The vacuum constriction device consists of a vacuum cylinder, various sizes of tension rings, and a vacuum pump, either hand-operated or electric. The penis is placed in a cylinder to which a tension ring is attached. Air is evacuated from the cylinder by means of the pump, creating a vacuum, which produces the erection. The cylinder is removed, leaving the tension ring at the base of the penis to maintain the erection.
The use of penile support device such as penile cast worn externally during intercourse has been tried to provide length and rigidity to the penile shaft (24). Each device can be customised to the patient’s penile size and provided an option for patients who are seeking non-pharmaceutical/non-invasive treatment, or have end-organ failure who may not be candidates for, or unable to afford, penile prosthesis implant.
Basaria S,  Coviello AD,  Travison TG,  Storer TW,  Farwell WR,  Jette AM,  Eder R,  Tennstedt S,  Ulloor J,  Zhang A,  Choong K,  Lakshman KM,  Mazer NA,  Miciek R,  Krasnoff J,  Elmi A,  Knapp PE,  Brooks B,  Appleman E,  Aggarwal S,  Bhasin G,  Hede-Brierley L,  Bhatia A,  Collins L,  LeBrasseur N,  Fiore LD,  Bhasin S. Adverse events associated with testosterone administration, N Engl J Med , 2010, vol. 36 (pg. 109-122)https://doi.org/10.1056/NEJMoa1000485
There are blood pressure medications that do not cause erectile dysfunction (ED). Some older blood pressure medications, especially beta blockers and thiazide diuretics, are the most likely to cause ED as a side effect. Better options include calcium channel blockers, which lower high blood pressure through a different mechanism. Don't just go off your medications, though; high blood pressure itself is a common cause of ED, so lowering your blood pressure is an important part of your ED treatment plan. And if you stop taking your blood pressure medications 'cold turkey', your blood pressure could actually sky rocket, putting you at risk for a heart attack or a stroke. Work with your doctor on ways to lower your blood pressure without lowering your sex drive.
Crossref | PubMed | Scopus (23) | Google ScholarSee all References, 73x73Rajagopalan, P, Mazzu, A, Xia, C, Dawkins, R, and Sundaresan, P. Effect of high-fat breakfast and moderate-fat evening meal on the pharmacokinetics of vardenafil, an oral phosphodiesterase-5 inhibitor for the treatment of erectile dysfunction. J Clin Pharmacol. 2003; 43: 260–267
Abstract | Full Text | Full Text PDF | PubMed | Scopus (95) | Google ScholarSee all References In conclusion, sildenafil, when used alone, seems to produce minimal decreases in blood pressure level, which are well tolerated in healthy patients and in those with stable ischemic coronary disease.3x3Zusman, RM, Morales, A, Glasser, DB, and Osterloh, IH. Overall cardiovascular profile of sildenafil citrate. Am J Cardiol. 1999; 83: 35C–44C
Despite the existing controversies, available data so far imply the old generation b-blockers (e.g., propranolol) as the major culprits for sexual dysfunction with the newer ones (carvedilol, celiprolol) to exert a less pronounced negative effect[21-24]. A luminous exception to the rule, nebivolol, is a newer agent of its class which significantly ameliorates erectile dysfunction through increased nitric oxide generation, an effect consistently demonstrated in recent studies[25,26]. Diuretics, even on adjunct therapy, constitute another antihypertensive agent negatively associated with sexual function[27-29]. On the other hand, calcium antagonists and angiotensin converting enzyme inhibitors seem to demonstrate a neutral effect[30-32]. Interestingly, angiotensin receptor blockers (ARBs) by blocking the vasoconstrictive action of angiotensin II seem to positively affect erectile function and are thus regarded as a first-line treatment in hypertensive patients with erectile dysfunction[22,25,33-35].
A study conducted by Prince Henry’s Institute in Melbourne Australia published in the Medical Journal of Australia found that men over 20 years of age with erectile dysfunction (ED) have twice the risk of cardiovascular incidents than those of men with normal sexual health. It was also found out that 2% of men aged 55 and older experienced major stroke and cardiac arrest after the initial episode of ED, within a year; 11% experienced something within five years.  Experts from Prince Henry’s Institute warned men with these failures to seek advice on erectile dysfunction and high blood pressure. This may indicate a missing vital warning sign of impending heart disease. Why is this happening? Do men with ED predispose themselves to have cardiovascular diseases and strokes or just the other way around?

