How does tamoxifen work

The reason of breast cancer is not fully understood, but it is known that the occurrence of certain cancers is dependent on the excessive concentration of estrogen in the blood.

When to use tamoxifen

Nolvadex (tamoxifen) is used as an essential in the treatment of breast cancer or as an auxiliary-complementary next operation, cytostatic drugs or radiotherapy.

Dosing and administration

The dose is determined by your doctor. Generally the dose is 10-20 mg 1-2 times a day.


The recommended daily dose is 20 mg. When Nolvadex is administered in larger doses, there is no additional benefits such as delay recurrence or improve survival of patients. They are not available relevant clinical data to justify the use of tamoxifen at a dose of 30 to 40 mg daily, although some patients with advanced disease received tamoxifen at these doses.


Doses used in elderly patients are the same as in other adult patients. Some patients Nolvadex formulation was used as a sole treatment.

What is tamoxifen

Tamoxifen (brand names: Valodex, Nolvadex, Istubal) is a non-steroidal compound acting primarily antiestrogen. From a medical point of view is used most often in the non-operative treatment of breast cancer (as adjuvant therapy). Their antiestrogenic due primarily to competition with endogenous estrogen for binding with the cellular receptor, thereby preventing or minimizing the possibility of binding of estrogens in the target tissue - largely nipples and uterus.

In sport is used as probably the most popular antiestrogen or a means of blocking action of estrogen in the body. Applies here only in men, because they have to worry about processing the aromatization of androgen excess in estrogens. These in turn cause in men effects feminizing such as:

  • Gynecomastia or growth of adipose tissue around the breast
  • fat, especially around the thighs, buttocks and abdomen
  • the more 'plump' appearance as a result of the above-mentioned
  • and also disrupt the hormonal balance... making us as a result of 'half-girl'

This is why men use tamoxifen for sport. One of the many myths that continue to circulate in the gyms, a statement allegedly weakened the action of anabolic steroids, mainly testosterone. Fortunately, there is no professional publications speaking about the fact that this is happening. Tamoxifen competes for the binding of the estrogen receptor and not the anabolic steroid ! In clinical studies have been carried out on a group of volunteers who were administered either testosterone (400 mg / week) as well as tamoxifen citrate (20 mg / day), the strength of the effect of testosterone and its metabolites ranged plus 3.4%, minus 3.6 %. Thus Test showed however that if affects tamoxyfen potency of testosterone, it has a positive impact on both the impact strength and the slight negative. And in fact, you can test other factors justify or say that, contrary to the fears of tamoxifen does not weaken, and certainly as much as suggested anabolic effects of testosterone.

  • One film-coated tablet contains 10 mg of Nolvadex (tamoxifen citrate - 15.2 mg)
  • One film-coated tablet Nolvadex D contains 20 mg of tamoxifen citrate - 30.4 mg

Excipients: lactose, corn starch, gelatin, sodium carboxymethyl cellulose polymer, magnesium stearate.

Coating: methylhydroxypropylcellulose, titanium dioxide, polyethylene glycol.


No data on the effects of Nolvadex on ability to drive and use machines in motion.

Treated patients may experience loss of menses. The drug may impair psychomotor performance, and therefore you should not drive or perform acts of precision in its application.

Do not drink alcohol during treatment because it increases the effects of alcohol.

The expected effect of treatment may change if Nolvadex is used in combination with other medicines. The intention to use of other drugs, including preparation should consult with a doctor.

The use of tamoxifen in premenopausal women some inhibition of menstruation occurs. During treatment with tamoxifen, an increase in the frequency of changes in the endometrium, such as hyperplasia, polyps, cancer. There was also an increased incidence of uterine sarcoma (mostly malignant mixed mesodermal tumors). The mechanism of these changes is not known. They are probably the result of the action of tamoxifen similar to estrogen. Particular caution should be exercised in patients who were previously treated with tamoxifen and during treatment occurred in these effects from the reproductive system especially vaginal bleeding, menstrual disorders, vaginal discharge, pain and (or) a feeling of heaviness in the lower abdomen. Caution should be exercised if, during the re-treatment with tamoxifen experience similar symptoms.

