Erectile dysfunction (impotence) facts
What is erectile dysfunction (ED)?
Erectile dysfunction (ED), also known as impotence, is the inability to achieve or sustain an erection for satisfactory sexual activity. Erectile dysfunction is different from other conditions that interfere with male sexual intercourse, such as lack of sexual desire (decreased libido) and problems with ejaculation and orgasm (ejaculatory dysfunction). This article focuses on the evaluation and treatment of erectile dysfunction.
What are erectile dysfunction symptoms and signs?
Symptoms of erectile dysfunction may include the following:
What is normal penis anatomy?
The penis contains two chambers, called the corpora cavernosa, which run the length of the upper side of the penis (see figure 1 below). The urethra, which is the channel for urine and ejaculate, runs along the underside of the corpora cavernosa. Filling the corpora cavernosa is a spongy tissue consisting of smooth muscles, fibrous tissues, veins, and arteries. A membrane, called the tunica albuginea, surrounds the corpora cavernosa. Veins located in the tunica albuginea drain blood out of the penis. The corpus spongiosum helps maintain the urethra open during an erection for passage of the ejaculate (sperm and prostatic fluid).
Picture of arteries and veins involved in erectile dysfunction (ED); SOURCE: NIHHow common is erectile dysfunction?
Erectile dysfunction (ED, impotence) varies in severity; some men have a total inability to achieve an erection, others have an inconsistent ability to achieve an erection, and still others can sustain only brief erections. The variations in severity of erectile dysfunction make estimating its frequency difficult. Many men also are reluctant to discuss erectile dysfunction with their doctors due to embarrassment, and thus the condition is underdiagnosed. Nevertheless, experts have estimated that erectile dysfunction affects 18-30 million men in the United States.
While erectile dysfunction can occur at any age, it is uncommon among young men and more common in the elderly. By age 45, most men have experienced erectile dysfunction at least some of the time. According to the Massachusetts Male Aging Study, complete impotence increases from 5% among men 40 years of age to 15% among men 70 years and older. Population studies conducted in the Netherlands found that some degree of erectile dysfunction occurred in 20% of men between ages 50-54 and in 50% of men between ages 70-78. In 1999, the National Ambulatory Medical Care Survey counted 1,520,000 doctor-office visits for erectile dysfunction. Other studies have noted that approximately 35% of men 40-70 years of age suffer from moderate to severe ED, and an additional 15% may have milder forms. Further studies report similar findings.
How does erection occur?
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 generates electrical impulses along the nerves going to the penis and causes the nerves to release nitric oxide, which in turn increases the production of cyclic GMP (cGMP) in the smooth muscle cells of the corpora cavernosa. The cGMP causes the smooth muscles of the corpora cavernosa to relax and allow rapid blood flow into the penis. The incoming blood fills the corpora cavernosa, making the penis expand.
How is erection sustained?
The pressure from the expanding penis compresses the veins (blood vessels that drain the blood out of the penis) in the tunica albuginea, helping to trap the blood in the corpora cavernosa, thereby sustaining erection. Erection is reversed when cGMP levels in the corpora cavernosa fall, causing the smooth muscles of the corpora cavernosa to contract, stopping the inflow of blood and opening veins that drain blood away from the penis. The levels of the cGMP in the corpora cavernosa fall because it is destroyed by an enzyme called phosphodiesterase type 5 (PDE5).
What are erectile dysfunction risk factors?
The common risk factors for ED include the following:
What causes erectile dysfunction?
The ability to achieve and sustain erections requires the following:
Erectile dysfunction can occur if one or more of these requirements are not met. The following are causes of erectile dysfunction, and many men have more than one potential cause:
How is erectile dysfunction diagnosed?
