Improving cystine stone therapy:: An in vitro study of dissolution

Objectives. To perform an in vitro study analyzing the possibilities in therapeutic strategies for an effective treatment of cystine stones. Methods. Artificial stones made of cystine [Bon(n)-Stones] with a ball-shaped size of 0.9 cm in diameter were used. Chemolysis of artificial cystine stones with different solvents (artificial urine, physiologic sodium chloride solution, acetylcysteine, tris-(hydroxymethylene)-aminomethane [THAM], and combinations of these) was investigated. An experimental arrangement with computer-assisted online measurement of data simulating the physiologic conditions in the upper urinary tract at varying pH values was used. Results. All solutions showed a statistical improvement in the solubility of cystine stones compared with artificial urine and physiologic sodium chloride solution. The combination of THAM (pH 10) and 2% acetylcysteine was most effective (13.91 +/- 1.73 mg/hr) and demonstrated a 41-fold higher ability 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, Elsevier Science Inc.