The causes of ED are varies from one individual to another. For whatever cause, since an erection requires a precise sequence of events, ED can occur when any of the events is disrupted. This sequence includes nerve impulses in the brain, spinal column, and area around the penis, and response in muscles, fibrous tissues, veins, and arteries in and near the corpora cavernosa23. Thus, ED causes reported include, damage to nerves, arteries, smooth muscles, and fibrous tissues. These are often as a result of diseases, such as diabetes, kidney disease, chronic alcoholism, multiple sclerosis, atherosclerosis, vascular disease, and neurologic diseases that account for about 70 percent of ED cases23. NIH23 reported that between 35 and 50 percent of men with diabetes experience ED. NIH23 further reported that the usage of many common medicines such as blood pressure drugs, antihistamines, antidepressants, tranquilizers, appetite suppressants, and cimetidine (an ulcer drug) can produce ED as a side effect. Nevertheless, psychological factors such as stress, anxiety, guilt, depression, low self-esteem, and fear of sexual failure cause 10 to 20 percent of ED cases. In addition, men with a physical cause for ED frequently experience the same sort of psychological reactions (stress, anxiety, guilt, depression)23. Other possible causes are smoking, which affects blood flow in veins and arteries, and hormonal abnormalities, such as not enough testosterone23.
It doesn’t look good for the herbs. So far, there’s no data from controlled human trials that support the erection-promoting claims for any 5 of the most frequently used herbs. The icariin in the horny goat weed can help get it up, but since you’re getting the herb rather than a purified molecule, the concentration probably isn’t high enough to have much of an effect. Worse, it turns out that Viagra is much better at blocking that erection-killing enzyme than icariin is.
In diabetes, vasoconstrictors and vasoactive factors are increased in addition to structural changes and attenuation of relaxation responses in the corpus cavernosum. A shifting of the balance of vasoactive factors occurs such that relaxation factors (eg, nitric oxide [NO]) are inhibited and contractile factors are induced in microvascular disease. With epidemiological predictions suggesting that the incidence of diabetes mellitus will increase to 300 million by 2025, management of diabetes-induced ED is increasingly important.
Sildenafil citrate, tadalafil and vardenafil hydrochloride are contraindicated in patients with a known hypersensitivity to any organic nitrates (oral, sublingual, transdermal or by inhalation) due to the risk of developing potentially life-threatening hypotension. Concomitant use of PDE-5 inhibitors is contraindicated with HIV protease inhihibitors (indinavir, ritinovir, saquinavir) as well as ketoconazole, itraconazole, cimetidine and erythromycin, because these drugs are potent inhibitors of cytochrome P450 3A4 and can raise the plasma levels of PDE-5 inhibitors. Coadministration of PDE-5 inhibitors to patients taking alpha-adrenergic blockers such as alfluzocin or tamsulosin may lead to symptomatic postural hypotension, including dizziness and lighheadedness in some individuals.