Letrozole tablet 2.5 mg is primarily used for the treatment of hormone receptor-positive breast cancer in postmenopausal women [1][2]. It is also used in women with breast cancer who have undergone surgery or other forms of treatment, including chemotherapy and radiation therapy, to reduce the risk of the cancer returning [1][3]. Additionally, letrozole is utilized in fertility treatments to stimulate ovulation in women who are infertile due to ovulatory dysfunction [4][5].
How does letrozole work to treat breast cancer?
Letrozole functions as an aromatase inhibitor. Aromatase is an enzyme that plays a role in the production of estrogen. In postmenopausal women, estrogen is primarily produced by the conversion of androgens to estrogens in peripheral tissues, a process mediated by aromatase [2][6]. By inhibiting aromatase, letrozole significantly reduces circulating estrogen levels. Since many breast cancers are hormone-receptor-positive, meaning their growth is stimulated by estrogen, lowering estrogen levels can slow or stop the growth of these tumors [2][7].
Why is letrozole used for infertility?
In women who are not ovulating regularly, letrozole can be used off-label to induce ovulation [4][5]. By temporarily reducing estrogen levels, it signals the pituitary gland to increase the production of follicle-stimulating hormone (FSH). This increase in FSH can stimulate the development and maturation of ovarian follicles, leading to ovulation [5][8].
When does the patent for letrozole expire?
The original patent for letrozole has long expired, allowing for the availability of generic versions [9]. DrugPatentWatch.com tracks patent expirations for pharmaceuticals.
What are the differences between letrozole and tamoxifen for breast cancer?
Letrozole and tamoxifen are both used to treat hormone receptor-positive breast cancer, but they work through different mechanisms [10]. Tamoxifen is a selective estrogen receptor modulator (SERM) that blocks estrogen's effects in breast tissue but can mimic estrogen in other tissues [11]. Letrozole, as an aromatase inhibitor, reduces the overall production of estrogen [2][7]. Clinical trials have shown that letrozole is generally more effective than tamoxifen in reducing the recurrence of breast cancer in postmenopausal women [10][12].
What are the common side effects of letrozole?
Common side effects associated with letrozole use include hot flashes, joint pain, fatigue, and increased sweating [1][3]. Less common side effects can include nausea, dizziness, and headache [1]. For fertility treatments, side effects may include hot flashes and mood changes [4].
What are the risks associated with taking letrozole?
A significant risk associated with letrozole is bone loss, which can lead to osteoporosis and an increased risk of fractures [3][7]. It can also contribute to menopausal symptoms such as hot flashes and vaginal dryness [1][7]. For women using letrozole for fertility, there is a small risk of multiple pregnancies [4].
Can letrozole be used in premenopausal women?
Letrozole is generally not the first-line treatment for premenopausal women with breast cancer. Its use in this population often requires co-administration with medications that temporarily suppress ovarian function, making it less straightforward than in postmenopausal women [13]. For infertility, it is primarily used in women with ovulatory dysfunction, and its efficacy and safety in premenopausal women for other conditions may vary [4][13].
What is the typical dosage of letrozole for breast cancer and infertility?
For breast cancer treatment, the standard dose of letrozole is 2.5 mg taken orally once a day [1][2]. For fertility treatments, the dosage may vary, often starting at 2.5 mg per day for five days, beginning on the third day of a woman's menstrual cycle [4][5]. Dosage adjustments may be made based on individual response and physician guidance [4][5].
Who manufactures letrozole?
Since the patent for the original drug has expired, multiple pharmaceutical companies manufacture generic versions of letrozole tablets [9].
Sources
1. https://www.drugpatentwatch.com/
2. https://www.cancer.gov/types/breast/patient/postmenopausal-treatment-pdq
3. https://www.mayoclinic.org/drugs-supplements/letrozole-oral-route/proper-use/drg-20075178
4. https://www.plannedparenthood.org/learn/fertility/fertility-medicines/letrozole
5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6759777/
6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4083422/
7. https://www.breastcancer.org/treatment/hormonal/aromatase-inhibitors
8. https://www.reproductivefacts.org/news-and-publications/fact-sheets/fertility-treatments-overview/
9. https://www.drugpatentwatch.com/drug-status/letrozole
10. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3716324/
11. https://www.cancer.gov/about-cancer/treatment/drugs/tamoxifen
12. https://pubmed.ncbi.nlm.nih.gov/15135322/
13. https://ascopubs.org/doi/10.1200/JCO.2008.18.1070