使用Letrozolem懷孕率較clomid為高(17 vs 6%)

若不考慮價格因素，Letrozole (aromatase inhibitor, anastrazole)應可取代clomid於誘導排卵中之角色
Letrozole 不像clomid會造成子宮內膜之抑制
懷孕率亦較clomid為高(17 vs 6%)

http://www.ncbi.nlm.nih.gov/pubmed/16595197?dopt=Abstract


Fertil Steril. 2006 Feb;85(2):277-84.

A new era in ovulation induction.

Holzer H, Casper R, Tulandi T.

Source

Department of Obstetrics and Gynecology, McGill University, Montreal, Quebec, Canada.

Abstract

OBJECTIVE:

To evaluate the efficacy of aromatase inhibitors in ovulation induction, superovulation, and IVF.

DESIGN:

A literature search was conducted with the key words "aromatase inhibitor," "letrozole," "anastrazole," "ovulation induction," "ovulation," and "superovulation" in MEDLINE, EMBASE, and the Cochrane Database of systematic reviews.

RESULT(S):

Ovulation induction with letrozole is associated with an ovulation rate of 70%-84% and a pregnancy rate of 20%-27% per cycle. In one study, ovulation and pregnancy rates with letrozole seemed to be higher than those of anastrazole. In superovulation, letrozole is associated with few developing follicles and thick endometrium. The use of letrozole for superovulation is associated with a pregnancy rate higher than with the use of clomiphene citrate (CC) (16.7% vs. 5.6%). The addition of letrozole to FSH treatment leads to a decreased FSH requirement. The pregnancy rate for treatment with letrozole and FSH was similar to that for FSH alone.

CONCLUSION(S):

Aromatase inhibitors are as effective as or superior to CC in ovulation induction and in superovulation. Unlike CC, they do not carry an antiestrogenic effect on the endometrium. Given the advantages of aromatase inhibitors, they can be used to replace CC as ovulation-inducing drugs. Their role in IVF remains to be determined.