Saturable Binding of Finasteride to Steroid 5α-Reductase as Determinant of Nonlinear Pharmacokinetics

January 2010 in “ Drug Metabolism and Pharmacokinetics ”

Rie Suzuki, Hiroki Satoh, Hisakazu Ohtani, Satoko Hori, Yasufumi Sawada

finasteride steroid 5α-reductase dihydrotestosterone DHT 5αR1 5αR2 pharmacokinetics pharmacodynamics Propecia

TLDR Finasteride's effect on hair loss and prostate enlargement depends on its binding to an enzyme, with maximum impact at 0.2 mg dose.

This study investigated the pharmacokinetics and pharmacodynamics of finasteride, a drug used to treat hair loss and prostate enlargement. The study found that the drug's binding to steroid 5α-reductase, an enzyme involved in the production of dihydrotestosterone (DHT), is a determinant of its nonlinear pharmacokinetics. The study also found that the drug's inhibition of 5αR1 is negligible in the dose range up to 1 mg, and that the serum DHT-reducing effect of finasteride reaches its maximum at a dose of 0.2 mg in the case of repeated administration. The study concludes that the time-dependent increase in AUC observed during repeated oral administrations of finasteride may be explained by the saturation of finasteride binding to 5αR2.

View this study on sciencedirect.com →

Discuss this study in the Community →

Research cited in this study

6 / 6 results

A Model for the Turnover of Dihydrotestosterone in the Presence of the Irreversible 5α-Reductase Inhibitors GI198745 and Finasteride

research A Model for the Turnover of Dihydrotestosterone in the Presence of the Irreversible 5α-Reductase Inhibitors GI198745 and Finasteride

60 citations , December 1998 in “Clinical Pharmacology & Therapeutics”

Both drugs lower DHT levels, with GI198745 being more effective.

research PNU 157706, A Novel Dual Type I and II 5α-Reductase Inhibitor

42 citations , February 1998 in “The Journal of Steroid Biochemistry and Molecular Biology”

PNU 157706 is a more effective treatment than finasteride for conditions caused by DHT, like enlarged prostate and hair loss.

Mechanism-Based Inhibition of Human Steroid 5α-Reductase by Finasteride: Enzyme-Catalyzed Formation of NADP-Dihydrofinasteride, a Potent Bisubstrate Analog Inhibitor

research Mechanism-Based Inhibition of Human Steroid 5α-Reductase by Finasteride: Enzyme-Catalyzed Formation of NADP-Dihydrofinasteride, a Potent Bisubstrate Analog Inhibitor

136 citations , March 1996 in “Journal of the American Chemical Society”

Finasteride effectively blocks enzyme causing male pattern baldness.

research Clinical Pharmacokinetics and Pharmacodynamics of Finasteride

93 citations , January 1996 in “Clinical Pharmacokinectics”

Finasteride helps regrow hair and shrink prostate by reducing DHT, with some sexual side effects.

research 5α-Metabolism in Finasteride-Treated Subjects and Male Pseudohermaphrodites with Inherited 5α-Reductase Deficiency

8 citations , January 1991 in “European Urology”

Finasteride lowers DHT levels and raises testosterone in a dose-dependent way.

research Species Differences in Prostatic Steroid 5α-Reductases of Rat, Dog, and Human

193 citations , August 1985 in “Endocrinology”

Different animals have unique versions of the enzyme that changes testosterone into another hormone, which is important for creating effective treatments for prostate and hair loss conditions.

Related Community Posts Join

6 / 1000+ results

community Can I still save my hairline at age of 15?

in General 471 upvotes 1 week ago

A 15-year-old is concerned about hair loss, possibly at Norwood 2 or 3, and is using shampoos and conditioners recommended by a trichologist. Suggestions include considering topical minoxidil and consulting a doctor about topical anti-DHT treatments like finasteride or RU58841, but avoiding 5-alpha-reductase inhibitors at this age.

community 28M experiencing thinning - first timer here, please help

in Treatments 368 upvotes 4 days ago

A 28-year-old male experiencing hair thinning is considering minoxidil and finasteride. Minoxidil helps regrow hair, while finasteride prevents further loss; both are usually lifelong treatments.

community risks with finasteride and dutasteride

in Research/Science 144 upvotes 4 months ago

Finasteride and dutasteride have potential risks, including post-finasteride syndrome, but are commonly used for hair loss. RU58841, minoxidil, and needling are suggested as alternatives, though all treatments carry risks.

community My Testosterone results before and after Finasteride

in Update 147 upvotes 4 years ago

Finasteride significantly increased testosterone levels for the user, with no major side effects except watery semen, which was resolved with zinc supplements. The user's hairline stopped receding and slightly improved.

community A systematic bro-science review of DHT, 5AR, neurosteroids, sexual health and 5AR inhibitors

in Research/Science 37 upvotes 3 years ago

Hair loss treatments, specifically 5AR inhibitors, can impact neurosteroids and sexual health. The effects of topical fin/dut on tissue-specific DHT levels are unclear.

community Finasteride does deplete important nuero-active steroids

in Research/Science 9 upvotes 2 years ago

Finasteride can reduce neuroactive steroids, causing side effects like depression, anxiety, and sexual dysfunction. Some users experience persistent symptoms after stopping finasteride, while others use alternative treatments like topical solutions.

Related Research

2 / 2 results

research Saturable Binding of Finasteride to Steroid 5α-Reductase as Determinant of Nonlinear Pharmacokinetics

16 citations , January 2010 in “Drug Metabolism and Pharmacokinetics”

Finasteride's effect on hair loss and prostate enlargement depends on its binding to an enzyme, with maximum impact at 0.2 mg dose.

research Effect of Finasteride, a 5 Alpha-Reductase Inhibitor, on Serum Gonadotropins in Normal Men

30 citations , August 1992 in “The Journal of Clinical Endocrinology and Metabolism”

Finasteride doesn't affect hormone levels in normal men.