Viagra risk factors

New Viagra risks

Scientific research recently identified three new risks connected with Viagra use. They are permanent vision loss, interruption of the electrical pacing of the heart and elevated clotting factor. The last two have caused death by cardiac arrest and heart attack (myocardial infarction). Viagra labeling addresses risks connected with vision impairment, dangerously low blood pressure when taken with nitrites and hearing loss.

There are less than 100 cases of  Viagra induced permanent blindness. There are less than 7,000 cases of cardiac death connected with Viagra use. Risks are elevated for men with heart disease, high blood pressure, diabetes, high cholesterol and high lipoprotein levels. Viagra’s interaction with statin drugs are a problem, especially for men with heart disease. Post heart attack men are in a dangerously high risk group.  Some scientists recommend post heart attack men not use Viagra.

Pfizer received FDA approval for Viagra in 1989. This product generated a two billion dollar market for treatment of erectile dysfunction (ED). Pfizer claims 30 million users to date.

Vision risks:

The FDA clinical trials identified a temporary vision impairment side effect related to light sensitivity and blue, green color distortion. These warnings are on the package labeling.

The University of Minnesota published evidence linking Viagra to non-arteritic ischemic optic neuropathy (NAION). NAION is described as a “stroke of the eye,” occurring when blood flow to the optic nerve is cut. Of the 42 reports of blindness, 38 of them have been made in regard to Viagra blindness and the other four related to Cialis.

Because of this linkage, the FDA is in discussions to revise package warnings to include the risk of permanent blindness. Pfizer’s position is the incidence of Viagra induced NAION is less than that occurring in the general population and can not be linked directly to Viagra usage.

The onset of permanent blindness occurs within 24 to 36 hours after Viagra usage. There is an anatomical predisposition to permanent vision loss identified by a low cup to disk ratio. This ratio is an expression of the blood flow in the optic nerve to eyeball connection. Patients with a low ratio are higher risk for vision loss when using Viagra.  Elevated blood pressure, cholesterol, blood lipids and diabetes increase the risk of permanent vision loss.

Viagra constricts the vestals in the eye causing an interruption of the normal blood flow to the optic nerve eyeball connection. Some patients experience temporary vision impairment and others permanent vision loss.

Cardiac risks:

As of July 1999, a period of one year after Viagra release, an estimated 16 million men worldwide had taken Viagra. According to data in the Journal of the American Medical Association, 564 deaths were reported by this date.

The number of cardiac deaths related to Viagra, Cilias and Levitra are poorly reported. Extrapolating the above data and considering increased user volume, would indicate that there have been 7,000 to 10,000 Viagra related heart attack deaths to date. The above numbers are related only to Viagra. The total for all three ED products would be much greater.

It is difficult to identify Viagra’s roll in cardiac death. Pfizer, Ely Lily and Glaxo Smith Kline produce Viagra, Cialis and Levitra respectively. These pharma giants are motivated to minimize reporting significance and manipulate data related to their products. Post release reporting is not the same caliber as FDA approval trials. Once the drug is released it is difficult to contradict the FDA trial data with case studies.

Viagra labeling warns against use in conjunction with nitrates which are used by heart patients with advanced heart disease for relief of angina (chest pain). Both nitrates and Viagra are vasodilators which relax blood vestals and allow more blood flow through compromised coronary arteries. In combination this can lead to insufficient blood supply to compromised coronary arteries due to dangerously low blood pressure. You might think of it as an over dose of vasodilator. The lack of adequate blood supply can lead to a myocardial infarction (heart attack), myocardial meaning heart tissue and infarction meaning cessation of blood supply.

There are two additional cardiac risks that are poorly recognized at this point.  The first affects heart patients and the second men with no history of heart disease. Both have caused cardiac deaths.

Men with heart disease:

Cardiac deaths fall into two categories, cardiac arrest which is an interruption of the electrical pacing of the heart and infarction a cessation of blood supply to heart mussel tissue due to coronary artery blockage typically by a blood clot. This risk is related to the electrical pacing of the heart. There is an interaction between Viagra and common cardiac drugs. The danger is related to the interruption of normal electrical impulses that cause the heart to beat which may lead to cardiac arrest.

In the normal heart contraction and rest cycle there is a regeneration of electrical potential during the rest period which prepares the heart for the next contraction. This regeneration of electrical potential is called repolarization. It is most critical in ventricle contraction because these chambers are considered the main pumping component of the heart. The mineral calcium plays the major roll in repolarization.

Common heart drugs that interact with Viagra are statins, such as  Zocore and Lipator, calcium channel blockers such as Norvasc and, Lotrel as well as over the counter antihistamines. Viagra in conjunction with these drugs in men with heart conditions cause an extended QT (repolarization) segment which can lead to cardiac arrest.

This is the conclusion of a scientific study at the University of Montreal, Québec, Canada. The language is a little technical but you can get the idea.

Conclusions
Sildenafil (Viagra) blocks IKr and prolongs cardiac repolarization (QT) at concentrations that may be seen after drug overdose (elevated dosages i.e. 100 mg Viagra) or in the presence of impaired drug elimination (poor kidney function). Clinical attention to QT prolongation and triggered ventricular tachyarrhythmias (irregular heart beat) is warranted in patients with hepatic (liver) or renal (kidney) insufficiency or suffering from the long QT syndrome (post heart attack – heart disease) and in patients on multi-drug regimens (meaning the typical heart patient).

Men with no cardiac history:

This risk is related to clotting factors that cause healthy men as well as men with heart disease to experience elevated clotting that has caused myocardial infarction (heart attack) in both groups. It is difficult to sort out the causes of death because the pattern is the same for non Viagra users.

Researchers have identified an unexpected effect from a drug group that was thought to decrease clotting. The research produced an outcome that dramatically surprised researchers. The biochemical cGMP in past investigation was thought to lower clotting factor. However this new research showed that its initial effect was to increase clotting factor then reduce it. Earlier research keyed onto the later effect of reduction. Scientists identified a dramatic increase in initial clotting (platelet aggregation) when Viagra is taken. They characterized the effect this way. “It is similar to an external wound. The platelets initially respond by becoming sticky and aggregate (clot) to stop blood loss. When this phase is over platelets decrease clotting to allow blood flow to heal the wound.”

This elevated clotting factor combined with moderately narrowed (ischemic) arteries can trigger a heart attack. Men perceived to be healthy may actually be at risk for a cardiac event. Studies have shown that men in their twenties have 50% to 70% blockage. This coupled with Viagra’s elevated clotting effect is like Russian roulette. You don’t know if your make up will trigger a fatal event.

Hearing loss:

On October 18, 2007 the FDA announced changes to Viagra labeling to include sudden hearing loss. Two thirds of hearing loss cases resulted in permanent hearing loss. There has been minimal scientific investigation on the cause of hearing loss experienced by Viagra users. Other diseases assign hearing loss to reduced blood supply. Given the vascular constriction documented in NAION blindness above it seems apparent that this effect may be the cause of hearing loss.

Source: Medsonline365reviews.com