title: A prospective randomized trial comparing anastrozole and clomiphene citrate in an ovulation induction protocol using gonadotropins.
abstract: OBJECTIVE
  To compare the ovarian and endometrial effects of anastrozole and clomiphene when used with gonadotropins in a combination protocol.
  
  
  METHODS
  Prospective randomized trial.
  
  
  METHODS
  Academic infertility center.
  
  
  METHODS
  Fifty infertile women.
  
  
  METHODS
  Women were randomized to receive either 1 mg anastrozole or 100 mg clomiphene citrate for 5 days (cycle days 3-7) followed by FSH injections (days 7-11) for ovulation induction. A subset participated in a crossover arm of the study.
  
  
  METHODS
  Ovarian follicle number and size, E(2) levels, endometrial thickness, pregnancy, and cancellation rates.
  
  
  RESULTS
  On cycle day 12, anastrozole cycles were associated with fewer total follicles (1.4 vs. 3.6, P=0.01), fewer mature follicles (0.6 vs. 1.6, P<.01), lower serum E(2) (131 pg/mL vs. 613 pg/mL, P<.01,) and the same endometrial stripe thickness compared with clomiphene citrate cycles. Cycle cancellation rates were similar between the two groups. On the day of hCG administration in noncancelled cycles, anastrozole cycles were associated with fewer total follicles (1.6 vs. 3.8, P<.01), fewer mature follicles (1.3 vs. 2.1, P<.01), and an equal endometrial stripe thickness compared with clomiphene citrate cycles. Pregnancy rates were similar between clomiphene (20%) and anastrozole (12%) cycles.
  
  
  CONCLUSIONS
  Anastrozole when used in conjunction with gonadotropins results in lower E(2) levels and fewer follicles than clomiphene citrate. A combination protocol of anastrozole and gonadotropins may be a safer protocol for patients at higher risk of hyperstimulation and multiple births after infertility treatments.
authors.affiliation: Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, University of Iowa Hospitals and Clinics, Iowa City, Iowa 52242-1080, USA. christopher-sipe@uiowa.edu
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Sipe
authors.forename: William A
authors.initials: WA
authors.lastname: Davis
authors.forename: Michelle
authors.initials: M
authors.lastname: Maifeld
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Van Voorhis
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000077384:Anastrozole; D002996:Clomiphene / Q000008:administration & dosage*; D004338:Drug Combinations; D005260:Female; D005300:Fertility Agents, Female / Q000008:administration & dosage; D006062:Gonadotropins / Q000008:administration & dosage*; D006801:Humans; D007247:Infertility, Female / Q000188:drug therapy*; D009570:Nitriles / Q000008:administration & dosage; D010062:Ovulation Induction / Q000379:methods*; D011247:Pregnancy; D011256:Pregnancy Outcome; D011446:Prospective Studies; D014230:Triazoles / Q000008:administration & dosage
chemical_list: D004338:Drug Combinations; D005300:Fertility Agents, Female; D006062:Gonadotropins; D009570:Nitriles; D014230:Triazoles; D002996:Clomiphene; D000077384:Anastrozole