“If a diabetic patient has erectile dysfunction, it’s not enough to provide Viagra [sildenafil] or Cialis [tadalafil] and then send him on his merry way,” J. Francois Eid, MD, a New York City urologist, said at the annual meeting of the American Association of Diabetes Educators. “It’s important to let individuals know the drug has not cured the erectile dysfunction. If patients don’t take care of the diabetes, the erectile dysfunction progresses.”
The initial step in evaluating ED is a thorough sexual history and physical exam. The history can help in distinguishing between the primary and psychogenic causes. It is important to explore the onset, progression, and duration of the problem. If a man gives a history of “no sexual problems until one night,” the problem is most likely related to performance anxiety, disaffection, or an emotional problem. Aside from these causes, only radical prostatectomy or other overt genital tract trauma causes a sudden loss of male sexual function.
Cardiovascular tolerance for sex is based on “functional reserve,” which corresponds to how closely the cardiovascular response to sex (in terms of heart rate, blood pressure level, and oxygen consumption) approaches the patient's peak response to exercise.85x85DeBusk, RF. Evaluating the cardiovascular tolerance for sex. Am J Cardiol. 2000; 86: 51F–56F
Age is a critical risk factor for the development of ED and endothelial dysfunction.4,5 ED is the most common condition occurring in middle-aged and older men.5 Kinsey et al. reported that 25 % of 65-year-old men and 75 % of ≥80-year-old men have ED.39 Moreover, ageing also decreases endothelial function, which is responsible for IHD.5 The incidence and severity of ED increases with age (a man aged 70 years is three-times more likely to have ED than a man aged 40 years).40
For many men, stopping smoking is an erectile dysfunction remedy, particularly when ED is the result of vascular disease, which occurs when blood supply to the penis becomes restricted because of blockage or narrowing of the arteries. Smoking and even smokeless tobacco can also cause the narrowing of important blood vessels and have the same negative impact. 
Abstract | Full Text | Full Text PDF | PubMed | Scopus (124) | Google ScholarSee all References This was a doubleblind, single-dose crossover study involving 41 men with stable coronary artery disease characterized by reproducible stable exertional angina. After taking either 10 mg of vardenafil or placebo, these men underwent treadmill exercise tolerance testing to 5 to 10 METs. Compared with placebo, vardenafil use did not result in a change in exercise treadmill time or time to first awareness of angina but significantly increased the time to ischemic threshold. At peak exercise levels, vardenafil did not cause a change in either heart rate or blood pressure level. This study concluded that 10 mg of vardenafil did not impair the ability of men with stable coronary artery disease to exercise at levels consistent with the exertion associated with sexual intercourse.
The medicine causes blood vessels to expand, increasing blood flow in the body and to the penis, thus helping patients to get an erection. Invasive surgeries that involve rods and balloons are also available to patients suffering from ED. While these treatments often come with potential side effects, discomfort and a financial burden, some ED patients may see success with them.

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.


