Pharmacological action of Casodex

Antiandrogenic non-steroidal drug. It is a racemic mixture, with antiandrogenic activity being predominantly (R) -enantiomer. The drug has no other types of endocrine activity. Casodex® binds to androgen receptors and, without activating gene expression, suppresses the stimulating effect of androgens. As a result, regression of prostate neoplasms occurs.

In some patients, discontinuation of Casodex may lead to the development of a clinical antiandrogen withdrawal syndrome.

Pharmacokinetics

Absorption

After oral administration, it is rapidly and completely absorbed from the gastrointestinal tract. Concomitant food intake does not affect absorption.

Distribution

With a daily intake of Casodex at a dose of 50 mg of Css (R) -enantiomer in plasma is about 9 μg / ml. At equilibrium, about 99% of all enantiomers circulating in the blood are the active (R) -enantiomer.

With daily intake of Casodex, the concentration of the (R) -enantiomer in plasma increases by about 10 times due to prolonged T1/2, which allows taking Casodex 1 time / day.

The connection with plasma proteins is high (96% for the racemic mixture, 99.6% for the (R) -enantiomer).

Metabolism

It is extensively metabolized in the liver by oxidation and the formation of conjugates with glucuronic acid.

Excretion

Metabolites are excreted in urine and bile in approximately equal proportions.

The (S) -enantiomer is excreted from the body much faster than the (R) -enantiomer, T1/2 of the latter about 7 days.

Pharmacokinetics in special clinical situations

The pharmacokinetics of the (R) -enantiomer are not affected by age, renal dysfunction, mild to moderate liver dysfunction.

There is evidence that the elimination of the (R) -enantiomer from plasma slows down in patients with severe hepatic dysfunction.

In patients with moderate to severe impairment of liver function, accumulation of bicalutamide in the body may be observed.

Indications for Casodex®

• advanced prostate cancer (in combination with a GnRH analog or with surgical castration).

Dosage regimen

Casodex® is prescribed for adult men (including the elderly) with advanced prostate cancer in combination with a GnRH analog or with surgical castration at a dose of 50 mg 1 time / day. Treatment should be started at the same time as the initiation of a GnRH analog or surgical castration.

Patients with impaired renal function and mild impaired liver function do not require dose adjustment.

In patients with moderate to severe impaired liver function, increased accumulation of the drug may be observed.

Contraindications for use

• simultaneous administration with terfenadine, astemizole, cisapride;
• hypersensitivity to bicalutamide and other components of the drug.

Casodex® is not prescribed for women and children.

With careful use Casodex® in patients with impaired liver function, lactose intolerance, lactase deficiency and malabsorption syndrome glucose / galactose.

Application during pregnancy and lactation

Casodex® is contraindicated in women and should not be administered to pregnant women or during lactation.

Application for violations of liver function

Patients with minor violations of liver function dose adjustment is not required. With carefulof useCasodex in patients with impaired hepatic function. Considering the possibility of slowing down the elimination of bicalutamide and the accumulation of bicalutamide in patients with impaired liver function, it is advisable to periodically assess liver function.

Application for impaired renal function

Patients with impaired renal function do not require dose adjustment.

Application in children

Casodex is not prescribed for children.

Application in elderly patients

Application is possible according to the dosage regimen.

Special instructions

The drug is metabolized in the liver. Considering the possibility of slowing down the elimination of bicalutamide and the accumulation of bicalutamide in patients with severe liver dysfunction, it is advisable to periodically assess liver function. Most changes in liver function occur during the first 6 months of treatment with Casodex.

Casodex® should be used with caution in patients with moderate to severe liver dysfunction.

Severe liver dysfunctions with Casodex are rare (fatal cases have been reported).

In case of development of pronounced changes in liver function, taking Casodex should be discontinued.

In patients with progression of the disease against the background of increased levels of prostate-specific antigen (PSA), it is necessary to consider stopping treatment with Casodex.

