The cross-link below will take you to a NABCO fact sheet regarding aromatase inhibitors. In question #7, it is noted that Arimidex and Femara are reversible inhibitors. Aromasin (exemestane) is an irreversible inactivator. Unlike Arimidex and Femara, Aromasin permanently blocks aromatase from producing estrogen once a woman has taken it.
Faslodex, is not an aromatase inhibitor, it is an estrogen receptor down-regulator and permanently damages the estrogen receptor, unlike tamoxifen that simply blocks the receptor while the drug is taken.
There is no long-term survival data that addresses which drug is best. There are several studies that show that the AIs and ERDs are better than tamoxifen in reducing recurence. Limited studies are available comparing the AIs and ERDs.
The drugs that are FDA-approved for adjuvant therapy are Tamoxifen and Arimidex. Femara, Aromasin and Faslodex are FDA-approved for Stage IV use.
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