In clinical studies in patients treated with tamoxifen for breast cancer incidence of primary tumors other than breast or other cancer of the endometrium. Not been established causal link between the occurrence of these tumors and the administration of tamoxifen. The clinical significance of these findings is not clear.

Side effects

The drug is generally well tolerated.


  • Digestive Disorders-nausea, vomit
  • Flushing, sweating
  • Menstrual disorders
  • The accumulation of water in the body
  • Too high levels of calcium in the blood
  • Reduction in the number of platelets


  • Vaginal discharge and itching of the vagina
  • Pain in the area of cancer
  • Dizziness
  • Rash
  • The formation of blood clots


  • Swelling of the ovaries, hair loss
  • Disorders of liver function
  • Elevated blood calcium levels in patients with metastatic cancer to the bone
  • The weakening of eyesight

The side effects seen with tamoxifen result either from the pharmacological action of the drug, such as hot flashes, vaginal bleeding, vaginal discharge, itching of the vulva, transient symptoms of cancer, or the operation of general gastrointestinal disorders, headaches, poor attention and in very rare cases, fluid retention in the body, and alopecia. If side effects are severe, reduction of dose (dose not less than 20 mg per day) may reduce their severity. If, despite dose reduction severity of adverse reactions does not change, it may be necessary to discontinue the drug. In very rare cases, skin lesions, including isolated cases of multiform erythema, Stevens-Johnson syndrome, pemphigus. In rare cases, hypersensitivity reactions have occurred also in the form of angioedema. A small number of patients whose bone metastases were found during the initial period of treatment have elevated serum calcium.

During treatment with tamoxifen were reduced platelet count to 80 000 - 90 000 cells/mm3. In individual cases, the number was smaller. In patients treated with tamoxifen was also observed abnormal vision, including changes in the cornea, retinopathy, cataracts. Have been reported cases of uterine fibroids, endometriosis, and other changes in the endometrium, ie hyperplasia and polyps. For women aged premenopausal patients treated with Nolvadex in a few cases observed increase ovarian cysts. After application of Nolvadex has been observed leukopenia, sometimes she has performed with anemia and (or) thrombocytopenia. In very rare cases, neutropenia, sometimes severe. During tamoxifen treatment, cases of deep vein thrombosis and pulmonary embolism. Concomitant use of Nolvadex and cytotoxic drugs increases the risk of thromboembolic complications. In very rare cases, the occurrence of interstitial pneumonia. When treatment with Nolvadex, changes in liver enzymes. In rare cases other severe liver dysfunction, such as fatty liver, cholestasis and hepatitis. In rare cases, after application of Nolvadex, an increase in serum triglycerides, sometimes occurring simultaneously with pancreatitis. During treatment with Nolvadex an increased incidence of endometrial cancer and uterine sarcoma (mostly malignant mixed mesodermal tumors).

Contraindications Drug interaction Pregnancy and breastfeeding
Do not use tamoxifen in pregnant women. Patients in the period before menopause before starting treatment with tamoxifen pregnancy must be excluded. Drug Nolvadex should not be used in patients with known hypersensitivity to tamoxifen or any of the ingredients.

Limited experience with the use of the drug during pregnancy, you should therefore consult a doctor if you intend to use during pregnancy.

It is not known whether this medicine is excreted in breast milk, you should therefore consult a doctor if you intend to use during breastfeeding.

Do not use tamoxifen in pregnant women. There has been a few cases of spontaneous abortion, fetal defects and fetal deaths after use of tamoxifen. No causal these changes with the use of tamoxifen. Studies in rats, rabbits and monkeys have shown no teratogenic action of tamoxifen. In studies on the effects on the development of the reproductive system in rodents tamoxifen showed a similar effect as estradiol, ethinyl estradiol, clomiphene and diethylstilbestrol (DES).

