The liver enzyme, cytochrome P450 2D6 or CYP2D6 for short, that breaks tamoxifen down into its active forms is suppressed by common medications that many woman may be taking <a href=http://cialis.makeup>comprar cialis online</a> This is not the only drug used in treatment; commonly treatment will begin with an AI and then will be switched to a SERM like Tamoxifen Citrate