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Fulvestrant: the second line of treatment in breast cancer

The fulvestrant is a pure estrogen receptor antagonist drug which is used as a second line of treatment in metastatic…

The fulvestrant is a pure estrogen receptor antagonist drug which is used as a second line of treatment in metastatic breast cancer.

Indicated in postmenopausal women with progression of the disease after having been previously treated with another antiestrogenic therapy.

In addition to being indicated in the treatment of breast cancer that metastasizes, It is also used in women who are in the period of adolescence who present early puberty .

What is breast cancer?

Breast or breast cancer develops when The cells of the breast begin to grow and divide uncontrollably. Growing in this way, the cells form a tumor that can be palmarized by an examination and can be observed by an x-ray.

Breast cancer It can be formed in different parts of the mammary structure, however, most start in the ductal ducts, which are the ones that carry milk from the glands to the nipple.

Almost any cell in the body can become cancerous and spread to other parts of the body. When this happens, we talk about metastasis . This disease is more typical in women than in men, but also people of this gender can suffer from it.

Malignant or benign?

Fulvestrant: the second line of treatment in breast cancer

It is important to differentiate the malignant from the benign tumor. In many cases women have breast lumps that are abnormal growths but that do not spread, therefore they do not put the life of the person in danger. These tumors are benign tumors.

Any mass or change that can be seen in the breast it is important that you study by a specialized person to be able to distinguish it in benign or malignant. Although it is benign, it can increase the risk of suffering from the opposite.

He The most common symptom of breast cancer is that a new mass appears. This lump is characterized by being non-painful, hard and with irregular edges, but this is not always the case and that is why it should always be checked by the doctor. Other possible symptom They may be:

  • Skin irritation or dimpling
  • Chest or nipple pain
  • Contraction of the nipples.
  • Swelling of the entire breast or part of it.
  • Nipple discharge other than breast milk

Once we have known in general terms the disease for which the fulvestrant is indicated, we can understand more easily the following aspects of the same:

  • Mechanism of action.
  • Adverse reactions.
  • Pharmacokinetics

Mechanism of action of fulvestrant

The estrogen they enter the cells of the breast and they form a complex with its steroid type receptor. This complex can be formed both in the cytoplasm and in the nucleus. However, even if it is formed in the cytoplasm or nucleus, the complex must occupy a specific place in that nucleus.

Once inside, it will give the transcription of a specific protein. The formation of this complex is essential for estrogen to develop its functions.

The fulvestrant prevents the formation of this complex by reversibly and competitively inhibiting the estrogen receptor. Therefore it prevents the actions of estrogen from being carried out by inhibiting the transcription dependent on them.

Adverse reactions

Fulvestrant: the second line of treatment in breast cancer

The most frequently reported adverse reactions of fulvestrant were, first and most often, pain at the injection site, since it is an intramuscular administration drug as we will see later.

Further, Many patients have suffered from nausea and bone pain as frequent adverse reactions. Other symptoms may also appear, although less frequently, such as:

  • Headache and fatigue
  • Hot flushes
  • Vomiting
  • Loss of appetite
  • Cough and dyspnea (choking sensation)
  • Constipation


Fulvestrant: the second line of treatment in breast cancer

Fulvestrant is a drug that, as we mentioned before, it requires intramuscular administration, being the most painful injections for the patient, so it is inconvenient.

After the administration, it is absorbed slowly and the maximum concentrations in the plasma can be found spent from 1 to 5 days.

One thing to keep in mind is that the fulvestrant it is highly bound to plasma proteins. That is why caution should be exercised if you are being medicated at the same time with another drug that also binds to plasmatic proteins in a high proportion.

It can happen that the other drug displaces the estrogen antagonist, increasing its free levels in plasma and possibly producing toxic effects in the patient.

Suffers from hepatic metabolism and, above all, the cytochrome P-450 3A4 isoenzyme is involved in the oxidation reactions undergone by the drug. Once metabolized, it is eliminated by hepatobiliary route and excreted in the faeces.

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