Evaluation of functional capacity is the mainstay for the management of patients with ED.30 However, it should be kept in mind that in men with heart failure sexual activity may affect the heart differently from physical activity of similar METS due to differences in psychological anticipation and sympathetic activation.30,49 Cardiac echocardiography may offer valuable information for left ventricular performance and valvular function. For risk categories of heart failure patients and their management, please refer to Table 3 and Figure 5.
ED can be caused by many things. The most common causes in men with diabetes are problems related to blood vessel– and nerve-related complications. Sometimes, though rarely, ED can be caused by a hormonal imbalance. Depression can also cause ED, as can stress and excessive worrying about sexual performance. Certain medications can cause temporary ED.
Men with diabetes are at a higher risk of erectile dysfunction or impotence, especially if their diabetes is not well controlled. Erectile dysfunction means you cannot have an erection that is sufficient to perform sexual intercourse. Many men experience short-term episodes of erectile dysfunction but, for about one in 10 men, the problem may continue.
Erectile dysfunction can be a symptom of heart disease. An erection is caused by engorgement of blood into the penile tissues which later becomes rigid for penetration. Men with heart problem suffer from an inadequate blood flow to the smooth tissues of the penis to achieve erection. A major cardiovascular disease known as Atherosclerosis is a result of fat accumulation in the arterial blood vessels. This build up of multiple plaques or fatty material causes the arteries to narrow and harden thus limiting blood flow. The arteries supplying your penis are smaller than those supplying your heart. In fact, ED can be an initial symptom of heart diseases like Atherosclerosis. Cardiovascular problems can also damage penile nerves and arteries, inhibiting erectile function. Experts found a consistent link between ED and heart disease. Other recent research conducted by health professionals has shown a direct connection between erection dysfunctions and heart problems.
If you’re taking medication to treat blood pressure, depression, pain, allergies, inflammation, seizures, or heart conditions, you’re one of the tens of millions of people at risk for medically induced erectile dysfunction. It’s just the nature of drug side effects. Yet erectile dysfunction is one of the least talked about side effects of prescription medication.
Heart disease describes a range of conditions that affect your heart. Diseases under the heart disease umbrella include blood vessel diseases, such as coronary artery disease; heart rhythm problems (arrhythmias); and heart defects you’re born with (congenital heart defects), among others.The term “heart disease” is often used interchangeably with the term “cardiovascular disease.” Cardiovascular disease generally refers to conditions that involve narrowed or blocked blood vessels that can lead to a heart attack, chest pain (angina) or stroke. Other heart conditions such as those that affect your heart’s muscle, valves or rhythm, also are considered forms of heart disease.
Abstract | Full Text | Full Text PDF | PubMed | Scopus (207) | Google ScholarSee all References Adverse-effect profiles of headaches, flushing, rhinitis, and dyspepsia, without visual changes, mimic those of vardenafil.74x74Gresser, U and Gleiter, CH. Erectile dysfunction: comparison of efficacy and side effects of the PDE-5 inhibitors sildenafil, vardenafil and tadalafil—review of the literature. Eur J Med Res. 2002; 7: 435–446
A number of nonprescription products claim to be herbal forms of Viagra. Some of these products contain unknown amounts of ingredients similar to those in prescription medications, which can cause dangerous side effects. Some actually contain the real drug, which should be given by prescription only. Although the Food and Drug Administration has banned many of these products, some potentially dangerous erectile dysfunction remedies remain on the market.

The following products are considered to be alternative treatments or natural remedies for Erectile Dysfunction. Their efficacy may not have been scientifically tested to the same degree as the drugs listed in the table above. However there may be historical, cultural or anecdotal evidence linking their use to the treatment of Erectile Dysfunction.


If impotence affects you or someone you love, don’t lose hope. You may be suffering from a medical or emotional issue that is causing low libido or impotence — possibly interfering with both your confidence and relationship — but the good news is there are effective natural remedies for impotence that can help reverse this problem in most men. Around 70 percent of ED cases are resolved with natural impotence remedies that can help restore your sexual health.

Abstract | Full Text | Full Text PDF | PubMed | Scopus (66) | Google ScholarSee all References Although some case studies have reported a relationship between calcium channel blockers and ED, most studies suggest that this effect is minimal and that any relationship is likely secondary to a decrease in blood pressure with consequent reflex sympathetic activation.42x42Weiss, RJ. Effects of antihypertensive agents on sexual function. Am Fam Physician. 1991; 44: 2075–2082

