generic viagra

Viagra, a little blue pill made by the pharmaceutical company Pfizer Inc., became the first oral medicine approved for male impotence by the U.S. Food and Drug Administration. Its approval in March 1998 set off a worldwide demand and sent Pfizer stock soaring. Hardly a day went by when newspapers, radio, and television did not have stories of the Viagra craze. The pill, which sold by prescription for about $10 apiece retail, was taken by men with sexual problems about an hour before they expected to have sexual activity. Their performance during the sex act improved dramatically. The drug, chemically named sildenafil, had been used unsuccessfully as a medicine for heart problems. When some heart patients reported to doctors they were getting erections after taking the pill, it was developed to treat sexual impotence.

Clinical studies of about 4,000 men with erectile dysfunction showed that up to 72 percent reported they had successful intercourse after using Viagra, against 23 percent of men who took a placebo. Viagra works by improving the blood flow to the penis. More specifically, it inhibits the effects of an enzyme that acts to reverse erections after sex. Before Viagra came along, men with erectile problems had to forego sex, rely on mechanical devices such as a small pump to produce an erection, have surgical penile implants, or inject medicines directly into the penis.

Once the Viagra craze spread, so did reports of problems associated with taking the pill. Some men reported problems with their vision, seeing green or blue. There were stories of dizziness and headaches or upset stomachs. Men with heart problems who took nitroglycerin or nitrates were warned not to use Viagra because it could act to reduce blood pressure. By late 1998, the Food and Drug Administration issued warnings that Viagra could be hazardous to some men with heart ailments, and that using the pill could lead to heart attacks or strokes. The drug watchdog agency said that although Viagra was still considered safe and effective, it posed potential problems for men with very high or very low blood pressure, so that patients should get careful examinations before taking the pill. The FDA also said that 130 reported deaths of men who had taken Viagra could not be attributed directly to the drug. The average age of those who died was 64 and many of the men who died had had serious health problems aggravated by sexual activity, which ended in heart attacks or strokes. "The people who died had underlying cardiovascular problems," Dr. Lisa Rarick, director of an FDA division, told reporters during late 1998. She added that men with heart problems should ask their doctors, "Is sex good for me?" Many of the men who died had impotence problems because of their medical conditions. By the time of the warning some six million prescriptions had been written for about three million men.

Symptoms
During an angina attack, there are chest pains which may spread to the shoulders and both arms. Attacks are often triggered by physical activity and stop within minutes of the person resting. In severe cases, even everyday activities like climbing the stairs can start an attack.
Causes
Atherosclerosis is where arteries are partly blocked by fatty deposits that build up and harden on their inside wall. If this happens in a coronary artery it can cause angina or even a heart attack.The fatty deposits increase over a period of years. They are made worse by high levels of animal fats and cholesterol in the diet, although some people are genetically more susceptible to developing atherosclerosis than others.During activity the heart rate increases and demands more oxygen. The narrowed arteries cannot supply enough blood to keep up with this demand and this triggers the pain of an angina attack which forces the person to rest.
Diagnosis
Patients will describe the history of their angina attacks. A cardiac angiogram uses a dye in the blood to allow the flow through the cardiac arteries to be observed by x-ray. Doctors use an exercise tolerance test to observe the response to increased activity. As the patient exercises, their heart responds by beating more quickly. The heart muscle is working harder and so needs more blood to be supplied to it through the coronary arteries. The cardiac angiogram will show if the increase in blood supply to the heart muscle actually happens. In patients suffering from angina, the cardiac angiogram will show where blockages in the coronary arteries are preventing an increase in blood flow to the heart muscle. This allows doctors to decide on the best treatment and, in severe cases, where to place a coronary artery bypass graft.
Treatments
Angina sufferers may be able to avoid the activities that trigger an attack. They can put a tablet of glyceryl trinitrate under their tongue during an attack. This helps to reduce the strain on the heart and speed up recovery.

The underlying demand for Viagra could be linked to a major study, released in 1999 by the Journal of the American Medical Association, of the sexual habits of nearly 5,000 people, the largest such study since the report of biologist Alfred Kinsey some 50 years earlier. The new research revealed that sexual problems were widespread in the United States. On the basis of personal interviews with 1,749 women and 1,410 men, the research showed that about two out of five women and one out of three men had some forms of sexual dysfunction.

Viagra™: from laboratory to pharmacy
The chemical process used to produce Viagra™ is very complex. Picture 16 shows the steps that researchers had to go through to make Viagra™ when it was being developed for clinical use. A more efficient method was needed if it was ever going to be made in the large quantities needed to be a successful treatment for erectile dysfunction.The research method involved the synthesis of many smaller molecules that were gradually built up and joined together to produce the Viagra™ molecule. This required many stages of synthesis and purification. It was not efficient enough for the amounts of Viagra™ needed for large-scale clinical trials and use with patients.The production method builds up the Viagra™ from different starting molecules, which means that the reactions are more efficient and produce a lot less wastes. Chemists and chemical engineers are constantly improving this process to increase productivity and continue the reduction in wastes.

The clamor for Viagra in other countries spurred some swindlers to peddle pills made to look like Viagra. But cashing in on demands for a silver bullet to cure sex problems was not new. The search for a magic potion that could produce erections on demand has gone on for centuries, encouraging charlatans who sold bogus remedies to unwitting, desperate men. Among the miracle cures thus ballyhooed to have been miracle cures have been underwear electrified to stimulate the penis, rhinoceros horns pounded into powder, and tiger penises made into soups

Erectile dysfunction
Tests began in 1993 to see if Viagra™ could be used to treat erectile dysfunction. During the trials, Viagra™ was given to over 3,000 patients aged 19 to 87 years old. In 21 separate studies it proved to give statistically significant improvements when compared to the placebo.During trials, researchers recorded the effect of Viagra™ on the ability of patients to maintain an erection. A tablet of Viagra™ was taken and its effects were measured an hour later. Patients also completed a questionnaire which gave information about the influence of Viagra™ on their ability to have intercourse.
Why is the placebo important?
A patient receiving a placebo would get a tablet that looked exactly the same as the tablet containing Viagra™. However, it would not contain any of the active ingredient. This takes account of the fact that some patients show an improvement simply by taking a tablet (even without an active ingredient). The control group gives an indication of how many people in the test group were probably responding to the tablet rather than the active ingredient.

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