Etidronate versus clodronate in the prevention of postovariectomy bone loss. An experimental study in rats

We compared the diphosphonates etidronate and clodronate to find out which was more effective in inhibiting the loss of bone mass after ovariectomy in rats.

Five lots of female Sprague Dawley rats, each containing 15 rats (14 wks old; mean weight 290 g), were kept under identical living conditions (12 hrs of light and 12 hrs of darkness), habitat, and diet following the current norms of the European Economic Community. One lot was kept as a control; one lot underwent sham ovariectomy (Sham-OVX); and the remaining 3 lots were anesthesized and underwent double ovariectomy (OVX). One lot of ovariectomized rats was given etidronate by esophageal tube, 5 mg/kg/day (OVX-E); one lot was treated with intraperitoneal clodronate, 5 mg/kg/3 days (OVX-Cl). The remaining lot was not manipulated (OVX). The animals' right femurs were then dissected for measurements of the bone mineral content.

Bone densitometry revealed that loss of bone mass 2 months after ovariectomy in the OVX-Cl group was 2.3%, not differing from that of the control group; bone loss in the OVX-E group was 11.7%, significantly different from the control group and from the OVX-Cl group (p < 0.001). These results show that clodronate is superior to etidronate in inhibiting osteopenia after ovariectomy in rats.