Patient historyA diagnosis of erectile dysfunction is made in men who have repeated inability to achieve and/or maintain an erection for satisfactory sexual performance for at least three months. Candid communication between the patient and the doctor is important in establishing the diagnosis of erectile dysfunction, assessing its severity, and determining the cause. During patient interviews, doctors try to answer the following questions:
The physical examination can reveal clues for physical causes of erectile dysfunction. For example, if the penis does not respond as expected to touching, a problem in the nervous system may be the cause. Small testicles, lack of facial hair, and enlarged breasts (gynecomastia) can point to hormonal problems such as hypogonadism with low testosterone levels. A reduced flow of blood as a result of atherosclerosis can sometimes be diagnosed by finding diminished arterial pulses in the legs or listening with a stethoscope for bruits (the sound of blood flowing through narrowed arteries). Unusual characteristics of the penis itself could suggest the root of the erectile dysfunction, for example, bending of the penis with painful erection could be the result of Peyronie's disease. Particular attention is paid to any underlying risk factors for erectile dysfunction.
Laboratory testsThe following are common laboratory tests to evaluate erectile dysfunction:
In a setting of a previous pelvic trauma, X-rays may be performed to assess various bony abnormalities. Ultrasound of the penis and testicles is done occasionally to check for testicular size and structural abnormalities. Ultrasound with Doppler imaging can provide additional information about blood flow of the penis. Rarely, an angiogram may be performed in cases in which possible vascular surgery could be beneficial.
Other testsProstaglandin E1 injection test is sometimes performed to determine the penile blood flow. Prostaglandin is directly injected into the corpora cavernosa in order to cause dilation of blood vessels and promote blood flow into the penis. If erection ensues, it confirms normal or adequate blood flow to the penis. This can also provide information about possible therapeutic options.
Monitoring erections that occur during sleep (nocturnal penile tumescence) can help distinguish between erectile dysfunction of psychological and physical causes. A band is worn around the penis for two to three successive nights and it can signal intensity and duration of erections if they occur. If nocturnal erections do not occur, then the cause of erectile dysfunction is likely to be physical rather than psychological, however, tests of nocturnal erections are not completely reliable. Scientists have not standardized the tests and have not determined in whom they should be done.
Direct vibrational stimulation (biothesiometry) is occasionally done to evaluate penile nerve function. Small electromagnetic electrodes are placed on the shaft of the penis and vibration amplitude is slightly adjusted until sensation is noted by the patient. Although this test does not measure the exact nerve function, it serves as a screening method to detect any sensory nerve deficit as the cause of ED.
Psychosocial examinationA psychosocial examination using an interview and questionnaire may reveal psychological factors contributing to erectile dysfunction. The sexual partner also may be interviewed to determine expectations and perceptions encountered during sexual intercourse.
What drugs treat erectile dysfunction?
Medications for erectile dysfunction include the following:
A doctor can help decide what medication(s) may be the best for the patient.
What is the treatment for erectile dysfunction?
The following are treatments for erectile dysfunction:
Many common medications for treating hypertension, depression, and high blood lipids can contribute to erectile dysfunction (see above). Treatment of hypertension is an example. There are many different types (classes) of antihypertensive medications (medications that lower blood pressure); these include beta-blockers, calcium channel blockers, diuretics (medications that increase urine volume), angiotensin converting enzyme inhibitors (ACE inhibitors), and angiotensin receptor blockers (ARBs). Antihypertensives may be used alone or in combination to control blood pressure. Different classes of antihypertensives have different effects on erectile function. Inderal (a beta-blocker) and hydrochlorothiazide (a diuretic) are known to cause erectile dysfunction, while calcium channel blockers and ACE inhibitors do not seem to affect erectile function. On the other hand, angiotensin receptor blockers (ARBs) such as losartan (Cozaar) and valsartan (Diovan) may actually increase sexual appetite, improve sexual performance, and decrease erectile dysfunction. Therefore, choosing an optimal antihypertensive combination is an important part of treating erectile dysfunction.
Lifestyle improvementsQuitting smoking, exercising regularly, losing excess weight, curtailing excessive alcohol consumption, controlling hypertension, and optimizing blood glucose levels in patients with diabetes are not only important for maintaining good health but also may improve or even prevent erectile function. Some studies suggest that men who have made lifestyle improvements experience increased rates of success with oral medications.
