One of the best anti estrogens that I have used believe it or not and those that have used it as an estrogen blocker know what I am talking about is Gaspari's Novedex XT. Honestly have had better success with that then the real nolva. Our rep for our supplement distributor explained to me that Nolvadex does not work on estrogen bound in the blood but mainly estrogen in breast tissue. he said that Novedex XT works more like Arimidex and blocks the estrogen receptors at a much higher rate in the blood.