Clomiphene versus letrozole: a better agent for ovulation induction
Keywords:Clomiphene citrate, Letrozole, Ovulation induction
Background: Anovulatory dysfunction is a commonly encountered problem which is responsible for about 40% of female infertility. One of the leading causes of female infertility is polycystic ovarian syndrome (PCOS). Clomiphene citrate has been the drug of choice in treating women with anovulatory infertility. However, in recent years, letrozole, an aromatase inhibitor, has emerged as alternative ovulation induction agent. Aim of this study was to compare efficacy of clomiphene citrate and letrozole as first line therapy for ovulation induction in polycystic ovarian syndrome.
Methods: This study was a hospital based prospective comparative study done in MVJ MC and RH involving 100 females suffering from infertility due to anovulation. They were divided into 2 groups of 50 each. One group was given clomiphene citrate 50 mg while another group was given letrozole 2.5 mg from day 3 to day 7 of menstrual cycle. Ultrasonographic follicular monitoring was done and injection beta HCG 5000 IU was given once follicle reached optimum size (≥18 mm) and endometrial thickness was adequate (≥7 mm). Patients were advised for timed intercourse after 24-36 hours of HCG administration. Ovulation was detected by sonographic findings of follicular rupture done after 48 hours. Primary outcomes measured were number of growing follicles (≥18 mm), endometrial thickness, ovulation rate and pregnancy rate.
Results: In our study there was significant difference in the outcomes of ovulation induction between letrozole group and clomiphene group. Women who received letrozole showed improved endometrial growth (8.44 mm versus 7.86 mm), ovulation rate (72% versus 56%) and pregnancy rate (22.2% versus 14.3%) than those who received clomiphene. However, variation in follicular growth was negligible between the two groups (1.28 versus 1.36).
Conclusions: Letrozole is a superior alternative to clomiphene citrate for ovulation induction in cases of PCOS with anovulatory menstrual cycle, and can be considered as first-line therapy for ovulation induction in such women.
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