The development of PDE5-inhibitors is a clear example of how Western medicine approached the problem of ED differently from Eastern medicine. The erectogenic effect of sildenafil (Viagra®) was discovered by accident when patients undergoing heart clinical trials reported better erections as a side effect after taking sildenafil. This observation led to further elucidation of the NO/cGMP signalling pathway and development of PDE5-inhibitors as a first-line therapy in ED (5).
In men without cardiovascular disease, erectile dysfunction (ED) pills are very safe. The three rivals -- Viagra, Cialis, and Levitra -- have similar side effects, including headache, facial flushing, nasal congestion, diarrhea, backache, and, in a few Viagra or Levitra users, temporary impaired color vision (men with retinitis pigmentosa, a rare eye disease, should check with their ophthalmologists before using these medications).
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.
PDE-5 inhibitors amplify the intacavernosal production of cGMP in response to nitric oxide. This is achieved through the inhibition of cGMP's breakdown by the enzyme, PDE-5. If the predominant abnormality in the individual EDDM patient is molecular, the higher tissue levels of cGMP will overcome these inhibitory factors and the patient will regain erectile function. If the physical structure (eg, the compliance) of the cavernosal tissue has been significantly compromised by apoptosis of smooth muscle or increased collagen deposits, restoration of erectile function will not be achieved. These structural changes explain the lower efficacy rates of PDE-5 inhibitors in EDDM than in the general population.

Abstract | Full Text | Full Text PDF | PubMed | Scopus (30) | Google ScholarSee all References Erections result from relaxation of the corpora cavernosa, which is mediated either by increasing intracellular cyclic guanosine monophosphate (cGMP) or cyclic adenosine monophosphate or by inhibition of their degradation. Increased parasympathetic tone results in a decrease in norepinephrine release and an increase in the release of acetylcholine; subsequently, NO synthase activity increases, which releases NO from both endothelial cells and nonadrenergic, noncholinergic neurons.10x10Kloner, RA and Zusman, RM. Cardiovascular effects of sildenafil citrate and recommendations for its use. Am J Cardiol. 1999; 84: 11N–17N


More than 11 million people in the United States have cardiovascular disease, and each year, about 500,000 survive a myocardial infarction. These patients often seek counseling on their relative risk of resuming sexual activity. In the past, it was often assumed that if a patient could climb 2 flights of stairs without symptoms, it was safe for the patient to engage in sexual activity.82x82Hellerstein, HK and Friedman, EH. Sexual activity and the postcoronary patient. Arch Intern Med. 1970; 125: 987–999
Most studies into the effect of beta-blockers on ED point to negative effects of first- and second-generation beta-blockers, while beta-blockers with vasodilating effects can improve erectile function. Alpha-blockers, calcium channel blockers, and angiotensin-converting enzyme inhibitors seem to have a neutral effect on erectile function. Multiple previous studies have demonstrated a beneficial effect of angiotensin receptor blockers on erectile function and they should probably be the favoured antihypertensive agents in patients with ED.29
The causes of ED are numerous but generally fall into two categories: organic or psychogenic. The organic causes can be subdivied into five categories: vascular, traumatic/postsurgical, neurological, endocrine-induced, and drug-induced. Examples of the psychogenic causes are depression, performance anxiety, and relationship problems. In people with diabetes, the main risk factors are neuropathy, vascular insufficiency, poor glycemic control, hypertension, low testosterone levels, and possibly a history of smoking.
There are two kinds of penis implants. One kind is a rigid but flexible rod implanted in the penis. You bend it up for sex or down for daily living. The other kind is an inflatable implant. The device stores fluid in a reservoir under the skin of your abdomen or scrotum. You press on the reservoir to pump fluid into cylinders in the penis. That creates an erection. A valve drains the fluid out of the penis when you're done.

