The effects of disodium ethane-hydroxy-1,1-diphosphonate and disodium dichloromethylene diphosphonate on lanthanide-induced calcergy.

Systemic treatment with disodium ethane-hydroxy-1,1-diphosphonate is ineffective in inhibiting the calcergenic reactions induced in mouse skin by the lanthanides. In contrast, disodium dichloromethylene diphosphonate prevents lanthanide calcergy induced by 12 of the 15 compounds tested but only when treatment with Cl2MDP is given prior to the subcutaneous (sc) injection of the lanthanide. This is the first experimental calcification system in which EHDP was ineffective in inhibiting the calcification and the first in which Cl2MDP was found to be effective in this regard. It is increasingly apparent that individual members of the diphosphonates show variable anti-calcific effects, that the activity of one particular compound may vary from one test system to another and that the time of application of treatment of the compounds in respect to the application of the initiating stimulus to calcification may be an important factor in determining the efficacy of a particular compound.