Effectiveness and Tolerability of Conivaptan and Tolvaptan for the Treatment of Hyponatremia in Neurocritically Ill Patients.

Study Objective: To describe the effectiveness and tolerability of conivaptan and tolvaptan for the correction of hyponatremia in neurocritically ill patients.
Design: Retrospective cohort study.
Setting: Neurointensive care units at two academic medical centers.
Patients: Thirty-six adults admitted to the neurocritical care unit who received at least one dose of conivaptan (5 patients) or tolvaptan (31 patients) between June 2012 and May 2013.
Measurements and Main Results: A single oral dose or intravenous bolus was administered to 23 (74%) patients who received tolvaptan and 2 (40%) patients who received conivaptan, respectively. The mean maximal increase in serum sodium level at 24 hours following the last dose compared with baseline was 5.2 mEq/L for conivaptan (p=0.05) and 7.9 mEq/L for tolvaptan (p<0.001). The mean ± SD maximal increases in serum sodium level at 48, 72, and 96 hours following the last dose of vaptan therapy compared with baseline were 5.5 ± 2.2 mEq/L (p=0.01), 5.6 ± 2.0 mEq/L (p=0.005), and 4.8 ± 2.2 mEq/L (p=0.03), respectively. Sodium overcorrection occurred in six patients (19%) receiving tolvaptan and none of the patients receiving conivaptan. Hypotension occurred in 20% of patients receiving conivaptan and 52% of patients receiving tolvaptan, whereas hypokalemia was observed in 40% of patients receiving conivaptan.
Conclusion: Use of vaptans in neurocritically ill patients led to a significant increase in serum sodium level at 24 hours after the last dose, which was sustained for 96 hours, with the majority of patients receiving a single dose. Risk of sodium overcorrection was high and necessitates appropriate patient selection and frequent monitoring.
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