
Erectile dysfunction (ED) is the inability to achieve or maintain satisfactory erection of penis during sexual intercourse. It is usually an age related condition but can also be triggered by psychological factors. It may occur due to various reasons such as smoking, sedentary lifestyle and administration of certain drugs such as antidepressants, psychotropic drugs, antihypertensive and recreational drugs. Presently, oral phosphodiesterase type 5 inhibitors (PDE 5) commonly form the first line of treatment prescribed by doctors for ED. These include drugs namely, Viagra (sildenafil citrate), Cialis (tadalafil), Levitra/Staxyn (vardenafil), Stendra/Spedra (avanafil) and Zydena (udenafil). The demand for erectile dysfunction drugs is high and is continuously rising as it caters to the needs of the growing elderly population and the high incidence rates of chronic disorders comprising hypertension, renal diseases and diabetes, neurological disorders and hormonal insufficiencies.