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.


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.

Erectile dysfunction (ED) related to compromise of the nervous system is an increasingly common occurrence. This may be due to the multifactorial nature of ED, the myriad of disorders affecting the neurotransmission of erectogenic signals, and improved awareness and diagnosis of ED. Nevertheless, neurogenic ED remains poorly understood and characterized. Disease related factors such as depression, decreased physical and mental function, the burden of chronic illness, and loss of independence may preclude sexual intimacy and lead to ED as well. The amount of data regarding treatment options in subpopulations of differing neurologic disorders remains scarce except for men with spinal cord injury. The treatment options including phosphodiesterase inhibitors, intracavernosal or intraurethral vasoactive agents, vacuum erection devices (VED) and penile prosthetic implantation remain constant. This review discusses the options in specific neurologic conditions, and briefly provides insight into new and future developments that may reshape the management of neurogenic ED.
Having your current medication checked – if you are taking medication already, it could be that your erection problems are a side effect. Have a doctor check whether this is the cause of your problems and if it is, you might be able to switch medications and then find that your erectile dysfunction goes away completely – or at least improves. Medications that can cause erection problems include:
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, doctors have to lower the dose and frequency of tadalafil in the following examples:
The availability of phosphodiesterase-5 (PDE5) inhibitors—sildenafil, vardenafil, tadalafil, and avanafil—has fundamentally altered the medical management of ED. In addition, direct-to-consumer marketing of these agents over the last 15 years has increased the general public’s awareness of ED as a medical condition with underlying causes and effective treatments.
Her remark was entirely destructive of poetry, since it was to the effect that poetry had nothing whatever to do with her; all her friends spent their lives in making up phrases, she said; all his feeling was an illusion, and next moment, as if to taunt him with his impotence, she had sunk into one of those dreamy states which took no account whatever of his existence.

The percentage of men who engage in some form of sexual activity decreases from 73% for men aged 57–64 years to 26% for men aged 75–85 years.3 For some men, this constitutes a problem, but for others it does not. The aetiology for this decline in sexual activity is multifactorial and is in part due to the fact that most of the female partners undergo menopause at 52 years of age with a significant decline in their libido and desire to engage in sexual activity. A study by Lindau and colleagues3 that examined sexuality in older Americans showed that 50% of the men in a probability sample of more than 3000 US adults reported at least one bothersome sexual problem and 33% had at least two such problems.3 This article will review the normal changes that occur with ageing, factors that influence these changes, individual variations and perspectives, and the available treatment options for ED and androgen deficiency.
The mechanisms by which testosterone plays a role in erectile function are not completely understood. A study evaluating the effect of testosterone on erections in surgically castrated rabbits and control animals, in which the rabbits’ intracavernosal pressures were compared after cavernosal nerve stimulation, determined that castrated rabbits had much lower pressures after stimulation than control rabbits did. [21] Notably, the pressures increased when castrated rabbits received exogenous testosterone replacement.
Q. I started to suffer from erectile dysfunction? Why is this happening and what can I do to treat it? I am a healthy 52 year old. I have hypertension but i take pills to treat it and my levels are around 130/80. except that I am at great shape. In the last few months I feel that a problem in my sex life. I want to have sex but i can't due to erectile dysfunction. What can be the reason for this? and more important what can I do?
Many common medications for treating hypertension, depression, and high blood lipids (high cholesterol) can contribute to erectile dysfunction (see above). Treatment of hypertension is an example. There are many different types (classes) of medications for high 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). Patients may use these medications alone or in combination to control blood pressure. Some of these medications can cause troubles with erections. For example, Inderal (a beta-blocker) and hydrochlorothiazide (a diuretic) cause erectile dysfunction, while calcium channel blockers and ACE inhibitors do not seem to affect erectile function. On the other hand, other medications (such as angiotensin receptor blockers [ARB] including losartan [Cozaar] and valsartan [Diovan]) may actually help with erections. Therefore, if possible, you may benefit from changing your medications, but this requires approval by your prescribing health care provider.
Both ED and low testosterone (hypogonadism) increase with age. The incidence of the latter is 40% in men aged 45 years and older. [15] Testosterone is known to be important in mood, cognition, vitality, bone health, and muscle and fat composition. It also plays a key role in sexual dysfunction (eg, low libido, poor erection quality, ejaculatory or orgasmic dysfunction, reduced spontaneous erections, or reduced sexual activity). [16]
Positron emission tomorgraphy (PET), and functional magnetic resonance imaging (fMRI) have led to a greater understanding to which center are activated during arousal. These imaging studies measure increases in cerebral blood flow or changes in cerebral activity on a real-time basis. Studies are performed when male subject are aroused by visual cues (usually sexual explicit photos or videos) and compared to images obtained during exposure to sexually neutral cues differences can be measured. Several studies have identified that the inferior frontal lobes, inferior temporal lobes and insular gyrus, and occipital lobes are involved with processing arousal cues, although each are likely to process different stimuli (20-23).

