Use of drugs for nephrolithiasis.

Renal stone disease often begins by renal colic. In order to manage this event adequately, several goals should be pursued: first, attenuate pain; second, favour progression and spontaneous expulsion of stones; third, prevent from obstructive and infectious complications. All of the aforementioned points pertain to medical management of this disease. Concerning prevention, it is widely agreed that pathogenesis of kidney stones is a consequence of abnormalities in urine environment, leading to a disequilibrium between promoters and inhibitors of crystallization. Therefore, the rationale for therapy is to make urine less conductive to stone formation, by both decreasing state of saturation and increasing inhibitory potential. In only some types of stone-forming salts it is possible to obtain undersaturation with the solid phase. Indeed, uric acid stones can be chemically dissolved by using alkali and allopurinol. To a lesser extent, this also applies to cystine stones, with the use of thiols and alkali. In these subsets, the aforementioned tools are also effective to prevent new stone formation. Much more challenging appears the treatment of calcium containing stones. About 10% of such stones is caused by systemic disorders and, in these cases, the prevention of new stones is successfully accomplished by curing the underlying disease. For instance, parathyroidectomy cures calcium nephrolithiasis in case of hyperparathyroidism. However, the majority of patients with calcium stones are idiopathic stone-formers, in whom metabolic abnormalities often occur, namely, hypercalciuria, hyperoxaluria, hypocitraturia. The correction of these abnormalities by using thiazide diuretics, alkaline citrates, potassium phosphate and bisphosphonates is based on the prevailing metabolic defect. Among the most recent available tools, Oxalobacter Formigenes and probiotics have been proposed to treat primary or secondary hyperoxalurias. In general, the treatment of stone disease reduces its recurrence rate, but only seldom results in stable remission. Anyway, less stones mean reduction of the need for urological procedures and the associated infective or obstructive complications. Of course, medical prevention implies financial efforts, but a careful cost to benefit analysis demonstrates that these are well justified.