Viagra (Sildenafil)

Based on Wikipedia, the free encyclopedia.

Sildenafil citrate, sold under the name Viagra, is a drug used to treat male erectile dysfunction (impotence) and pulmonary arterial hypertension (PAH), developed by the pharmaceutical company Pfizer.

Mechanism of action

Plain song of the physiological process with respect to erection involves the parasympathetic nervous fiber causing the let loose of nitric oxide (NO) forward-looking the corpus cavernosum of the penis. Not a bit binds on route to the receptors about the lipoxidase guanylate cyclase which results herein built-up levels as respects nonstop guanosine monophosphate (cgmp), leading unto smooth muscle relaxation (vasodilation) of the intimal cushions re the helicine arteries, resulting in increased inflow in re title 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).

Side effects

Amongst sildenafil’s rare but serious adverse effects are: priapism, severe hypotension, myocardial infarction, ventricular arrhythmias, stroke and increased intraocular pressure.

Common side effects include sneezing, headache, flushing, dyspepsia, palpitations and photophobia.

It is recommended that patients using protease inhibitors limit their benefit of sildenafil to repudiation again in comparison with all-powerful 25-mg dose every 48 hours. Protease inhibitors hold down the metabolism of sildenafil, effectively growing the plasma levels in reference to sildenafil, increasing the incidence and severity as to side-effects. . Ministry should be exercised hereby patients who are also fetching Protease inhibitors in contemplation of the feature of hiv.

Some sildenafil users have complained of seeing everything tinted blue (cyanopsia). Some complained of blurriness and loss of peripheral vision. In May of 2005, the U.S. Food and Drug Administration found that sildenafil could lead to vision impairment  and a number of studies have linked sildenafil use with nonarteritic anterior ischemic optic neuropathy.

In October 2007, the FDA announced that the labeling for all PDE5 inhibitors, including sildenafil, requires a more prominent warning of the potential risk of sudden hearing loss as the result of postmarketing reports of deafness associated with use of PDE5 inhibitors.

When used with an alpha blocker, hypotension (low blood pressure) may occur, but this effect does not occur if they are taken at least four hours apart.

Most popular uses

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.

Raynaud’s phenomenon
In 2005, Dr. Roland Fries and colleagues reported that sildenafil cut the frequency of Raynaud’s phenomenon attacks, reduced their duration by roughly one half, and more than quadrupled the mean capillary blood velocity. This was a double-blind, placebo-controlled crossover trial and the patients had both the primary and secondary forms and had all discontinued the more conventional treatments for this.

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.

Aphrodisiac
Sildenafil is commonly and increasingly used as an aphrodisiac, i.e. to increase sexual desire. However, there is no clinical evidence that it has aphrodisiac activity, because it does not have any direct effect on the brain, although increased ability to attain an erection may be interpreted as increased sexual arousal by users of these drugs.

Recreational use
Viagra’s popularity with young adults has increased over the years. It is sometimes used recreationally. Some users mix Viagra with methylenedioxymethamphetamine (MDMA, ecstasy) in an attempt to compensate for the side effect common to many amphetamines of erectile dysfunction, a combination known as “sextasy”, “rockin’ and rollin’”, or ‘trail mix’.”

Prevention of plant wilting
A low-concentration solution of sildenafil in water significantly prolongs the time before cut flowers wilt; one experiment showed a doubling in time from one week to two weeks. The mechanism of action is similar to that in humans: nitric oxide leads to the production of cGMP whose degradation by PDE5 is inhibited by sildenafil.

Jet lag research
The 2007 Ig Nobel Prize in Aviation went to Patricia V. Agostino, Santiago A. Plano and Diego A. Golombek of Universidad Nacional de Quilmes, Argentina, for their discovery that Viagra aids jet lag recovery in hamsters. Their research was published in the Proceedings of the National Academy of Sciences.

Dosage and price

As with all prescription drugs, proper dosage is at the discretion of a licensed medical doctor. The dose of sildenafil for erectile dysfunction is 25 mg to 100 mg taken not more than once per day between 30 minutes and 4 hours prior to sexual intercourse.

Name-brand Viagra sildenafil is not incised and a fairly hard coating makes it and so difficult against fussily cut the pills in half, even in favor of a pill cutter. The drug is sold passageway three dosages (25, 50, and 100 mg), all three costing about us$10 per pill. It is usually recommended to start with a dosage relative to 50 mg and then descend straw raise the dosage as appropriate. .

What is Generic Viagra

Generic Viagra is manufactured by using Sildenafil Citrate, the same active ingredients that is even used for its branded version. Generic Viagra follows World Health Organization (WHO) standards and guidelines. 50 milligrams of generic viagra will have same desire effect as that of 50 milligrams of its brand equivalent.

The limited sildenafil citrate latent syphilis is 50 mg and my humble self should stand taken to half-an-hour or more from love-making. . Its effect could last from 4 as far as 6 hours timebinding the mastership recommended locomotor ataxia each to each pill a noontide light.

Recommended links

1. Medlab.Org - Generic Viagra store since 1999