Combination Letrozole and Clomiphene Citrate Versus Letrozole Alone

Clomiphene citrate is a non-steroidal triphenylethylene derivative distantly related to diethylstilbestrol. It acts as a selective estrogen receptor modulator (SERM), similar to tamoxifen and raloxifene. All three drugs are competitive inhibitors of estrogen binding to estrogen receptors (ERs) and have mixed agonist and antagonist activity, depending upon the target tissue. Letrozole is a potent, nonsteroidal, aromatase inhibitor, originally used for postmenopausal breast cancer therapy.