Improving cystine stone therapy: An in vitro study of dissolution

Objectives. To perform an in vitro study analyzing the possibilities in the rapeutic strategies for an effective treatment of cystine stones. Methods. Artificial stones made of cystine [Bon(n)-Stones] with a ball-shap ed size of 0.9 cm in diameter were used. Chemolysis of artificial cystine s tones with different solvents (artificial urine, physiologic sodium chlorid e solution, acetylcysteine, tris-(hydroxymethylene)-aminomethane [THAM], an d combinations of these) was investigated. An experimental arrangement with computer-assisted online measurement of data simulating the physiologic co nditions in the upper urinary tract at varying pH values was used. Results. All solutions showed a statistical improvement in the solubility o f cystine stones compared with artificial urine and physiologic sodium chlo ride solution. The combination of THAM (pH 10) and 2% acetylcysteine was mo st effective (13.91 +/- 1.73 mg/hr) and demonstrated a 41-fold higher abili ty to dissolve cystine calculi compared with artificial urine. Conclusions. Our data indicate that local chemolysis with special solutions is an effective treatment modality in cystine stone therapy. (C) 2000, Els evier Science Inc.