Finast, 5 mg 30 pcs.

Pharmacodynamics

Finasteride, a synthetic 4-azasteroid compound, is a specific inhibitor of 5-alpha reductase type II, an intracellular enzyme that converts testosterone to the more active androgen, dihydrotestosterone (DHT). In benign prostatic hyperplasia (BPH), its increase depends on the conversion of testosterone to DHT in the prostate gland. Finasteride is highly effective in reducing the concentration of DHT both in blood and in prostate tissue.

Suppression of DHT formation is accompanied by decrease in size of prostate gland, increase in maximum urine flow rate and decrease in severity of symptoms associated with prostatic hyperplasia. Finasteride has no affinity to the androgen receptor. The drug has no significant effect on lipid profile (total cholesterol, low-density lipoproteins (LDL), high-density lipoproteins (HDL) and triglycerides) and bone mineral density.
Finasteride has no effect on blood levels of cortisol, estradiol, prolactin, thyrotropic hormone and thyroxine compared to placebo.

A single administration of finasteride at a dose of 5 mg leads to a rapid decrease in serum DHT concentration with maximum effect after 8 hours. Although plasma concentrations of finasteride fluctuate over 24 hours, DHT concentrations remain constant. This means that the plasma concentration of finasteride is not directly related to the plasma DHT concentration.

In patients with BPH who were prescribed finasteride at a dose of 5 mg daily for 4 years, there was an approximately 70% reduction in blood DHT concentration, which was associated with a reduction in prostate volume of approximately 20%. In addition, prostate-specific antigen (PSA) concentrations were approximately 50% lower than baseline, suggesting reduced prostate epithelial cell growth. The decrease in DHT concentration and reduction in the severity of prostatic hyperplasia, accompanied by a decrease in PSA concentration, persisted in the studies for up to 4 years.

In these studies, blood testosterone levels increased by approximately 10-20% while remaining within physiological limits. When finasteride was used for 7-10 days in patients referred for prostatectomy, there was an approximately 80% reduction in DHT concentrations in prostate tissue and a 10-fold increase in testosterone concentrations in prostate tissue compared to pre-treatment concentrations.

Long-term (over 4 years) use of finasteride in patients with BPH and moderately or significantly pronounced symptoms of the disease was found to reduce the risk of all urologic complications (surgical interventions: transurethral resection of the prostate or prostatectomy; acute urinary retention requiring catheterization) by 51% and was accompanied by a pronounced and sustained reduction in prostate volume, as well as a sustained increase in maximum urine flow rate and improvement in symptoms (PLESS Study).

In patients taking finasteride for 3 months when a reduction of approximately 20% in prostate volume was achieved, the prostate volume returned to its previous size after 3 months when treatment was discontinued.
Thus, treatment with finasteride helps reduce the size of the enlarged prostate, increases urine flow rate, and reduces symptoms associated with BPH.

Pharmacokinetics

Absorption

Maximum plasma concentration of finasteride is reached approximately 2 hours after oral administration. Absorption of finasteride from the gastrointestinal tract is completed 6-8 hours after oral administration. Bioavailability is approximately 80% and is independent of food intake.

Distribution

Binding to plasma proteins is approximately 93%. Plasma clearance is about 165 ml/min, the volume of distribution is 76 l.

Slow accumulation of finasteride in small amounts is observed during long-term therapy. When finasteride is taken orally daily at a dose of 5 mg, its minimum equilibrium plasma concentration reaches 8-10 ng/mL and remains stable over time.

In patients who received finasteride for 7-10 days, the drug was detected in the cerebrospinal fluid. When finasteride was administered at a dose of 5 mg per day, finasteride was also detected in seminal fluid. The content of finasteride in seminal fluid was 50-100 times less than the finasteride dose taken.

Metabolism

The half-life (T1/2) of finasteride averages 6 hours.

Elimation

In men, after a single oral dose of 14C-labeled finasteride, 39% of the dose taken is excreted by the kidneys as metabolites (unchanged finasteride is virtually not excreted by the kidneys); 57% is excreted through the gut. In this study, 2 metabolites of finasteride were identified that have a slight inhibitory effect on 5-alpha reductase compared to finasteride.

In older age, the excretion rate of finasteride is slightly reduced. The T1/2 increases with age: in men 18-60 years old the average T1/2 is 6 hours and in men over 70 years old it is 8 hours. These changes are not clinically significant and, therefore, no dose reduction is required in elderly men.

In patients with chronic renal impairment (creatinine clearance (CK) of 9 to 55 ml/min) the distribution of 14C-labeled finasteride at a single dose was not different from that in healthy volunteers. The binding of finasteride to plasma proteins also did not differ in patients with impaired renal function.

In renal failure, a portion of finasteride metabolites that are normally excreted by the kidneys is excreted through the intestine. This is manifested by an increase in the amount of metabolites of finasteride in the feces with a corresponding decrease in their concentration in the urine. No dose adjustment of finasteride is required in patients with renal insufficiency on dialysis.

Indications

Active ingredient

Composition

How to take, the dosage

Interaction

No clinically significant interaction of finasteride with other drugs has been found.

Finasteride has no effect on cytochome P450, the enzyme system that ensures drug metabolism.

Concomitant intake of food decreases the absorption rate of finasteride; however, food does not affect overall bioavailability.

Special Instructions

Synopsis

Contraindications

Side effects

Pregnancy use

Similarities