A deficiency of L-arginine, however, does not generally disrupt nitric oxide synthesis because L-arginine availability is not the rate-limiting step in this process. In fact, research over the past five years has identified an endogenous (occurs in the body naturally) inhibitor called “asymmetric dimethylarginine” or ADMA, an amino acid which blocks the production of nitric oxide. By acting as an L-arginine mimic, this damaging look-alike effectively elbows out L-arginine and pushes it off to the side in the biochemical pathway leading to the synthesis of nitric oxide. ADMA is relatively elevated in patients with hypertension, high levels of cholesterol, triglycerides, homocysteine and low-density lipoprotein (LDL), and low levels of high-density lipoprotein (HDL), as well as with aging itself. This inhibitor of nitric oxide synthesis may very well be the common factor shared by all of these abnormal conditions. Increased levels of this detrimental inhibitor (ADMA) block nitric oxide production, leading to endothelial dysfunction.
In subsequent clinical studies, a surprisingly high percentage of EDDM patients–10% to 20%–claimed that the placebo "improved my erections," thus indicating a psychological basis for their ED. In the latter half of the 1980s, objective means were developed that could help determine if a EDDM patient had organic or psychogenic ED. The absence of rigid sleep erections confirmed by penile monitors was one criterion for organic ED. The failure of vasoactive agents (papaverine, Trimix, or prostaglandin E-1 [PGE-1]) injected into the corpora cavernosa to induce penile rigidity was another criterion for organic disease. Intracavernosal maintenance flow rates during pharmacocavernosometry and maximum cavernosal arterial flow during penile Doppler ultrasonography were additional determinants.
Diaclina (also known as Panzer’s Darkling Beetle), Korean bug are used as aphrodisiacs in China, Korea and Southeast Asia. These are consumed either whole or as compounds within capsules. It is felt that the aphrodisiac properties come by stimulating the urogenital structures. Flies have been studied for their aphrodisiac effects, including Spanish fly, Chinese cantharide, and Eastern-Indian cantharide (32). The active compound found in the dried and mashed up bodies of these flies is cantharidin, which is a pheromone produced in the accessory glands of the male flies’ genitals. Cantharidin, stimulates the urogenital tract, causing pelvic hyperemia and possibly erections. As cantharidin is toxic and its safety dose not well determined, its use cannot be recommended. Cantharidin is lethal at high doses and exposure can lead to gastrointestinal and urogenital hemorrhage as well as acute renal failure.
Red Ginseng — One small randomized trial found evidence that red ginseng may offer modest improvements in ED symptoms (as compared with placebo). A meta-anaylsis published in the British Journal of Clinical Pharmacology states, “Traditionally red ginseng has been used to restore and enhance normal well-being, and is often referred to as an adaptogenic….Possible mechanisms of action of red ginseng include hormonal effects similar to those of testosterone. Others have postulated that red ginseng might induce relaxation of the smooth muscles.”  (5)
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

There are other treatment options for erectile dysfunction (ED). Alprostadil is a medication that improves blood flow to the penis and improves erections. It can be given either by injection (Caverject and other brands) at the base of the penis or by putting an alprostadil gel (brand name MUSE) directly into the urethra, using a thin tube and a little lubricant so it slides in easily. The medicine is absorbed from the lining of the urethra into the surrounding tissues. The shot is less appealing to most people, of course, but more effective.
