Viagra

VIAGRA

Viagra  is a drug used to treat erectile dysfunction and pulmonary arterial hypertension. It acts by inhibiting cGMP-specific phosphodiesterase type 5, an enzyme that promotes degradation of cGMP, which regulates blood flow in the penis.Sildenafil citrate is the generic name for Viagra.Sildenafil has been the prime treatment for erectile dysfunction.Other than Sildenafil, Tadalafil and Vardenafil carry the same function.

USES OF  VIAGRA:

Sexual dysfunction

The primary indication of sildenafil is treatment of erectile dysfunction (inability to sustain a satisfactory erection to complete intercourse). Its 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. 

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. 

DOSES:

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.For most patients, the recommended dose is 50 mg taken, as needed, approximately 1 hour before sexual activity. However, Viagra  may be taken anywhere from 4 hours to 0.5 hour before sexual activity. Based on effectiveness and toleration, the dose may be increased to a maximum recommended dose of 100 mg or decreased to 25 mg. The maximum recommended dosing frequency is once per day.Simultaneous administration of Viagra doses above 25 mg and an alpha-blocker may lead to symptomatic hypotension in some patients. Doses of 50 mg or 100 mg of VIAGRA should not be taken within 4 hours of alpha-blocker administration.

The dosage for pulmonary arterial hypertension is one 20 mg tablet three times a day.

THE TECHNOLOGY OF AN ERECTION

The penis can be either limp or erect, depending on the flow of blood.The penis contains two cigar-shaped structures, called corpora cavernosa that it uses to become erect.Arteries­ bring blood into these two tubes, and veins carry blood away from them.When a man becomes aroused, the arteries leading into the penis open up so that pressurized blood can enter the penis quickly. The veins leaving the penis constrict. Pressurized blood is trapped in the corpora cavernosa, and this blood causes the penis to elongate and stiffen. The penis is erect.

In a non-erect state, the arteries that transport b­lood into the corpora cavernosa are somewhat constricted, while the veins that drain the blood from the penis are open. There is no way for pressure to build inside the penis. In this state, the penis is limp.

If the arteries leading to the penis don't open up properly, it's difficult or impossible for a man's penis to become erect. This problem is the leading cause of erectile dysfunction .

THE MECHANISM DILATION:

a)The brain sends a signal down a particular nerve fiber. This nerve fiber ends in a nerve cell in an artery, somewhere near the point where blood flow needs to change.

b)These nerve cells -- called nonadrenergic-noncholinergic, or NANC -- produce nitric oxide and inject it into the blood and surrounding cells.

c)The nitric oxide stimulates an enzyme (guanylate cyclase) in nearby cells that starts producing a chemical called cyclic guanosine monophosphate (cGMP).

d)cGMP tells smooth muscles that line an artery to relax. When they relax, blood flow increases.

There is one final part to this chemical machine: Another enzyme, called phosphodiesterase (PDE), is deactivating the cGMP all the while.

cGMP is produced as long as the brain is sending messages down the nerve fibers in the artery. When the brain stops sending the signal, all of the cGMP goes away because PDE is deactivating it.

WHAT HAPPEN IF YOU TAKE VIAGRA:

AFTER FIVE MINUTES: You won’t feel the effect straight away. Wait for the drug to be absorbed into your bloodstream.

You may feel warmth and flushing of the face. This is because Viagra affects your blood flow and not just because you are excited about what is going on down there.

30 MINUTES: As the active ingredient in Viagra – sildenafil citrate – is absorbed, it disables an enzyme in the penis called PDE5. This frees up a chemical called cGMP, which is crucial for hot bedroom action.

30-60 MINUTES: Once the PDE enzymes have been disabled, levels of calcium within the penis muscle cells rise. This relaxes the muscle and increases blood flow.

And the better the blood flow, the better the erection.  Viagra won’t work if there isn’t any stimulation.

ONE TO THREE HOURS: Your body will be primed for an erection for about three hours so within that time, and with the right stimulation, an erection can be achieved.You will orgasm as normal, but may recover more quickly and, while your body is still primed, you can become aroused again.

Viagra is not taken according to a schedule like most other medications. It is taken when needed, meaning when you plan to have sex. You will need to take it at least an hour before the sexual intercourse. It takes an hour for Viagra to start working and once it does, you will have about 4 to 6 hours to spare. After that, the effects will subside. The most important thing to remember here is that you must not take another pill straight away. Only one pill is allowed in one 24-hour time period. Also, you must never take a double dose in order to improve the effects. The effects will stay the same and the duration will stay the same and you will only risk suffering from different side effects.

If you experience indigestion once you have taken Viagra or if you feel that your stomach is upset, you can take it with food as it will not affect the way in which it is absorbed. You should take it with a full glass of water and you must not drink alcohol when using it. This is due to the fact that alcohol makes it much more likely that you will experience side effects. Furthermore, your blood pressure might become too low.

You must also avoid taking any other medication concomitantly with Viagra until the medication has been approved as safe by your physician or a pharmacist. You should also inform yourself about the possible side effects. If you experience symptoms like dizziness, nausea, or any pain or numbness in your neck, arms, jaw or chest during sex, you have to stop right away and contact your physician. You should do the same if you experience an erection that lasts more than 4 hours or that is painful.

SIDE EFFECT OF VIAGRA:

-headache

-flushing

- dyspepsia

- nasal congestion

- impaired vision

-including photophobia 

-blurred vision.

-seeing everything tinted blue (cyanopsia).

-blurriness and loss of peripheral vision. 

- could lead to vision impairment in rare cases

-nonarteritic anterior ischemic optic neuropathy

-priapism

-severe hypotension

- myocardial infarction (heart attack)

- ventricular arrhythmias

-stroke

- increased intraocular pressure

- sudden hearing loss

THINGS TO REMEMBER WHILE TAKING VIAGRA AND DON'T TAKE WHEN:

-Viagra shouldn’t be mixed with grapefruit juice because grapefruit can react with Viagra, increasing  the risk of side effects.

-When taking nitric oxide donors, organic nitrites and nitrates, such as glyceryl trinitrate (nitroglycerin), sodium nitroprusside, amyl nitrite 

-In men for whom sexual intercourse is inadvisable due to cardiovascular risk factors

-Severe hepatic impairment (decreased liver function)

-Severe impairment in renal function

-Hypotension (low blood pressure)

-Recent stroke or heart attack

-Hereditary degenerative retinal disorders (including genetic disorders of retinal phosphodiesterases)

by Lakdhes.