Ability of multifunctional sodium carboxylates to favor crystal growth of calcium oxalate dihydrate and trihydrate in lecithin-water liposome systems

The effects of multifunctional sodium carboxylates on the phase composition of calcium oxalate (CaOxa) crystals grown in lecithin-water liposomes were investigated using X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. In the presence of monocarboxylate sodium acetate (NaAc), only calcium oxalate monohydrate (COM) with a preferential growth of (0 2 0) crystal face was precipitated, while in the presence of multicarboxylates such as disodium tartrate (Na2tart), trisodium citrate (Na3cit), and the disodium salt of ethylene diamine tetraacetic acid (Na2edta), calcium oxalate dihydrate (COD), and trihydrate (COT) crystals were also induced. The portions of COM, COD, and COT in the CaOxa crystals depended on the concentration of the multifunctional carboxylates. In a low concentration range from about 0.30 to 1.0 mmol/L, a mixture of COM with a preferential growth of (0 2 0) crystal face and COD with a preferential growth of (2 1 3) crystal face was obtained. With increasing concentration of the multicarboxylates, the COM content decreased and the COD content increased in logarithmic fashion. In a medium concentration range from about 1.0 to 10.0 mmol/L, the portions of COD in the precipitates were 35% for Na2tart, and 100% for Na3cit and Na2edta. In a high concentration range from about 10 to 33.3 mmol/L, COT was nucleated with a preferential growth of the (1 0 0) face and sometimes the (2 0 0) crystal face. In this concentration range, a linear relationship was also obtained between the increase of COT or the decrease of COD, and the logarithm of the concentration of the three multifunctional carboxylates. If the concentration of the additive was larger than 33.3 mmol/L, COT was the dominant phase with less than 3% of the mono- and dihydrate for all the three additives. At equal concentration of additives, the ability to suppress the nucleation and growth of COM and thereby to favor the nucleation and growth of COD and COT follows the order: Na3cit > Na2edta ≫ Na2tart ≫ NaAc. Our study supports the potential clinical advantage of citrate therapy over tartrate and edta treatment in nephrolithiasis patients.