Effect of diphosphonate on crystallization of calcium oxalate in vitro.

Reliable techniques for the calculation of activity product (state of saturation), formation product (limit of metastability) and crystal growth of calcium oxalate were devised. The activity product at saturation was 2.53 times 10 minus 9 M2, and was independent of duration of incubation, solid-to-solution ratio, pH, calcium concentration or ionic strength. These tehcniques were utilized to assess the effect of disodium ethane-1-hydroxy-1, 1-diphosphonate (EHDP) on crystallization of calcium oxalate in an aqueous salt solution in vitro. EHDP increased the formation product of calcium oxalate, indicating an inhibition of nucleation of calcium oxalate. Further, it inhibited the crystal growth of calcium oxalate.