Oral phosphodiesterase type 5 (PDE5) inhibitors
The common PDE5 inhibitor drugs approved in the United States are sildenafil (Viagra), vardenafil (Levitra), tadalafil (Cialis), or avanafil (Stendra). Actual head-to-head trials between these drugs have not been done to date to see which is the superior drug. Details on each of these medications for erectile dysfunction are outlined below.
Sildenafil (Viagra)
What is sildenafil (Viagra)?Sildenafil (Viagra) was the first oral phosphodiesterase type 5 (PDE5) inhibitor approved by the FDA in the United States for the treatment of erectile dysfunction (it is not approved for women). Sildenafil inhibits PDE5, which is an enzyme that destroys cGMP. By inhibiting the destruction of cGMP by PDE5, sildenafil allows cGMP to accumulate. The cGMP in turn prolongs relaxation of the smooth muscle of the corpora cavernosa. Relaxation of the corpora cavernosa smooth muscle allows blood to flow into the penis resulting in increased engorgement of the penis. In short, sildenafil increases blood flow into the penis and decreases blood flow out of the penis.
How effective is sildenafil (Viagra)?Sildenafil is used for the treatment of erectile dysfunction of either physical or psychological cause. It has been found to be effective in treating erectile dysfunction in men with coronary artery disease, diabetes mellitus, hypertension, depression, coronary artery bypass surgery, and men who are taking antidepressants and several classes of antihypertensives.
In randomized controlled trials, an estimated 60% of men with diabetes, and 80% of men without diabetes experienced improved erections with sildenafil.
How should sildenafil (Viagra) be administered?Sildenafil is available as oral tablets at doses of 25 mg, 50 mg, and 100 mg. It should be taken approximately one hour before sexual activity. In some men, the onset of action of the drug may be as early as 11-20 minutes. Sildenafil should be taken on an empty stomach for best results since absorption and effectiveness of sildenafil can be diminished if it is taken shortly after a meal, particularly a meal that is high in fat.
What is the dose of sildenafil (Viagra)?In prescribing sildenafil, a doctor considers the age, general health status, and other medication(s) the patient is taking. The usual starting dose for most men is 50 mg, however, the doctor may increase or decrease the dose depending on side effects and effectiveness. The maximum recommended dose is 100 mg every 24 hours, however, many men will need 100 mg of sildenafil for optimal effectiveness, and some doctors are recommending 100 mg as the starting dose.
Metabolism (breakdown) of sildenafil is slowed by aging, liver and kidney dysfunction, and concurrent use of certain medications (such as erythromycin [an antibiotic] and protease inhibitors for HIV). Slowed breakdown allows sildenafil to accumulate in the body and potentially may increase the risk of side effects. Therefore in men over 65, in men with substantial kidney and liver disease, and in men who also are taking 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.
What are the side effects of sildenafil (Viagra)?Sildenafil has been found to be well tolerated without important side effects. The reported side effects are usually mild and include headache, flushing, nasal congestion, nausea, dyspepsia (stomach discomfort), diarrhea, and abnormal vision (seeing a bluish hue or brightness).
Sildenafil can cause hypotension (abnormally low blood pressure that can lead to fainting and even shock) when given to patients who are taking nitrates (for heart disease). Therefore, patients taking nitrates daily should not take sildenafil. Nitrates are used most commonly to relieve angina (chest pain due to insufficient blood supply to the heart muscle because of narrowing of the coronary arteries); these include nitroglycerine tablets, patches, ointments, sprays, and pastes, as well as isosorbide dinitrate, and isosorbide mononitrate. Other nitrates such as amyl nitrate and butyl nitrate also are found in some recreational drugs called "poppers."
Sildenafil should be used cautiously in men on alpha-blockers such as doxazosin (Cardura), terazosin (Hytrin), and tamsulosin (Flomax). There have been occasional reports of low blood pressure in men who have taken the two classes of drugs simultaneously and therefore it is recommended that there be at least a span of four to six hours between the ingestion of sildenafil and alpha-blockers.
