This Article Full Text Full Text (PDF) All Versions of this Article: 91/3/760    most recent Author Manuscript (PDF) Submit a related Letter to the Editor Purchase Article View Shopping Cart Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Casper, R. F. Articles by Mitwally, M. F. M. Search for Related Content PubMed PubMed Citation Articles by Casper, R. F. Articles by Mitwally, M. F. M. Related Collections Female Endocrinology

Aromatase Inhibitors for Ovulation Induction

Division of Reproductive Sciences (R.F.C.), Fran and Lawrence Bloomberg Department of Obstetrics and Gynecology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital and The University of Toronto, Toronto, Ontario, Canada M5S 2X9; and Division of Reproductive Endocrinology and Infertility (M.F.M.M.), Department of Obstetrics and Gynecology, Wayne State University, Detroit, Michigan 48202

Address all correspondence and requests for reprints to: Robert F. Casper, M.D., F.R.C.S.(C), 150 Bloor Street West, Suite 210, Toronto, Ontario, Canada M5S 2X9. E-mail: rfcasper{at}aol.com.

Context: For the last 40 yr, the first line of treatment for anovulation in infertile women has been clomiphene citrate (CC). CC is a safe, effective oral agent but is known to have relatively common antiestrogenic endometrial and cervical mucous side effects that could prevent pregnancy in the face of successful ovulation. In addition, there is a significant risk of multiple pregnancy with CC, compared with natural cycles. Because of these problems, we proposed the concept of aromatase inhibition as a new method of ovulation induction that could avoid many of the adverse effects of CC. The objective of this review was to describe the different physiological mechanisms of action for CC and aromatase inhibitors (AIs) and compare studies of efficacy for both agents for ovulation induction.

Evidence Acquisition: We conducted a systematic review of all the published studies, both controlled and noncontrolled, comparing CC and AI treatment, either alone or in combination with gonadotropins, for ovulation induction or augmentation, identified through the Entrez-PubMed search engine.

Evidence Synthesis: Because of the recent acceptance of the concept of using AIs for ovulation induction, few controlled studies were identified, and the rest of the studies were pilot or preliminary comparisons. Based on these studies, it appears that AIs are as effective as CC in inducing ovulation, are devoid of any antiestrogenic side effects, result in lower serum estrogen concentrations, and are associated with good pregnancy rates with a lower incidence of multiple pregnancy than CC. When combined with gonadotropins for assisted reproductive technologies, AIs reduce the dose of FSH required for optimal follicle recruitment and improve the response to FSH in poor responders.

Conclusions: Preliminary evidence suggests that AIs may replace CC in the future because of similar efficacy with a reduced side effect profile. Although worldwide experience with AIs for ovulation induction is increasing, at present, definitive studies in the form of randomized controlled trials comparing CC with AIs are lacking.

This article has been cited by other articles:

				A. Requena, J. Herrero, J. Landeras, E. Navarro, J. L. Neyro, C. Salvador, R. Tur, J. Callejo, M. A. Checa, M. Farre, et al. Use of letrozole in assisted reproduction: a systematic review and meta-analysis Hum. Reprod. Update, November 1, 2008; 14(6): 571 - 582. [Abstract] [Full Text] [PDF]

				G.M. Tiboni, F. Marotta, C. Rossi, and F. Giampietro Effects of the aromatase inhibitor letrozole on in utero development in rats Hum. Reprod., August 1, 2008; 23(8): 1719 - 1723. [Abstract] [Full Text] [PDF]

				N. Mauras, L. Gonzalez de Pijem, H. Y. Hsiang, P. Desrosiers, R. Rapaport, I. D. Schwartz, K. O. Klein, R. J. Singh, A. Miyamoto, and K. Bishop Anastrozole Increases Predicted Adult Height of Short Adolescent Males Treated with Growth Hormone: A Randomized, Placebo-Controlled, Multicenter Trial for One to Three Years J. Clin. Endocrinol. Metab., March 1, 2008; 93(3): 823 - 831. [Abstract] [Full Text] [PDF]

				A. A. Azim, M. Costantini-Ferrando, K. Lostritto, and K. Oktay Relative Potencies of Anastrozole and Letrozole to Suppress Estradiol in Breast Cancer Patients Undergoing Ovarian Stimulation before in Vitro Fertilization J. Clin. Endocrinol. Metab., June 1, 2007; 92(6): 2197 - 2200. [Abstract] [Full Text] [PDF]

				M. A. Bedaiwy, N. A. Mousa, N. Esfandiari, R. Forman, and R. F. Casper Follicular Phase Dynamics with Combined Aromatase Inhibitor and Follicle Stimulating Hormone Treatment J. Clin. Endocrinol. Metab., March 1, 2007; 92(3): 825 - 833. [Abstract] [Full Text] [PDF]

				R. S. Legro A 27-Year-Old Woman With a Diagnosis of Polycystic Ovary Syndrome JAMA, February 7, 2007; 297(5): 509 - 519. [Abstract] [Full Text] [PDF]