Although the clinical significance of these changes is not established, some of them, such as dysplasia, vaginal glands were similar to those seen in young women who were in utero exposed to DES. In these women, the probability of clear cell carcinoma of the cervix or the vagina is 1 in 1000. There has been a few cases of tamoxifen in pregnant women. In daughters of mothers taking tamoxifen during pregnancy, there was no cell carcinoma of the cervix or vagina or vaginal dysplasia glands.

Women who during treatment may become pregnant should use effective methods of contraception other than hormonal contraceptives. Patients in the pre-menopausal pregnancy must be excluded before starting treatment with tamoxifen. The patient should be informed of the possibility of damage to the fetus if pregnancy occurs during use of tamoxifen or within two months after the end of treatment.

There are no data on the excretion of tamoxifen in breast milk, so you should avoid the use of tamoxifen in this group of patients. The decision to discontinue feeding or discontinuation of treatment with Nolvadex should be made taking into account the benefits to the mother resulting from continued treatment.

During concomitant use of tamoxifen and anticoagulants of coumarin may increase the anticoagulant effect. You need to monitor coagulation parameters in patients treated concomitantly with these drugs. During concomitant use of Nolvadex and cytotoxic drugs are at an increased risk of thromboembolic complications. Due to the increased risk of thromboembolic team in this group of patients should be considered for thromboprophylaxis during chemotherapy. Caution should be exercised with the concomitant use of tamoxifen and other drugs that increase the activity of the enzyme CYP 3A4 cytochrome P450 enzymes (eg, rifampicin). Increased activity of the enzyme CYP 3A4, which is involved in the metabolism of tamoxifen, may cause reduction in the serum. It is not known whether this is of clinical relevance.
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Store at 30 C, protected from light. Store in original container. It should not be used after the expiry date which is stated on the packaging. The product should be stored out of the reach and sight of children.

Tamoxifen in bodybuilding

Tamoxifen is an estrogen antagonist. By blocking the estrogen receptors prevents the negative effects of elevated their level, which is the cause feminization side effects such as gynecomastia, fat deposition, painful swelling and excessive water retention. As it is strictly selective (works directionally estrogen receptors) is therefore mainly used only in cycles, which have been used in flavoring agents - the stronger the aromatization (conversion to estrogen) the greater the likelihood of undesirable side effects. The use of this drug is highly individual, depending on the used SAA, the doses and the general sensitivity to estrogen. You should know that Nolvadex does not reduce the production of estrogen (not blocking aromatase), but only blocks the estrogen receptors and therefore abrupt discontinuation of Nolvadex may increase estrogen levels to a gigantic extent and cause feminization of the body. The average protective dose is 10 - 20mg per day used in the second week to the end of the cycle. But this is not a medicine necessary - if not found in / on side effects there is no need, however, its use should always have it at hand in order to avoid a possible gynecomastia, which is manifested by itching/baking/ nipple enlargement - in this case, as soon as a single dose 40mg until symptoms disappear and then used to end the cycle Nolvadex at 10 - 20mg. But you can’t completely eliminate estrogen because it is necessary for the proper operation of the SAA. Without the SAA does not reach its maximum capacity and can produce unsatisfactory results (Nolvadex no ability to reduce IGF -1 which may affect growth). In addition to its antiestrogenic properties Nolvadex also acts directly on the hypothalamus to stimulate gonadotropin secretion which results in stimulation of the testes to the production of endogenous testosterone. Thus, it can equally well be used to ' unlock '. It should combine it with Clomid which resulted in the majority of cases it is normal (or higher) level of androgen production and libido. Nolvadex as such, has no side effects or are very rare. They can happen vomiting or nausea, mood swings.

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