Sildenafil (Viagra®)

But because the nitrates and ED pills all act on nitric oxide, they do not mix. Men who are taking nitrates should never use any of the ED pills. This ban includes all preparations of nitroglycerin (short-acting, under-the-tongue tablets or sprays); long-acting nitrates (isosorbide dinitrate, or Isordil, Sorbitrate, and others, and isosorbide mononitrate, Imdur, ISMO, and others); nitroglycerin patches and pastes; and amyl nitrite (so-called poppers, used for sexual stimulation by some men). ED pills are quite safe for men with stable cardiovascular disease who do not take nitrates. This group includes patients with stable angina, previous heart attacks, mild congestive heart failure, well-controlled hypertension, and previous strokes.

What to avoid

At least 2/3 of men experience improved erectile function after taking Viagra; however, this is not the case for everyone. If Viagra is ineffective, it is important to rule out other physiological causes such as emotional deficiencies, prolonged waiting, or insufficient dosage. Some medications can cause erectile dysfunction or reduce libido, such as SSRI antidepressants, blood pressure medications, antihistamines, and prostate medications, among others. In cases of non-response to Viagra, other medications such as Cialis (tadalafil), Spedra (avanafil), or Levitra (vardenafil) may be tried, as they work through similar mechanisms as Viagra, or Alprostadil, which acts as a male hormone replacement. Some non-drug alternative therapies include vacuum pumps, psychological therapy with a sex specialist, and pelvic floor muscle exercises.

Side effects

Vinmec International General Hospital, with its modern facilities and medical equipment, along with a team of experienced specialists and doctors in diagnosing and treating diseases, ensures that patients can feel confident in seeking examination and treatment for erectile dysfunction at the hospital. To arrange an appointment, please call HOTLINE or make your reservation directly HERE. You may also download the MyVinmec app to schedule appointments faster and manage your reservations more conveniently. When the history of men's health is written, 1998 will go down as a banner year. That's when sildenafil (Viagra) was approved by the FDA to treat erectile dysfunction (ED).

Does Viagra treat ED that’s related to diabetes?

But when the history of sildenafil is written, 2005 will also be special. That's when the FDA approved the medication that revolutionized male sexuality for a nonsexual condition. The illness is pulmonary hypertension, and sildenafil is prescribed for it under the brand name Revatio. Sildenafil was the first effective oral medication for ED. Although there are some differences between these drugs (vardenafil starts working sooner and tadalafil works longer), they all act in exactly the same way to combat ED. But men with recent heart attacks and strokes should wait until they have recovered fully, and patients with unstable blood pressure, active angina, or any other complex or unusual problem should hold off and get specific medical guidance. And men who take alpha blockers (particularly terazosin, or Hytrin, and doxazosin, or Cardura) for hypertension or benign prostatic hyperplasia (BPH) should use ED pills (particularly vardenafil or tadalafil) with great caution, if at all.

• Viagra’s patent expired, leading to generic versions being available.
• The medication should be taken at least half an hour before sex.
• Some men experience rapid or delayed onset of action.
• Sildenafil, the active compound, also treats pulmonary hypertension.
• It’s important to discuss potential drug interactions with your doctor.
• Viagra is not suitable for everyone, especially those with certain health issues.
• Side effects usually resolve within a few hours of taking the drug.

Studies also suggest that sildenafil may increase respiratory distress in men with severe sleep apnea and that it slows gallbladder function, which might increase the risk of gallstones.

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Scientists who noticed that the ED pills can produce side effects in many parts of the body are asking if they can also serve therapeutic roles beyond male (or female) sexuality. Because of its seniority, most of the research has used sildenafil, so it's not clear if the newer medications will fill similar roles. But for sildenafil, at least, some new uses appear promising. It's the only nonsexual condition that has earned FDA approval for sildenafil.

What other information should I know?

The three drugs are so similar because they share a common target, an enzyme called phosphodiesterase-5 (PDE-5). To understand why blocking PDE-5 improves sexual function, however, you have to know how erections develop. Normal erections require a receptive state of mind, adequate levels of testosterone, and healthy arteries, veins, and nerves. But they also require a tiny chemical messenger called nitric oxide (NO). It serves two crucial functions: transmitting the impulses of arousal between nerves and relaxing the smooth muscle cells in the arteries, allowing them to widen and admit more blood to the penis.

Drug details

Nitric oxide is essential because it signals the arterial cells to produce cyclic guanosine monophosphate (cGMP), the chemical that increases the flow of blood to the penis. But the tissues of the penis also produce PDE-5, the enzyme that breaks down cGMP. In normal circumstances, the penis generates enough cGMP to produce a rigid erection and enough PDE-5 to end the erection when ejaculation is complete. In many men with ED, this intricate system is out of balance, but one of the three oral medications can often make it right. By inhibiting PDE-5, they increase the supply of cGMP, which for many men will allow erections to develop.

Can Viagra cause side effects?

