Exemestane - Aromasin. All Aromatase Inhibitors will have a negative impact on your lipids. The one that does so the least is Aromasin, followed by Anastrozole - Arimidex, and lastly Femara - Letrozole. They all have their uses, time and place. Aromasin is a suicide inhibitor, unlike Letro and Adex, it will not cause any estrogenic rebound that may cause gynocomastia, acne and other side effects to suddenly flare up. It is harder to crash your Estradiol (E2) with Aromasin. It is the prefered AI nowadays, which makes it more costy and harder to get. I hope this helps. Maybe other members could shine in on the half life because I don't really remember about that from the top of my head. I will have to look that up again