Cystone^® for 1 year did not change urine chemistry or decrease stone burden in cystine stone formers

Cystine kidney stones frequently recur because inadequate prevention exists. We recruited documented recurrent cystine kidney stone formers (6 men, 4 women, 44 ± 17 years) into a 2-phased study to assess safety and effectiveness of Cystone^®, a herbal treatment used to prevent and facilitate passage of cystine kidney stones. The first phase was a randomized double-blinded 12 weeks crossover study assessing the effect of Cystone^® versus placebo (2 tablets BID) on urinary chemistries. The second phase was an open label 1 year study of Cystone^® to determine if renal stone burden decreased, as assessed by quantitative and subjective assessment of CT. There was no statistically significant change of urinary composition from baseline short (6 weeks) or long (52 weeks) term on Cystone^®, including volume (2,525, 2,611, 2,730 ml), pH (6.7, 6.7, 7.05), and cystine excretion (2,770, 2,889, 4,025 μmol). Pre and post-CT was available in nine patients. Although seven kidneys lost stones spontaneously or surgically, overall stone burden increased in seven kidneys, was unchanged in nine, and fell in only two. Quantitative scoring increased in both the left and right kidneys (1,602–1667 and 301–2,064 volumetric units, respectively). Therefore, this study does not suggest that Cystone^® has a favorable effect on urinary chemistries that could decrease cystine stone formation, nor does it appear to prevent stone growth or promote stone passage over a 1-year period.