Metabolism (breakdown) of vardenafil can be slowed by aging, liver disease, and concurrent use of certain medications (such as erythromycin [an antibiotic], ketoconazole [Nizoral, a medication for fungal/yeast infections], and protease inhibitors [medications used to treat AIDS]). 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 disease, 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,


Medications: Many common medicines produce erectile dysfunction as a side effect. Medicines that can cause erectile dysfunction include many used to treat high blood pressure, antihistamines, antidepressants, tranquilizers, and appetite suppressants. Examples of common medicines that can cause erectile dysfunction include propranolol (Inderal) or other beta-blockers, hydrochlorothiazide, digoxin (Lanoxin), amitriptyline (Elavil), famotidine (Pepcid), cimetidine (Tagamet), metoclopramide (Reglan), naproxen, indomethacin (Indocin), lithium (Eskalith, Lithobid), verapamil (Calan, Verelan, Isoptin), phenytoin (Dilantin), gemfibrozil (Lopid), amphetamine/dextroamphetamine (Adderall), and phentermine. Prostate cancer medications that lower testosterone levels such as leuprolide (Lupron) may affect erectile function. Some chemotherapies such as cyclophosphamide (Cytoxan) may affect erectile function.

This inflatable penile prosthesis has 3 major components. The 2 cylinders are placed within the corpora cavernosa, a reservoir is placed beneath the rectus muscle, and the pump is placed in the scrotum. When the pump is squeezed, fluid from the reservoir is transferred into the 2 cylinders, producing a firm erection. The deflation mechanism is also located on the pump and differs by manufacturer.
Testosterone replacement therapy may improve energy, mood, and bone density, increase muscle mass and weight, and heighten sexual interest in older men who may have deficient levels of testosterone. Testosterone supplementation is not recommended for men who have normal testosterone levels for their age group due to the risk of prostate enlargement and other side effects. Testosterone replacement therapy is available as a cream or gel, topical solution, skin patch, injectable form and pellet form placed under the skin.
The bad news: Men with diabetes are three times more likely to report having problems with sex than non-diabetic men. The most common sexual problem is Erectile Dysfunction, or ED, sometimes called impotence. Even worse, because ED is such a private issue, many men feel embarrassed to discuss the problem with their doctor, or even their partner, so the problem is never addressed.

Ultimately, PDE5i have had a significant impact on the treatment of ED in men with SCI. The ease of use and tolerability of the medication has also led to improved satisfaction and quality of life that had been previously affected by SD. Head to head trials evaluating specific PDE5i within the SCI population are required to further elucidate drug preference. PDE5i should be considered first line therapy, however men with high thoracic and cervical lesions should be warned about an increased chance of dizziness with sildenafil and possibly other PDE5i use.
The FDA recommends that men follow general precautions before taking a medication for ED. Men who are taking medications that contain nitrates, such as nitroglycerin, should NOT use these medications. Taking nitrates with one of these medications can lower blood pressure too much. In addition, men who take tadalafil or vardenfil should use alpha blockers with care and only as instructed by their physician, as they could result in hypotension (abnormally low blood pressure). Experts recommend that men have a complete medical history and physical examination to determine the cause of ED. Men should tell their doctor about all the medications they are taking, including over-the-counter medications.
ED is easily and successfully treated! If your sex drive is unaffected, but you experience problems achieving or sustaining erection for a period of four to five weeks, you may have ED. Talk to your doctor immediately. Don’t delay—erectile dysfunction doesn’t “just go away!” Additionally, ED could be a sign of a serious, even life-threatening complication, such as congestive heart failure or kidney disease. Ignoring your ED because it’s embarrassing could jeopardize your health.
Patients with both ED and cardiovascular disease who receive treatment with an oral PDE5 inhibitor require education regarding what to do if anginal episodes develop while the drug is in their system. Such education includes stressing the importance of alerting emergency care providers to the presence of the drug so that nitrate treatment is avoided.

