Buy 99.2% Purity Anti Estrogen AI Hormone Letrozole (Femara) Powder Online   Letrozole Description Letrozole is an anti-estrogen of the Aromatase Inhibitor (AI) family and is one of the most potent and powerfully effective of all AI’s. Letrozole was first developed in an effort to combat breast cancer in post-menopausal women. In fact, it would prove to be virtually identical …