Comparison of the efficacy of the aromatase inhibitor letrozole and clomiphene citrate as adjuvants to recombinant follicle-stimulating hormone in controlled ovarian hyperstimulation: a prospective, randomized, blinded clinical trial.
OBJECTIVE
To study the efficacy of the aromatase inhibitor letrozole as adjuvant to recombinant FSH (rFSH) in controlled ovarian hyperstimulation (COH).


METHODS
Prospective, randomized, and blinded clinical study.


METHODS
Academic tertiary institute.


METHODS
Forty-one patients with unexplained infertility undergoing intrauterine insemination (IUI) therapy were randomized to receive either letrozole or clomiphene citrate (CC) as adjuvants to rFSH.


METHODS
From day 3 to 7 of the cycle 2.5 mg/d letrozole or 100 mg/d CC were administrated. All patients received 75 IU rFSH starting on day 7 of stimulation until the day of hCG administration. Ovulation was triggered with recombinant hCG (250 microg) when the leading follicle(s) reached 18 mm in diameter. A single IUI was performed 36 hours later. The luteal phase was supplemented with micronized progesterone vaginally.


METHODS
Ovarian stimulation response (E(2) levels and number of follicles) was our primary outcome.


RESULTS
There were no differences in demographic characteristics between groups. Although there was a significantly lower peak serum E(2) level in the group receiving letrozole + rFSH compared with CC + rFSH (914 +/- 187 vs. 1,207 +/- 309 pg/mL, respectively; P<.007), there were no differences in the number of mature (>16 mm) preovulatory follicles. A significantly higher endometrial thickness was observed at the time of hCG administration in patients that received letrozole (9.5 +/- 1.5 mm vs. 7.3 +/- 1.1 mm; P=.0001). The clinical pregnancy rate was similar between groups (23.8% vs. 20%, respectively).


CONCLUSIONS
The aromatase inhibitor letrozole appears to constitute a good alternative to CC in patients with unexplained infertility undergoing gonadotropin-stimulated COH cycles combined with IUI therapy.
Barroso
Gerardo
G
Assisted Reproductive Division, Instituto Nacional de Perinatología, Mexico City, Mexico. asistida@servidor.inper.edu.mx
Menocal
Gerardo
G
Felix
Hector
H
Rojas-Ruiz
Juan Carlos
JC
Arslan
Murat
M
Oehninger
Sergio
S
D000328:Adult; D047072:Aromatase Inhibitors / Q000008:administration & dosage; D017024:Chemotherapy, Adjuvant; D002996:Clomiphene / Q000008:administration & dosage*; D004338:Drug Combinations; D005260:Female; D005300:Fertility Agents, Female / Q000008:administration & dosage; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage*; D006801:Humans; D007247:Infertility, Female / Q000188:drug therapy*; D000077289:Letrozole; D009570:Nitriles / Q000008:administration & dosage*; D010062:Ovulation Induction / Q000379:methods*; D011247:Pregnancy; D018873:Pregnancy Rate; D011994:Recombinant Proteins / Q000008:administration & dosage; D016037:Single-Blind Method; D016896:Treatment Outcome; D014230:Triazoles / Q000008:administration & dosage*
D047072:Aromatase Inhibitors; D004338:Drug Combinations; D005300:Fertility Agents, Female; D009570:Nitriles; D011994:Recombinant Proteins; D014230:Triazoles; D002996:Clomiphene; D000077289:Letrozole; D005640:Follicle Stimulating Hormone