Penester is a drug for the treatment of benign prostatic hyperplasia. Finasteride is a synthetic 4-azasteroid compound. It is a competitive and specific inhibitor of steroid 5-alpha reductase, an intracellular enzyme that converts testosterone into the active androgen 5-dihydrotestosterone.
The growth of prostate tissue and the development of benign hyperplasia are due to the conversion of testosterone into dihydrotestosterone in prostate cells. Under the influence of the drug, there is a significant decrease in the concentration of dihydrosterone both in the blood plasma and in the gland tissue. Finasteride does not bind to androgen receptors.
As a result of using the drug, the size of the prostate gland decreases, the severity of symptoms associated with prostatic hyperplasia decreases.
The drug does not affect the concentration of plasma lipids, as well as the content of cortisol, estradiol, prolactin, thyroid-stimulating hormone, thyroxine in the blood plasma.
Pharmacokinetics
Absorption and distribution
After oral administration, finasteride is rapidly absorbed from the gastrointestinal tract. Bioavailability is about 80% and does not depend on food intake. Cmax in blood plasma is achieved 1-2 hours after oral administration. Plasma protein binding is about 90%.
Metabolism and excretion
Finasteride is metabolized in the liver and excreted as metabolites in urine and feces.
Pharmacokinetics in special clinical situations
T1/2 in patients over 60 years old is 6 hours, in patients over 70 years old it can be extended to 8 hours.
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