Nerves originating in the spinal cord and peripheral ganglia innervate the penis. There are autonomic (parasympathetic and sympathetic), and somatic separate and integrated pathways. The autonomic pathways neurons originate in the spinal cord and peripheral ganglia from the sympathetic and parasympathetic systems, respectively. They merge to form the cavernous nerves that travel alongside the prostate, enter the corpora cavernosa and corpus spongiosum to affect the neurovascular events required for tumescence and detumescence. The somatic nerves send sensory information from the penile skin, glans, and urethra via the dorsal penile nerve and pudendal nerve to the spinal cord. The somatic nerves also initiate contraction of the ischio- and bulbocavernosus muscles.

Finally, gene therapy and stem cell research has widened the frontier of ED treatment proposed as possibility to even reverse ED. Specifically, gene therapy pertains to repairing the cause of ED by restoring defective gene function and/or altering the expression of the mutant gene (32). Most of the available data on gene therapy are in the animal model. However, a phase I clinical trial in men with ED undergoing intracavernous injection with a DNA plasmid carrying the alpha-subunit of the corporal smooth muscle Maxi-K channel showed promise in increased erectile function based on IIEF assessment sustained throughout the 3-month study period (122).


Erectile dysfunction or disorder (ED) is the inability to develop and maintain an erection for satisfactory sexual intercourse or activity. Erectile dysfunction or erectile disorder are the preferred terms as opposed to impotence. There are no uniform criteria defining how consistent the problem has to be and for what duration it must be present to considered ED. The Diagnostic and Statistical Manual of Mental Disorder-5 specifies a duration of at least 6 months in its definition of ED.1
Vascular damage may result from radiation therapy to the pelvis and prostate in the treatment of prostate cancer. [36] Both the blood vessels and the nerves to the penis may be affected. Radiation damage to the crura of the penis, which are highly susceptible to radiation damage, can induce ED. Data indicate that 50% of men undergoing radiation therapy lose erectile function within 5 years after completing therapy; fortunately, some respond to one of the PDE5 inhibitors.
When other treatments haven’t helped, a penile implant may be the right solution. A penile implant is a medical device that is surgically placed into a penis to mimic the look and performance of a natural erection9. Implants are custom-fitted to your anatomy. Sensitivity and the ability to ejaculate aren’t typically affected either, so you’ll be able to have an orgasm normally (unless you have a medical condition that prevents this)7.
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.
The role of the endothelium in erectile function became clearer with the observation that the phosphodiesterase type 5 (PDE5) inhibitor, sildenafil, enhanced erectile function. Erection occurs with the release of nitric oxide (NO) from the vascular endothelial cells.17 The reduction in endothelial cell production of NO results in the negative impact on the smooth muscles in the corporal bodies and results in less relaxation of the smooth muscle cells with decrease in blood supply and resulting ED. A similar phenomenon is well known to impact the coronary arterial system resulting in CVD.
Talk with your doctor about going to a counselor if psychological or emotional issues are affecting your ED. A counselor can teach you how to lower your anxiety or stress related to sex. Your counselor may suggest that you bring your partner to counseling sessions to learn how to support you. As you work on relieving your anxiety or stress, a doctor can focus on treating the physical causes of ED.
In their extensive review, Bassil and coworkers summarise the benefits and risks, with benefits such as improvement of sexual function, bone density, muscle strength, cognition and overall improvement in quality of life. Among the risks that have been suggested include erythrocytosis, liver toxicity, worsening of sleep apnoea and cardiac function, possibly increasing symptoms of benign prostatic hyperplasia (BPH). They also note that although a possibility of stimulation of prostate cancer has been hypothesised, no scientific or clinical evidence exists to this possible risk.38
Penile implants - are generally used if physical damage (like an accident) makes the anatomical parts needed for an erection not work. These are inserted by surgery and can provide a permanent treatment choice if others fail to work. The implants can be semi-rigid or inflatable. They can be pretty expensive and are not usually available on the NHS.