Before taking any medication for erectile dysfunction, including over-the-counter supplements and herbal remedies, get your doctor's OK. Medications for erectile dysfunction do not work in all men and might be less effective in certain conditions, such as after prostate surgery or if you have diabetes. Some medications might also be dangerous if you:
Guidelines recommend that phosphodiesterase type 5 (PDE5) inhibitors are the first-line drug for the treatment of ED (Table 1). Sildenafil citrate was the first oral drug approved for ED in the US.59 The newer PDE5 inhibitors include vardenafil, tadalafil and avanafil. The inhibition of PDE5 enhances cyclic guanosine monophosphate (cGMP)-NO-mediated vasodilatation by preventing PDE5 catabolism of cGMP and so delaying detumescence. PDE5 inhibitors increase the number and duration of erections, as well as the percentage of successful sexual intercourse.60
Beta-blockers: A popular blood pressure medication that affects part of the nervous system in an attempt to slow and regulate heartbeats, helping reduce blood pressure. Unfortunately, this same part of the nervous system is also responsible for causing erections, and when beta blockers are used, it indirectly reduces the amount of blood flow to the penis.
Apart from their beneficial effect in erectile dysfunction and their safe profile in antihypertensive medication, PDE-5 inhibitors have even more advantages to demonstrate. Several lines of evidence has proven that patients receiving PDE-5 inhibitors are more likely to initiate an antihypertensive regime and more willing to add a new agent to their existing treatment, a fact that raises significantly patient’s adherence and as a matter of fact control of high blood pressure and quality of life[63,64]. Moreover, a handful of clinical data has demonstrated the considerable vasodilating and anti-proliferative properties of PDE-5 inhibitors in the pulmonary vasculature, establishing them as a first-line treatment in patients with pulmonary arterial hypertension[65,66]. The same properties have been considered as potentially responsible for improving microcirculation in patients with secondary Raynaud phenomenon and ameliorating cardiopulmonary exercise performance in patients with heart failure[67,68]. In addition, the therapeutic implementation of PDE-5 inhibitors has expanded in the field of benign prostate hyperplasia-lower urinary tract symptoms (BPH-LUTS). The common pathophysiologic substrate between erectile dysfunction and BPH-LUTS has rendered PDE-5 inhibitors an effective treatment which significantly improves measures of both conditions while at the same time exhibits high efficacy and safety. The beneficial effect is much more pronounced when taking into consideration the fact that a-blockers, the mainstay of therapy for benign prostate hyperplasia frequently provoke sexual side effects, erectile dysfunction included[69].
If the cause is believed to be organic but not hormonal, or if the patient defers psychological intervention, he can be offered the VCD or oral drug therapy. EDDM patients on organic nitrates or who have experienced or are concerned about potential adverse reaction to PDE-5 inhibitors are suitable candidates for the VCD. The VCD induces functional rigidity in 75% of patients with diabetes with autonomic neuropathy. Some patients or their partners may reject or discontinue the use of the VCD because it induces an unnatural erection, causes bruising and numbness of the penis, and or inhibits antegrade ejaculation.8
Erectile dysfunction is common in the patient with cardiovascular disease. It is an important component of the quality of life and it also confers an independent risk for future cardiovascular events. The usual 3-year time period between the onset of erectile dysfunction symptoms and a cardiovascular event offers an opportunity for risk mitigation. Thus, sexual function should be incorporated into cardiovascular disease risk assessment for all men. A comprehensive approach to cardiovascular risk reduction (comprising of both lifestyle changes and pharmacological treatment) improves overall vascular health, including sexual function. Proper sexual counselling improves the quality of life and increases adherence to medication. This review explores the critical connection between erectile dysfunction and cardiovascular disease and evaluates how this relationship may influence clinical practice. Algorithms for the management of patient with erectile dysfunction according to the risk for sexual activity and future cardiovascular events are proposed.
Abstract | Full Text | Full Text PDF | PubMed | Scopus (66) | Google ScholarSee all References However, some researchers have questioned whether the strain of sexual activity can be compared accurately with standard types of physical activity and whether sexual activity is more closely related to episodes of anger or fear.85x85DeBusk, RF. Evaluating the cardiovascular tolerance for sex. Am J Cardiol. 2000; 86: 51F–56F
If the cause is believed to be organic but not hormonal, or if the patient defers psychological intervention, he can be offered the VCD or oral drug therapy. EDDM patients on organic nitrates or who have experienced or are concerned about potential adverse reaction to PDE-5 inhibitors are suitable candidates for the VCD. The VCD induces functional rigidity in 75% of patients with diabetes with autonomic neuropathy. Some patients or their partners may reject or discontinue the use of the VCD because it induces an unnatural erection, causes bruising and numbness of the penis, and or inhibits antegrade ejaculation.8
Not surprisingly, they found that diabetic patients rated kidney disease and blindness as the two most important complications of their condition. Diabetic men with ED ranked ED as the third most important complication of diabetes, followed on average in order by foot ulcers, high blood pressure, high cholesterol, migraine headaches, sleeping disorders, and mild indigestion. Diabetic men without ED found ED slightly less important, ranking it behind foot ulcers and high blood pressure, although all three were grouped fairly close together (mean ranks were 4.59, 4.23, and 4.52, respectively). Interestingly, in men both with and without ED, subjects were willing to pay more per month to avoid ED than all other conditions except blindness and kidney disease (mean values for diabetic patients with ED were £50.5, £88.0, and £66.1, respectively). In summary, erectile function is important to diabetic men, and when ED is present, it has a significant negative effect on quality of life.
The third Princeton Consensus (Expert Panel) Conference recommends assessing cardiovascular risk in all patients with ED and CVD. This refers to estimating the risk of mortality and morbidity associated with sexual activity. The current recommendations classify patients into low-, intermediate- and high-risk, based on their New York Heart Association class.57 The consensus also recommended that all patients with ED and CVD should undergo lifestyle changes, such as exercise, smoking cessation, healthy diet and weight reduction. These measures are likely to reduce cardiovascular risk and improve erectile function.58

