Thursday May 1, 2008
Conivaptan's (Vaprisol) drug interactions
Q: Conivaptan (Vaprisol), a Vasopressin Antagonist, which is indicated for the management of euvolemic hyponatremia - can increase the concentration of following drugs if use concomittently? (choose one)

A) Amlodipine (Norvasc)
B) Simvastatin (Zocor)
C) Digoxin (Lanoxin)
D) Midazolam (Versed)
E) All of the above


Answer is E: All of the above

Administration of oral conivaptan 40 mg twice daily with amlodipine besylate (Norvasc) resulted in a two-fold increase in the AUC concentration and increased half-life of amlodipine.

The combined use of IV conivaptan and midazolam should be avoided, because the AUC concentration of midazolam may be increased by two-fold to three-fold when these agents are used together.

The coadministration of conivaptan and HMG-CoA reductase inhibitors (statins) such as simvastatin (Zocor) should also be avoided because the AUC concentration of the statin is increased by three-fold.

Digoxin when taken with oral conivaptan, results in a 30% reduction in clearance of digoxin.


Read nice review on Conivaptan
(reference: P&T • March 2007 • Vol. 32 No. 3, Page 140)