In a man, an erection is a response to physical or emotional sexual stimuli. Nerve signals from the brain cause the release of nitric oxide, a chemical that relaxes the muscles in the penis, allows more blood to flow through the arteries, and temporarily close the valves in the veins. Increased blood flow creates pressure, causing the penis to expand (an erection). Later, blood flow is slowed and the valves in the veins are opened, allowing the penis to relax.
Erectile dysfunction (E.D.) is a condition in which a man can't achieve an erection or sustain an erection that is sufficient for successful sexual intercourse. According to the American Urological Association, about 25 million adult males have some degree of E.D. Incidence increases with age. Underlying conditions, like diabetes, heart disease, high blood pressure and kidney disease, increase the risk of developing E.D. Symptoms may also be caused by alcoholism or use of certain drugs.
Drug Treatments for E.D.
The first medication for E.D. was VIAGRA® (sildenafil citrate), approved in March 1998. Last year, the FDA approved two more medications: LEVITRA® (vardenafil HCl), and Cialis® (tadalafil). All three drugs work in the same manner they block the action of the natural enzyme, phosphodiesterase-5, which enhances smooth muscle relaxation and allows more blood to flow into the penis. VIAGRA and LEVITRA take effect in less than 30 minutes and last about four hours. Cialis takes effect in about 45 minutes, but lasts for up to 36 hours. According to the Medical Letter on Drugs and Therapeutics, the average cost per pill is comparable for all three medications (roughly $9.00/pill).
So far, no one has performed any studies comparing the effectiveness of the three medications. Health experts say if one drug doesn't seem to help, patients may want to try one of the others. The medications should not be used by patients taking nitrates or alpha blockers because of the increased risk of sudden, low blood pressure. The drugs are also not recommended for patients who have had a recent heart attack or stroke, those with very low blood pressure, uncontrolled high blood pressure, unstable angina, severe liver or kidney disease, or an eye condition called retinitis pigmentosa. Potential side effects of the drugs include headache, flushing, runny nose, dizziness, nasal congestion and stomach upset. Doctors caution the medications are not a cure for erectile dysfunction and patients still require sexual stimulation to attain an erection.
For specific concerns about medications for erectile dysfunction, talk to your health care provider. For information about the drugs:
For general information on erectile dysfunction: American Urological Association, http://www.urologyhealth.org
The Endocrine Society, http://www.endo-society.org
National Kidney and Urologic Diseases Information Clearinghouse, http://kidney.niddk.nih.gov
End of article.
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