Sunday April 11, 2010


Q: What is the advantage of Tolvaptan (Samsca) over Conivaptan (Vaprisol) in treatment of hyponatremia?



Answer: It can be given orally.

Tolvaptan (Samsca) is a selective vasopressin V2 -receptor antagonist. Indicated for hypervolemic and euvolemic hyponatremia (ie, serum sodium level less than 125 mEq/L) or less marked hyponatremia that is symptomatic and has resisted correction with fluid restriction. Dose is 15 mg PO qd initially; may increase at 24-h intervals to 30 mg/d but not to exceed 60 mg/d.

Conivaptan (Vaprisol) is a Arginine vasopressin antagonist (V1A, V2) indicated for euvolemic (dilutional) and hypervolemic hyponatremia. Increases urine output of mostly free water, with little electrolyte loss. Dose is 20 mg IV loading dose (infuse over 30 min), followed by 20 mg via continuous IV infusion over 24 h; continue treatment for additional 1-3 d as a 20-mg/d continuous IV infusion; may titrate up to 40 mg/d if necessary.