Inhibition by sodium-potassium citrate (CG-120) of calcium oxalate crystal growth on to kidney stone fragments obtained from extracorporeal shock wave lithotripsy.

Retention of fragments within the kidney after extracorporeal shock wave lithotripsy (ESWL) continues to be a major shortcoming of this form of stone treatment. The aim of this study was to evaluate the ability of sodium-potassium citrate to inhibit calcium oxalate crystal nucleation and growth on to stone fragments remaining after ESWL. The continuous flow crystallisation technique was adapted to induce calcium oxalate crystal nucleation and growth on to the surface of fragmented kidney stones and the inhibitory effect of sodium-potassium citrate was assessed by scanning electron microscopy and by determining the relative increase in crystalline mass at final concentrations of 0, 2, 4, 6, 8, 10 mmol/l. Sodium-potassium citrate significantly inhibited the deposition of new crystalline calcium oxalate in a dose-dependent manner above 2 mmol/l; these findings were confirmed by scanning electron microscopy. It was concluded that sodium-potassium citrate may provide an effective means of preventing the formation of new kidney stones by the deposition of calcium oxalate on to residual stone fragments resulting from ESWL and that the technique used is an efficient means of testing the efficacy of therapeutic agents to prevent stone recurrence in patients treated with ESWL.