Efficacy and safety of 30-minute infusions of conivaptan in euvolemic and hypervolemic hyponatremia.

Purpose: The efficacy and safety of conivaptan administered via 30-minute i.v. infusion to patients with euvolemic or hypervolemic hyponatremia were evaluated.

Methods: Hospitalized adults with a baseline serum sodium concentration (SSC) of 115-130 meq/L and euvolemia or hypervolemia on clinical evaluation were randomized to receive conivaptan hydrochloride 20 mg once or twice daily or placebo via 30-minute i.v. infusion. The primary efficacy measure was the change in SSC from baseline to 48 hours.

Results: A total of 49 patients received one of the three treatment regimens. Conivaptan once and twice daily produced significant least-squares mean changes from baseline in SSC at 48 hours of 3.46 meq/L (95% confidence interval [CI], 1.75-5.18 meq/L) and 6.22 meq/L (95% CI, 4.34-8.10 meq/L), respectively (p = 0.028 between conivaptan-treated groups). These changes were significantly greater compared with those in the placebo group at hour 4 (p = 0.049) and at all time points onward of hour 28 (p ≤ 0.019) for the once-daily regimen and at all time points for the twice-daily regimen (p = 0.045 at hour 4, then p ≤ 0.010). Both conivaptan regimens were more efficacious than placebo in all secondary efficacy outcomes. Conivaptan was generally well tolerated, with infusion-site reactions being the most common adverse effects (AEs).

Conclusion: Conivaptan hydrochloride 20 mg, administered once or twice daily via 30-minute i.v. infusion, significantly increased SSCs over 48 hours in patients with euvolemic or hypervolemic hyponatremia when compared with placebo. Common AEs were similar to those seen with continuous conivaptan infusions.