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
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Erection is a neurovascular event that involves spinal and supra spinal pathways. The final common pathway involves the release of nitric oxide (NO) from both endothelial cells and neurons, which acts as a vasodilator causing penile engorgement and erection. NO is degraded by the enzyme phosphodiesterase (PDE) type 5 in the penis. Erectile dysfunction (ED), defined as the persistent inability to achieve and/or maintain an erection sufficient for satisfactory sexual performance, results when the neurovascular pathway is interrupted by medical conditions or drugs. A 15-item self-administered questionnaire, the International Index of Erectile Function (IIEF), is one of the most useful tools to evaluate erectile function (EF) in clinical trials, although of much less use in routine clinical practice. The MMAS (Massachusetts Male Aging Study) was the first major epidemiological investigation to study the prevalence of ED. The study found that ED was three times more common in patients with diabetes mellitus. The aetiopathogenesis of ED in diabetes is multifactorial, with vascular and neural factors being equally implicated. Hyperglycaemia is believed to give rise to biochemical perturbations that lead to these microvascular changes. In the MMAS, ED in diabetes was strongly correlated with glycaemic control, duration of disease and diabetic complications. The incidence increased with increasing age, duration of diabetes and deteriorating metabolic control, and was higher in individuals with type 2 diabetes than those with type 1.ED in men with diabetes often affects their quality of life and, as patients are often reluctant to come forward with their symptoms, a carefully taken history is one of the most useful approaches in identifying affected individuals. The PDE inhibitors have revolutionised the management of ED and oral drug therapy is currently first-line therapy for the condition. These agents act by potentiating the action of intracavernosal NO, thereby leading to a more sustained erection. Sildenafil was the first PDE5 inhibitor to undergo evaluation and has been studied extensively. More recently two other agents, vardenafil and tadalafil, have been introduced. All the drugs have been shown to be effective across a wide range of aetiologies of ED, including diabetes. The drugs have been shown to improve EF domain scores, penetration and maintenance of erection, resulting in more successful intercourse. Their effects are greater at higher doses. Sildenafil and vardenafil are shorter-acting agents, while tadalafil has a longer half-life allowing the user more flexibility in sexual activity. Common adverse effects include headache, nasal congestion and dyspepsia, all actions related to inhibition of PDE5. The drugs are generally well tolerated and withdrawal from the clinical studies as a result of drug-related adverse effects were rare. The use of PDE5 inhibitors in the presence of oral nitrates is absolutely contraindicated. The clinical studies to date have not evaluated the use of one drug in the case of treatment failure with another agent. Sublingual apomorphine, which stimulates central neurogenic pathways, is a new agent and may be a suitable alternative in those patients in whom PDE5 inhibitors are ineffective or contraindicated. In clinical trials, all IIEF domains except sexual desire were found to have improved after apomorphine. The median times to erection in these studies were 18.9 and 18.8 minutes for the 2 and 3mg doses, respectively. Intraurethral and intracavernosal alprostadil may be a useful alternative when oral drug therapy is ineffective or contraindicated. The management of ED in the diabetic patient may often involve a multidisciplinary approach where psychosexual counselling and specialist urologist advice is required in addition to the skills and expertise of the diabetologist. Finally, the introduction of the new oral agents have completely revolutionised the management of ED and allowed more individuals to come forward for treatment.
Luckily, awareness of ED as a significant and common complication of diabetes has increased in recent years, mainly because of increasing knowledge of male sexual function and the rapidly expanding armamentarium of novel treatments being developed for impotence. Studies of ED suggest that its prevalence in men with diabetes ranges from 35–75% versus 26% in general population. The onset of ED also occurs 10–15 years earlier in men with diabetes than it does in sex-matched counterparts without diabetes.
In DM patients with a documented androgen deficiency, testosterone replacement may correct or facilitate the treatment of ED.7 A transdermal testosterone gel or patch, or intramuscular testosterone cypionate are the alternatives. Oral testosterone is contraindicated in the United States due to hepatotoxicity, but a new product has been developed that allows for buccal absorption of testosterone. Thyroid supplements rarely alleviate EDDM.
Figure. Progression of atherosclerosis. Endothelial dysfunction occurs early in atherosclerosis and prevents blood vessels from dilating properly. When the blood vessels that supply the penis are not able to dilate during sexual stimulation because of endothelial dysfunction, the penis cannot fill with blood, and the man develops erectile dysfunction. As atherosclerosis progresses, plaques build up in blood vessels and blood flow is slowed, further worsening erectile function. A heart attack occurs when an atherosclerotic plaque in a coronary artery ruptures, a blood clot forms over the plaque, and blood flow to the heart muscle is completely blocked. Atherosclerotic risk factors (black arrows) worsen cardiovascular health; modification of these risk factors (red arrows) improves cardiovascular health.
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.
A considerable number of patients with ED can have psychogenic factors as the only cause, or in combination with organic causes of ED. Depression, low self-esteem and social stresses are among the psychogenic factors that can lead to ED. Depression is an independent risk factor for both ED and IHD; these three disease conditions are interlinked.51 Psychogenic ED can be managed by multiple psychological interventions such as cognitive behavioural therapy, couples counselling and guided sexual stimulation techniques.52
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.
To understand what happens in ED, it's helpful to know some anatomical basics. When aroused by either sensory or mental stimuli, the brain sends a signal through the nerves to the penis, causing the muscles there to relax. This opens up space for blood to flow in and engorge the penis. A membrane within the penis traps blood inside to help maintain the erection, which subsides when the penile muscles contract, forcing blood back into the rest of the body. Any number of things can go wrong in this process, leading to erectile dysfunction.
