Anastrozole

Anastrozole (Anastrozole) is a medicine that belongs to the class of aromatase inhibitors. It is used in oncology, especially in the treatment of breast cancer in postmenopausal women.

Breast cancer can be sensitive to estrogen, a female sex hormone that can stimulate the growth of cancer cells. Anastrozole works by blocking the action of aromatase enzymease, which converts androgens (male sex hormones) into estrogen in tissues, such as fatty tissue, that have not been exposed to the hormone. This reduces estrogen levels in a woman's body, which can slow the growth and spread of estrogen-sensitive cancer cells.

Anastrozole is usually taken in tablet form once a day. Use and dosage are determined by the doctor depending on the patient's specific situation and the nature of the breast cancer.

It is important to note that anastrozole can cause side effects including muscle pain, fatigue, headache, hypertension, skin redness, and others. Patients should discuss any side effects with their doctor and ensure regular medical monitoring during treatment.

Indications Anastrozole

1. Hormone-sensitive breast cancer: Anastrozole is used as part of the comprehensive treatment of hormone-dependent breast cancer in postmenopausal women.
2. Prevention of recurrence: After surgical removal of a breast tumor (mammectomy), anastrozole may be used in some patients to reduce the risk of cancer recurrence.
3. Preventing breast cancer in women at high risk: In some cases, anastrozole may be recommended for women at high risk of developing breast cancer to reduce the likelihood of developing it.

Release form

Coated tablets: Anastrozole is most commonly available as 1 mg oral tablets. This is the standard dosage used for daily administration as part of antihormonal therapy for breast cancer.

Pharmacodynamics

1. Aromatase inhibition: The main action of anastrozole is to inhibit the aromatase enzyme, which is responsible for converting androgens (such as testosterone) into estrogens. This leads to a decrease in the level of estrogen in the blood.
2. Reducing estrogen levels: By inhibiting aromatase, anastrozole reduces the level of circulating estrogen in the body. This is especially useful in cases where elevated estrogen levels may be the cause of certain diseases or complications, such as breast cancer or estrogen-dependent tumors.
3. Use in Oncology: Anastrozole is widely used in the treatment of breast cancer in postmenopausal women, especially in those patients whose tumors are estrogenreceptor-positive.
4. Gynecologic Use: Anastrozole is sometimes used to treat certain gynecologic conditions associated with hyperestrogenemia or high estrogen levels.
5. Sports Use: Anastrozole is sometimes used in sports medicine to lower estrogen levels in men, especially when using anabolic steroids, which can lead to increased estrogen levels in the body.
6. Side Effects: Although anastrozole is generally well tolerated, it can cause side effects such as headache, hypertension, muscle pain, arthralgia, bone pain, and poor bone health (especially in post-menopausal women).

Pharmacokinetics

1. Absorption: Anastrozole is rapidly and completely absorbed from the gastrointestinal tract after oral administration. It is usually taken daily in tablet form.
2. Distribution: Anastrozole has high affinity to blood plasma proteins (about 40%), especially to albumin. It penetrates well into body tissues, including breast tumors.
3. Metabolism: Anastrozole is metabolized in the liver to form active metabolites, including hydroxyanastrozole and triazolanastrozole. The main route of metabolism is hydroxylation of the aromatic ring.
4. Excretion: The main mechanism of excretion of anastrozole and its metabolites is renal excretion, mainly in the form of metabolites. About 10% of the dose is excreted unchanged in the urine.
5. Half-life: The half-life of anastrozole from plasma is about 50 hours. This means that its concentration in the body decreases by half about 50 hours after administration.

Dosing and administration

Method of application

Anastrozole is taken orally, regardless of food intake. It is recommended to take the tablet at the same time every day to maintain a stable concentration of the active substance in the blood.

• Tablets should be swallowed whole, drinking sufficient water.
• It is not recommended to chew or crush the tablet.

Dosage

The standard dosage of anastrozole is 1 mg once daily. Dosing recommendations for different clinical situations are given below:

Early breast cancer

• Take 1 mg once daily.
• The usual course of treatment lasts 5 years, but can be extended up to 10 years depending on the doctor's judgment and individual risk factors.

Disseminated breast cancer

• Take 1 mg once daily.
• Treatment continues as long as there is a positive clinical response or until there are signs of disease progression.