Crossref | PubMed | Scopus (174) | Google ScholarSee all References All these men had ED and twice underwent symptom-limited supine bicycle exercise echocardiography 1 hour after taking either sildenafil (50 mg or 100 mg) or placebo. This study found no significant changes in resting heart rate, diastolic blood pressure level, or wall motion score index, and the exercise capacity of the 2 groups was similar. Both groups had similar numbers of patients who experienced dyspnea and/or chest pain, had a positive exercise echocardiographic test, and had exercise-induced wall motion abnormalities. Sildenafil caused a mean decrease of 7 mm Hg in the resting systolic blood pressure level compared with the placebo group. In conclusion, this study showed that in patients with stable coronary artery disease, sildenafil caused no change in symptoms, exercise endurance, or presence/extent of exercise-induced ischemia as measured by exercise echocardiography.
Third, men with Diabetes need to control their blood sugar levels. When your blood sugar is not under control, your body does not produce enough Nitric Oxide (NO) and vascular tissues don’t respond as effectively to NO. When enough blood flows into the penis, penile veins close off and block the blood from flowing out. This process results in an erection. If your body does not produce enough NO or if your penile tissues do not respond to NO, the pressure of the blood flowing into your penis is not sufficient to trap the blood, you penis will not get hard.
Crossref | PubMed | Scopus (335) | Google ScholarSee all References Additionally, the presence of nephropathy has been correlated with onset of ED, as has the length of time the patient has had diabetes; most of these patients experience ED within 10 years of being diagnosed as having insulin-dependent or non–insulin-dependent diabetes mellitus.4x4Feldman, HA, Goldstein, I, Hatzichristou, DG, Krane, RJ, and McKinlay, JB. Impotence and its medical and psychosocial correlates: results of the Massachusetts Male Aging Study. J Urol. 1994; 151: 54–61

Abstract | Full Text PDF | PubMed | Scopus (3562) | Google ScholarSee all References By 1996, fueled by the availability of the new oral agent sildenafil, the number of outpatient visits for ED as estimated by the National Ambulatory Medical Care Survey had increased to 1.3 million per year.5x5Feldman, HA, Johannes, CB, Derby, CA et al. Erectile dysfunction and coronary risk factors: prospective results from the Massachusetts Male Aging Study. Prev Med. 2000; 30: 328–338
When it comes to combating heart disease, most information sources promote drugs and surgery as the only viable options, with lip service to dietary advice that simply does not work. As a result, the demand for high-tech, expensive, but largely ineffective medical care is soaring, causing medical costs and insurance rates to skyrocket. This chase for "cures" is both financially devastating and futile. Morbidity and premature mortality from heart disease continue to rise, with no sign of abating.
Abstract | Full Text | Full Text PDF | PubMed | Scopus (95) | Google ScholarSee all References Rates of severe cardiovascular adverse effects were also similar at 1.7 per 1000 person-years of treatment with sildenafil compared with 1.0 events per 1000 personyears with placebo treatment.10x10Kloner, RA and Zusman, RM. Cardiovascular effects of sildenafil citrate and recommendations for its use. Am J Cardiol. 1999; 84: 11N–17N
Most importantly, herbal supplements are not well regulated in the United States.  Studies have shown that 40-50% of herbal supplements do not even contain the supposed main ingredient, and many contain substances that are not listed which may have dangerous side effects2.  Another study found that over two thirds of the products tested had substituted other plant species for the plants listed on the label, and a third of products also contained other fillers or contaminants3.  A study by the New York State Attorney General of herbal products sold at GNC, Target, Walgreens, and Walmart found that four out of every five products didn’t contain the ingredient they claimed!  Fourteen US states and territories have petitioned Congress to regulate the herbal supplements industry.
According to Harvard Special Health Report Erectile Dysfunction, one study in the European Heart Journal looked at men newly diagnosed with heart disease, but without ED, who started treatment with the beta-blocker atenolol (Tenormin). Some of the study participants were told about the sexual side effect of the blood pressure drug, and ED was reported by almost one-third of the participants. In contrast, among those who were not told the drug's name or its side effects, only 3% said they experienced ED.
Penile implants - are generally used if physical damage (like an accident) makes the anatomical parts needed for an erection not work. These are inserted by surgery and can provide a permanent treatment choice if others fail to work. The implants can be semi-rigid or inflatable. They can be pretty expensive and are not usually available on the NHS.

