Diphosphonates inhibit bone resorption by macrophages in vitro

Abstract

The diphosphonates are a group of synthetic compounds which are adsorbed onto hydroxylapatite crystal surfaces and inhibit the growth and dissolution of these crystals. They also inhibit mineralization and resorption of bone in vivo. Mice were used to study the effects of diphosphonates were tested on the attachment of macrophages to bone and on the dissolution of bone mineral by macrophages. Attachment was unaffected, but resorption was inhibited. Diphosphonates were cytotoxic at much lower concentrations when bone mineral was present. Apparently, diphosphonate inhibits bone resorption by adsorbing onto the mineral surface where it reaches cytotoxic concentrations.