and/or poor quality of semen

If any of these side effects gets serious, or if you notice any side effects not listed on patient information leaflet you should contact immediately your doctor or pharmacist.

Before taking finasteride

Before taking finasteride, tell your doctor or pharmacist if you are allergic to it or if you have any other allergies.

To be sure that finasteride is safe for you, tell your healthcare professional if you suffer for one of the following conditions:

liver disease, or abnormal liver enzyme tests;
prostate cancer;
a bladder muscle disorder;
stricture of your urethra;
if you are unable to urinate;
if you have ever had an allergic reaction to a similar medicine called dutasteride (Avodart).

Drug interaction

Finasteride has not been seen to have clinically significant interactions with other drugs. Finasteride is metabolized primarily via cytochrome 450 but does not affect the cytochrome P450-linked drug metabolizing enzyme system. Although the risk for finasteride to affect the pharmacokinetics of other drugs is estimated to be small, it is probable that the inhibitors and inducers of cytochrome P450 3A4 will affect the plasma concentration of finasteride. However, based on established safety margins, any increase due to concomitant use of such inhibitors is unlikely to be of clinical significance. Compounds which have been tested in man have included antipyrine, digoxin, glibenclamide, propranolol, theophylline and warfarin and no interactions were found. Concomitant use of finasteride and topical minoxidil in male pattern hair loss is not recommended due to the lack of clinical data.

How to take the drug?

Finasteride may be administered with or without meals.

The recommended dose is one tablet (1 mg) taken once daily. The tablet should be swallowed whole and must not be divided or crushed.

In general, 3 to 6 months of once-daily treatment are required before evidence of stabilization of hair loss can be expected. Continuous use is recommended to sustain benefit. If treatment is stopped, the beneficial effects begin to reverse by 6 months and return to baseline by 9 to 12 months.

Is a magic treatment available, that can grow hair back?

Of the many treatments available for androgenetic alopecia, only two (finasteride and minoxidil) have been scientifically shown to be useful in the treatment of hair loss.

Generally, daily administration for three months or more is necessary before benefit is observed.

Continued use is recommended to sustain benefit, which should be re-evaluated periodically.

Finasteride Male Pattern Hair Loss Study Group

A study group formed by dermatologists with the purpose to determine whether finasteride treatment leads to clinical improvement in men with male pattern hair loss performed a 1-year comparative study recruiting 1553 men aged 18 to 41.

Men with male pattern hair loss received oral finasteride 1 mg/d or placebo, and 1215 men continued in blinded extension studies for the second year.

Efficacy was evaluated by scalp hair counts, patient and investigator assessments, and review of photographs by an expert panel.

Finasteride treatment improved scalp hair by all evaluation techniques at 1 and 2 years.

Clinically significant increases in hair count (baseline = 876 hairs), measured in a 1-inch diameter circular area (5.1 cm²) of balding vertex scalp, were observed with finasteride treatment (107 and 138 hairs vs placebo at 1 and 2 years, respectively). Treatment with placebo resulted in progressive hair loss.

Patients’ self-assessment demonstrated that finasteride treatment slowed hair loss, increased hair growth, and improved appearance of hair. Adverse effects were minimal.

Conclusions

Propecia contains 1 mg of Finasteride and is available for acquisition online with a prescription. Propecia is recommended to be administrated for an interval between 3-6 months or until the hair loss is stopped. It’s efficacy and the treatment duration must be evaluated by a physician.

Finasteride is a safe and effective treatment for controlling male pattern baldness with long-term daily use even in men over the age of 40 years. The satisfactory clinical results, the few side effects observed, and the lack of alternative medications points out that finasteride is an effective treatment especially if taken in the early stages of Androgenetic alopecia.

Propecia is a safe and effective hair loss medication, even when used long-term.

It is effective in patients older than 40 years and it is particularly beneficial for patients over 30 and who are in the early stages of hair loss.

If you are intending to use Propecia, and if you have questions related to its use, effectiveness or side-effects, please contact our pharmacy on 01625 460 621.