The first stem cell study for the treatment of ED was published in 2004. This study used embryonic stem cells to treat ED. At this time, there is a total of 36 published basic studies assessing stem cell therapy for ED, with two clinical trials. The mechanism of action of stem cells is to generate angiogenesis with subsequent increase in cavernosal smooth muscle cells within the corporal bodies.46
Tadalafil shares the common side effects of the PDE5 inhibitors, however, due to its effect on PDE11, another phosphodiesterase located in muscle, tadalafil has been associated with muscle aches. Back pain and muscle aches occur in less than 7% of men taking tadalafil and in most patients will go away without treatment within 48 hours. When treatment was necessary, acetaminophen (Tylenol) and nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Motrin, Advil) or naproxen (Aleve) were effective. Rarely do the muscle aches and back pain cause men to stop using tadalafil.
After the history, physical examination, and laboratory testing, a clinical impression can be obtained of a primarily psychogenic, organic, or mixed etiology for erectile dysfunction. Patients with primary or associated psychogenic factors may be offered further psychologic evaluation, and patients with endocrine abnormalities may be referred to an endocrinologist to evaluate the possibility of a pituitary lesion or hypogonadism. Unless previously diagnosed, suspicion of neurologic deficit may be further assessed by complete neurologic evaluation. No further diagnostic tests appear necessary for those patients who favor noninvasive treatment (e.g., vacuum constrictive devices, or pharmacologic injection therapy). Patients who do not respond satisfactorily to these noninvasive treatments may be candidates for penile implant surgery or further diagnostic testing for possible additional invasive therapies.
Thanks to over a decade of primetime television commercials, most of us can name at least one drug that treats erectile problems. However, far fewer of us can name drugs that may actually cause the problem. In reality, MedlinePlus reported that there are far more of these, and even common drugs such those to treat depression and heartburn can make it difficult to get an erection.

What’s important to take away from this is that, because erections can occur throughout the day for no reason, erectile dysfunction can be difficult to diagnose. Some men achieve erections for no reason, yet when provided with stimuli, they aren’t able to. Some men, on the other hand, only get aroused when directly stimulated. This means that healthcare professionals need to take into account many variables prior to diagnosing and treating erectile dysfunction.


However, men are affected psychologically when it comes to achieving erections. For instance, if a man is with a woman for the first time, or even before he feels comfortable with her, he may suffer from performance anxiety. In such a situation, his mind and body are both saying yes, but then they become out of sync. The body is then saying yes, but the mind is filled with question. “Will I be able to perform?” “How long will I last?” “Am I big enough to satisfy her?” “Is she looking at that mole on my stomach?” All kinds of questions may be going through a man’s mind upon getting in bed, and these can be distracting, they can lead to self-doubt, and therefore, failure to achieve or maintain an erection.
Another common problem for men who have trouble in the bedroom is substance use or abuse. In some cases, a man suffering from erectile dysfunction may be diagnosed with depression and be prescribed selective serotonin reuptake inhibitors, or SSRIs. These medications may be able to assist in alleviating the symptoms of depression, but they can also lead to erectile dysfunction.
Erythrocytosis has been noted in men on TRT, and should be monitored every 6–12 months depending upon the patients’ response to changes in haematocrit levels. For mild elevations, the dosage of testosterone can be decreased or the interval of using the medication can be increased. With the haematocrit greater than 50%, decisions to temporarily discontinue the medication or periodic phlebotomy may be indicated.38
Normal erectile function depends on the release of NO and endothelial-dependent vasodilation of the penile arteries. The ‘artery size’ hypothesis, first described by Dr Montorsi, offers an explanation why men are more likely to develop ED before a myocardial infacrtion. It is believed that atherosclerosis affects all vascular beds equally but smaller arteries are more likely to become occluded than larger arteries.31 32 The penile arteries are 1–2 mm while the coronary arteries are 3–4 mm. Thus, the same degree of endothelial dysfunction and atherosclerosis is more likely to occlude blood flow in the penile arteries compared with the coronary arteries. The penile arteries therefore serve as a sensitive indicator for subsequent CVD. This theory is supported by the fact that ED occurs approximately 3 years prior to cardiac symptoms in virtually all patients with chronic coronary syndrome whereas patients with acute coronary syndrome have a much lower prevalence of sexual dysfunction.32

