PHILADELPHIA — The jury is still out on whether aromatase inhibitors could offer an alternative to clomiphene in the treatment of infertility associated with polycystic ovary syndrome, said endocrinologist Andrea D. Coviello of Boston University.
Aromatase inhibitors have been approved for use in breast cancer but are still experimental for ovulation induction, Dr. Coviello said at Endocrinology in the News, sponsored by Boston University, INTERNAL MEDICINE NEWS, and FAMILY PRACTICE NEWS.
Instead of blocking the receptors centrally in the hypothalamus and the pituitary, aromatase inhibitors block estradiol production. Like clomiphene, aromatase inhibitors are used during the follicular phase.
The rationale for moving to aromatase inhibitors is that this class of drugs is thought to have fewer antiestrogenic side effects, including a lower risk of ovarian hyperstimulation syndrome and a lower risk of multiple gestation. But there are also significant concerns about fetal development problems in the babies conceived using aromatase inhibitors, she said. A definitive study to help physicians assess how aromatase inhibitors stack up to clomiphene has yet to be done. Current data are from small studies, said Dr. Coviello, who said she has no commercial support to disclose.
In a prospective, randomized trial of 74 patients, there was no significant difference in pregnancy rates between those receiving clomiphene and those receiving the aromatase inhibitor, letrozole (Fertil. Steril. 2006;86:1447-51). But estrogen levels were significantly lower in the letrozole group on the day of human chorionic gonadotropin administration, indicating potential for a better side-effect profile with letrozole.
INTERNAL MEDICINE NEWS, FAMILY PRACTICE NEWS, and this newspaper are published by the International Medical News Group, a division of Elsevier.