Treatment of ED which was previously confined to invasive procedures, cavernosal injections or to rather ineffective oral medications was revolutionized in 1999 with the introduction of the orally administered PDE5 inhibitor sildenafil. Phosphodiesterase type 5 inhibitors are the first-line therapy for ED of organic aetiology unless there is a specific contraindication to their use. This class of agents is widely used because of its effectiveness and safety.38 Interactions with cardiovascular drugs have been minimal with the exception of nitrates and other nitric oxide (NO) donors (such as nicorandil), where co-administration may result in severe vasodilation and hypotension. However, nitrates are often overused in clinical practice; therefore, the option of their discontinuation should be considered. A strong body of clinical data shows that all three agents (sildenafil, tadalafil, and vardenafil) do not increase the risk of non-fatal myocardial infarction, stroke, or cardiovascular deaths. These drugs do not exacerbate ischaemia or worsen exercise tolerance in patients with known CAD who achieve levels of exercise comparable or greater than that achieved during sexual intercourse.38,39 Phosphodiesterase type 5 is expressed throughout the human body, including the pulmonary and systemic vasculature and hypertrophied myocardium. While currently their only additional indication, beyond ED, is idiopathic pulmonary hypertension (for sildenafil and tadalafil), they show potential to be of benefit in several other conditions, such as CAD and systolic heart failure.39 Mechanisms of benefit of PDE5 inhibitors include pulmonary and systemic vasodilation, increased myocardial contractility, reduced large artery stiffness and wave reflections, improved endothelial function, and reduced apoptosis, fibrosis and hypertrophy through mechanisms involving NO, cyclic guanosine monophosphate, protein kinase G and Rho kinase.39 A very important issue is whether treatment of ED per se (and not of its risk factors and comorbidities) will have an impact on cardiovascular risk. While this applies to all therapeutic modalities of ED, it is particularly pertinent for PDE5 inhibitors, since they represent the mainstay of ED therapy. Data are limited to date. Gazzaruso et al.21 showed a trend of PDE5 inhibitors to reduce cardiovascular morbidity and mortality in diabetic patients with silent CAD and ED, while Frantzen et al.40 showed that 2 years after the introduction of sildenafil, the relative risk of the incidence of CVD among men with ED compared with healthy men significantly decreased from 1.7 to 1.1.
Cigarette smoking is an established risk factor in the development of atherosclerotic vascular changes and thus would be expected to play a role in the development of vasculogenic ED. The MMAS 9-year follow-up study found that the risk of developing moderate or complete ED in smokers was nearly doubled (odds ratio, 1.97) compared with that in matched nonsmokers.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
Penile erection is largely a vascular process, and the penile endothelium and smooth muscle tissue are very sensitive to functional and structural changes. Vasculogenic ED results from an impairment of endothelial dependent or independent smooth muscle relaxation (functional vascular ED, initial stages), occlusion of the cavernosal arteries by atherosclerosis (structural vascular ED, late stages), or a combination of these.3 Current data support a complex interplay between endothelial dysfunction, subclinical inflammation, and androgen deficiency (Figure 1). The relationship between ED and CAD at the clinical level is supported by this common pathophysiological basis. The ‘artery size’ hypothesis explains why patients with CAD frequently report ED before CAD detection.10 According to this hypothesis, for a given atherosclerotic burden, the smaller penile arteries suffer obstruction earlier than the larger coronary arteries (Figure 2). The same concept holds also true in the case of non-obstructing atherosclerosis: since the smaller penile artery have a greater endothelial surface and erection requires a large degree of vasodilation to occur when compared with arteries in other organs, the same degree of endothelial dysfunction will be symptomatic in these smaller vessels but subclinical in the larger ones (i.e. coronaries). In the same context, accelerated arterial ageing (as indicated by increased arterial stiffening that also affects large arteries of ED patients) may be a common background.11,12 Erectile dysfunction is associated with an incremental inflammatory and endothelial-pro-thrombotic activation.13 Interestingly, this activation is equal to that found in CAD patients with no ED, while when these two conditions are combined the burden is additive. Androgen deficiency may be also implicated in the common pathogenetic pathways of ED and CVD; however, this warrants further substantiation.2
Yohimbine is an indole alkaloid derived from the bark of the African yohimbe tree (33). Yohimbine has been noted to treat fatigue, depression, diabetes, and sexual dysfunction. A meta-analysis of seven placebo-controlled trials (34) deemed yohimbine superior to placebo for the treatment of ED with rare adverse events. The proposed mechanism of action (35) is via the inhibition of central alpha-2-adrenergic receptors, decreasing central inhibition of arousal, and increasing penile nerve stimulation resulting in increased NO. Common side effects include headache, sweating, agitation, hypertension and insomnia. Contraindications include patients on tricyclic antidepressants, anti-hypertensives and central nervous system stimulants.
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.
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
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
Abstract | PubMed | Scopus (136) | Google ScholarSee all References Other candidate mechanisms linking ED and cigarette smoking include hypercoagulability and increased platelet aggregation, increased release of free fatty acids and catecholamines, changes in NO synthetic pathways, and a possible direct toxic effect on vascular endothelium.13x13Chung, WS, Shim, BS, and Park, YY. Hemodynamic insult by vascular risk factors and pharmacologic erection in men with erectile dysfunction: Doppler sonography study. World J Urol. 2000; 18: 427–430
Some doctors prefer to start a man on the lowest dose of an oral medicine and increase the dose until an effective one is found. Others prefer to start with the highest dose and go to a lower dose only if a man complains of side effects. In either case, it’s important for a man to communicate with his doctor to let him know how the dose he’s using is working.