Safety and efficacy of tolvaptan sodium phosphate in patients undergoing open-heart surgery.

PURPOSES: Tolvaptan sodium phosphate (TSP) is an intravenous aquaretic agent that is rapidly converted to tolvaptan after administration. This study aimed to evaluate the safety and efficacy of TSP in open-heart surgery cases. METHODS: This study included 103 patients (31 women; mean age, 70.5 ± 10.8 years) who received intravenous TSP following open-heart surgery. The urine output was measured hourly from 1 h before to 6 h after administration, and time-dependent changes were assessed. The magnitude of the response was defined as ΔU1-6 = (U1+U2+U3+U4+U5+U6) - U-1. Patients were ranked according to ΔU1-6, and the top 25 (marked responders) and bottom 25 (poor responders) were compared. RESULTS: The urine output was significantly increased within 1-3 h after TSP administration, peaked at 2-3 h, and remained above the baseline through 6 h (all p < 0.05). In a multivariable linear regression analysis, the serum sodium level at the time of TSP administration was independently associated with ΔU1-6 (p=0.018). The serum sodium levels at TSP administration were lower in marked responders (p=0.033). No TSP-related adverse events were observed in any of the cases. CONCLUSIONS: Intravenous TSP can induce a rapid and sustained diuretic response following open-heart surgery, and the serum sodium levels determine the magnitude of the aquaretic response to intravenous TSP.