Effects of propane-2, 2-diphosphonate (PDP) on matrix-induced ectopic bone formation in comparison to ethane-1-hydroxy-1, 1-diphosphonate (EHDP).

The most prominent effect of propane-2, 2-diphosphonate (PDP) and ethane-1-hydroxy-1, 1-diphosphonate (EHDP) on matrix-induced ectopic bone in the rat was a dose-dependent inhibition of osteogenesis in the early phases of development. The delay was seen as a consequence of osteoprogenitor cell inhibition. Additionally, later phases of bone maturation were disturbed by interference with the mineralization and remodeling processes. However, direct effects on the calcium phosphates of bone are only of minor additional value, which remains of lesser importance in comparison to the cellular impairment. After withdrawal of diphosphonates, the effects were nearly completely remitted. Neither PDP nor EHDP, even given in high doses, resulted in a lasting reduction in ectopic mass. The remission may be referred to the recovery of cell activities, whereas the mineral impregnation of osteoidosis was, if at all, of little importance. For treatment of ectopic osteogenesis PDP proved inefficient.