Letrozole what we the gynecologists should know and remember in day to day practice .

  

Letrozole what we the gynecologists should know and remember in day to day practice . 

Q.1: What are third generation Aromatase inhibitors?  . Third generation AI is reported to be effective in ovulation induction in women with PCO resistant to clomiphene citrate. Letrozole is the most prevalently used AI in a dose of 2.5 to 5 mg daily orally from D3 to D7 . Various other doses and protocols of administration have been suggested but the standard dose have still remains  between 2.5 and 5 mg daily in the early follicular  phase.

Q.2: Which kind of women is best benefited? Ans: The drug is more effective in Hyperestrogenic  rather   (PCO) than normo  or hypoestrogenic PCOS women.

Q.3: Is Anastrozole (Brand name- ADOVA)  superior to  Letrozole??  What is Anastrozole? It  is another AI  reported to be a useful ovulatory agent in CC resistant PCOS. There is no significant   advantage for anastrazole over letrozole with regard to ovulation pregnancy or miscarriage rates.

Q. 4:  How does all Aromatase inhibitors (AI) work in the body?   Ans: AI are competitive reversible aromatase inhibitor act by suppression of aromatase enzyme  in the early follicular phase at ovaries . As an effect, it prevents conversion of Androstenedione (ADD)  and testosterone to E1 and E2 at all levels of the body(not only at ovarian levels) .

Q 5: How it induces ovulation?? Ans Reduction of ovarian oestrogens --à as a result  hypothalamus is  relieved  of the negative estrogen  feedback in early  follicular  phase. Normal  level of FSH is  released and follicles get the advantage of exposure to normal level of endogenous FSH.  In addition elevation of testosterone level locally at ovarian level enhances follicular  response  to the action of endogenous FSH. This helps acceleration of follicular growth  and development .

 . Q 6: What are the added adv of Letrozole over CC? The beauty of the product is that “The action of aromatase inhibitor is short lived “. Therefore normal level  of estrogen is restored  immediately after withdrawal  of aromatase inhibitor. This is unlike the action of CC where the pharmacologic action of CC continues to persist for a period of six months even after  its  withdrawal --