Erections are neurovascular events, meaning that nerves and blood vessels (arteries and veins) are involved in the process of an erection and all must work properly to develop a hard erection that lasts long enough. Erection begins with sexual stimulation. Sexual stimulation can be tactile (for example, by a partner touching the penis or by masturbation) or mental (for example, by having sexual fantasies, viewing porn). Sexual stimulation or sexual arousal causes the nerves going to the penis to release a chemical, nitric oxide. Nitric oxide increases the production of another chemical, cyclic GMP (cGMP), in the muscle of the corpora cavernosa. The cGMP causes the muscles of the corpora cavernosa to relax, and this allows more blood to flow into the penis. The incoming blood fills the corpora cavernosa, making the penis expand.
Alprostadil should not be used in men at higher risk for priapism (erection lasting longer than six hours) including men with sickle cell anemia, thrombocytopenia (low platelet count), polycythemia (increased red blood cell count), multiple myeloma (a cancer of the white blood cells), and is contraindicated in men prone to venous thrombosis (blood clots in the veins) or hyperviscosity syndrome who are at increased risk for priapism.
Nearly every primary care physician, internist and geriatrician now understand that many older men retain an interest in sexual activity as they age. Some primary care physicians think that sexual potency in older men is the norm, and that if it is lacking, it is ‘all in the head.’ This viewpoint has not been supported by current literature. The Massachusetts Male Aging Study (MMAS) found that 52% of men between 40 and 70 years old reported having some form of erectile dysfunction (ED).1 The reality is that ED is a natural part of ageing and that the prevalence increases with age. In the MMAS, they found that roughly 50% of men at 50 years old, 60% of men at 60 years old and 70% of men at 70 years old had ED. Thus, nearly all men who live long enough should develop ED. The myths that surround the problems of impotence or ED confound the attempts of patients to receive treatment and the attempts of physicians to help them.1
Lifestyle choices that impair blood circulation can contribute to ED. Smoking, excessive drinking, and drug abuse may damage the blood vessels and reduce blood flow to the penis. Smoking makes men with atherosclerosis particularly vulnerable to ED. Being overweight and getting too little exercise also contribute to ED. Studies indicate that men who exercise regularly have a lower risk of ED.
ED exists in approximately 75% of men with SB and is dependent upon the level of the neurologic lesion (54). The level of the neurologic lesions usually corresponds to sensation and penile sensation indicates pudendal nerve signaling. With absent sacral reflexes ED is variable. Furthermore, Diamond et al. reported that 64% of men with lesions below T10 obtained erections versus 14% with a lesion above T10 (55). It has also been suggested that ED may be underreported due to lack of sexual education even in men without associated cognitive impairment (56).
Sexual dysfunction and ED become more common as men age. The percentage of complete ED increases from 5% to 15% as age increases from 40 to 70 years. But this does not mean growing older is the end of your sex life. ED can be treated at any age. Also, ED may be more common in Hispanic men and in those with a history of diabetes, obesity, smoking, and hypertension. Research shows that African-American men sought medical care for ED twice the rate of other racial groups.
Finally, there are NO-releasing polymers that are capable of delivering NO in a pharmacologically useful way. Such compounds include compounds that release NO upon being metabolised and compounds that release NO spontaneously in aqueous solution. Initial animal studies suggest that cavernosal injections of NO polymers can significantly improve erectile function.48