PDE5 Inhibitors: In Vitro and In Vivo Pharmacological Profile

PDE5 inhibitors have been clearly established as first-line therapy for the treatment of erectile dysfunction (ED). Three PDE5 inhibitors - sildenafil (Viagra (R)), vardenafil (Levitra (R)) and tadalafil (Cialis (R)) - are currently approved by the FDA and the EMEA for use in ED, whereas sildenafil is also marketed under a different proprietary name (Revatio (R)) for the treatment of pulmonary arterial hypertension (PAH). A forth PDE5 inhibitor, udenafil (Zydena (R)) is currently marketed. In the present review the molecular basis and the mechanism of action of PDE5 inhibitors is discussed. In addition experimental and clinical data concerning their effects on different tissues, organs and systems is systematically reviewed and their possible beneficial action in numerous disorders is presented.