The effects of methenamine-hippurate upon urinary risk factors for renal stone formation

Among the various treatments for renal calcium stone disease, none has been documented to reduce urinary oxalate. Methenamine-hippurate (Hiprex) has been used extensively in the treatment of urinary tract infections and from micropuncture studies in the rat, using para-aminohippurate, it could be expected to reduce the renal secretion of oxalate. A daily dose of 3 g was given orally to 15 healthy subjects for 2 weeks. However, there was no net decrease in the urinary excretion of oxalate, but a risk index based on the urinary content of calcium, magnesium, oxalate, citrate and urine became reduced during treatment. The urinary inhibition of calcium oxalate crystal growth was unaffected. It is concluded that there may be a potential in methenamine-hippurate for the treatment of calcium stone disease, which can only be evaluated, however, by a clinical trial in stone patients.