Absence of clinically important HERG channel blockade by three compounds that inhibit phosphodiesterase 5--sildenafil, tadalafil, and vardenafil.

Compounds that inhibit phosphodiesterase 5 (PDE5) have been developed for the treatment of erectile dysfunction. Because men with erectile dysfunction frequently have comorbid cardiovascular disease, they may have limited cardiac repolarization reserve and be at risk of arrhythmia if treated with medications that prolong ventricular repolarization. The human ether-a-go-go related gene (HERG) channel is important for repolarization in human myocardium and is a common target for drugs that prolong the QT interval.