the effect of letrozole in induction of ovulation in clomiphene resistant patients

Background: in patients with anovulatory infertility the first choice of treatment for ovulationinduction is an antiestrogen, most commonly clomiphene citrate (cc). however, 20-25% of thewomen are resistant to cc and do not ovulate perhaps due to antiestrogenic mechanism of the ccaction, which involves long-lasting estrogen receptor (er) depletion.objective: the objective of the study was to mimic the action of cc without depletion of ers bythe administration of an aromatase inhibitor letrozole in a selected group of poly cystic ovary(pco) patients who demonstrated failure to ovulate after treatment with cc.materials and methods: 20 patients with anovulation due to polycystic ovary syndrome (pcos),who had previously inadequately responded to cc were selected for study. the aromatase inhibitorletrozole was administered orally in a dose of 2.5 mg on days 3-7 of the menstrual cycle. then,occurrence of ovulation, endometrial thickness, and pregnancy rates were determined.result(s): only one patient had one dominant follicle (1.8 cm diameter) on day 14 of the cycle(estradiol = 200 pg/ml). iui was done; however, no pregnancy took place. in the remaining cases,several sonographies were done between days 9 to 15 of the cycle; however, all cycles werecancelled due to absence of a dominant follicle ( > 1.4 cm).conclusion(s): our study did not confirm the favorable effect of letrozole for induction ofovulation in patients with clomiphene resistant pco.