Crossref | PubMed | Scopus (53) | Google ScholarSee all References A study of 24 patients with ED and untreated essential hypertension showed decreased levels of free and total serum testosterone compared with normal controls.31x31Hughes, GS, Mathur, RS, and Margolius, HS. Sex steroid hormones are altered in essential hypertension. J Hypertens. 1989; 7: 181–187

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

PubMed | Google ScholarSee all References They evaluated 40 patients with coronary artery disease who underwent coronary artery catheterization and whose penile brachial index (PBI) was measured by Doppler ultrasonography. Although a positive correlation was noted between the PBI and the severity of coronary artery obstruction, the relationship was not strong. Also, the degree of PBI abnormality did not effectively stratify the patients according to the severity of their coronary artery blockage. This study concluded that the PBI used alone would not be an effective predictor of ischemic heart disease.


Table 3Metabolic Equivalent (MET) Values for Various Physical Activities56x56Wallis, RM, Corbin, JD, Francis, SH, and Ellis, P. Tissue distribution of phosphodiesterase families and the effects of sildenafil on tissue cyclic nucleotides, platelet function, and the contractile responses of trabeculae carneae and aortic rings in vitro. Am J Cardiol. 1999; 83: 3C–12C
Medicines known as PDE5 inhibitors can help two-thirds of men with ED. These include Viagra (sildenafil), Cialis (tadalafil) and Levitra (vardenafil). You may need to take several doses over time before they work properly, and you may need to adjust the dose. National guidelines say you can be prescribed these drugs from six months after a heart attack, providing your condition is stable.
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.
Ginkgo biloba. Known primarily as a treatment for cognitive decline, ginkgo has also been used to treat erectile dysfunction -- especially cases caused by the use of certain antidepressant medications. But the evidence isn't very convincing. One 1998 study published in the Journal of Sex & Marital Therapy found that it did work. But a more rigorous study, published in Human Pharmacology in 2002, failed to replicate this finding. "Ginkgo has come out of fashion in the past few years," says Ronald Tamler, MD, assistant professor of medicine and codirector of the men's health program at Mount Sinai Medical Center in New York City. "That's because it doesn't do much. I can say that in my practice, I have not seen ginkgo work -- ever."
Since time immemorial, TCM has been adopted by many cultures and is widely practiced in Asian countries despite paucity of level 1 clinical evidence and limited published safety records. TCM is more congruent with Asian values, beliefs and philosophical orientation to health, simple administration, readily available and ease of access or procurement, and general belief that TCM is safer. While Asian males are clearly different from their Western counterparts with respect to biology, culture and beliefs, the practice of TCM appears to be adopted by many Western nations lately. Many men seek TCM to avoid embarrassing visits to physicians and potential side effects of pharmaceutical drugs, or after becoming frustrated with the outcome of modern medicine. Patients are choosing to take more responsibility for their health by exploring a variety of non-pharmaceutical drugs and wellness practices. Furthermore, TCM such as herbal medicine does not address a specific organ system only and is meant to restore and realign the vital energy within the body, which is responsible for ageing, clinical diseases and the deterioration of bodily function; while in Western medicine, each pill is intended for a specific organ/system and that a patient may need a collection of pills to treat multiple comorbidities, rendering modern medicine less attractive to TCM.
The common associations between cardiovascular disease and ED have led some researchers to explore whether onset of ED can be an effective predictor of the presence of cardiovascular disease. A study of 40 patients with cardiac disease found an association between sexual dysfunction and the presence of cardiovascular disease, as well as a correlation between the severity of ED and the number of coronary arteries with extensive atherosclerosis.16x16Greenstein, A, Chen, J, Miller, H, Matzkin, H, Villa, Y, and Braf, Z. Does severity of ischemic coronary disease correlate with erectile function?. Int J Impot Res. 1997; 9: 123–126
