A prospective randomized trial comparing anastrozole and clomiphene citrate in an ovulation induction protocol using gonadotropins.
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.
Sipe
Christopher S
CS
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
Davis
William A
WA
Maifeld
Michelle
M
Van Voorhis
Bradley J
BJ
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
D004338:Drug Combinations; D005300:Fertility Agents, Female; D006062:Gonadotropins; D009570:Nitriles; D014230:Triazoles; D002996:Clomiphene; D000077384:Anastrozole