ABSTRACT

Phosphodiesterase 5 (PDE-5) Inhibitors are drugs that inhibit Phosphodiesterase 5 (PDE-5), the cGMP degrading isoenzyme causing rise in concentration of cGMP in smooth muscle cells thereby reducing muscular tone. They are used for treating Pulmonary artery hypertension, erectile dysfunction, reducing symptoms of Lower Urinary Tract secondary to Benign Prostatic Hyperplasia (BPH) and recently on Cardio-protective effect for which the exact mechanism is not known. To investigate and compare the anti-oxidant potential of currently available PDE-5 inhibitors: Tadalafil, Vardenafil and Sildenafil by in-vitro Nitric oxide (NO) radical scavenging assay. Method: The anti-oxidant activities of PDE-5 inhibitors were done using In-vitro Nitric Oxide (NO) radical scavenging assay. The nitric oxide radical scavenging activity was highest for Tadalafil followed by Sildenafil and Vardenafil showing topmost activity of 64.74%, 54.34% and 49.83% respectively at 1000 μg /ml whereas at the same concentration ascorbic acid (i.e. standard anti-oxidant) shows 90.16% inhibition. From our study it showed all PDE-5 inhibitors have good anti-oxidant property that may probably play a Cardio-protective role by improving Endothelial Dysfunction.

Key words: PDE-5 inhibitors, Sildenafil, Tadalafil, Vardenafil, Antioxidant, Nitric Oxide Scavenging activity.