RANDOMIZED PROSPECTIVE-STUDY OF A NONTHIAZIDE DIURETIC, INDAPAMIDE, IN PREVENTING CALCIUM STONE RECURRENCES

We examined the biochemical changes and the efficacy of indapamide in the prevention of calcium stone recurrences. Seventy-five patients wit h calcium nephrolithiasis and hypercalciuria were randomly assigned to three different therapies: diet and fluid (group A), diet and fluid p lus indapamide 2.5 mg/day (group B), and diet and fluid plus indapamid e 2.5 mg/day plus allopurinol 300 mg/day (group C). Before treatment a nd after 6, 12, 24, and 36 months of therapy, we evaluated blood press ure, serum and urine risk parameters (including relative supersaturati ons of calcium oxalate, calcium phosphate and uric acid), stone rate, and the proportion of calculi-free patients. During the 3 years of tre atment, urinary calcium greatly decreased in groups B and C, dropping to 50% of the pretreatment values; urinary oxalate also significantly declined in group B (-24%) and group C (-27%). Relative supersaturatio ns of calcium oxalate and calcium phosphate decreased to the same exte nt in groups B and C (about one-half of the pretreatment value), and r elative supersaturation of uric acid was particularly reduced in group C (-65% of the pretreatment value). The stone rate improved in all th ree groups (p < 0.005), but using actuarial analysis in the evaluation of calculi-free patients, indapamide, and indapamide plus allopurinol groups were found to have a significantly more favorable effect than diet and fluid treatment (p < 0.02), without any difference between th e two drug groups. Because indapamide has fewer side effects than thia zide diuretics, we conclude that indapamide could be an interesting al ternative to thiazides in the prevention of calcium stones in hypercal ciuric patients.