Augmentation of renal citrate excretion by oral potassium citrate administration: time course, dose frequency schedule, and dose-response relationship.

The time course, dose frequency schedule, and dose-response relationship of the citraturic response to orally administered potassium citrate was examined in 22 normal volunteers and 21 patients with uric acid or calcium nephrolithiasis. The slow-release (wax matrix) preparation of potassium citrate produced a rapid and sustained rise in urinary citrate lasting for up to 12 hours following a single oral administration. Probably owing to this prolonged action, the slow-release preparation when given in a twice-daily or thrice-daily schedule at a dosage of 60 meq or 3.78 Gm citrate/day virtually eliminated the normally wide circadian fluctuation in urinary citrate and maintained urinary citrate at a higher, more constant level throughout the day. The liquid preparation of potassium citrate was less effective in this regard. However, the two preparations of potassium citrate caused an equivalent rise in total 24-hour urinary citrate. When 24-hour excretions of citrate were examined, urinary citrate was shown to reach its peak level by the second day of potassium citrate treatment and to return to the pretreatment level by the second day after the treatment was stopped. The rise in urinary citrate produced by treatment was directly proportional to the dose of potassium citrate. In most hypocitraturic patients with renal stones, potassium citrate 60 meq/day restored normal urinary citrate (greater than 320 mg/day).