Breast cancer is a malignant neoplasm in the chest, which is not only a serious medical, but also a social problem. According to statistics, this type of cancer is one of the first among all other cancers. Experts say that more than 1.5 million women worldwide suffer from the ailment. Moreover, 400 thousand cases of them end in death.
According to the instructions for use, the drug "Fareston" is one of the most effective antitumor anti-estrogenic non-steroidal drugs. It is very often prescribed for breast cancer. About how this drug works and in what cases it is forbidden to use, and we will discuss further.
The form of the release of the drug, its packaging and the full composition
“Fareston” - tablets of white color, with a beveled edge, round and flat, with the code “TO60” on one side.
The active component of the drug is toremifene (60 mg) in the form of citrate. The medication also includes such auxiliary substances as sodium starch glycolate, colloidal silicon dioxide, corn starch, MCC, lactose monohydrate, magnesium stearate and povidone.
Detailed instructions for the use of “Fareston” can be found in a cardboard box along with the drug, which is packaged in contour cells or plastic bottles.
The principle of action of the drug
According to reviews and instructions for use, “Fareston” is a triphenylethylene derivative, a popular antitumor non-steroidal antiestrogen drug. The active substance of this medication is able to quickly bind to estrogen receptors and have not only an estrogen-like, but also an anti-estrogenic effect (depending on the duration of therapy, the target organ, gender and other characteristics of the human body).
The instructions to “Fareston” contain information that during treatment with people with breast cancer during the postmenopause, a moderate decrease in LDL and serum cholesterol is detected. This is due to the fact that toremifene is able to competitively bind to estrogen receptors and significantly slow down estrogen-mediated stimulation of cell replication and DNA synthesis.
It should be noted that during experiments on cancer models, the active component of the drug in question at high doses had an estrogen-independent antitumor effect.
Attached to the “Fareston” instruction contains information that the antitumor properties of toremifene are due to its antiestrogenic effect. Although it cannot be ruled out that other mechanisms (for example, effects on the kinetics of the cell cycle, changes in the expression of oncogenes, induction of apoptosis, secretion of growth factors) can also have a detrimental effect on malignant neoplasms.
Pharmacokinetic features of the drug
According to the information in the instructions to "Fareston", toremifene after oral administration is completely absorbed. Its maximum concentration in the blood is detected after 3 hours (usually 2-5 hours). Eating in no way affects the duration of absorption of the drug. However, in this case, the time to reach the maximum concentration of the drug may increase by 1.6 or 2 hours. However, such changes do not affect the course of treatment.
The kinetics of toremifene in the blood when taken orally at a dosage of 11-680 mg per day is linear.
Communication with plasma proteins (mainly with albumin) is approximately 99.5%. Css (Cascading Style Sheets) at a dosage of 60 mg per day is 0.9 ÎĽg / ml. Due to the slow elimination of Cascading Style Sheets in the blood, it is reached within 28-42 days.
The metabolism of toremifene is carried out in the liver through demethylation and hydroxylation with the participation of the CYP3A4 isoenzyme. In this case, an active metabolite is formed - N-demethyltoremiphene. The latter has a similar antiestrogenic effect, although somewhat reduced than toremifene. Its association with plasma proteins is about 99.9%. The average elimination half-life of the mentioned metabolite varies within 4-20 days.
Also, three more derivatives are found in the blood serum, namely: 4-hydroxytoremiphene deaminohydroxytoremifen and N, N-didemethyltoremiphene.
The attached instructions to “Fareston” indicate that the predominant part of toremifene is excreted from the patient’s body in the form of metabolites with feces and about 10% of the dose with urine.
Indications for appointment
In what cases can a patient be prescribed a drug like Fareston? Instructions and reviews of experts report that this tool works well with metastatic hormone-dependent breast cancer in the postmenopausal period (as a first-line treatment). Also, the medication in question can be used for the treatment and prevention of dishormonal breast hyperplasia.
Contraindications to taking pills
The use of "Fareston" is prohibited when:
- high sensitivity of the patient to toremifene;
- endometrial hyperplasia (history);
- changes in cardiac conduction (including with acquired or congenital lengthening of the QT period);
- clinically significant bradycardia;
- severe liver failure;
- violation of electrolyte balance, including uncorrected hypokalemia;
- heart failure (clinically significant) with a decrease in part of the ejection of the left ventricle.
Also, the drug in question is contraindicated in symptomatic asystole (history).
Instructions for use, side effects of "Fareston"
Only the oncologist should prescribe the medication in question, after a complete examination of the patient. Take the drug, regardless of food intake, inside.
In the diagnosis of dishormonal breast hyperplasia, the recommended dosage is 20 mg per day, and with estrogen-dependent oncology - 60 mg per day.
According to reviews, “Fareston” may cause side-effects such as:
- hot flashes, loss of appetite, uterine bleeding, weight gain, vaginal discharge;
- fatigue, endometrial hypertrophy, increased transaminase activity, endometrial polyps;
- hypercalcemia, endometrial hyperplasia, short-term corneal opacity, endometrial cancer;
- alopecia, dizziness, jaundice, edema, thromboembolic episodes, nausea, deep vein thrombosis;
- vomiting, thrombophlebitis, depression, constipation, headache, excessive sweating, disorientation in space, rash, insomnia, itching, pulmonary embolism.
