Erectile Dysfunction ('ED' or 'Impotence') is defined as 'the inability to achieve or maintain an erection sufficient for satisfactory sexual performance'. It has been suggested that ED is one of the most common chronic medical disorders in men over 40 years old. A recent study found that 36% of men ages between 40 and 70 years old were moderately to completely impotent. Alarmingly, the prevalence of ED is increasing. It was estimated in 2005 that 25 million men in the United States experienced some form of ED.