All NOS subtypes produce NO, but each may play a different biologic role in various tissues. nNOS and eNOS are considered constitutive forms because they share biochemical features: They are calcium-dependent, they require calmodulin and reduced nicotinamide adenine dinucleotide phosphate for catalytic activity, and they are competitively inhibited by arginine derivatives. nNOS is involved in the regulation of neurotransmission, and eNOS is involved in the regulation of blood flow.

ICI therapy often produces a reliable erection, which comes down after 20-30 minutes or with climax. Since the ICI erection is not regulated by your penile nerves, you should not be surprised if the erection lasts after orgasm. The most common side effect of ICI therapy is a prolonged erection. Prolonged erections (>1 hour) can be reversed by a second injection (antidote) in the office.
A vacuum erection device helps draw blood into the penis by applying negative pressure. This type of device is sometimes referred to as penis pump and may be used just prior to sexual intercourse. Several types of FDA approved vacuum therapy devices are available under prescription. When pharmacological methods fail, a purpose-designed external vacuum pump can be used to attain erection, with a separate compression ring fitted to the base of the penis to maintain it. These pumps should be distinguished from other penis pumps (supplied without compression rings) which, rather than being used for temporary treatment of impotence, are claimed to increase penis length if used frequently, or vibrate as an aid to masturbation. More drastically, inflatable or rigid penile implants may be fitted surgically.
Recently, the US Food and Drug Administration (FDA) has issued a safety announcement regarding TRT. In part it reads ‘The benefit and safety of these medications have not been established. We are also requiring these manufacturers to add information to the labeling about a possible increased risk of heart attacks and strokes in patients taking testosterone.’37
Erectile dysfunction (previously called impotence) is the inability to get or maintain an erection that is sufficient to ensure satisfactory sex for both partners. This problem can cause significant distress for couples. Fortunately more and more men of all ages are seeking help, and treatment for ED has advanced rapidly. The enormous demand for “anti-impotence” drugs suggests that erection problems may be more common than was previously thought. Find out more about the causes and treatment of erectile dysfunction here.
Other factors leading to erectile dysfunction are diabetes mellitus, which is a well-known cause of neuropathy).[2] ED is also related to generally poor physical health, poor dietary habits, obesity, and most specifically cardiovascular disease, such as coronary artery disease and peripheral vascular disease.[2] Screening for cardiovascular risk factors, such as smoking, dyslipidemia, hypertension, and alcoholism is helpful.[2]
Ultimately, PDE5i have had a significant impact on the treatment of ED in men with SCI. The ease of use and tolerability of the medication has also led to improved satisfaction and quality of life that had been previously affected by SD. Head to head trials evaluating specific PDE5i within the SCI population are required to further elucidate drug preference. PDE5i should be considered first line therapy, however men with high thoracic and cervical lesions should be warned about an increased chance of dizziness with sildenafil and possibly other PDE5i use.
Diabetes. Erectile Dysfunction is common in people with diabetes. An estimated 10.9 million adult men in the U.S. have diabetes, and 35 to 50 percent of these men are impotent. The process involves premature and unusually severe hardening of the arteries. Peripheral neuropathy, with involvement of the nerves controlling erections, is commonly seen in people with diabetes.
Multiple combinations of intracavernosal therapy exist and the effectiveness of them varies based on patient characteristics and varying dosing strength (Table 1). Combination therapy have been extremely effective in the SCI population, and have several advantages including a reduction in cost per dose and side effects base on the lowered dose of each component (101,102). Effectiveness of combination therapy in the spinal cord population is well established, but no specific dose recommendations can be made based on the data (103-106). The use of combination therapy on other forms of neurogenic ED have not been well studied, but there use can be trialed as second-line therapy, or for populations were the side effects of PDE5i may preclude use such as in MSA due to hypotension.
Palmer MR, Holt SK, Sarma AV, Dunn RL, Hotaling JM, Cleary PA, Braffett BH, Martin C, Herman WH, Jacobson AM, Wessells H; Diabetes Control and Complications Trial and Epidemiology of Diabetes Interventions and Complications Research Group. Longitudinal Patterns of Occurrence and Remission of Erectile Dysfunction in Men With Type 1 Diabetes. J Sex Med. 2017 Oct;14(10):1187-1194. Doi: 10.1016/j.jsxm.2017.07.012. Epub 2017 Aug 26.
Then you have to be able to make the right diagnosis. What is the basis for their erectile dysfunction? Is it psychogenic? Is it some sort of neurological or blood vessel or hormonal issue? So you have to make a diagnosis. You have to be able to make an assessment. And then only after those things are done, then you start to think about medications.
Specially designed vacuum devices to produce erections have been used successfully for many years. Vacuum devices are safe, relatively inexpensive, and reliable. Vacuum devices do not require surgery. Vacuum devices are available over the counter or by prescription. It is important to make sure that the vacuum device have a mechanism to prevent too high of a vacuum (negative pressure).
Erectile dysfunction (ED) affects 50% of men older than 40 years, [4] exerting substantial effects on quality of life. [5] 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.
Soler et al. compared sildenafil to vardenafil and tadalafil (69). Sildenafil was effective in 85% of SCI patients, 74% of the patients on vardenafil and 72% of the patients on tadalafil. Sildenafil was associated with more rigid and longer lasting erections. Additionally, 50 mg of sildenafil was effective in 55% of patients compared to more than 70% of the patients on vardenafil and tadalafil requiring 20 mg for a similar response. Men who used tadalafil were able to achieve erections 24 hours after administration, improving overall satisfaction related to the possible spontaneity of sexual encounters. Del Popolo also evaluated the time/duration effectiveness of PDE5i sildenafil 50 mg versus tadalafil 10 mg (64). Tadalafil 10 mg significantly increased the percentage of successful intercourse attempts at 12–24 hours compared with sildenafil. One can suspect that vardenafil, which has a longer half-life than sildenafil, could offer a similar benefit but a study investigating this occurrence has yet to be performed.

