General
Description & Use
Treats
impotence (problems having sex) by helping you have an erection.
Sildenafil citrate, sold as Viagra, Revatio, Kamagra, Intagra
and under various other trade names, is a drug used to treat erectile
dysfunction (male impotence) and pulmonary arterial hypertension
(PAH). It was developed and is being marketed by the pharmaceutical
company Pfizer. It acts by inhibiting cGMP specific phosphodiesterase
type 5, an enzyme that regulates blood flow in the penis. Since
becoming available in 1998, sildenafil has been the prime treatment
for erectile dysfunction; its primary competitors on the market
are tadalafil (Cialis) and vardenafil (Levitra).
Viagra
(Sildenafil Citrate)
The
mechanism of action of Sildenafil citrate involves the release
of nitric oxide (NO) in the corpus cavernosum of the penis. NO
binds to the receptors of the enzyme guanylate cyclase which results
in increased levels of cyclic guanosine monophosphate (cGMP),
leading to smooth muscle relaxation (vasodilation) of the intimal
cushions of the helicine arteries, resulting in increased inflow
of blood and an erection. Sildenafil is a potent and selective
inhibitor of cGMP specific phosphodiesterase type 5 (PDE5) which
is responsible for degradation of cGMP in the corpus cavernosum.
The molecular structure of sildenafil is similar to that of cGMP
and acts as a competitive binding agent of PDE5 in the corpus
cavernosum, resulting in more cGMP and better erections. Without
sexual stimulation, and therefore lack of activation of the NO/cGMP
system, sildenafil should not cause an erection. Other drugs that
operate by the same mechanism include tadalafil (Cialis) and vardenafil
(Levitra). Sildenafil is metabolised by liver enzymes and excreted
by both the liver and kidneys. If taken with a high-fat meal,
absorption is reduced; the time taken to reach the maximum plasma
concentration increases by around one hour, and the maximum concentration
itself is decreased by nearly one-third.
Uses ..
Sexual
dysfunction
The primary
indication of sildenafil is treatment of erectile dysfunction
(inability to sustain a satisfactory erection to complete intercourse).
It use is now standard treatment for erectile dysfunction in all
settings, including diabetes. People on antidepressants may experience
sexual dysfunction, either as a result of their illness or as
a result of their treatment. A 2003 study showed that sildenafil
improved sexual function in men in this situation. Following up
to earlier reports from 1999, the same researchers found that
sildenafil was able to improve sexual function in female patients
on antidepressants as well.
Pulmonary hypertension
As well as erectile dysfunction, sildenafil citrate is also effective
in the rare disease pulmonary arterial hypertension (PAH). It
relaxes the arterial wall, leading to decreased pulmonary arterial
resistance and pressure. This in turn reduces the workload of
the right ventricle of the heart and improves symptoms of right-sided
heart failure. Because PDE-5 is primarily distributed within the
arterial wall smooth muscle of the lungs and penis, sildenafil
acts selectively in both these areas without inducing vasodilation
in other areas of the body. Pfizer submitted an additional registration
for sildenafil to the FDA, and sildenafil was approved for this
indication in June 2005. The preparation is named Revatio, to
avoid confusion with Viagra, and the 20 milligram tablets are
white and round. Sildenafil joins bosentan and prostacyclin-based
therapies for this condition.
Altitude sickness
Sildenafil has been shown to be useful for the prevention and
treatment of High altitude pulmonary edema associated with altitude
sickness such as that suffered by mountain climbers. While this
effect has only recently been discovered, sildenafil is already
becoming an accepted treatment for this condition, particularly
in situations where the standard treatment of rapid descent has
been delayed for some reason.
Use in sports
Professional sports players have been using drugs such as Viagra
thinking that the opening of their blood vessels will enrich their
muscles, therefore enhancing their performance.
Tadalafil
Tadalafil
is an orally administered drug for treating impotence (erectile
dysfunction), that initially was developed by the biotechnology
company ICOS, and then developed and marketed world-wide as Cialis,
by Lilly ICOS, LLC, the joint venture of ICOS Corporation and
Eli Lilly and Company. Cialis tablets, in 5mg, 10mg, and 20mg
doses, are yellow, film-coated, and almond-shaped. In
December 2003, the Food and Drug Administration approved tadalafil
(as Cialis) for sale in the U.S. as the third impotence prescription
drug after sildenafil (Viagra) and vardenafil (Levitra). Cialis's
36-hour effectiveness earned it the nickname, "The Weekend
Pill"; like sildenafil and vardenafil, tadalafil is recommended
as a 'as needed' medication. Cialis is the only one of the three
that is also offered as a once daily medication. Moreover, besides
impotence, tadalafil currently is in Phase 3 clinical trials for
treating pulmonary arterial hypertension.
Also
see Veradanafil (Levitra)
Drug
interactions
Since PDE5 inhibitors such as tadalafil may cause transiently
low blood pressure (hypotension), organic nitrates should not
be taken for at least 48 hours after taking the last dose of tadalafil.
Using organic nitrites (such as the sex drug amyl nitrite) within
this timeframe may increase the risk of hypotension.
Kamagra
Kamagra
(generic name sildenafil) is a medication used to treat men who
have trouble getting an erection, a condition called erectile
dysfunction or impotence. The U.S. Food and Drug Administration
approved Kamagra for erectile dysfunction, but not to prolong
erections. Kamagra will not help delay ejaculation. Kamagra works
by increasing blood flow to the penis. With sexual stimulation,
this causes an erection. For
better sex and enhanced life, here’s Kamagra for you. Initially,
when Kamagra entered the market as a drug for male impotence,
there weren’t enough takers. People were skeptical, shy
and unaware. But soon it became a household name and users raved
about the competency of the drug.
Today Kamagra is one of the most popular drugs
to treat male impotence. But is it only a drug prescribed for
men suffering from Erectile Dysfunction? The answer is a big NO.
Though its primary purpose is to help men attain sexual satisfaction
by maintaining an erection, Kamagra has many more functions than
one.
Firstly, it is a blessing in disguise for those
couples who look forward to something new in their sex life, every
day. In order to experiment with various postures and methods,
you need to maintain an erection for a longer time. But it just
does not happen when you want it. That’s where Kamagra comes
in. With its long lasting effect, Kamagra acts as a friend, guide
and a companion to men who simply don’t want to disappoint
their partners. Thus, Kamagra not only influences a marriage to
survive but gives it more vigor and happiness.
Similarly, men have periods of psychological imbalances
related to work pressure, stress, anxiety or depression. During
this phase, no matter how hard they try, achieving an erection
almost seems impossible. Unfortunately, it triggers the already
worse situation and slowly men cease to have interest in sex mainly
due to their underperformance. Both partners get affected in due
course, leading to serious gaps in marriage. Think of Kamagra
which can help you get out of this mayhem.
When you are mentally unfit to perform in bed,
rely on Kamagra to get rid of the erectile failures which can
hamper your confidence. So before you fall into such a situation,
be intelligent and take the necessary precaution.