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.
Levitra is available in two strengths: 10 mg and 20 mg. It is not necessary to take it on an empty stomach. Levitra should be started at low dose in men taking certain medications called CYP3A4 inhibitors (ketoconazole, medications for HIV, and clarithromycin) and should be not be used in individuals with a known heart problem called prolonged QT interval or with medications that prolong the QT interval.
Her remark was entirely destructive of poetry, since it was to the effect that poetry had nothing whatever to do with her; all her friends spent their lives in making up phrases, she said; all his feeling was an illusion, and next moment, as if to taunt him with his impotence, she had sunk into one of those dreamy states which took no account whatever of his existence.

Psychosexual counselling, or sex therapy, is an appropriate recommendation especially for men who are experiencing discord with their partner especially if the conflict is related to the man’s ED. Counselling usually consists of 5–20 sessions with counsellor. It is our recommendation that referral doctors treating men with ED make a referral to a psychotherapist or sex therapist who is certified by AASECT (American Association of Sexuality Educators, Counselors and Therapists) of certified sexuality educator.43

Using a tiny needle and syringe, the man injects a small amount of medicine into the side of his penis. The medicine relaxes the blood vessels, allowing blood to flow into the penis. This treatment has been widely used and accepted since the early 1980s. The three most common medicines are prostaglandin E1 (alprostadil), papaverine (Papacon®), and phentolamine (Regitine®).
Another tip is to make sure you communicate with your partner what you like during the process of sex.  Many men are not communicative about what really turns them on.  If you are not aroused by what is going on, then you might experience ED.  Make sure you tell your partner what turns you on.  Communicating about intimacy should also lead to feeling more connected with your partner aiding in relaxing when you are sexual together.
Patients should continue testosterone therapy only if there is improvement in the symptoms of hypogonadism and should be monitored regularly. You will need periodic blood tests for testosterone levels and blood tests to monitor your blood count and PSA. Testosterone therapy has health risks, and thus doctors should closely monitor its use. Testosterone therapy can worsen sleep apnea and congestive heart failure.
Finally, there are NO-releasing polymers that are capable of delivering NO in a pharmacologically useful way. Such compounds include compounds that release NO upon being metabolised and compounds that release NO spontaneously in aqueous solution. Initial animal studies suggest that cavernosal injections of NO polymers can significantly improve erectile function.48
Dr Kenny du Toit is a urologist practicing in Rondebosch, Cape Town. He is also consultant at Tygerberg hospital, where he is a senior lecturer at Stellenbosch University. He is a member of the South African Urological Association, Colleges of Medicine South Africa and Société Internationale d’Urologie. Board registered with both the HPCSA (Health professions council of South Africa) and GMC (General medical council UK). He has a keen interest in oncology, kidney stones and erectile dysfunction.http://www.dutoiturology.co.za
Of particularly concern are antihypertensive medications for CVD (eg, digoxin, disopyramide [Norpace], gemfibrozil [Lopid]), anxiety, depression (eg, lithium, monoamine oxidase inhibitors, selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, tricyclic antidepressants), or psychosis (eg, chlorpromazine, haloperidol, pimozide [Orap], thioridazine, thiothixene). Antihypertensive drugs, such as diuretics (eg, spironolactone, thiazides) and beta blockers, may be associated with ED. Discontinuation or switching to alternative drugs, such as angiotensin-converting enzyme inhibitors or calcium channel blockers (eg, diltiazem, nifedipine, amlodipine), may reduce ED. The newer angiotensin II receptor antagonists may be less problematic with respect to ED, but long-term data is needed to evaluate this.
In rare cases, the drug Viagra ® can cause blue-green shading to vision that lasts for a short time. In rare cases, the drug Cialis® can cause or increase back pain or aching muscles in the back. In most cases, the side effects are linked to PDE5 inhibitor effects on other tissues in the body, meaning they are working to increase blood flow to your penis and at the same time impacting other vascular tissues in your body. These are not ‘allergic reactions'.
×