The inhibitory effect of new diphosphonic acids on aortic and kidney calcification in vivo.

Three new diphosphonic acids, i.e. compounds containing a P-C-P bond, have been investigated for their ability to inhibit the vitamin D-induced calcification of aortas and kidneys in rats. The compounds were applied orally in various doses. All of the compounds, which had previously been shown to effectively inhibit the in vitro crystallization of apatite, markedly decreased the amount of calcium deposited in aortas and kidneys. One of the new compounds was substantially more effective than ethane-1-hydroxy-1,1-diphosphonic acid (EHDP), which was used as a reference compound. Diphosphonic acids might be used therapeutically in man against soft tissue calcification.