There have been rare reports of priapism (prolonged and painful erections lasting more than six hours) with the use of PDE5 inhibitors such as sildenafil, vardenafil, and tadalafil, especially when sildenafil is used in combination with injection of medications into the corpora cavernosa or intraurethral suppositories. Patients with blood cell diseases such as sickle cell anemia, leukemia, and multiple myeloma have higher than normal risks of developing priapism. Untreated priapism can cause injury to the penis and lead to permanent impotence. Therefore, sildenafil should not be used in combination with intraurethral suppositories and corpora cavernosa injections. If there is prolonged erection (longer than four hours), immediate medical assistance should be obtained.
Is it safe for men with heart disease to use sildenafil (Viagra)?Sildenafil has been found to be effective and safe in the treatment of erectile dysfunction in men with stable heart disease due to atherosclerosis of the coronary arteries, provided that they are not on any type of nitrates. The real concern is not as much the safety of sildenafil but the risk of sexual activity in triggering heart attacks or abnormal heart rhythms in patients with heart disease.
The risk of developing heart attacks or abnormal heart rhythms during sex is low in men with well-controlled hypertension, mild disease of the heart valves, well-controlled heart failure, mild and stable angina (with a favorable treadmill stress test), successful coronary stenting or bypass surgery, and a remote history of heart attack (more than eight weeks previously). Sildenafil can be used safely in men in these lower-risk groups.
The risk of heart attack or abnormal heart rhythms during sex is higher in men with unstable angina (angina that occurs at rest or with minimal exertion), poorly controlled hypertension, moderate to severe heart failure, moderate to severe disease of the heart valves, recent heart attack (less than two weeks previously), potentially life-threatening disorders of heart rhythm such as recurrent ventricular tachycardia, and moderate to severe disease of the heart muscles. In these men, doctors usually stabilize or treat the heart conditions before prescribing sildenafil.
Before starting sildenafil for erectile dysfunction, a doctor may need to determine whether the heart can safely achieve the workload necessary for sexual activity. For example, in men with coronary artery heart disease, a doctor may perform a treadmill stress test to determine whether there is adequate blood supply to the heart muscle while exercising at levels comparable to sexual activity.
Vardenafil (Levitra)
What is vardenafil (Levitra)?Vardenafil (Levitra) was the second oral medicine approved by the U.S. FDA for the treatment of erectile dysfunction. Like sildenafil (Viagra), vardenafil (Levitra) inhibits PDE5 which destroys cGMP (as discussed earlier).
How effective is vardenafil (Levitra)?Vardenafil was evaluated in four multicenter, randomized, placebo-controlled trials involving more than 2,400 men (78% white, 7% black, 2% Asian, 3% Hispanic) with erectile dysfunction. Two of these trials were conducted in special erectile dysfunction populations; one in men with diabetes mellitus, another in men who developed erectile dysfunction after prostate surgery. The doses of vardenafil in the four studies were 5 mg, 10 mg, and 20 mg.
In all four studies, vardenafil was significantly better than placebo in improving men's ability to achieve and maintain erections in all age categories (less than 45, 45-65, and greater than 65 years of age) and in all races.
How should vardenafil (Levitra) be administered?The recommended starting dose of vardenafil is 10 mg taken orally approximately one hour before sexual activity. The dose may be adjusted higher or lower depending on efficacy and side effects. The maximum recommended dose is 20 mg, and the maximum recommended dosing frequency is no more than once per day. Vardenafil can be taken with or without food.
What are the side effects of vardenafil (Levitra)?Vardenafil is generally well tolerated with only mild side effects. These side effects include headache, flushing, nasal congestion, dyspepsia, body aches, dizziness, nausea, and increased blood levels of the muscle enzyme creatine kinase.
