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

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.

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.

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.

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.