Breast cancer prevention

• In some cases, anastrozole may be prescribed to prevent breast cancer in women at high risk for the disease.
• Take 1 mg once daily for a period determined by your doctor.

Special Instructions

• In renal insufficiency: Dose adjustment is usually not required.
• In hepatic insufficiency: Caution should be exercised when prescribing anastrozole, especially in severe forms of hepatic dysfunction.
• Overdose: Cases of overdose are rare, but if symptoms occur, symptomatic treatment is necessary.

Use Anastrozole during pregnancy

It is intended solely for use in postmenopausal women and may result in endangerment of pregnancy if used during pregnancy.

Here are some of the potential risks of using anastrozole during pregnancy:

1. Birth defects: Use of anastrozole during pregnancy may increase the risk of birth defects in the fetus.
2. Fetal Delay: Anastrozole may adversely affect fetal development and cause fetal delay.
3. Abortion: Use of anastrozole in the first trimester of pregnancy may increase the risk of abortion.
4. Risk of maternal complications: Anastrozole can also have a negative impact on the mother's health during pregnancy, causing a number of complications.

Contraindications

1. Hypersensitivity: People with known hypersensitivity to anastrozole or to any of the ingredients of the drug should avoid its use.
2. Pregnancy: The use of anastrozole is contraindicated in pregnant women, as it may cause congenital anomalies in the fetus. In women during treatment with anastrozole it is necessary to use effective contraceptive methods.
3. Breastfeeding: Anastrozole is also not recommended during breastfeeding because its effects on the infant have not been studied.
4. Pediatric age: The safety and efficacy of anastrozole in children has not been established, therefore it is not recommended for children.
5. Items requiring caution: Patients should be cautious when operating machinery and participating in activities requiring increased concentration, as anastrozole may cause drowsiness or fatigue.
6. Bone and skeletal diseases: In patients with osteoporosis or other bone diseases, anastrozole should be used with caution because it may worsen bone health.
7. Heart and vascular disease: Anastrozole may also increase the risk of cardiovascular complications, so it should be used with caution in patients with heart and vascular disease.

Side effects Anastrozole

1. Muscle and joint pain: This is one of the most common side effects of anastrozole. Patients may experience pain and discomfort in the muscles and joints.
2. Headache: Some patients may experience headaches while using anastrozole.
3. Hypertension: Some patients may experience high blood pressure.
4. Hypercholesterolemia: Increased blood cholesterol levels may be a side effect of anastrozole.
5. Osteoporosis: Long-term use of anastrozole may increase the risk of osteoporosis and bone fractures.
6. Rapid fatigue: Some patients may experience fatigue and weakness during treatment with anastrozole.
7. Gynecomastia: Men may experience enlargement of the mammary glands.
8. Increased risk of cardiovascular disease: Some patients, especially those with a predisposition, may experience heart and vascular problems.
9. Psycho-emotional disorders: Includes depression, anxiety, sleep disturbances and other psychiatric symptoms.
10. Vaginal bleeding: May occur in some patients.

Overdose

Information on anastrozole overdose is limited, as cases of serious overdose are not usually described in the literature due to the low toxicity of the drug.

Interactions with other drugs

1. Drugs affecting cytochrome P450: Anastrozole is metabolized in the liver with the participation of enzymes of the cytochrome P450 system, mainly CYP3A4 and CYP2D6. Therefore, drugs that induce or inhibit these enzymes may alter the blood concentration of anastrozole. For example, CYP3A4 inhibitors (e.g. Ketoconazole, itraconazole) may increase the concentration of anastrozole, and inducers (e.g. Rifampicin, phenytoin) may decrease it.
2. Hyperestrogenic drugs: Drugs containing estrogens (e.g., hormone therapy or contraceptives) may reduce the efficacy of anastrozole because they conflict with its mechanism of action.
3. Hypoestrogenic drugs: Drugs that can cause hypoestrogenism (e.g., gonadotropin-releasing hormone agonists or endometriosis drugs) may increase the effect of anastrozole.
4. Drugs affecting hematopoiesis: Some drugs, such as cytostatics or drugs used in the treatment of cancer, may increase the risk of anemia when used together with anastrozole.
5. Drugsaffecting bone tissue: Drugs that affect bone resorption or bone formation (e.g., bisphosphonates or raloxifene) may improve the effect of anastrozole in preventing osteoporosis caused by its administration.