Erectile dysfunction (ED) affects 50% of men older than 40 years,  exerting substantial effects on quality of life.  This common problem is complex and involves multiple pathways. Penile erections are produced by an integration of physiologic processes involving the central nervous, peripheral nervous, hormonal, and vascular systems. Any abnormality in these systems, whether from medication or disease, has a significant impact on the ability to develop and sustain an erection, ejaculate, and experience orgasm.
Some men should not take PDE5 inhibitors. They can cause hypotension (abnormally low blood pressure that can lead to fainting and even shock) when given to patients who are taking nitrates (medications taken for heart disease). Therefore, patients taking nitrates daily should not take any of the PDE5 inhibitors. Nitrates relieve angina (chest pain due to insufficient blood supply to the heart muscle because of narrowing of the coronary arteries); these include nitroglycerine tablets, patches, ointments, sprays, and pastes, as well as isosorbide dinitrate and isosorbide mononitrate. Other nitrates such as amyl nitrate and butyl nitrate also are in some recreational drugs called "poppers."
In most healthy men, some of the drug will remain in the body for more than two days after a single dose of tadalafil. Metabolism (clearing of the drug from the body) of tadalafil can be slowed by liver disease, kidney disease, and concurrent use of certain medications (such as erythromycin, ketoconazole, and protease inhibitors). Slowed breakdown allows tadalafil to stay in the body longer and potentially increase the risk for side effects. Therefore, doctors have to lower the dose and frequency of tadalafil in the following examples:
…have traditionally been classified as impotence (inability of a man to achieve or maintain penile erection) and frigidity (inability of a woman to achieve arousal or orgasm during sexual intercourse). Because these terms—impotence and frigidity—have developed pejorative and misleading connotations, they are no longer used as scientific classifications, having been…
This process comprises a variety of physical aspects with important psychological and behavioral overtones. In analyzing the material presented and discussed at this conference, this consensus statement addresses issues of male erectile dysfunction, as implied by the term "impotence." However, it should be recognized that desire, orgasmic capability, and ejaculatory capacity may be intact even in the presence of erectile dysfunction or may be deficient to some extent and contribute to the sense of inadequate sexual function.
Kimberly Hildebrant, ARNP is a board certified Family Nurse practitioner. She graduated with a Bachelor of Science in Nursing from the University of Pittsburgh and a Masters in Nursing from Duquesne University. She has practiced as a nurse practitioner in the field of Infectious Disease as well as HIV for 4 years. She has over 13 years of experience as a critical care nurse. Kimberly is passionate about providing affordable healthcare to all individuals to ensure that all can live their best life. She is an advocate for preventative care and early treatment to avoid lasting illness.
Additionally, the physiologic processes involving erections begin at the genetic level. Certain genes become activated at critical times to produce proteins vital to sustaining this pathway. Some researchers have focused on identifying particular genes that place men at risk for ED. At present, these studies are limited to animal models, and little success has been reported to date.  Nevertheless, this research has given rise to many new treatment targets and a better understanding of the entire process.
Acetylcholine released by the parasympathetic nerves is thought to act primarily on endothelial cells to release a second nonadrenergic-noncholinergic carrier of the signal that relaxes the trabecular smooth muscle. Nitric oxide released by the endothelial cells, and possibly also of neural origin, is currently thought to be the leading of several candidates as this nonadrenergic-noncholinergic transmitter; but this has not yet been conclusively demonstrated to the exclusion of other potentially important substances (e.g., vasoactive intestinal polypeptide). The relaxing effect of nitric oxide on the trabecular smooth muscle may be mediated through its stimulation of guanylate cyclase and the production of cyclic guanosine monophosphate (cGMP), which would then function as a second messenger in this system.
Prostate cancer isn’t considered a cause of ED on its own, but radiation treatments, hormone therapy, and surgery to remove the entire prostate gland can lead to difficulty in getting or keeping an erection. Sometimes erectile dysfunction related to prostate cancer treatment is only temporary, but many guys experience ongoing difficulties that need to be addressed by other means.
Patients should continue testosterone therapy only if there is improvement in the symptoms of hypogonadism and should be monitored regularly. You will need periodic blood tests for testosterone levels and blood tests to monitor your blood count and PSA. Testosterone therapy has health risks, and thus doctors should closely monitor its use. Testosterone therapy can worsen sleep apnea and congestive heart failure.
In some cases, nocturnal penile tumescence testing is performed to find out whether the man has erections while asleep. Healthy men usually have about four or five erections throughout the night. The man applies a device to the penis called a Rigiscan before going to bed at night, and the device can determine whether he has had erections. (If a man is able to have normal erections at night, this suggests a psychological cause for his impotence.)
Quitting smoking, exercising regularly, losing excess weight, curtailing excessive alcohol consumption, controlling hypertension, and optimizing blood glucose levels in patients with diabetes are not only important for maintaining good health but also may improve or even prevent progression of erectile dysfunction. It is unclear if such lifestyle changes can reverse erectile dysfunction. However, lifestyle improvements may prevent progression of the erectile dysfunction. Some studies suggest that men who have made lifestyle improvements experience increased rates of success with oral medications.
While pills for ED are convenient, some men sustain stronger erections by injecting medication directly into the penis. Drugs approved for this purpose work by widening the blood vessels, causing the penis to become engorged with blood. Another option is inserting a medicated pellet into the urethra. The pellet can trigger an erection within 10 minutes.