Idoxifene: A Novel Selective Estrogen Receptor Modulator Prevents Bone Loss and Lowers Cholesterol Levels in Ovariectomized Rats and Decreases Uterine Weight in Intact Rats

Idoxifene, a novel selective estrogen receptor modulator, was tested for its effects on bone loss, serum cholesterol, and uterine wet weight and histology in the ovariectomized (Ovx) rat. Idoxifene (0.5 mg/kg·day) completely prevented loss of both lumbar and proximal tibial bone mineral density (BMD). In an intervention study, idoxifene (0.5 and 2.5 mg/kg·day) completely prevented further loss of both lumbar and proximal tibial BMD during a 2-month treatment period commencing 1 month after surgery, when significant loss of BMD had occurred in the Ovx control group. Idoxifene reduced total serum cholesterol, which was maximal at 0.5 mg/kg·day. Idoxifene alone displayed minimal uterotrophic activity in Ovx rats and inhibited the agonist activity of estrogen in intact rats. Histologically, myometrial and endometrial atrophy were observed in both idoxifene and vehicle-treated Ovx rats. In this report, we also provide molecular-based evidence to support the observations in vivo of a novel selective estrogen re...