A study of comparison of effectiveness of letrozole (5mg) versus clomephene citrate (100 mg) for ovulation induction among infertile women
Authors: Pandya Manish R , Patel Khushbu 
Published: November 2021

Clomiphene citrate has been traditionally used as the drug of the choice for treatment of women with anovulatory infertility. In the last decade, an aromatase inhibitor, letrozole has emerged as an alternative ovulation induction agent among anovulatory women with polycystic ovarian syndrome. Letrozole has a definitive role in anovulatory women who have not responded to the clomiphene citrate therapy is confirmed by literatures.

Anovulatory dysfunction is a common problem and is responsible for about 40% of female infertility and among causes; PCOS (polycystic ovarian syndrome) is the leading cause.

Clomiphene citrate is considered as the drug of choice for the first line treatment of anovulatory dysfunction for a variety of reasons. Clomiphene citrate has some side effects like multi-follicular development and cyst formation and resistance of clomiphene are areas of concern and desire for an effective alternative persists.

An aromatase inhibitor, letrozole, was introduced into infertility practice in the year 2000 and is regarded as a second line option, particularly in women with clomiphene resistance, and it has found acceptance in various clinical situations and the indications for use have expanded.,

To compare the efficacy of letrozole and clomiphene citrate (CC) for ovulation induction in infertile women.

The study included 100 women presented with anovulatory infertility. The infertile women were divided into 2 groups of 50: Group A received 100 mg Clomiphene Citrate from day 3 to day 5 of menstruation and Estradiol Valerate 4 mg on the 12 day of menstruation until 16 day of menstruation; Group B treated by 5 mg Letrozole from day 3 to day 5 of the menstruation and as Group A, Estradiol Valerate 4 mg on the 12 day of menstruation until 16 day of menstruation given to Group B, with visits to determine ovulation and pregnancy, followed by tracking of pregnancies. Participants were of 20 to 39 years age, had normal uterine cavity and had a male partner with a sperm concentration of at least 14 million per millilitre; and during the study the women and their partners agreed to have regular intercourse with the intent of conception. The live birth during the treatment period was the primary outcome.

Women who received letrozole had more cumulative live births than those women who had received clomiphene citrate (36 out of 50 [72%] vs. 28 out of 50 [56%]), without significant differences in overall congenital anomalies, there were no congenital anomalies. With letrozole as compared to clomiphene the cumulative ovulation rate was higher. Higher incidence of hot flushes was associated with a clomiphene, and letrozole was associated with fatigue and dizziness. Rates of other adverse effects were almost similar among these 2 groups. A significant difference in the follicular and endometrial development was evident among these 2 groups.

As compared to with clomiphene, an aromatase inhibitor, letrozole was associated with higher live-birth and ovulation rates among infertile women. The results of the study demonstrated letrozole to be superior to clomiphene citrate in the maintenance of endometrial thickness.