Atepros Mechanism of Action

Pharmacotherapeutic Group: 5α-Reductase Inhibitor.
Pharmacology: Pharmacodynamics: Finasteride is a member of the 4-azasteroid family of compounds. It is a competitive and specific inhibitor of Type II 5α-reductase. Type II 5α-reductase is an intracellular enzyme which converts testosterone into the more potent androgen 5-dihydrotestosterone (DHT), the principal androgen responsible for stimulation of prostatic growth.
Benign prostatic hyperplasia (BPH), the abnormal enlargement of the prostate gland dependent upon the conversion of testosterone to DHT within the prostate, produces manifestations such as weak urinary stream, difficulty in initiating urination, urinary frequency and urgency. Inhibition of the conversion of testosterone to DHT by finasteride leads to reduced prostatic size and improvement of urinary flow and associated manifestations of urinary obstruction.
Finasteride has no androgenic, antiandrogenic, or other steroid hormone-related properties.
Pharmacokinetics: Finasteride is rapidly and almost completely absorbed after oral administration. Peak plasma concentrations (Cmax) are attained two hours after an oral dose of 5 mg finasteride and absorption is complete after 6 to 8 hours. There is slow accumulation of the drug during chronic administration. Steady state concentrations of finasteride 5 mg daily are 8 to 10 µg/L.
Oral bioavailability is 80%. Food does not affect absorption or bioavailability of finasteride. Finasteride is extensively bound to plasma proteins (~93%); its volume of distribution is 76 liters.
Small amounts of finasteride are excreted in seminal fluid in subjects receiving finasteride 5 mg daily but the amount of finasteride in ejaculate is only 1 to 2% of the minimum daily oral dose needed to produce a measurable reduction in circulating DHT levels. Finasteride crosses the blood-brain barrier. The extent to which finasteride is excreted in breast milk is unknown.
Finasteride is eliminated relatively rapidly from plasma and its terminal elimination half-life is 6 hours.
Finasteride is metabolized extensively in the liver primarily through the cytochrome P450 3A4 enzyme subfamily. Its metabolites, t-butyl side chain monohydroxylated and monocarboxylic acid metabolites, possess ≤20% the 5α-reductase inhibitory activity of finasteride. These metabolites are excreted in both the urine (39%) and feces (57%) with only trace amounts of finasteride excreted unchanged in urine (0.04%) or feces. Finasteride's total body clearance is 165 mL/min.
No dosage adjustment in the elderly (≥70 years old) is required although finasteride's elimination rate in these patients increases to 8 hours compared with 6 hours in younger subjects (45-60 years old).