Dear Dr. B: I have erectile dysfunction (impotence) and have been on Viagra (sildenafil) for sometime. Can you tell me more about this drug and is it safe to take Viagra if a person has heart disease? Yours Anxious.
Dear Mr. Anxious: About 100 million people worldwide are estimated to be affected by erectile dysfunction. Since the introduction of Viagra (sildenafil), the treatment of erectile dysfunction has significantly improved. It is a medication easy to take by mouth and is effective in 84 percent of the people with erectile dysfunction. Viagra (sildenafil) is quite specific in improving penile circulation and thus effective in producing penile erection.
A recent review article in the Canadian Medical Association Journal (CMAJ) says that there are several risk factors common to both, erectile dysfunction and cardiovascular diseases. These are: age, high blood pressure, hardening of the arteries, smoking, and diabetes. Therefore, cardiovascular disease and erectile dysfunction frequently occur together.
Sildenafil was first tested on patients with angina to relax coronary arteries to improve blood supply to the heart. One of the side effects was penile erection. This is how the researchers discovered that sildenafil might be beneficial to patients with erectile dysfunction. But the erection occurs only after sexual stimulation. Sildenafil does not cause spontaneous erection.
Sildenafil dosage can be anywhere from 25mg to 100mg. The drug is metabolized in the liver and excreted in the feces and urine. So sildenafil should be used with caution in patients with liver failure and kidney failure. Under normal conditions, the drug disappears from the body within four hours.
The most common side effects are from the drugs property to relax the blood vessels this leads to headache, flushing and runny nose. Some people get heartburn due to relaxation of the muscle at the junction of oesophagus and stomach. In about three percent of sildenafil users, there is visual abnormality related to blue-green colour vision.
Sildenafils effect on blood pressure is small and lasts for approximately four hours. Heart rate is not significantly affected. The article says, The increase in sexual activity that can be expected after a patient receives a prescription for sildenafil should not be of concern for men with stable coronary artery disease (and negative results on exercise stress testing).
But the situation is different for patients who are taking nitrates in any form (pill under the tongue, spray, patch) for the treatment of angina. There is a potential for the interaction between sildenafil and nitrates resulting in significant prolonged drop in blood pressure and heart attack. This may lead to death. Sildenafil is absolutely contraindicated in patients who take nitrate in any form.
Sildenafil should be used with caution in patients who have recent positive result on cardiac stress test, who have congestive heart failure, who are on multidrug therapy for high blood pressure and patients who are on any drug that could prolong the disappearance of sildenafil from the body.
The article says that overall, sildenafil does not appear to increase the incidence of heart attack or death in men with erectile dysfunction. So, if you are on sildenafil and have heart problems then you must discuss this with your family doctor. Although your heart may not be your most favourite organ, it is necessary to have good heart to enjoy the good effects of sildenafil!
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