Comparative study of etidronate and SR 41319, a new diphosphonate, on passive cutaneous anaphylaxis and phospholipase A2 activity.

Diphosphonates are known to affect calcium metabolism. It was therefore felt of interest to investigate the effects of SR 41319, a new Diphosphonate, comparatively to Etidronate disodium (EHDP) on Passive Cutaneous Anaphylaxis (PCA) and on Phospholipase A2 (PLA2) activity which are both mediated by calcium-dependent mechanisms. Results showed that: (1) intravenously, SR 41319 induced a dose-dependent inhibition of PCA more pronounced than the EHDP one; (2) in PLA2 assay, marked inhibition was obtained with SR 41319 whereas EHDP was slightly active. Decrease in Ca entry into mast cells and anti-PLA2 activity of SR 41319 might partly explain the SR 41319 inhibition of PCA.