Gazzaruso C,  Solerte SB,  Pujia A,  Coppola A,  Vezzoli M,  Salvucci F,  Valenti C,  Giustina A,  Garzaniti A. Erectile dysfunction as a predictor of cardiovascular events and death in diabetic patients with angiographically proven asymptomatic coronary artery disease: a potential protective role for statins and 5-phosphodiesterase inhibitors, J Am Coll Cardiol , 2008, vol. 51 (pg. 2040-2044)https://doi.org/10.1016/j.jacc.2007.10.069
Logically, ED secondary to testosterone deficiency should be treated by testosterone replacement. Testosterone levels in men decrease with age.4 Both epidemiological and observational studies have demonstrated that reduced testosterone is associated with increased cardiovascular risk. One meta-analysis showed lower testosterone and higher 17β oestradiol as significant risk predictors despite adjustment for age and body mass index.4 Patients with coronary artery disease (CAD) have been found to have lower testosterone levels than controls, and there is inverse correlation between testosterone and the incidence of major cardiovascular disease (CVD).4 A significant negative correlation has been reported between total testosterone levels and Framingham risk score.4 However, it has been pointed out that ‘It is unclear if this is a causal association or due to low testosterone being a biomarker of poor health’.4 Testosterone replacement as a treatment for …
Abstract | Full Text | Full Text PDF | PubMed | Scopus (58) | Google ScholarSee all References Avoiding sexual activity between 6 AM and noon may be recommended to higher-risk patients because this is the time of peak incidence of most arrhythmias, myocardial ischemia, sudden cardiac death, and cerebrovascular accidents.1x1Muller, JE. Sexual activity as a trigger for cardiovascular events: what is the risk?. Am J Cardiol. 1999; 84: 2N–5N
Erectile dysfunction (ED), or impotence, is when a man has difficulty getting or maintaining a strong enough erection for sexual intercourse or other sexual activity. It can be caused by stress, anxiety or excessive alcohol consumption. But it can also be a symptom of an underlying condition such as atherosclerosis (narrowing of the arteries), diabetes or high blood pressure. Some medications can cause erectile dysfunction, for example beta-blockers and diuretics (commonly used to treat a variety of heart-related conditions such as high blood pressure and heart failure).
Another study showed a forty percent increase of blood flow to the heart within one year of starting a dietary program designed similar to the one described in my book, The End of Heart Disease. Of pertinent note is that, in the same study, the patients following a high-protein Atkins’ diet decreased blood flow to the heart by forty percent in one year.8 These dangerous high-protein diets are a certain path to erectile impotence and a premature cardiac death.
In years past, before nitric oxide and its role in the erectile response was appreciated, testosterone was used to treat sexual dysfunction in men. It proved a partial success as a standalone therapy, resulting in improved erectile potency in 40–60% of men with low-to-normal testosterone levels. The likelihood of success increased, however, if starting testosterone levels were low (usually defined as below 300 ng/dL), in which case improved erections were experienced by as many as 65% of men, compared with 16.7% receiving placebo; topical testosterone preparations were also noted to be superior to oral replacement or injections.21 These findings were confirmed by another study that showed testosterone produced modest improvements in erectile function and libido in men with low-to-normal testosterone levels.22
Erections are extremely complicated and surprisingly fragile. Erections involve chemical signals, nerve impulses, complicated blood pressure changes, and overall fitness in systems ranging from your heart and hormones to your mood. When medication changes how one of these factors works—like blood pressure drops or depression medication—ED is a common side effect. The problem with these completely predictable medically induced side effects is how people react.
Finding a potential early sign of heart disease is vital: Every minute in the United States someone dies from a heart disease-related event. Doctors know to watch for risks like obesity and high blood pressure; however, Men’s Health reports 50 percent of men who die from heart disease have never had one of these symptoms. For younger men, treating ED as an indicator of heart health could be a lifesaver.

