Finasteride-OBL, 5 mg 30 pcs.

Pharmacodynamics

Finasteride is a 4-azasteroid compound that selectively and competitively inhibits 5α-reductase. This nicotinamide adenine dinucleotide phosphate (NADPH)-dependent enzyme converts testosterone to dihydrotestosterone.

The drug specifically inhibits type 2 isoenzyme 5α-reductase, which leads to a significant reduction in dihydrotestosterone levels in the prostate (>90%) and circulatory system (60% to 80%).

Finasteride increases prostatic testosterone levels (by approximately 85%) in patients with BPH; it has no effect on prostate growth or morphology. The drug has no pronounced affinity for androgen receptors. Finasteride significantly reduces plasma PSA levels by 41% to 71% in patients with symptoms of BPH. However, the ratio of unbound to total PSA levels is not affected by the drug.

The size of the prostate gland decreases under the influence of finasteride due to atrophy and apoptosis. Histological changes conditioned by action of the drug were observed after 6 months from the beginning of treatment. Glandular elements of prostate tissues are the most sensitive to finasteride. The drug reduces detrusor tone in patients with urinary retention caused by BPH.

Pharmacokinetics

Finasteride is well absorbed in the gastrointestinal tract, food slows the rate of absorption but does not affect the volume of absorption. The average bioavailability of finasteride is 63% (range 34 – 71%), based on the area under the curve ratio to the intravenous control dose. The maximum plasma concentration of finasteride is 37 ng/ml (27 – 49%) and is reached within 1 – 2 hours after administration. The drug accumulates in the body with repeated multiple administrations. Establishment of equilibrium concentration occurs after 17 days, the exact time is not known.

Approximately 90% of finasteride circulates in a bound to plasma proteins. The volume of distribution of finasteride is high (76 liters in the stable state); the drug penetrates the blood-brain barrier and a small amount is found in semen. The drug may be absorbed through the skin by contact with crushed tablets.

Finasteride is metabolized primarily by the liver to form inactive metabolites. The plasma clearance of finasteride is 165 mL/min (70 -279 mL/min) and the elimination half-life is 6 hours. About 39% (32 – 46%) of the dose taken is excreted in the urine as metabolites and 57 (51 – 64%) through the intestine.

The pharmacokinetics of the drug generally does not change with increasing renal failure. The pharmacokinetics of the drug in conditions of hepatic function insufficiency have not been studied.

Indications

Treatment of benign prostatic hypertrophy.

Active ingredient

Composition

1 coated tablet contains:

the active ingredient:

finasteride 5 mg,

excipients:

Lactose monohydrate,

calcium hydrophosphate dihydrate,

sodium croscarmellose,

sodium dodecyl sulfate,

microcrystalline cellulose,

hyprolosea (hydroxypropyl cellulose),

Magnesium stearate

How to take, the dosage

Orally, with liquid and swallowing the tablet whole (tablets must not be divided or crushed), regardless of meals.
The recommended dose is 5 mg (1 tablet) once a day.

The duration of treatment is up to 6 months; if necessary, treatment may be continued until clinical effect is achieved.
In patients with hepatic impairment, no dose adjustment is required.

In patients with renal insufficiency of various degrees of severity (when CK decreases to 9 ml/min) dosage adjustment is not required.

Dose adjustment is not required in elderly patients.

Interaction

No clinically significant interactions of finasteride with other drugs have been found.
When combining finasteride with propranolol, digoxin, glibenclamide, warfarin, theophylline, angiotensin-converting enzyme inhibitors, paracetamol, acetylsalicylic acid, alpha-adrenoblockers, beta-adrenoblockers, No clinically significant manifestations of drug interaction were observed with calcium channel blockers, nitrates, diuretics, H2-histamine receptor blockers, HMG-CoA reductase inhibitors, nonsteroidal anti-inflammatory drugs, quinolones and benzodiazepines.

