LETROZOLE ALVOGEN FILM-COATED TABLET 2.5mg

Letrozole

Source of information: Drugbank (External Link). Last updated on: 3rd July 18
*Trade Name used in the content below may not be the same as the HSA-registered product.

Active Ingredient / Synonyms

Letrozol | Letrozole |

Description

Letrozole (INN, trade name Femara®) is an oral non-steroidal aromatase inhibitor that has been introduced for the adjuvant treatment of hormonally-responsive breast cancer Estrogens are produced by the conversion of androgens through the activity of the aromatase enzyme. Letrozole blocks production of estrogens in this way by competitive, reversible binding to the heme of its cytochrome P450 unit. The action is specific, and letrozole does not reduce production of mineralo- or corticosteroids. In contrast, the antiestrogenic action of tamoxifen, the major medical therapy prior to the arrival of aromatase inhibitors, is due to its interfering with the estrogen receptor, rather than inhibiting estrogen production. Letrozole is approved by the United States Food and Drug Administration (FDA) for the treatment of local or metastatic breast cancer that is hormone receptor positive or has an unknown receptor status in postmenopausal women. Side effects include signs and symptoms of hypoestrogenism. There is concern that long term use may lead to osteoporosis, which is why prescriptions of Letrozole are often accompanied by prescriptions of osteoporosis-fighting medication such as Fosamax. Letrozole has shown to reduce estrogen levels by 98 percent while raising testosterone levels. The anti-estrogen action of letrozole is preferred by athletes and bodybuilders for use during a steroid cycle to reduce bloating due to excess water retention and prevent the formation of gynecomastia related breast tissue that is a side effect of some anabolic steroids. Usage above 2.5 mg/day is known to potentially temporarily kill sex drive. Above 5mg/day for extended periods may cause kidney problems. Letrozole has also been shown to delay the fusing of the growth plates in adolescents. This may boost the effectiveness of growth hormone, and thus Letrozole is used to treat adolescents and children with short stature.

Indication

For the extended adjuvant treatment of early breast cancer in postmenopausal women who have received 5 years of adjuvant tamoxifen therapy. Also for first-line treatment of postmenopausal women with hormone receptor positive or hormone receptor unknown locally advanced or metastatic breast cancer. Also indicated for the treatment of advanced breast cancer in postmenopausal women with disease progression following antiestrogen therapy.

Mechanism of Action

Letrozole is a nonsteroidal competitive inhibitor of the aromatase enzyme system; it inhibits the conversion of androgens to estrogens. In adult nontumor- and tumorbearing female animals, letrozole is as effective as ovariectomy in reducing uterine weight, elevating serum Leuteinizing hormone (LH), and causing the regression of estrogen-dependent tumors. In contrast to ovariectomy, treatment with letrozole does not lead to an increase in serum (folicile stimulating hormone (FSH). Letrozole selectively inhibits gonadal steroidogenesis but has no significant effect on adrenal mineralocorticoid or glucocorticoid synthesis.

Pharmacodynamics

Letrozole is an aromatase inhibitor used in the treatment of breast cancer. Aromatase inhibitors work by inhibiting the action of the enzyme aromatase, which converts androgens into estrogens by a process called aromatization. As breast tissue is stimulated by estrogens, decreasing their production is a way of suppressing recurrence of the breast tumor tissue.

Pharmacokinetics

Absorption:

Rapidly and completely absorbed. Absorption is not affected by food.

Distribution:

Not Available

Metabolism:

Primarily hepatic via CYP3A4 and CYP2A6. Letrozole inhibits the aromatase enzyme by competitively binding to the heme of the cytochrome P450 subunit of the enzyme, resulting in a reduction of estrogen biosynthesis in all tissues. It is metabolized slowly to an inactive metabolite whose glucuronide conjugate is excreted renally, representing the major clearance pathway.

Elimination:

Not Available

Half-life

2 days

Clearance

Not Available

Toxicity

Not Available

References

  1. Health Science Authority of Singapore - Reclassified POM
  2. Drugbank

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Approval Information

LETROZOLE ALVOGEN FILM-COATED TABLET 2.5mg was registered with Health Science Authority of Singapore by ALVOGEN SINGAPORE PTE LTD. It is marketed with the registration number of SIN14406P with effective from 2013-07-09.

This product contains 2.5mg of Letrozole in the form of TABLET, FILM-COATED.

The medicine was manufactured by Genepharm S.A in GREECE

It is a Presciption Only Medicine which can only be obtained from a doctor or a dentist, or from a pharmacist with a prescription from a Singapore-registered doctor or dentist.

Anatomical Therapeutic Chemical (ATC) Classification

ATC Code: L02BG04

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