There have been rare reports of priapism (prolonged and painful erections lasting more than six hours) with the use of oral PDE5 inhibitors such as vardenafil, sildenafil, and tadalafil. Men with blood cell diseases such as sickle cell anemia, leukemia, and multiple myeloma have higher than normal risks of developing priapism. Untreated priapism can cause injury to the penis tissue and lead to permanent loss of potency. If there is prolonged erection (longer than four hours), immediate medical assistance should be sought.
Who should not use vardenafil (Levitra)?Vardenafil (Levitra) can cause hypotension (abnormally low blood pressure, which can lead to fainting and even shock) when given to patients who are taking nitrates. People taking nitrates daily should not take vardenafil. Most commonly used nitrates are medications to relieve angina (chest pain due to insufficient blood supply to heart muscle because of narrowing of the coronary arteries). These include nitroglycerine tablets, patches, ointments, sprays, pastes, and isosorbide dinitrate and isosorbide mononitrate. Other nitrates such as amyl nitrate and butyl nitrate are found in some recreational drugs called poppers.
Vardenafil should not be used with alpha-blockers, medicines used to treat high blood pressure and benign prostate hypertrophy (BPH), because the combination of vardenafil and an alpha-blocker may lower the blood pressure greatly and lead to dizziness and fainting. Examples of alpha-blockers include tamsulosin (Flomax), terazosin (Hytrin), doxazosin (Cardura), alfuzosin (Uroxatral), and prazosin (Minipress).
Men with a rare heart condition known as long QT syndrome should not take vardenafil since this may lead to abnormal heart rhythms. The QT interval is the time it takes for the heart's muscle to recover after it has contracted. The QT interval is measured with an electrocardiogram (EKG). Some people have longer than normal QT intervals, and they may develop potentially life-threatening abnormal heart rhythms, especially when given certain medications. Since long QT syndrome can be inherited, men with a family history of long QT syndrome should not take vardenafil. Furthermore, vardenafil is not recommended for men who are taking medications that can affect the QT interval such as quinidine (Quinaglute, Quinidex), procainamide (Pronestyl, Procan-SR, Procanbid), amiodarone (Cordarone), and sotalol (Betapace).
There is insufficient information on the safety of vardenafil in men with the following conditions:
Therefore, men with these conditions should not use vardenafil without having these conditions evaluated and stabilized first. For example, men with uncontrolled high blood pressure should have their blood pressure controlled; and men with potentially life-threatening abnormal heart rhythms should have these rhythms controlled.
When there is angina or heart failure, the doctor may need to determine whether the heart has enough reserve to safely carry out the work necessary for sexual activity by performing cardiac treadmill stress testing.
What precautions should be taken when using vardenafil (Levitra)?Metabolism (breakdown) of vardenafil can be slowed by aging, liver disease, and concurrent use of certain medications (such as erythromycin, ketoconazole [Nizoral], and protease inhibitors). Slowed breakdown allows vardenafil to accumulate in the body and potentially increase the risk for side effects. Therefore, in men over 65 years of age, with liver dysfunction, or who are also taking medication(s) that can slow the breakdown of vardenafil, the doctor will initiate vardenafil at low doses to avoid its accumulation. For example
Tadalafil (Cialis)
What is tadalafil (Cialis)?Tadalafil (Cialis) is the third oral medicine approved by the U.S. FDA for the treatment of erectile dysfunction. Like sildenafil (Viagra) and vardenafil (Levitra), tadalafil inhibits PDE5 (as described earlier).
How effective is tadalafil (Cialis)?The safety and efficacy of tadalafil in the treatment of erectile dysfunction was evaluated in 22 clinical trials involving more than 4,000 men. Seven of these trials were randomized, prospective, placebo-controlled studies of 12 weeks' duration. Two of these studies (involving 402 men) were conducted in the United States, and the other five studies (involving 1,112 men) were conducted outside the United States. Two of these trials were conducted in special populations with erectile dysfunction; one in men with diabetes mellitus, another in men who developed erectile dysfunction after nerve-sparing prostate cancer surgery.