Testosterone cypionate and testosterone enanthate injections are used for replacement therapy in patients with low testosterone. Other formulations, such as gels and patches, are recommended in older patients with chronic conditions.57 Serum prostate specific antigen should be measured before starting testosterone replacement, then 3–6 months after starting the treatment, followed by annual measurement.74


In most men, ED is recognised as sharing vascular aetiology with IHD.17 ED and IHD share common risk factors, such as hypertension, hyperlipidaemia, diabetes, obesity, lack of physical exercise, cigarette smoking, poor diet, excess alcohol consumption and psychological stress, including depression.30 Endothelial dysfunction has been implicated as a common mechanism between CAD and ED and it has an important role in the development of atherosclerosis.31
Penile prosthesis implant remains the most effective and permanent treatment for ED. Penile prosthesis implants can be broadly divided into malleable and inflatable prostheses (20). Malleable penile prosthesis, also known as semi-rigid prosthesis, does not allow for (physiological) flaccid state of the penis. The patient can bend the prosthesis upwards for sexual intercourse and downwards for concealment. Although the angle of prosthesis concealment has improved with recent devices, however due to the constant rigid state of the penis, they are still less comfortable compared to their inflatable counterparts, are more likely to cause social embarrassment and associated with higher risk of implant erosions (21). However, malleable prosthesis still has its place for the treatment of ED as these implants are easier to handle, easier to place and would benefit patients with impaired manual dexterity.
Myocardial ischaemia is caused by the reduction of coronary blood flow as a result of fixed or dynamic epicardial coronary artery stenosis, abnormal constriction or deficient relaxation of coronary microcirculation, or because of reduced oxygen-carrying capacity of the blood.56 Atherosclerosis is the major cause of myocardial ischaemia. Plaque that develops in atherosclerosis can rupture causing platelet aggregation and subsequent thrombus formation, which leads to MI. The other mechanisms of myocardial ischaemia are encountered far less than atherosclerosis. Endothelial dysfunction has an important role in the progression of atherosclerosis. Endothelial dysfunction enhances the intimal proliferation and malregulation that results in plaque destabilisation in the arteries.6 This process, coupled with paradoxical vasoconstriction, can result in major cardiovascular events such as MI.32
Andersson said the results came as a surprise because erectile dysfunction is associated with an increased risk of heart disease in otherwise healthy men. However, previous studies have associated the use of PDE5 inhibitors with a decreased blood pressure in the left ventricle, which reduces the amount of work required to pump blood and therefore could help explain why the drugs might benefit people with heart failure. PDE5 inhibitors were initially developed to treat angina, a type of chest pain that results from constricted arteries.
Whereas lifestyle modification is a reasonable initial step when approaching a hypertensive patient with sexual dysfunction, finding the appropriate antihypertensive treatment is usually the next “complicated” move to care for. Several observational and clinical studieshave consistently associated antihypertensive medication with sexual dysfunction[20]. Whether one class of antihypertensive agents is associated exclusively or more with erectile dysfunction compared to another, however, is a difficult puzzle to solve as there are many other factors (comorbid conditions, concomitant medications, personal characteristics) to be taken into account at the same time. In addition, erectile dysfunction has never been studied as the primary end-point before and as a result a definite causative relationship between antihypertensive medication and sexual dysfunction has never been proven.
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

Abstract | Full Text PDF | PubMed | Scopus (19) | Google ScholarSee all References However, there has been disagreement regarding the effects of diuretics on erectile function; many studies found that only rarely have these medications been implicated convincingly as the cause of a patient's ED.36x36Wein, AJ and Van Arsdalen, KN. Drug-induced male sexual dysfunction. Urol Clin North Am. 1988; 15: 23–31
Conversely, and of significant clinical importance, is how often patients with ED as their first and sole clinical manifestation suffer from subclinical CAD.17 Previous studies reported a rate of inducible ischaemia by exercise stress testing (EST) in 22% (with a wide range of 5–56%) of ED patients reflecting differences in patient population, risk factors and criteria used for ED and CAD diagnosis. Interestingly, those patients further assessed with coronary angiography had obstructive atherosclerosis in >90% of cases.4,18 In a prospective angiographic study, we documented that 19% of ED patients suffer from clinically silent obstructive CAD.18

Due to their vasorelaxing effect, administration of PDE-5 inhibitors in hypertensive individuals was initially confronted with great suspicion. A wealth of clinical data however has proven that PDE-5 inhibitors are associated with few side effects and provoke a small and insignificant reduction in blood pressure with minimal heart rate alterations in both normotensive and hypertensive patients as well. As a matter of fact, they can be safely and effectively administered to hypertensive individuals even when they are already taking multiple antihypertensive agents[51-56]. The sole exception to the rule is co-administration with organic nitrates, which is an absolute contraindication due to profound and possibly hazardous hypotension effect[57,58]. Moreover, precaution should be taken when PDE-5 inhibitors are combined with a-blockers where, due to possible orthostatic hypotension effect, lower starting doses should be implemented in the therapeutic regime[59-62].


