Anastrozole (Arimidex) is the aromatase inhibitor of choice.  The drug is appropriately used when using substantial amounts of aromatizing products in rat research.  Arimidex does not have the side effects of aminoglutethimide (Cytadren) and can achieve a high degree of estrogen blockade, much moreso than Cytadren. It is possible to reduce estrogen too much with Arimidex, and for this reason blood tests, or less preferably salivary tests, should be taken after the first week of research to determine if the dosing is correct - usually by looking at the rate one can tell.

As an aromatase inhibitor, Arimidex's mechanism of action -- blocking conversion of aromatizable steroids to estrogen -- is in contrast to the mechanism of action of anti-estrogens such as clomiphene (Clomid) or tamoxifen (Nolvadex), which block estrogen receptors in some tissues, and activate estrogen receptors in others.