Effectiveness of tadalafil in these studies was assessed using a sexual function questionnaire. Study participants also were asked if they were able to achieve vaginal penetration and to maintain erections long enough for successful intercourse.
In all seven trials, tadalafil was significantly better than placebo in improving men's ability to achieve and maintain erections. Improvements in erectile function was observed in some patients at 30 minutes after taking a dose; and improvements can last for up to 36 hours after taking Cialis when compared to placebo.
How should tadalafil (Cialis) be administered?The recommended starting dose of tadalafil for most patients is 10 mg taken orally approximately one hour before sexual activity. The dose may be adjusted higher to 20 mg or lower to 5 mg depending on efficacy and tolerability. The maximum recommended dosing frequency is once per day, although for many patients tadalafil can be taken less frequently since the improvement in erectile function may last 36 hours. Tadalafil may be taken with or without food. Tadalafil is also available in 2.5 mg or 5 mg dosages for daily use.
What are the side effects of tadalafil (Cialis)?Tadalafil is generally well tolerated with only mild side effects. The most common side effects reported include headache, indigestion, back pain, muscle aches, facial flushing, and nasal congestion.
Back pain and muscle aches occurred in less than 7% of patients and usually occurred 12-24 hours after taking tadalafil. The back pain and muscle aches associated with tadalafil were characterized by mild to moderate muscle discomfort in the lower back, buttocks, and thighs, often aggravated by lying down. The back and muscle aches resolved in most patients 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. Approximately 0.5% of all the patients using tadalafil discontinued the drug due to back pain or muscle aches.
Reports of abnormal vision were rare; it occurred in less than 0.1% of patients using tadalafil.
There have been rare reports of priapism (prolonged and painful erections lasting more than six hours) with the use of oral PDE5 inhibitors such as vardenafil, sildenafil, and tadalafil. Men with blood cell diseases such as sickle cell anemia, leukemia, and multiple myeloma have higher than normal risks of developing priapism. Untreated priapism can cause injury to the penile tissue and lead to permanent loss of potency. If there is prolonged erection (longer than four hours), immediate medical assistance should be sought.
Who should not use tadalafil (Cialis)?Tadalafil can cause hypotension (abnormally low blood pressure, which can lead to fainting and even shock) when given to patients who are taking nitrates. Patients taking nitrates daily should not take tadalafil. Most commonly used nitrates are medications to relieve angina (chest pain due to insufficient blood supply to heart muscle because of narrowing of the coronary arteries). These include nitroglycerine tablets, patches, ointments, sprays, pastes, and isosorbide dinitrate and isosorbide mononitrate. Other nitrates such as amyl nitrate and butyl nitrate are found in some recreational drugs called poppers.
Tadalafil should not be used with alpha-blockers (except Flomax), medicines used to treat high blood pressure and benign prostate hypertrophy (BPH) because the combination of tadalafil and an alpha-blocker may lower the blood pressure greatly and lead to dizziness and fainting. Examples of alpha-blockers include tamsulosin (Flomax), terazosin (Hytrin), doxazosin (Cardura), alfuzosin (Uroxatral), and prazosin (Minipress). The only alpha-blocker that can be used safely with tadalafil is tamsulosin (Flomax). When tadalafil (20 mg) was given to healthy men taking 0.4 mg of Flomax daily, there was no significant decrease in blood pressure and so patients on this dose of tamsulosin (Flomax) can be prescribed tadalafil. The only alpha-blocker that has not been tested with tadalafil is alfuzosin (Uroxatral) and no recommendations can be made regarding the interaction between the two.
Tadalafil is not recommended for men with the following conditions:
Therefore, men with these conditions should not use tadalafil without having these conditions evaluated and stabilized first. For example, men with uncontrolled high blood pressure should have their blood pressure controlled; and men with potentially life-threatening abnormal heart rhythms should have these rhythms controlled.
