Pentosan Polysulfate As An Inhibitor of Calcium Oxalate Crystal Growth

Abstract

Pentosan polysulfate was studied as a calcium oxalate crystal growth inhibitor. The inhibition from pentosan polysulfate at concentrations ranging from 3.5 to 110mg./l. was measured in simple inorganic calcium oxalate solutions at pH 5, 6 and 7. Pentosan polysulfate also was mixed with urine at concentrations from 10 to 350mg./l. and inhibition determined. Measurement of calcium oxalate crystal growth inhibition was performed in a seeded crystal growth system. One inhibitory unit (concentration of pentosan polysulfate necessary to give a 50 per cent reduction in the rate of crystal growth) was 5.7 ± 2mg./l. at pH 5, 7.2 ± 1.1mg./l. at pH 6 and 6.0 ± 2.1mg./l. at pH 7. Urine-pentosan polysulfate mixtures showed more inhibitory activity than the predicted inhibition present. Addition of pentosan polysulfate to urine at a concentration of 10mg./l. increased the inhibitory activity from 45 ± 3 to 59 ± 3IU/l. Pentosan polysulfate is a potent calcium oxalate crystal growth inhibitor in urine at physiologic pH levels. If the urinary concentration of pentosan polysulfate after oral administration reaches 10mg./l., the increase in inhibitory activity in urine that may occur might be important in the treatment of patients who form calcium oxalate calculi within the urinary tract.