Letrozole

 

Letrozole :-

Q. 1: What is letrozole ? Letrozole is an aromatase inhibitor. What are aromatase group of enzymes?  Ans: Aromatase is a microsomal enzyme that mediates conversion of androstenedione to estrogen, and testosterone(C 19 steroid family) to estradiol(C 18) .

Q.2: Where is the presence of Aromase enzyme? Ans; It is present in several tissues, including the ovary, brain, placenta, adipose tissue, muscle, liver, and breast.

Q.3: What is the main function of Aromatase inhibitors ?  Ans : Aromatase is a good target to control estrogen secretion, because estrogen is the final step in the biosynthetic pathway(C-18 steroid family). Several studies have demonstrated the effectiveness of aromatase inhibitors in induction of ovulation. As such Anastrazole (another kind of aromatase inhibitor) is used in oestrogen sensitive breast Cancer.

 Q.4: What is the success rate of Letrozole in OI(Ovulation induction)? Ans: Monofollicular ovulation is another example of the advantages of the aromatase inhibitors. 

Q. 5: Comparison with clomiphene : Recently, aromatase inhibitors have become an alternative to clomiphene citrate as first-line therapy for stimulation of ovulation in ovulating and also in  non-ovulating infertile women.  The advantages are 1) monofollicular growth 2) Normal endometrial growth 3) less teratogenecity in comparison to Clomiphene.

 Q.6: What are the other advantages of Letrozole? Ans: Letrozole, as opposed to clomiphene, is rapidly excreted, and causes ovulation in 60%–80% of patients in clomiphene-resistant patients. By and large the success rate letrozole  cause ovulation in 62% of cases, and pregnancy occurred in 14.7% of patients.

Q.7: Is letrozole superior agent than Clomiphene? Ans-Recently, letrozole has been proposed as the most effective infertility medication and is being used for induction of ovulation in PCOS. This drug has been recommended as a substitute for clomiphene as first-line treatment to induce ovulation in PCOS .In recent practice, Moreover, use of letrozole has been recommended for patients who ovulate with clomiphene but have a thin endometrium.

Q.8: Comparison with gonadotrophins ?  Ans; Ans; Considering its low risk of adverse effects and low cost, letrozole is used instead of gonadotropins in patients resistant to clomiphene. Moreover, with letrozole, the risk of multiple pregnancies is reduced. It is excreted from the body quite rapidly and does not have fetotoxicity 

Q 9 : Teratogenecity?  In a cohort study, the frequency of fetal anomaly after using letrozole was 2.4% and after clomiphene was 3%, which is not significant Letrozole does not have any adverse effects on the fetus and is safe.

 Q.10 : Mechanism of action  : Letrozole decreases the secretion of estrogen both in the brain and in the periphery, and causes an increase in gonadotropins, which in turn causes maturation of the ovarian follicles.