Effects of promethazine on bone mass and on bone remodeling in ovariectomized rats: A morphometric, densitometric, and histomorphometric experimentalstudy

The effect of promethazine on bone is debated. We studied the effect of pro methazine on bone and the mechanism of action involved by densitometric and histomorphometric measurements in female Wistar rats (100 days old, mean w eight 25 +/- 20 g). A control group of 15 rats was not manipulated. An expe rimental group of 15 rats were ovariectomized (OVX) at 100 days of life and fed a diet supplemented with 4.8 mg/kg promethazine hydrochloride (OVX + F rom). The group that underwent OVX and a group of 15 rats that underwent sh am ovariectomy (Sham-OVX) were not treated with promethazine. After 30 days , all the rats were killed. Their femur and 5th lumbar vertebra were dissec ted and cleaned of soft tissue. Femoral length and vertebral height were me asured with a caliper and bones were weighed on a precision balance. The bo ne mineral content (BMC) and bone mineral density (BMD) of the whole right femurs and 5th lumbar vertebras were measured by dual-energy X-ray absorpti ometry (DXA). Trabecular bone volume (Cn-BV-TV%), trabecular number (Tb-N m m(-1)), trabecular thickness (Tb-Th mu m), and trabecular mm separation (Tb -Sp mu m) were measured in the femurs by histomorphometric study of nondeca lcified bone. Our re; suits showed that promethazine significantly inhibite d postovariectomy loss of bone mass (P < 0.0001) by significantly reducing bone resorption, as shown by the smaller trabecular spaces observed in the treated OVX rats (P < 0.0001).