Influence of a Diphosphonate and 1,25-Dihydroxycholecalciferol on Calcium Metabolism

Abstract

The diphosphonate, disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) has been shown to modify several variables of calcium metabolism in the rat (GASSER et al., 1972). In their kinetic and balance study the authors (GASSER et al., 1972) demonstrated that EHDP according to the dose administered could evoke opposite effects on some variables of calcium metabolism. At a daily dose of 1 mg P/kg s.c. EHDP brought about a decrease in the mobilization of calcium from bone, but did not affect significantly the rate of bone mineralization. At this dose also an augmentation in the intestinal absorption and retention of calcium was observed, and no alteration in the process of cartilage and bone mineralization could be detected morphologically (SCHENK et al., 1973). In the same studies (GASSER et al., 1972; SCHENK et al., 1973) it was observed that the effects of EHDP differ markedly at a dose ten times greater (10 mg P/kg s.c.). In this case the diphosphonate induced a decrease in the rate of bone mineralization accompanied by a significant reduction in intestinal absorption and retention of calcium (GASSER et al., 1972). Morphologically an impairment in the mineralization of growth cartilage and bone was described in rats treated with the same large doses of EHDP (SCHENK et al., 1973). The inhibitory action of large doses of EHDP on both bone mineralization and intestinal calcium absorption suggested (MORGAN et al., 1971) the existence of a link between the two processes, in accordance with the hypothesis conceived by NICOLAYSEN (1943).