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.


Physicians make a diagnosis of erectile dysfunction in men who complain of troubles having a hard enough erection or a hard erection that does not last long enough. It is important as you talk with your doctor that you be candid in terms of when your troubles started, how bothersome your erectile dysfunction is, how severe it is, and discuss all your medical conditions along with all prescribed and nonprescribed medications that you are taking. Your doctor will ask several questions to determine if your symptoms are suggestive of erectile dysfunction and to assess its severity and possible causes. Your doctor will try to get information to answer the following questions:
Vacuum pumps are effective in most men. Successful erections are achieved in up to 90% of men using the vacuum device, however only about 69% men continue to use the device for two years or longer. The most common cause of failure is improper use of or unfamiliarity with the device. Other drawbacks to the use of vacuum devices include the need to assemble the equipment and the difficulty in transporting it. Many men also lose interest in the device because of
Acupuncture may help treat psychological ED, though studies are limited and inconclusive. You’ll likely need several appointments before you begin to notice any improvements. When choosing an acupuncturist, look for a certified practitioner who uses disposable needles and follows U.S. Food and Drug Administration guidelines for needle disposal and sterilization.
The use of injection therapy requires being taught how to properly inject the medication, determination of the best dose, and monitoring for side effects. It is recommended that one inject on the side of the penis at the base and to alternate sides. Injection therapy should be used no more frequently than once every 24 hours. Individuals on blood thinners must be careful with use of injection therapy.
PDE 5 inhibitors are broken down primarily by enzyme, cytochrome P450enzyme CYP3A4. Medications that decrease or increase the activity of CYP3A4 may affect levels and effectiveness of PDE 5 inhibitors. Such drugs include medications for the treatment of HIV (protease inhibitors) and the antifungal medications ketoconazole and itraconazole. Thus caution is recommended.
You’ve probably heard of Viagra, but it’s not the only pill for ED. This class of drugs also includes Cialis, Levitra,  Staxyn, and Stendra. All work by improving blood flow to the penis during arousal. They're generally taken 30-60 minutes before sexual activity and should not be used more than once a day. Cialis can be taken up to 36 hours before sexual activity and also comes in a lower, daily dose. Staxyn dissolves in the mouth. All require an OK from your doctor first for safety.
×