Use of Tolvaptan to Reduce Urinary Supersaturation: a Pilot Proof of Principle Study

In this study the investigators propose to use a daily dose of 45 mg (30 mg at 8 AM and 15 mg at 4 PM). This relatively small well-tolerated dose is likely to persistently increase urine volume and reduce urine supersaturation and to be well tolerated by patients with kidney stone disease and normal renal function (see below). The twice-daily (8 AM and 4 PM) regimen is designed to produce a maximal AVP inhibition on waking with a gradual fall-off of effect during the night. To this end, a higher dose is used in the morning, with a lower dose in the afternoon.