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Open Access Research article

New chemolysis for urological calcium phosphate calculi – a study in vitro

Zhang Xiang-bo12, Wang Zhi-ping12*, Duan Jian-min2, Lu Jian-zhong2 and Ma Bao-liang2

Author Affiliations

1 School of Life Sciences, LanZhou University, LanZhou, 730030, China

2 Institute of Urology, the 2nd Hospital of LanZhou University, Cuiyingmen 80, LanZhou, 730030, China

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BMC Urology 2005, 5:9  doi:10.1186/1471-2490-5-9

Published: 22 May 2005

Abstract

Background

Advances in techniques have left very few indications for open surgical extraction of urinary stones currently. These advances notwithstanding, the search continues for medical approaches to urinary stone management. In this study, we perform an in vitro study analyzing the efficiency and prospect of two new complex solutions in urological calcium phosphate calculi dissolution.

Methods

Eighteen stones composed mainly of calcium phosphates were taken from patients who underwent kidney stone surgery. These stones were large enough (weight range 0.514–0.928 g) to be fragmented and matched equally into six groups. Chemolysis of phosphate stones was done with six different solvents and was repeated 3 times with 6 stones for each solution. At 24, 48 and 72 h, reduction in weight, percentage weight change, and dissolution rate; the dissolution rates at pH 5.0, 7.0 and 8.5 for each solution, using different cations (Na+, K+ or Ca2+), according to different dilutions (1:1, 1:2, 1:3, 1:4) of S1 and S2 were simultaneously determined.

Results

Calcium phosphate calculi were poorly dissolved by Phys and Art, and they had a low dissolution rate in pH 8.5 EDTA. The most effective solutions were S1, S2 and R, with 72 h mean dissolution rates: 5.75 ± 0.44 mg/hr (S1), 5.2 ± 0.63 mg/hr (S2), 4.55 ± 0.46 mg/hr (R) ( ± s, p < 0.01 R, S1 and S2 vs Phys, Art and EDTA; p < 0.05, S1 vs R, LSD-test). The mean percentage weight loss at 72 h was: 52.1 ± 15.75 % (S1), 44.4 ± 7.37 % (S2) and 40.5 ± 3.67 % (R) ( ± s, p < 0.01 R, S1 and S2 vs Phys, Art and EDTA, LSD-test). Diluted twice, S1 and S2 had even better effectiveness than their initial solution. The additive of Na+, K+ or Ca2+ greatly reduced the dissolution rates of S1, S2.

Conclusion

Our data indicate that test solutions S1 and S2 are effective solvents in the chemolysis of calcium phosphate stones. At twice dilutions, these solutions are even more useful in the treatment of stone disease.