Special Instructions

Finasteride is used in patients with an enlarged prostate gland with a volume greater than 40 cm3.

Patients with a large residual urine volume and/or significantly decreased urine flow require close monitoring for obstructive uropathy.

Patients taking finasteride should be monitored by a urologist.

Before treatment with finasteride, diseases that stimulate prostate growth and urethral obstruction – prostate cancer, urethral stricture, bladder hypotension, bladder innervation disorders, and infectious prostatitis – should be ruled out.

Because there is no experience in treating BPH with finasteride in patients with hepatic impairment, these patients should be treated with caution as an increase in plasma concentrations of finasteride cannot be ruled out.

Impact on PSA concentration and prostate cancer diagnosis Rectal examination and other prostate cancer diagnostic methods should be performed before treatment with finasteride and periodically during treatment. Determination of serum PSA concentration is also used to detect prostate cancer. A baseline PSA concentration above 10 ng/ml suggests a broader evaluation of the patient, including a prostate biopsy.

When PSA concentrations range from 4-10 ng/ml, further evaluation of the patient is recommended. PSA concentrations in patients with prostate cancer and patients without the disease may overlap significantly. Consequently, in men with BPH, a normal PSA concentration does not rule out prostate cancer regardless of finasteride treatment. A baseline PSA concentration below 4 ng/ml also cannot exclude prostate cancer.

Finasteride causes a decrease in serum PSA concentration of approximately 50% in patients with BPH even in the presence of prostate cancer. Therefore, it should be kept in mind that a decrease in PSA concentrations in patients with BPH treated with finasteride does not rule out concomitant prostate cancer.

In patients receiving finasteride for 6 months or more, PSA concentrations should be doubled to compare with normal values in untreated patients. This correction preserves the sensitivity and specificity of PSA testing and the ability to detect prostate cancer.

Any prolonged increase in PSA concentrations in patients treated with finasteride requires careful evaluation to determine the cause, including disruption of the finasteride regimen.

Finasteride does not significantly decrease the percentage of free PSA fraction (free PSA/total PSA ratio). This index remains constant even under the influence of finasteride. If percentage of free PSA is used for prostate cancer diagnosis, correction of values of this parameter is not necessary.

Impact on laboratory values

The PSA serum PSA concentration correlates to age of patient and prostate volume, and prostate volume in turn correlates to age of patient. When determining PSA concentration, it should be noted that this index decreases in patients taking finasteride.

In most patients a rapid decrease of PSA concentration is observed during the first months of therapy, after which there is a stabilization of this indicator at a new value, which is usually half of the value obtained before the start of treatment. Therefore, in patients taking finasteride for 6 months or more, PSA concentrations should be doubled to compare to normal values in men not taking finasteride.

Impact on driving and operating machinery

A caution should be exercised when driving and operating machinery due to the possible adverse reaction such as drowsiness when using the drug.

Contraindications

Side effects

The frequency of side effects is classified according to the recommendations of the World Health Organization: very frequently – at least 10%; frequently – at least 1%, but less than 10%; infrequently – at least 0.1%, but less than 1%; rarely – at least 0.01%, but less than 0.1%; very rarely (including isolated cases) – less than 0.01%.

Nervous system disorders: infrequent – somnolence.

Gender and mammary gland disorders: very often – impotence, often – decreased libido, ejaculation disorders, decreased ejaculate volume, enlarged and painful breasts; infrequently – pain in testicles; very rarely – secretion of mammary gland secretion, formation of mammary gland nodules. In most patients, these phenomena were transient.

Allergic reactions: often – skin rash; rarely – skin itching, urticaria, angioedema of lips and face.

Laboratory measures: rare – decreased concentration of PSA.

Overdose

Patients received finasteride in single doses of up to 400 mg and in multiple doses of up to 80 mg/day for 3 months, with no adverse effects observed.

There are no recommendations for specific treatment of finasteride overdose.

Pregnancy use

Finasteride is not prescribed for women and children.

Similarities