Given the possibility of Casodex inhibition of the activity of cytochrome P450 (CYP3A4), caution should be exercised when Casodex is administered concurrently with drugs that are predominantly metabolized with the participation of CYP3A4.

A decrease in glucose tolerance was observed in patients taking GnRH agonists. This effect can lead to the development of diabetes mellitus or a decrease in glucose tolerance in patients with diabetes mellitus. Therefore, in patients taking Casodex® and GnRH agonists, it is necessary to control the concentration of glucose in the blood.

Impact on the ability to drive vehicles and control mechanisms

When using Casodex, drowsiness and dizziness may occur, and therefore, care should be taken when driving vehicles or other moving mechanisms.

Overdose

Cases of overdose in humans have not been described. There is no specific antidote, therefore, symptomatic therapy is carried out if necessary. Dialysis is ineffective because bicalutamide binds strongly to proteins and is not excreted unchanged in the urine. Shown is general supportive therapy and monitoring of vital body functions.

Drug Interactions

There is no data on pharmacodynamic or pharmacokinetic interactions between Casodex and GnRH analogues.

In vitro studies have shown that the (R) -enantiomer of Casodex is an inhibitor of CYP3A4, to a lesser extent - CYP2C9, CYP2C19, CYP2D6. In clinical studies using phenazone as a marker of cytochrome P450 activity, the potential ability of Casodex to interact with other drugs was not found. However, when using Casodex for 28 days while taking midazolam, the AUC of midazolam increased by 80%.

The simultaneous use of Casodex with drugs such as terfenadine, astemizole and cisapride is contraindicated.

Caution should be exercised when prescribing Casodex concomitantly with cyclosporine or slow calcium channel blockers. It may be necessary to reduce the dose of these drugs, especially in the case of potentiation or the development of adverse reactions. After starting the use or discontinuation of Casodex, it is recommended to carefully monitor the concentration of cyclosporine in the blood plasma and the clinical condition of the patient.

Caution should be taken simultaneously with Casodex® and drugs that inhibit liver microsomal enzymes (for example, cimetidine, ketoconazole). The use of these combinations can lead to an increase in the concentration of bicalutamide in plasma and, possibly, to an increase in the incidence of adverse reactions.

Casodex® enhances the effect of indirect coumarin anticoagulants (including warfarin), because can displace these drugs from their protein binding sites. It is recommended to regularly monitor the prothrombin time when prescribing Casodex to patients receiving indirect coumarin anticoagulants.

Storage conditions of the drug Casodex®

The drug should be stored out of the reach of children at a temperature not exceeding 30 ° C.

Side effect

Casodex® is well tolerated by most patients, and only in rare cases it has to be canceled because of the side effects it causes.

The pharmacological action of Casodex can cause the following side effects.

Very often (> 10%): gynecomastia (may persist even after stopping therapy, especially if the drug has been taken for a long time), breast tenderness, hot flashes.

Often (≥1% - <10%): hot flashes *, anemia *, dizziness *, abdominal pain *, constipation *, nausea *, peripheral edema *, hematuria *, hepatotoxicity, transient elevation of liver transaminases, cholestasis, and jaundice (the described changes in liver function were rarely assessed as serious, were transient and completely disappeared or decreased despite continued therapy or after discontinuation of the drug), decreased appetite, decreased libido, depression, drowsiness, dyspepsia, flatulence, alopecia, hirsutism, or hair regrowth , dry skin, pruritus, erectile dysfunction, chest pain, weight gain.

Rarely (≥ 0.1% - <1%): hypersensitivity reactions, angioedema, urticaria, interstitial pulmonary diseases (fatal cases reported), heart failure.

Aboutry rare (≥ 0.01% - <0.1% hepatic failure (reported cases of fatal outcome).

* With the simultaneous use of Casodex and GnRH analogues, the side effect was often observed.