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
PubMed | Google ScholarSee all References As with sildenafil, use of nitrate or NO-donor medications is contraindicated while taking tadalafil because of the potential for marked hypotensive interactions.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

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).

Based on this testing, EDDM patients were treated with behavioral therapy, intracavernosal (papaverine, PGE-1, or Trimix) or intraurethral PGE-1, a vacuum constriction device (VCD), or implantation of a penile prosthesis. Novel surgical procedures, ligation of incompetent cavernosal veins or penile revascularization, were seldom efficacious with EDDM and were soon abandoned. Although these nonsurgical therapies were efficacious, they were not widely requested because of their invasive or mechanical nature.


For centuries, men have tried all sorts of natural remedies for erectile dysfunction (ED) -- the repeated inability to get or maintain an erection firm enough for sexual intercourse. But do they really work? It is simply not scientifically known at this point. Furthermore, you take these remedies at your own risk, because their safety profiles have not been established. What follows are commentaries by experts and reviews in the field of alternative treatments that are available over the counter for erectile dysfunction and impotence.
The research is based on a Swedish national database of health records that includes all hospitals in Sweden. Researchers analyzed the records of men age 80 years or younger who were hospitalized for a first heart attack between 2007 and 2013. Tracking the men for an average of 3.3 years following this first heart attack, they compared outcomes among those who subsequently filled a prescription for a PDE5 inhibitor or alprostadil to those who did not. Overall just over 7 percent of men were prescribed an erectile dysfunction drug, 92 percent of whom were prescribed a PDE5 inhibitor and 8 percent of whom were prescribed alprostadil.
But closer questioning often revealed a very different story—men would admit that struggles to achieve an erection usually preceded a heart attack or other cardiac event by one, two, or three years. Back then, the pattern of erectile dysfunction and cardiac disease was so widespread, that most in the medical profession attributed it to simple “aging,” as common as wrinkles and constipation.
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
When these drugs don't work, there are other options. Medications that dilate blood vessels, such as alprostadil, can be injected or deposited in the penis; they work in more than 80 percent of men with diabetes. Beyond that, penile implants can be an effective surgical solution. Implants are either malleable rods, which can be manually adjusted to the desired position, or inflatable cylinders that fill with fluid when a pump under the skin of the scrotum is pressed.
One study the authors reviewed measured these changes in middle-aged men with and without coronary artery disease. This study found that the peak heart rate during intercourse was lower than heart rates measured during the patients' normal daily activities. The study participants' peak oxygen consumption levels during intercourse were moderate -- comparable to their oxygen consumption levels during moderate activities such as walking on level ground at 3 to 4 miles per hour, climbing stairs slowly or doing general housework such as vacuuming.
Another common reason for failures of oral therapy is the absence of sexual or genital stimulation prior to attempting sexual intercourse. These medicines facilitate an erection by increasing blood flow to the penis, but they do not act as an aphrodisiac or as an initiator of the erection. A man who is not “in the mood” or does not have adequate physical stimulation will not respond with an erection.
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