Aging, liver and kidney problems, and concurrent use of certain medications (such as erythromycin [an antibiotic] and protease inhibitors for HIV) slows the metabolism (breakdown) of sildenafil. Slowed breakdown allows sildenafil to accumulate in the body and potentially may increase the risk of side effects. Therefore, in men over 65 years of age, in men with significant kidney and liver disease, and in men who also are taking medications called protease inhibitors, the doctor will initiate sildenafil at a lower dose (25 mg) to avoid accumulation of sildenafil in the body. A protease inhibitor ritonavir (Norvir) is especially potent in increasing the accumulation of sildenafil, thus men who are taking Norvir should not take sildenafil doses higher than 25 mg and at a frequency of no greater than once in 48 hours. Other medications that may affect the level of sildenafil include erythromycin and ketoconazole.

inability of the male to achieve or maintain an erection of sufficient rigidity to perform sexual intercourse successfully. An impotent man may produce sufficient numbers of normal spermatozoa; the condition is related to infertility only insofar as it prevents coitus with and impregnation of the female partner. Called also erectile dysfunction. adj., adj im´potent.
The U.S. FDA (Food and Drug Administration) has a list of 29 OTC products that claim to treat erectile dysfunction. Patients should avoid these because many contain harmful ingredients. Other natural or herbal remedies such as DHEA, L-arginine, ginseng, and yohimbe are supplements that have been used but have not been proven safe and effective according to some researchers. Before using such compounds, individuals should consult their doctor. According to some experts, acupuncture does not effectively treat erectile dysfunction. Other home remedies for reducing ED symptoms include diet changes such as eating blueberries and citrus fruits and drinking red wine.

Injection therapy involves injecting a substance into the penis to enhance blood flow and cause an erection. The Food and Drug Administration (FDA) approved a drug called alprostadil (Caverject) for this purpose in July of 1995. Alprostadil relaxes smooth muscle tissue to enhance blood flow into the penis. It must be injected shortly before intercourse. Another, similar drug that is sometimes used is papaverine—not yet been approved by the FDA for this use. Either drug may sometimes cause painful erections or priapism (uncomfortable, prolonged erections) that must be treated with a shot of epinephrine.
When stimulated by the nerves, the spongy tissue arranges itself in such a way that more blood can be stored in the penis. The veins running through the outer sheath of the penis then compress which stops the blood from leaving the penis. As the blood is stopped from flowing out, the penis fills with blood and stretches within the outer casing, giving an erection.

Surgery of the penile venous system, generally involving venous ligation, has been reported to be effective in patients who have been demonstrated to have venous leakage. However, the tests necessary to establish this diagnosis have been incompletely validated; therefore, it is difficult to select patients who will have a predictably good outcome. Moreover, decreased effectiveness of this approach has been reported as longer term followups have been obtained. This has tempered enthusiasm for these procedures, which are probably therefore best done in an investigational setting in medical centers by surgeons experienced in these procedures and their evaluation.
An alprostadil cream that patients apply into the tip of the penis (the urethral meatus, the opening that urine passes through) is currently available in the UK and Europe. It is currently under review by the U.S. Food and Drug Administration (FDA). After application of the cream, an erection occurs within five to 30 minutes, and the erection lasts one to two hours in men who respond to the cream. Doctors recommend that one use the cream for a maximum frequency of two to three times per week and no more frequent than once every 24 hours. It has essentially the same contraindications and side effects as the other formulations of alprostadil. The cream may cause vaginal burning in roughly 4% of partners. Men should not use alprostadil cream for sexual intercourse with women of childbearing potential unless a condom is used. Researchers have performed controlled trial studies to evaluate the safety and effectiveness of this drug. Overall, 52% of men reported improvement in their erections compared to 20% of men receiving placebo. A later analysis demonstrated that 36% of men using the alprostadil cream had a clinically relevant improvement in vaginal penetration ability and 31% clinically relevant improvement in ability to have successful intercourse to ejaculation.

The Massachusetts Male Aging Study (MMAS) documented an inverse correlation between ED risk and high-density lipoprotein (HDL) cholesterol levels but did not identify any effect from elevated total cholesterol levels. [15] Another study involving male subjects aged 45-54 years found a correlation with abnormal HDL cholesterol levels but also found a correlation with elevated total cholesterol levels. The MMAS included a preponderance of older men.