Abstract | Full Text | Full Text PDF | PubMed | Scopus (259) | Google ScholarSee all References Sildenafil should be used with caution in patients with liver dysfunction or renal impairment, as well as in patients taking any medications that inhibit the P-450 pathway such as cimetidine or erythromycin.3x3Zusman, RM, Morales, A, Glasser, DB, and Osterloh, IH. Overall cardiovascular profile of sildenafil citrate. Am J Cardiol. 1999; 83: 35C–44C


The drugs you take to lower your blood pressure may earn you lower marks in the bedroom, by leading to a bout of erectile dysfunction (ED), or the inability to get or maintain an erection during sex. High blood pressure medications such as beta blockers and diuretics do their life-saving job by lessening blood flow to your vital organs—and that includes down under. Less blood flow means no erection. The good news for guys is that not all high blood pressure medication cause ED. Talk with your doctor about switching to the ones that don't.
However, sildenafil should be used carefully with nitrates because their combination can result in severe hypotension and death.68 Both short- and long-acting nitrates are commonly prescribed to treat angina, but they have no prognostic benefit. In addition, there are numerous alternatives to treat angina, such as ranolazine and ivabradine, which do not interact with PDE5 inhibitors. As a result, patients with ED wishing to take PDE5 inhibitors can safely discontinue their nitrates and replace this treatment with the other anti-anginal agents.68
Abstract | Full Text | Full Text PDF | PubMed | Scopus (46) | Google ScholarSee all References Sedentary patients with a history of cardiac disease and patients with unstable angina or advanced congestive heart failure should undergo a full medical evaluation before resuming sexual activity.80x80Muller, JE. Triggering of cardiac events by sexual activity: findings from a case-crossover analysis. Am J Cardiol. 2000; 86: 14F–18F
Abstract | Full Text | Full Text PDF | PubMed | Scopus (95) | Google ScholarSee all References Rates of severe cardiovascular adverse effects were also similar at 1.7 per 1000 person-years of treatment with sildenafil compared with 1.0 events per 1000 personyears with placebo treatment.10x10Kloner, RA and Zusman, RM. Cardiovascular effects of sildenafil citrate and recommendations for its use. Am J Cardiol. 1999; 84: 11N–17N
PubMed | Google ScholarSee all References However, other studies have noted that, when blood pressure levels are monitored after initiation of antihypertensive therapy, changes in blood pressure level are not correlated with sexual function.38x38Rosen, RC, Kostis, JB, Jekelis, A, and Taska, LS. Sexual sequelae of antihypertensive drugs: treatment effects on self-report and physiological measures in middle-aged male hypertensives. Arch Sex Behav. 1994; 23: 135–152
Crossref | PubMed | Scopus (1) | Google ScholarSee all References Angiotensin-converting enzyme inhibitors also have low rates of secondary ED associated with their use in both animal and human studies.45x45Srilatha, B, Adaikan, PG, Arulkumaran, S, and Ng, SC. Sexual dysfunction related to antihypertensive agents: results from the animal model. Int J Impot Res. 1999; 11: 107–113

Current American College of Cardiology/American Heart Association guidelines quote an absolute contraindication to sildenafil use in the setting of chronic nitrate treatment or the use of short-acting nitrate medications.10x10Kloner, RA and Zusman, RM. Cardiovascular effects of sildenafil citrate and recommendations for its use. Am J Cardiol. 1999; 84: 11N–17N
Relaxation of erectile tissue requires nitric oxide from nonadrenergic-noncholinergic neurons and the endothelium.21 Penile tissue from diabetic men with ED demonstrates impaired neurogenic and endothelium-mediated relaxation of smooth muscle,22 increased accumulation of advanced glycation end products (AGEs),23 and upregulation arginase, a competitor with nitric oxide synthase for its substrate L-arginine.24 Normal responses to direct smooth muscle relaxants in most of these studies implies that the impairments are due to decreased synthesis, release, or activity of nitric oxide. The fundamental mechanisms mediating these changes are thought to be the same as for other diabetic complications: increased polyol pathway flux, intracellular accumulation of AGEs, activation of protein kinase C, and increased flux through the hexosamine pathway.25
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