In test tubes, vardenafil and tadalafil inhibit PDE-5 a bit more effectively than sildenafil does. But laboratory potency doesn't necessarily predict clinical activity. In this case, it means that lower doses of the newer drugs will achieve comparable results to the older drug's success rate. Vardenafil is marketed in 2.5-, 5-, 10-, and 20-milligram (mg) tablets; tadalafil in doses of 5, 10, and 20 mg; and sildenafil, 25, 50, and 100 mg. Each produces better results at higher doses, but the top doses are also more likely to cause side effects. But since it's a serious problem, any benefit is most welcome. When we think of blood pressure, we usually think of the systemic circulation, of the blood pumped from the heart's left ventricle to the aorta and then to the smaller arteries that carry oxygen-rich blood throughout the body. But to pick up vital oxygen, blood must first pass from the less powerful right ventricle through the pulmonary artery to the lungs, then back to the left side of the heart. The pressures in the pulmonary artery are much lower (about 20/10 millimeters of mercury, or mm Hg) than in the aorta (lower than 120/80 mm Hg is considered healthy).

Sildenafil (Generic Viagra®) FAQs

Nonarteritic anterior ischemic optic neuropathy (NAION) is a poorly understood disorder that can cause blindness. In March 2005, doctors reported that seven men experienced visual impairment within hours of using sildenafil. Since then, additional cases have been reported to the FDA related to sildenafil, tadalafil, and vardenafil. Fortunately, the number of cases is very small in relation to the millions of men who have used ED pills successfully. It's not clear that there is a cause-and-effect relationship between ED pills and NAION.

A Note on Gender and Sex Terminology

At present, the concern is not great enough to prevent men from using these pills, but all men should use them carefully and responsibly. The most important worry about ED pills is their ability to widen arteries enough to lower blood pressure. It's rarely a problem in healthy men, but it explains a crucial precaution that applies to all three medications. Nitrates are medications that temporarily widen arteries by increasing their supply of nitric oxide. That's how they widen partially blocked coronary arteries in patients with angina. Exercise is the most common cause of rising pulmonary artery pressure, but the elevation is mild and subsides promptly with rest. High altitudes are another cause, which can lead to mountain sickness (see below).

• Viagra may cause side effects like dizziness or upset stomach in some users.
• Alcohol consumption can reduce the effectiveness of Viagra.
• Avoid taking Viagra if you have heart problems without medical advice.
• The medication is available by prescription from a healthcare professional.
• Illegal or counterfeit Viagra can contain harmful ingredients.
• Tell your doctor about any health conditions before use.
• Viagra does not protect against sexually transmitted infections.

Far more serious are the large number of lung diseases, vascular diseases, heart disorders, and miscellaneous conditions that can cause pulmonary hypertension.

Country/Region	Legal Classification	Prescription Requirement	Over-the-counter Availability
USA	Prescription-only	Yes	No
EU Countries	Prescription-only	Yes	No
India	Both (depends on brand)	Usually prescription	Some generic brands available over-the-counter
Japan	Prescription only	Yes	No

And in primary pulmonary hypertension, no underlying cause is evident. Pulmonary hypertension causes shortness of breath, first during exertion but eventually at rest if the condition progresses. A variety of treatments are available, depending on the underlying problem. And the FDA has approved sildenafil (Revatio) in a dose of 20 mg three times a day for men and women with pulmonary hypertension. Clinical trials have demonstrated improved exercise tolerance with few side effects. Pulmonary hypertension is a feature of acute mountain sickness.

Detection in biological fluids

And all the drugs are more effective in men with mild ED than in those who are severely impaired. Doctors have had more clinical experience with sildenafil than its newer rivals. Still, all three drugs seem to achieve similar results. In broad terms, about 70% of men benefit. The response is best in men with no identifiable organic cause of ED (about 90%), but it's less favorable for diabetics (about 50%), and it's hard to predict for men who have been treated for prostate cancer.

Does Viagra work to treat ED?

If PDE-5 were found exclusively in the penis, the side effects of these drugs would be limited to that obdurate organ; in fact, a rare side effect is priapism, painful prolonged erections that require urgent treatment. But small amounts of PDE-5 are found in blood vessels in other parts of the body. In addition, PDE-5 is just one of 11 enzymes in the phosphodiesterase family. The others are concentrated in different parts of the body. While the ED pills have a much greater affinity for PDE-5 than the other PDEs, they have some ability to inhibit those closely related enzymes.

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Both factors explain why the ED pills sometimes produce side effects in many parts of the body. The most common side effects are headaches and facial flushing, which occur in about 15% of men. Other reactions include nasal congestion, indigestion, and back pain; blue-tinged vision is even pink viagra less common. In almost every case, these side effects are mild and transient. But new information has added a rare eye disease to the list. High altitudes produce low blood-oxygen levels. In turn, low oxygen produces a narrowing of the pulmonary arteries. The heart must therefore work harder, reducing the capacity to exercise.