Interaction with other medicines
The instruction to "Fareston" (20 mg, 60 mg) reports the following drug interaction of the drug in question:
- When taking toremifene along with drugs prolonging the QT interval, an additional lengthening of the QT period is likely, which can provoke a risk of ventricular arrhythmias, including flutter / flicker. In connection with the foregoing, the simultaneous use of Fareston and such drugs as antipsychotics (Pimozide, phenothiazine derivatives, Haloperidol, Certindol, Sulpiride), antiarrhythmic drugs of class IA (Disopyramide, Hydroquinidine) are contraindicated , "Quinidine"), antibacterial drugs ("Pentamidine", "Moxifloxacin"), antimalarials ("Erythromycin" intravenously, "Halofantrine"), class III antiarrhythmic drugs ("Amiodarone", "Dofetilide", "Sotalol", "Ibutilide" "), antihistamines (Astemizole, Terfenadine, mi-based drugs zolastine), as well as Vinkamin intravenously, Cisapride, Difemanil and Bepridil.
- With concurrent administration of drugs that reduce renal excretion of Ca (including thiazide diuretics), the patient may develop hypercalcemia.
- Inducers of liver enzyme systems, such as phenobarbital or carbamazepine, can accelerate the metabolism of the active substance “Fareston” and reduce the Css of toremifene in the blood (this combination of drugs requires doubling the daily dose of the drug in question).
- With the simultaneous administration of anticoagulants and antiestrogens (for example, "Warfarin"), the bleeding time increases significantly, so this combination of drugs should be avoided.
- Some drugs that inhibit the CYP3A isoenzyme can slow the metabolism of toremifene. This should be taken into account while taking "Erythromycin", "Ketoconazole" and "Troleandomycin."
Important information!
Instructions for use "Fareston", the analogues of which are listed below, states that before starting treatment with this medicine, the patient must undergo a complete gynecological examination. In this case, special attention should be paid to the endometrial mucosa. Further examinations in the field of gynecology must be repeated at least once a year.
People with an increased level of body mass index (over 30), diabetes mellitus, arterial hypertension, as well as those who received long-term hormone replacement therapy, are at risk for endometrial oncology, and therefore they need special monitoring.
The active substance “Fareston" can be dangerous for patients with severe thromboembolic diseases, including a history of it.
In some people, taking the drug causes a dose-dependent lengthening of the QT period.
It should be specially noted that toremifene should be used with caution by elderly patients with myocardial ischemia and proarrhythmic conditions, otherwise this can lead to ventricular arrhythmia and cardiac arrest. With the development of signs associated with cardiac arrhythmias (while taking toremifene), treatment should be stopped immediately and an ECG should be done.
It is forbidden to use toremifene at an interval of QTc> 500 ms.
People with heart failure (decompensated), as well as severe angina pectoris, bone metastases and hypercalcemia, need special monitoring.
Information on taking toremifene in patients with heart failure, unstable diabetes mellitus or a general serious condition is currently not available.
Experts say that the active substance of Fareston does not have any effect on the speed of a person’s reaction when driving a car or working with other mechanisms. However, it should be borne in mind that in isolated cases in some patients, visual impairment, dizziness and weakness are possible. In such situations, it is recommended to refrain from driving vehicles or working with other mechanisms.
Fareston tablets are not allowed to be used during breastfeeding and during pregnancy due to the lack of information on the efficacy and safety of toremifene in these periods.
Cases of drug overdose
What reactions are observed in patients with an overdose of the drug "Fareston"? Reviews of experts report that when taking this remedy in a daily dose of 680 mg, such negative manifestations as headaches, nausea, which turns into vomiting, and severe dizziness are detected. It should also be noted that theoretically, signs of an overdose may be the result of the estrogenic effects of the drug and may be manifested by increased vaginal bleeding. By the way, from the antiestrogenic properties of the drug, increased flushes may also appear.
If overdose symptoms are detected, symptomatic therapy is necessary.
Method for storing anticancer drugs, dispensing conditions from pharmacies
Fareston tablets must be kept only in a dry place inaccessible to small children. The storage temperature of the drug is 15-25 ° C, and its shelf life is five years.
In pharmacy chains, the medication in question is dispensed strictly according to a doctor’s prescription.
Similar drugs, drug cost
What can replace a medicine like Fareston? Analogues of the specified drug are selected by an oncologist individually. Thus, if there are any contraindications to taking the drug, the patient may be recommended: Vero-Tamoxifen, Tamoxifen, or Fazlodex. Before using the funds listed, you should read the instructions.
How much does Farston cost? The price of this medicine depends on several factors (for example, on the mass content of the active substance, the pharmacy network, the number of tablets in the package, etc.). On average, the cost of Fareston tablets No. 30 (20 mg) is 1300-1500 rubles, and 60 mg of drug No. 60 is 5000-6000 rubles.
Antitumor drug reviews
What do patients and doctors say about Fareston tablets? Unfortunately, there are not very many reports on the effect of this medication. However, those that are are more positive.
Most often, the drug "Fareston" is used in the treatment of estrogen-dependent breast cancer. At the same time, doctors always warn that such a medicine is not a panacea. In addition, they report that “Fareston” for one reason or another is not suitable for every patient. Although compared with its main counterpart, Tamoxifen, the drug in question exhibits much less negative effects and has greater therapeutic efficacy.
In any case, it should be remembered that treatment with Fareston tablets for breast cancer is possible only under the supervision of an oncologist with all control tests and recommended studies.