Clinical review: The use of aromatase inhibitors for ovulation induction and superovulation

Abstract

Context: Anovulation is likely responsible for 20% of female infertility. Although clomiphene citrate remains the first-line therapy for ovulation induction in anovulatory patients who are not estrogen-deficient and to treat unexplained infertility, there remains a discrepancy between ovulation and conception rates with its use, attributed to its antiestrogenic effects on cervical mucus and the endometrium. Alternative agents, including aromatase inhibitors, have been used that have not been associated with these side effects.

Evidence acquisition: A literature search was conducted to specifically explore the use of aromatase inhibitors for ovulation induction and superovulation.

Evidence synthesis: Recent studies have found that aromatase inhibitors may be safe and useful agents for ovulation induction in patients with polycystic ovarian syndrome as well a treatment option for superovulation in patients with either unexplained infertility or endometriosis.

Conclusions: Aromatase inhibitors may be an effective alternative treatment to clomiphene citrate for both ovulation induction and superovulation.

Figure 1.

The inhibition of aromatization decreases the circulating estrogen produced from both ovarian follicles and from the peripheral conversion of androgens and also decreases the locally produced estrogen in the brain. When given early in the menstrual cycle, this would then release the hypothalamic-pituitary axis from estrogenic negative feedback resulting in an increase in gonadotropin secretion and ovarian follicular growth.

Figure 2.

Treatment algorithm for management of PCOS or unexplained infertility incorporating the use of AIs.