So what do you do? If the guilt is too much, you can tell your boyfriend. It might be the only way to clear your conscience — and hopefully, if you explain the reasons why you did such a boneheaded thing, he'll understand. It will be hard and it may create drama for months to come, but my guess is that you can recover, if he's not a horribly jealous guy.
Cavallini, G., Modenini, F., Vitali, G., & Koverech, A. (2005, November). Acetyl-L-carnitine plus propionyl-L-carnitine improve efficacy of sildenafil in treatment of erectile dysfunction after bilateral nerve-sparing radical retropubic prostatectomy. Urology, 66(5), 1080-5. Retrieved from http://www.sciencedirect.com/science/article/pii/S0090429505006515
All studies demonstrate a strong association with age, even when data are adjusted for the confounding effects of other risk factors. The independent association with aging suggests that vascular changes in the arteries and sinusoids of the corpora cavernosa, similar to those found elsewhere in the body, are contributing factors. Other risk factors associated with aging include depression, sleep apnea, and low HDL levels.
Martha K Terris, MD, FACS is a member of the following medical societies: American Cancer Society, American College of Surgeons, American Institute of Ultrasound in Medicine, American Society of Clinical Oncology, American Urological Association, Association of Women Surgeons, New York Academy of Sciences, Society of Government Service Urologists, Society of University Urologists, Society of Urology Chairpersons and Program Directors, and Society of Women in Urology
But the main challenge to finding the best ED drug for you may turn out to be health insurance rules—not biochemistry. It's a common practice among insurers to limit the number of pills you can obtain per month. After you hit your limit, the out-of-pocket cost for a single pill can be as high as $20. "The main obstacle in my practice is the cost," Dr. Liou says. You'll need to work with your doctor to get the pill you need at a price you can afford.
Psychological factors — Psychological issues such as depression, anxiety, guilt or fear can sometimes cause sexual problems. At one time, these factors were thought to be the major cause of impotence. Doctors now know that physical factors cause impotence in most men with the problem. However, embarrassment or "performance anxiety" can make a physical problem worse.
In many cases, diagnosing erectile dysfunction requires little more than a physical exam and a review of your symptoms. If your doctor suspects that an underlying health problem may be at play, however, he may request additional testing. Once you’ve determined the cause for your ED, you and your doctor can decide on a form of treatment – here are some of the options:
This point is important – the anticipatory anxiety.  Sports men and women regularly use “mental rehearsal” to help them prepare for a match.  They imagine the shots, the game and perform according to plan when the event arises.  Research has show that musicians mentally practicing their instrument in their mind, use the same brain processes as when playing for real.

Prostate cancer isn’t considered a cause of ED on its own, but radiation treatments, hormone therapy, and surgery to remove the entire prostate gland can lead to difficulty in getting or keeping an erection. Sometimes erectile dysfunction related to prostate cancer treatment is only temporary, but many guys experience ongoing difficulties that need to be addressed by other means.
Erections are neurovascular events, meaning that nerves and blood vessels (arteries and veins) are involved in the process of an erection and all must work properly to develop a hard erection that lasts long enough. Erection begins with sexual stimulation. Sexual stimulation can be tactile (for example, by a partner touching the penis or by masturbation) or mental (for example, by having sexual fantasies, viewing porn). Sexual stimulation or sexual arousal causes the nerves going to the penis to release a chemical, nitric oxide. Nitric oxide increases the production of another chemical, cyclic GMP (cGMP), in the muscle of the corpora cavernosa. The cGMP causes the muscles of the corpora cavernosa to relax, and this allows more blood to flow into the penis. The incoming blood fills the corpora cavernosa, making the penis expand.

Pills such as Viagra® are the most common ED treatment, but they don’t work for everyone. Some guys find they cause bothersome headaches or persistent stomach troubles. Some have serious side effects such as chest pain and vision or hearing changes. Others don’t respond to the medication at all. And still others don’t like having to wait for the pill to take effect.

In diabetics, impotence that develops acutely in the setting of hyperglycemia and poor metabolic control is usually reversible. This is not true of the slowly progressive impotence of long-standing diabetes that is a manifestation of autonomic neuropathy. Intracavernosal self-injection of vasoactive drugs such as papaverine, which relaxes arteriolar smooth muscle is a promising new approach to treatment that is particularly suited for diabetic patients whose erectile dysfunction is on a neuropathic basis. It also has been used with success in spinal cord patients.
By contrast, psychogenic impotence typically is abrupt in onset, often in relation to psychological trauma, and may wax and wane. Patients with psychogenic impotence may have total erectile failure with one partner but not another, or be impotent during sexual intercourse but not during self-stimulation. Normally occurring spontaneous erections in the morning suggest psychogenic rather than organic causes for impotence.
There are, as you listen to all of the advertisements, if your erection lasts for more than four hours, there are very, very unusual cases where that can happen. There are very rare cases of visual problems. There are even rarer cases of hearing problems. But with every medication, there always a potential downside. But the absolute contraindication is an unstable medical condition, an unstable cardiovascular condition, being on nitrates.
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