When there is angina or heart failure, the doctor may need to determine whether the heart has enough reserve to safely carry out the work necessary for sexual activity by performing cardiac treadmill stress testing.
What precautions should be taken when using tadalafil?In most healthy men, some of the drug will remain in the body for more than two days after a single dose of tadalafil. Metabolism (clearing of the drug from the body) of tadalafil can be slowed by liver disease, kidney disease, and concurrent use of certain medications (such as erythromycin, ketoconazole, and protease inhibitors). Slowed breakdown allows tadalafil to stay in the body longer and potentially increase the risk for side effects. Therefore, the dose and frequency of tadalafil has to be lowered in the following examples:
Avanafil (Stendra)
Avanafil was recently FDA approved to treat erectile dysfunction. Common side effects may include headache, flushing, sore throat, stuffy and/or runny nose, and back pain. The drug is not recommended for patients with cardiac problems (in the last six months), hypotension or hypertension, unstable angina or congestive heart failure.
What are intracavernosal injections?
Medications can be injected directly into the corpora cavernosa to attain and maintain erections. Medications such as papaverine hydrochloride, phentolamine, and prostaglandin E1 (alprostadil) can be used alone or in combinations to attain erections. Combining small amounts of each drug is preferred over using a single drug because of increased efficacy and fewer side effects. Even though such injections can be effective in the management of erectile dysfunction (success rate of around 80%), they are not widely used because of their potential complications. These injections are painful, can cause scarring of the penis, and lead to a higher risk of developing priapism.
What are intraurethral suppositories?
Prostaglandin E1 (intraurethral alprostadil or MUSE) can be inserted in a pellet (suppository) form into the urethra to attain erections. This technique also is not popular because of occasional side effects of pain in the penis and sometimes in the testicles, mild urethral bleeding, dizziness, and vaginal itching in the sex partner. Men also need to remain standing after inserting the pellet in order to increase blood flow to the penis, and it may take 15-30 minutes to attain an erection. Prostaglandin can cause uterine contractions and should not be used by men having intercourse with pregnant women unless condoms or other barrier devices are used. This drug is now rarely used since the introduction of oral medications, however, it may play a role in management of erectile dysfunction in those who are not a candidate for oral PDE5 medications.
How effective is testosterone in treating erectile dysfunction?
In patients with hypogonadism, testosterone treatment can improve libido and erectile dysfunction, but the response of erectile dysfunction in men with hypogonadism to testosterone is not complete; many men still may need additional oral medications such as sildenafil, vardenafil, or tadalafil.
In men 40 years of age or older, a breast examination, digital examination of the prostate, and a PSA level (prostate specific antigen) blood test should be done to exclude breast and prostate cancer before starting testosterone treatment since testosterone can aggravate breast and prostate cancers. Patients who have breast and prostate cancers or are suspected of having them should not use testosterone.
Blood testosterone levels can be measured to detect deficiency. Although, there is no clear-cut testosterone level to define hypogonadism, levels lower than 250 nanograms per deciliter are considered low, and levels of greater than 350 nanograms per deciliter are considered normal. Testosterone levels in between these numbers may be labeled indeterminate.
Certain medications can alter the gonadal function, including thiazide diuretics, some seizure medications, long-acting oral opiate pain medications, antipsychotic medications, and oral steroids.
How common is erectile dysfunction?
Erectile dysfunction (ED, impotence) varies in severity; some men have a total inability to achieve an erection, others have an inconsistent ability to achieve an erection, and still others can sustain only brief erections. The variations in severity of erectile dysfunction make estimating its frequency difficult. Many men also are reluctant to discuss erectile dysfunction with their doctors due to embarrassment, and thus the condition is underdiagnosed. Nevertheless, experts have estimated that erectile dysfunction affects 18-30 million men in the United States.