Gene therapy has the potential to become a future management option for patients with CAD and ED. Animal studies have been conducted to evaluate the effects of gene therapy. A rat model was studied by Bivalacqua et al. to evaluate the effect of the combination of eNOS gene therapy and sildenafil. This research suggested that erectile response was greater in male rats with diabetes treated with combination eNOS gene therapy and sildenafil, compared with male rats with diabetes treated with eNOS gene therapy or sildenafil alone.76–78
Uses and risks of viagra Viagra treats erectile dysfunction and pulmonary arterial hypertension. For sexual purposes, it helps someone with erectile dysfunction achieve and maintain an erection. However, Viagra can have unpleasant side effects, and an overdose can be serious. We cover everything you need to know about Viagra in this article. Read now

In Eastern medicine, animal products are commonly used for their perceived health benefits. The philosophy “like nourishes like”, suggests that consuming the organ of an animal will bring benefits to the corresponding organ in one’s body is a common belief. Men seeking greater potency have turned to eating penises from goats, bull, deer, horses, seals and other mammals in the form of cooked dishes or herbal preparations. While there is no scientific evidence supporting this practice, the cultural beliefs remain strong and supplements containing extracts from animal penises are readily available in the form of capsules, often mixed with herbal compounds pitching similar erectogenic properties. A significant proportion of these potency-inducing supplements in Asia have been found to contain PDE5-inhibitors substrates such as tadalafil and sildenafil (30). However uncontrolled use of illicit PDE5-inhibitors under the guise of natural supplements remains a health threat to the general public.
The common associations between cardiovascular disease and ED have led some researchers to explore whether onset of ED can be an effective predictor of the presence of cardiovascular disease. A study of 40 patients with cardiac disease found an association between sexual dysfunction and the presence of cardiovascular disease, as well as a correlation between the severity of ED and the number of coronary arteries with extensive atherosclerosis.16x16Greenstein, A, Chen, J, Miller, H, Matzkin, H, Villa, Y, and Braf, Z. Does severity of ischemic coronary disease correlate with erectile function?. Int J Impot Res. 1997; 9: 123–126

Abstract | Full Text | Full Text PDF | PubMed | Scopus (95) | Google ScholarSee all References Sildenafil is absorbed rapidly, and peak plasma levels of 127 to 560 ng/mL are seen in a fasting state approximately 1 hour (range, 0.5-2 hours) after ingestion.3x3Zusman, RM, Morales, A, Glasser, DB, and Osterloh, IH. Overall cardiovascular profile of sildenafil citrate. Am J Cardiol. 1999; 83: 35C–44C


The Epimedium plant is a flowering perennial found throughout Asia and parts of the Mediterranean. Horny Goat Weed’s active ingredient is icariin, a falvonol glycoside and reputed to improve cardiovascular function, hormone regulation, modulation of immunological function and antitumor activity (44). Icariin has also been shown to have a PDE5i effect. Animal studies have been carried out showing improvements in penile hemodynamic parameters. There is one report of tachyarrhythmia and hypomania with the use of this herb (45).
Inflatable prostheses are complex mechanical devices that imitate the natural process of erection. Parts are inserted surgically into the penis and scrotum, and activated by squeezing. When erection is no longer desired, a valve on the pump is pressed, and the penis becomes flaccid. Self-contained single-unit prostheses are similar to the inflatable types, but more compact. The entire device is implanted into the penis. When erection is desired, the unit is activated by either squeezing or bending, depending on which of the two types of self-contained prostheses is used.
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