ED is defined as the inability to achieve a full erection or the inability to maintain an erection adequate for sexual intimacy. Other types of sexual dysfunction such as premature ejaculation and low libido may occur; however, the most common and disruptive problem in men is ED. Although most men will experience periodic episodes of ED, these episodes tend to become more frequent with advancing age.
Melanocortin receptor agonists were found to induce erections serendipitously. A study investigating the dermatologic use of Melanotan-II (MT-II) was found to generate erections unexpectedly leading to the development of MTII derivatives for ED treatment (120). MT-II was initially used to induce pigment changes in the skin for artificial tanning but has been suspected to induce melanoma, however (121).
An analysis of 14 studies involving more than 90,000 patients with ED confirmed the relation between ED and an increased risk of cardiovascular events and mortality.  Compared with patients without ED, those with ED had a 44% increased risk of cardiovascular events, a 25% increased risk of all-cause mortality, a 62% increased risk of MI, and a 39% increased risk of cerebrovascular events. Treatment of ED, either through lifestyle interventions or by pharmacologic means, may improve prognosis and reduce risk.
If PDE-5 inhibitors are not suitable or don’t work, other therapies include injections into the base of the penis, which cause flow of blood into the penis and a fairly immediate erection that lasts around an hour. The drugs injected are alprostadil (Caverject and Erectile dysfunctionex) and Invicorp (VIP and phentolamine). Alprostadil may also be inserted as a gel into the opening of the penis. This is not suitable if your partner is pregnant.
It is estimated that up to 20 million American men frequently suffer from impotence and that it strikes up to half of all men between the ages of 40 and 70. Doctors used to think that most cases of impotence were psychological in origin, but they now recognize that, at least in older men, physical causes may play a primary role in 60% or more of all cases. In men over the age of 60, the leading cause is atherosclerosis, or narrowing of the arteries, which can restrict the flow of blood to the penis. Injury or disease of the connective tissue, such as Peyronie's disease, may prevent the corpora cavernosa from completely expanding. Damage to the nerves of the penis, from certain types of surgery or neurological conditions, such as Parkinson's disease or multiple sclerosis, may also cause impotence. Men with diabetes are especially at risk for impotence because of their high risk of both atherosclerosis and a nerve disease called diabetic neuropathy.
Six herbs for treating erectile dysfunction Erectile dysfunction can be an embarrassing condition that can leave men unable to achieve an erection or a full orgasm. This MNT Knowledge Center article talks about six different herbal supplements that could help people with erectile dysfunction, including ginkgo biloba, horny goat weed, and red ginseng. Read now
For best results, men with ED take these pills about an hour or two before having sex. The drugs require normal nerve function to the penis. PDE5 inhibitors improve on normal erectile responses helping blood flow into the penis. Use these drugs as directed. About 7 out of 10 men do well and have better erections. Response rates are lower for Diabetics and cancer patients.