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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.
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Source | More Levitra
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