Crossref | PubMed | Google ScholarSee all References These hormonal findings were supported by a study of 1132 men aged 30 to 79 years that found an inverse relationship between blood pressure and serum testosterone levels.32x32Khaw, KT and Barrett-Connor, E. Blood pressure and endogenous testosterone in men: an inverse relationship. J Hypertens. 1988; 6: 329–332
Abstract | Full Text | Full Text PDF | PubMed | Scopus (66) | Google ScholarSee all References However, α-blockers are a well-known cause of retrograde ejaculation secondary to a reversible relaxation of bladder neck smooth muscle.50x50Meinhardt, W, Kropman, RF, Vermeij, P, Nijeholt, AA, and Zwartendijk, J. The influence of medication on erectile function. Int J Impot Res. 1997; 9: 17–26

According to the Cleveland Clinic, “because erectile dysfunction is caused by a complex set of psychosocial, neurologic, and vascular factors, a specific cause in a patient may remain ambiguous.” The root causes are often related to a blockage or dysfunction of blood vessels. For example, ED can be due to conditions like atherosclerosis or diabetes, hormonal imbalances or problems related to mental health. It’s been found that common causes typically include one or more of the following factors: (2)
SOURCES: American Urological Association, "AUA Guideline on the Management of Erectile Dysfunction: Diagnosis and Treatment Recommendations." Barksdale, J. Pharmacotherapy, May 1999; vol 19: pp 573-581. Ferrario, C. Journal of Clinical Hypertension, November/December 2002; vol 4: pp 424-432. Fogari, R. American Journal of Hypertension, January 2001; vol. 14: pp 27-31. Grimm, R. Hypertension, January 1997; vol 29: pp 8-14. Llisteri, J. American Journal of the Medical Sciences, May 2001; vol. 321: pp 336-341. WebMD Medical Reference provided in collaboration with The Cleveland Clinic: "Hypertension: Treatment With ACE Inhibitors."
There are currently two models of the inflatable penile prosthesis (IPP), namely, the two-piece IPP vs. the three-piece IPP. The three-piece IPP consists of a pair of corporal cylinders, a scrotal pump and an abdominal reservoir filled with saline. Owing to the presence of the reservoir, the corporal cylinders can be completely deflated to give the patient the physiological flaccid state when not in use, and likewise a maximally turgid state when inflated (21). The two-piece IPP lacks an abdominal reservoir and is often offered in patients with whom placement of reservoir is challenging or not possible such as following radical cysto-prostatectomy with orthotopic ileal neobladder creation, or patients who had previous open book fracture of the pelvis with metal implants. The concept of ectopic reservoir placement has allowed many of these men the option for three-piece IPP placement (22). Technological advances have improved mechanical reliability, reduced prosthesis infection risk and offered excellent patient and partner satisfaction rate (23).
Bohm M,  Baumhakel M,  Teo K,  Sleight P,  Probstfield J,  Gao P,  Mann JF,  Diaz R,  Dagenais GR,  Jennings GL,  Liu L,  Jansky P,  Yusuf S. ONTARGET/TRANSCEND Erectile Dysfunction Substudy InvestigatorsErectile dysfunction predicts cardiovascular events in high-risk patients receiving telmisartan, ramipril, or both: The ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial/Telmisartan Randomized AssessmeNt Study in ACE iNtolerant subjects with cardiovascular Disease (ONTARGET/TRANSCEND) Trials, Circulation , 2010, vol. 121 (pg. 1439-1446)https://doi.org/10.1161/CIRCULATIONAHA.109.864199
Abstract | Full Text | Full Text PDF | PubMed | Scopus (53) | Google ScholarSee all References Early work in this field, performed by Masters and Johnson in 1966, involved evaluation of young patients in a laboratory setting and found that heart rates and systolic blood pressure levels during sexual activity approached levels seen during maximal exercise.84x84Stein, RA. Cardiovascular response to sexual activity. Am J Cardiol. 2000; 86: 27F–29F
Unfortunately, government agencies often are slow to respond to new scientific information and economic and political forces make it difficult for our population to receive clear information informing them that heart disease is nutritionally induced and totally avoidable with dietary excellence. Sadly, even the American Heart Association advocates a diet that has been shown to actually increase heart disease.
It's an all too common problem: Roughly half of men with diabetes—and up to 25 percent of men overall—experience erectile dysfunction (ED) at some point in their lives. And it's a complicated problem, too, with diverse physical origins and complex emotional ramifications. Yet diabetes-related ED needn't be a no-sex sentence for men. There are ways to avoid this disorder and to treat it at any age. While much of the research on ED is still in its infancy, here is what science has to say so far.
ED is easily and successfully treated! If your sex drive is unaffected, but you experience problems achieving or sustaining erection for a period of four to five weeks, you may have ED. Talk to your doctor immediately. Don’t delay—erectile dysfunction doesn’t “just go away!” Additionally, ED could be a sign of a serious, even life-threatening complication, such as congestive heart failure or kidney disease. Ignoring your ED because it’s embarrassing could jeopardize your health.
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