While erectile dysfunction can occur at any age, it is uncommon among young men and more common in the elderly. By age 45, most men have experienced erectile dysfunction at least some of the time. According to the Massachusetts Male Aging Study, complete impotence increases from 5% among men 40 years of age to 15% among men 70 years and older. Population studies conducted in the Netherlands found that some degree of erectile dysfunction occurred in 20% of men between ages 50-54 and in 50% of men between ages 70-78. In 1999, the National Ambulatory Medical Care Survey counted 1,520,000 doctor-office visits for erectile dysfunction. Other studies have noted that approximately 35% of men 40-70 years of age suffer from moderate to severe ED, and an additional 15% may have milder forms. Further studies report similar findings.
How does erection occur?
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 generates electrical impulses along the nerves going to the penis and causes the nerves to release nitric oxide, which in turn increases the production of cyclic GMP (cGMP) in the smooth muscle cells of the corpora cavernosa. The cGMP causes the smooth muscles of the corpora cavernosa to relax and allow rapid blood flow into the penis. The incoming blood fills the corpora cavernosa, making the penis expand.
How is erection sustained?
The pressure from the expanding penis compresses the veins (blood vessels that drain the blood out of the penis) in the tunica albuginea, helping to trap the blood in the corpora cavernosa, thereby sustaining erection. Erection is reversed when cGMP levels in the corpora cavernosa fall, causing the smooth muscles of the corpora cavernosa to contract, stopping the inflow of blood and opening veins that drain blood away from the penis. The levels of the cGMP in the corpora cavernosa fall because it is destroyed by an enzyme called phosphodiesterase type 5 (PDE5).
What are erectile dysfunction risk factors?
The common risk factors for ED include the following:
What causes erectile dysfunction?
The ability to achieve and sustain erections requires the following:
Erectile dysfunction can occur if one or more of these requirements are not met. The following are causes of erectile dysfunction, and many men have more than one potential cause:
How is erectile dysfunction diagnosed?
Patient historyA diagnosis of erectile dysfunction is made in men who have repeated inability to achieve and/or maintain an erection for satisfactory sexual performance for at least three months. Candid communication between the patient and the doctor is important in establishing the diagnosis of erectile dysfunction, assessing its severity, and determining the cause. During patient interviews, doctors try to answer the following questions:
The physical examination can reveal clues for physical causes of erectile dysfunction. For example, if the penis does not respond as expected to touching, a problem in the nervous system may be the cause. Small testicles, lack of facial hair, and enlarged breasts (gynecomastia) can point to hormonal problems such as hypogonadism with low testosterone levels. A reduced flow of blood as a result of atherosclerosis can sometimes be diagnosed by finding diminished arterial pulses in the legs or listening with a stethoscope for bruits (the sound of blood flowing through narrowed arteries). Unusual characteristics of the penis itself could suggest the root of the erectile dysfunction, for example, bending of the penis with painful erection could be the result of Peyronie's disease. Particular attention is paid to any underlying risk factors for erectile dysfunction.
Laboratory testsThe following are common laboratory tests to evaluate erectile dysfunction:
In a setting of a previous pelvic trauma, X-rays may be performed to assess various bony abnormalities. Ultrasound of the penis and testicles is done occasionally to check for testicular size and structural abnormalities. Ultrasound with Doppler imaging can provide additional information about blood flow of the penis. Rarely, an angiogram may be performed in cases in which possible vascular surgery could be beneficial.
Other testsProstaglandin E1 injection test is sometimes performed to determine the penile blood flow. Prostaglandin is directly injected into the corpora cavernosa in order to cause dilation of blood vessels and promote blood flow into the penis. If erection ensues, it confirms normal or adequate blood flow to the penis. This can also provide information about possible therapeutic options.
Monitoring erections that occur during sleep (nocturnal penile tumescence) can help distinguish between erectile dysfunction of psychological and physical causes. A band is worn around the penis for two to three successive nights and it can signal intensity and duration of erections if they occur. If nocturnal erections do not occur, then the cause of erectile dysfunction is likely to be physical rather than psychological, however, tests of nocturnal erections are not completely reliable. Scientists have not standardized the tests a
Source: http://www.rxlist.com
Source: http://www.rxlist.com
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