Dutasteride is a double inhibitor of 5α-reductase. Suppresses the activity of 5α-reductase isoenzymes of the 1 st and 2 nd types, which are responsible for the conversion of testosterone to dihydrotestosterone (DHT). DHT is the main androgen responsible for hyperplasia of the glandular tissue of the prostate gland.
Effect on the concentration of DHT and testosterone. The maximum effect of dutasteride on decreasing the concentration of DHT is dose-dependent and is observed 1-2 weeks after the start of treatment. After 1 and 2 weeks of taking dutasteride at a dose of 0.5 mg / day, average values of serum DHT concentrations decrease by 85 and 90%, respectively.
After taking one dose of 0.5 mg Tmax dutasteride in the blood serum – 1-3 hours.
Absolute bioavailability of dDutasteride (Avodart) in men is about 60% with respect to a 2-hour IV infusion. Bioavailability of dutasteride does not depend on food intake.
Pharmacokinetic data obtained after a single and multiple dutasteride administration, indicate a large Vd (from 300 to 500 liters). Dutasteride has a high degree of binding to plasma proteins (> 99.5%).
With daily intake, the serum dutasteride concentration reaches 65% of the stable level after 1 month and approximately 90% of this level after 3 months. Stable concentrations of serum dutasteride (Css) of about 40 ng / ml are achieved after 6 months of daily intake of 0.5 mg of the drug. In sperm, as in serum, stable concentrations of dutasteride are also reached after 6 months. After 52 weeks of treatment, the concentrations of dutasteride in the sperm averaged 3.4 ng / ml (0.4 to 14 ng / ml). From serum to semen gets about 11.5% of dutasteride.
As a monotherapy:
Treatment and prevention of progression of benign prostatic hyperplasia by reducing the size of the prostate, improving urination, reducing the risk of acute urinary retention and the need for surgery.
As a combined therapy with α1-adrenoblockers:
Treatment and prevention of progression of benign prostatic hyperplasia by reducing the size of the prostate, improving urination, reducing the risk of acute urinary retention and the need for surgery. The combination of dutasteride and α1-adrenoblocker tamsulosin was mainly studied.
Hypersensitivity to dutasteride or any other component of the drug and other 5α-reductase inhibitors;
Women and children.
With caution: hepatic insufficiency.