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Propecia (Finasteride) for Hair Loss


Medical uses

Propecia (Finasteride) is a specific type II 5-alpha reductase inhibitor indicated for the treatment of:

  • Male pattern hair loss (androgenic alopecia) in men only
  • Benign prostatic hyperplasia (BPH) in men with enlarged prostate

Finasteride for Androgenic alopecia

Finasteride inhibits the enzyme responsible for regulating conversion of testosterone to powerful androgenic hormone dihydrotestosterone (DHT). Balding areas of the scalp are associated high levels of DHT, which induce shrinkage of hair follicles. By reducing DHT levels in the scalp, finasteride decreases the effects of DHT on the hair follicles, preventing the process of hair loss.

Propecia works for mild to moderate male pattern hair loss on the vertex (top of head) and anterior mid-scalp area (middle front of head). There is not sufficient evidence that it works for receding hairlines at the temples.

Effectiveness, potency, & hair growth results

A 1-mg dose reduces serum levels of DHT by 65% after 24 hours (but does not decrease testosterone levels).

According to the 5-year clinical study2 9 of 10 men who take Propecia have visible results - either regrowth of hair (48%) or no further hair loss (42%). Two of 3 men can expect to regrow hair. A majority of men who took Propecia reported that their bald spot got smaller, their hair loss slowed down, and the appearance of their hair improved.

Taking finasteride for over 5 years can decrease the likelihood of developing further visible hair loss by about 93%4.

When to expect results?

Daily use for three months or more may be necessary until a person will notice increased hair growth. It can take 12 months to see the full benefit and to judge how well it’s working for you.

You will need to take Propecia for as long as you want to grow or maintain your hair.

Finasteride and Minoxidil combination

The combination treatment with oral finasteride and topical minoxidil is more effective than finasteride alone 7, 8.

Topical minoxidil and finasteride combination is effective for maintenance of hair density achieved after treatment with oral finasteride and topical minoxidil 9.

Finasteride and Ketoconazole combination

Ketoconazole 2% shampoo is used as an adjunct to oral finasteride to promote more complete suppression of dihydrotestosterone 10.

Pharmacological characteristics

  • Absorption: bioavailability is 65%.
  • Metabolism: Extensively metabolized in the liver, primarily via the CYP-450 3A4 enzyme subfamily. Propecia has two active metabolites: t-butyl side chain monohydroxylated and monocarboxylic acid. Each metabolite possesses no more than 20% activity.
  • Elimination half-life: 3.3 to 13.4 h
  • li>Excretion: 32% to 46% is excreted in the urine as metabolites, and 51% to 64% is excreted in the feces.

Benefits

  • Increases growth and reduces hair loss. Finasteride address the root of the problem.
  • No drug interactions of clinical importance.

Concerns

  • Improvement takes 6-12 months.
  • Does not cure androgenic alopecia. Once you stop taking Propecia, you will likely lose any hair you have gained within 12 months.
  • Sexual disturbances. The most common side effects are decreased libido, impotence, decreased volume of ejaculate. Finasteride, even at low doses, may cause reduced sperm counts in some men5. The FDA notes6 that, "Despite the fact that clear causal links between finasteride (Propecia and Proscar) and sexual adverse events have NOT been established, the cases suggest a broader range of adverse effects than previously reported in patients taking these drugs."
  • It is better to avoid finasteride for any person who has a history of oligospermia, infertility, particularly if he is newly married and is trying to raise a family.
  • Expensive.

Mode of action

Male pattern hair loss, or androgenetic alopecia, is an androgen-dependent balding. In genetically susceptible men, dihydrotestosterone (DHT), a potent metabolite of the male androgen testosterone, contributes to miniaturization of hair follicles and a shortened hair growth cycle. The conversion of testosterone to DHT is regulated by the enzyme 5-alpha reductase, which is found primarily in scalp follicles.

Finasteride is a competitive and specific inhibitor of Type II 5-alpha-reductase, an intracellular enzyme that converts the androgen testosterone into 5α-dihydrotestosterone. The type II 5-alpha-reductase isozyme is primarily found in prostate, seminal vesicles, epididymides, and hair follicles as well as liver, and is responsible for two-thirds of circulating DHT.

Finasteride decreases DHT concentrations in the serum and the scalp by up to 70 and 60%, respectively. This prevents the miniaturisation of the scalp hair follicles, leading to reversal of the balding process. Finasteride may affect hair growth through reductions in scalp and serum DHT because the scalp is highly vascularized.

Finasteride has no affinity for the androgen receptor and has no androgenic, antiandrogenic, estrogenic, antiestrogenic, or progestational effects.

References

  • Finasteride on DermNet.NZ
  • 1. U.S. FDA Propecia Prescribing Information PDF
  • 2. Long-term (5-year) multinational experience with finasteride 1 mg in the treatment of men with androgenetic alopecia. Eur J Dermatol. 2002 Jan-Feb;12(1):38-49.
  • 4. Kaufman KD, Rotonda J, Shah AK, Meehan AG. Long-term finasteride treatment decreases the likelihood of developing further visible hair loss in men with androgenetic alopecia. Eur J Dermatol. 2008 Jul-Aug;18(4):400-6
  • 5. Samplaski MK, Lo K, Grober E, Jarvi K. Finasteride use in the male infertility population: effects on semen and hormone parameters. Fertil Steril. 2013 Dec;100(6):1542-6.
  • 6. Questions and Answers: Finasteride Label Changes FDA
  • 7. Hu R, Xu F, Sheng Y, Qi S, Han Y, Miao Y, Rui W, Yang Q. Combined treatment with oral finasteride and topical minoxidil in male androgenetic alopecia: a randomized and comparative study in Chinese patients. Dermatol Ther. 2015 Jun 2.
  • 8. Khandpur S, Suman M, Reddy BS. Comparative efficacy of various treatment regimens for androgenetic alopecia in men. J Dermatol. 2002 Aug;29(8):489-98.
  • 9. Chandrashekar BS, Nandhini T, Vasanth V, Sriram R, Navale S. Topical minoxidil fortified with finasteride: An account of maintenance of hair density after replacing oral finasteride. Indian Dermatol Online J. 2015 Jan-Feb;6(1):17-20. PubMed
  • 10. Hugo Perez BS. Ketocazole as an adjunct to finasteride in the treatment of androgenetic alopecia in men. Med Hypotheses. 2004;62(1):112-5.

By HealthyStock Research Group, October 2009
Medical resources reviewed: August 2018

Interesting facts

propecia

  • Generic name: Finasteride
  • Brand names: Propecia, Proscar
  • Dosages: Tablets 1 mg, 5 mg
  • Pharmacologic category: 5-alpha-reductase inhibitor
  • FDA approved: December 19, 1997
  • Pregnancy risk factor: X

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