INDAPAMIDE (NATRILIX) - THE AGENT OF CHOICE IN THE TREATMENT OF RECURRENT RENAL CALCULI ASSOCIATED WITH IDIOPATHIC HYPERCALCIURIA

Objective To compare the hypocalciuric and potential side-effects of h ydrochlorothiazide (HCT) to indapamide (IND; a thiazide-like drug) in patients with idiopathic hypercalciuria. Patients, subjects and method s Twelve patients with recurrent renal calculi and renal hypercalciuri a were studied using a randomized double-blind cross-over protocol. In addition, because the side-effects of HCT are attenuated using small doses, the hypocalciuric effect of 12.5, 25 and 50 mg daily was assess ed in six normal subjects. Results There was a significant reduction i n urinary calcium excretion using both agents, with a mean (so) of 6.0 6 (2.68) and 3.37 (2.00) mmol/24 h using IND, and 5.58 (1.98) and 3.93 (2.35) mmol/24 h using HCT, before and after treatment (P<0.05). The treatment was not sufficiently prolonged to assess adequately all the side-effects of either agent but both produced a similar decrease in s erum potassium, whilst HCT significantly increased the mean (so) serum mate levels, from 0.34 (0.09) to 0.43 (0.08) mmol/L (P<0.01). There w as also a significant decrease in mean (so) urinary citrate excretion in those receiving HCT, from 1.41 (1.05) to 1.00 (0.71) mmol/24 h (P<0 .001), but not in those receiving IND, from 1.19 (0.71) to 1.18 (0.79) mmol/24 h. Although there was a hypocalciuric effect with doses of 12 .5 and 25 mg HCT, it was sub-therapeutic when compared with the dose o f 50 mg. Conclusion At a daily dose of 2.5 mg, IND is at least as effe ctive as 50 mg HCT in controlling hypercalciuria. Because of its safet y profile and lack of effects on urinary citrate excretion, this agent should be the preferred therapy for patients with idiopathic hypercal ciuria and recurrent renal calculi.