Raloxifene ([6-hydroxy-2-(4-hydroxyphenyl)-benzothiophen-3-yl]-[4-[2-(1-piperidyl)ethoxy]phenyl]-methanone; see figure 9) belongs to the second-generation benzothiophene SERM drugs. It has a high affinity for the ER with potent antiestrogenic activity and tissue-specific effects distinct from estradiol. Raloxifene is an ER agonist in bone and the cardiovascular system, but in breast tissue and the endometrium it acts as an ER antagonist. It is extensively metabolized by glucuronide conjugation in the gut and because of that has a low bioavailability of only 2% while that of tamoxifen and toremifene is approximately 100%.