What is the mechanism of action of tamoxifen?

Asked by: Joey Beck

Tamoxifen (TAM) is known to have a dual mechanism of action: (1) to compete with 17β-estradiol (E₂) at the receptor site and to block the promotional role of E₂ in breast cancer; and (2) to bind DNA after metabolic activation and to initiate carcinogenesis.

What is the function of tamoxifen?

Tamoxifen is a hormone therapy for breast cancer in both women and men. It lowers the risk of early breast cancer coming back (recurring) after surgery or developing in the other breast. It can also control advanced breast cancer for some time.

How is tamoxifen an agonist and antagonist?

If a cell type requires activating factors 1 and 2 of the estrogen receptor to be functioning concurrently, tamoxifen is antagonistic. However, if a cell or tissue requires only activating factor 1 to interact with transcription factors at the promoter, tamoxifen is agonistic.

How does tamoxifen act What is the primary target of the drug?

Tamoxifen competitively inhibits estrogen binding to its receptor, which is critical for it’s activity in breast cancer cells. Tamoxifen leads to a decrease in tumor growth factor α and insulin-like growth factor 1, and an increase in sex hormone binding globulin.

What are the side effects commonly associated with tamoxifen?

Tamoxifen may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• increased bone or tumor pain.
• pain or reddening around the tumor site.
• hot flashes.
• nausea.
• excessive tiredness.
• dizziness.
• depression.
• headache.

How does tamoxifen work as an antagonist?

In breast tissue, tamoxifen acts as an ER antagonist so that transcription of estrogen-responsive genes is inhibited. A beneficial side effect of tamoxifen is that it prevents bone loss by acting as an ER agonist (i.e., mimicking the effects of estrogen) in this cell type.

What type of antagonist is tamoxifen?

Tamoxifen is a nonsteroidal estrogen receptor antagonist that is mainly used for the treatment of estrogen receptor-positive breast cancer. It also inhibits protein kinase C, an important component of several signal transduction pathways.

What are the worst side effects of tamoxifen?

Rarely, tamoxifen may cause serious problems such as:

• Blood clots, deep vein thrombosis (DVT) and strokes.
• Cataracts or other eye problems.
• Endometrial (uterine) cancer.

What is the most severe adverse effect of tamoxifen?

Side effects in women

The most serious health risks of tamoxifen, such as endometrial cancer (cancer of the lining of the uterus) and blood clots in the lungs, are rare [102].

Is there an alternative to tamoxifen?

If you have your menopause while on tamoxifen you might switch to an aromatase inhibitor. such as letrozole.

Does tamoxifen weaken the immune system?

Does hormone therapy affect the immune system? Taking hormone therapy, including tamoxifen, letrozole, anastrozole, exemestane and goserelin, does not affect your immune system. Hormone therapies do not increase your risk of getting coronavirus or of becoming seriously ill if you do get it.

What foods should not be eaten when taking tamoxifen?

Is there anything that I should avoid eating or drinking while on Tamoxifen?

• Grapefruit. Grapefruit and grapefruit juice are well-known disruptors of numerous medications ². …
• Turmeric/ Curcumin. …
• Black cohosh. …
• St. …
• St. …
• Ginseng. …
• Chamomile. …
• Soya.

What happens if I don’t take my tamoxifen?

Postmenopausal women diagnosed with hormone-receptor-positive disease are 35% to 61% more likely to have breast cancer come back if they don’t take hormonal therapy as prescribed.

Is 20 mg of tamoxifen a lot?

For people diagnosed with DCIS, ADH, or LCIS, the treatment is most commonly 5 years of tamoxifen, at a dose of 20 mg per day, after surgery to remove the abnormal cells. Still, like most cancer medicines, both tamoxifen and aromatase inhibitors can cause side effects.

Does tamoxifen affect sleep?

Background: Insomnia is a frequent adverse effect reported by women taking tamoxifen, an estradiol receptor-antagonist, for breast cancer.

What is the success rate of tamoxifen?

(Some women, however, receive tamoxifen followed by an aromatase inhibitor over a 5-year period.)
Ten Years of Tamoxifen Reduces Breast Cancer Recurrences, Improves Survival.

Can tamoxifen cause other cancers?

Because tamoxifen acts like estrogen in the uterus, it can increase your risk of cancers of the uterus, including endometrial cancer and uterine sarcoma. It’s also linked to a higher risk of endometrial pre-cancers. The increased risk seems to affect women over 50, but not younger women.

What is the best time of day to take tamoxifen?

Tamoxifen may be taken at any time of the day but should be taken at the same time each day. it is within 12 hours of the missed dose.

Does tamoxifen affect your kidneys?

As serious side effects of tamoxifen administered at high doses have been reported, a patient with decreased renal function and metastatic breast cancer was studied to determine the blood levels of tamoxifen while under therapy.

Can tamoxifen damage your liver?

Introduction. Tamoxifen is a nonsteroidal antiestrogen that is widely used in the treatment and prevention of breast cancer. Long term tamoxifen therapy has been associated with development of fatty liver, steatohepatitis, cirrhosis, and rare instances of clinically apparent acute liver injury.

Does tamoxifen make you tired?

Fatigue, the unusual and extreme feeling of tiredness or daily lack of energy, is a common side effect of cancer, treatment and tamoxifen specifically. It affects the whole body and is often described as “paralysing” and “exhaustion”, this is different to regular tiredness and may not be relieved by rest or sleep.

Does tamoxifen cause joint pain?

Joint pain and arthralgia are among the most commonly encountered side effects seen in patients receiving tamoxifen or aromatase inhibitors (AIs) as hormonal adjuvant treatment.

Can tamoxifen affect eyesight?

The usual daily dose of tamoxifen is 20-40 mgs. Ocular side effects are relatively uncommon and are usually associated with higher doses. The ocular side effects are blurred vision, decreased visual acuity, vortex keratopathy, retinotoxicity, and bilateral optic neuritis.

Does tamoxifen make you pee more?

Again, the hip-joint pain and the frequent peeing don’t surprise me. The doctors warned me that they are two of the 37 commonly experienced side effects of the drug. They rattled this information off to me in the same vague way they shared the additional 24 uncommon and three rare Tamoxifen pitfalls, as well.