Viagra is one of the best-known drugs of all time: " Billions of spam e-mail messages advertise Viagra every day. There is so much Viagra spam, in fact, that Pfizer (the maker of Viagra) has a page addressing the problem, called Avoid Fake Viagra. " Pfizer has spent untold millions of dollars advertising Viagra, so you see advertisements for the drug constantly on TV. " Pfizer claims on its Web site that nine Viagra pills are dispensed every second — nearly 300 million tablets per year. The name recognition of Viagra is so good that nearly every adult in America has heard of the drug and can tell you what it does. What Viagra does is simple: When it works as intended, Viagra causes a man who is sexual" stimulated to get an Erection. How does Viagra do that? And why does Viagra work only if the man is sexually stimulated? For that matter, what causes an erection in the first place? In this article, we’ll answer all of those questions and more. This is actually a fascinating story — it involves the technology of the human body and the techniques that scientists use to control different parts of the body with drugs. And in the case of Viagra, the story starts with the technology of the penis. Early Treatments for ED The first real breakthrough in the treatment of erection dysfunction came in 1983. Prior to that time, it was thought that erectile dysfunction — the inability to achieve an erection — was primarily mental. That concept came crashing down at the 1983 American Urological Association meeting in Las Vegas when Dr. Giles Brindley injected his penis with the drug phentolamine. Following the injection, Dr. Brindley appeared on stage and dropped his pants to display one of the first drug-induced erections to the incredulous audience of urologists. What did the phentolamine do? It relaxed a muscle. Inside the body there are several kinds of muscle: " Skeletal - Skeletal muscles are the muscles we see at the Olympics — bulging biceps and so on. " Cardiac - Cardiac muscle powers the heart. " Smooth - Smooth muscle can be found in things like blood vessels, the intestines and the stomach and usually acts involuntarily. " Smooth muscle plays a key role in every erection, and phentolamine is a drug that relaxes smooth muscle. The reason why an injection of phentolamine gave Brindley an erection was especially interesting in 1983 because no one had really thought about it before. Here’s what happened: " The arteries of a limp penis are constricted, and they keep blood from entering the corpora cavernosa. " Brindley’s injection relaxed the smooth muscle in the artery walls inside his penis, causing them to open up. " Blood surged into the corpora cavernosa, and the blood pressure inflated his penis, giving him an instant erection. Starting in the mid-1980s, it became common for men with erectile dysfunction to inject smooth-muscle-relaxing drugs as a treatment for the problem. Viagra makes the process a whole lot easier by doing the same kind of thing with a pill instead of an injection. Another advantage of Viagra over an injection of phentolamine is that Viagra only causes an erection when the man is sexually aroused. Phentolamine, by contrast, causes an immediate and uncontrolled erection. How can a pill work only on the smooth muscle in the penis and not the entire body, and only when the man is aroused? The answers to these questions begin with an understanding of how blood flow works in the body, so let’s start there. Treating ED With Viagra If you want to create a drug that increases blood flow to the penis, there are at least three ways to do it: 1. Increase the amount of nitric oxide produced in the penis 2. Increase the amount of cGMP produced in the penis in response to the nitric oxide 3. Eliminate the PDE in the penis so that the cGMP builds up instead of getting decomposed by the PDE The Nobel Prize In 1998, three scientists — Robert F. Furchgott, Dr. Ferid Murad and Louis J. Ignarro — won the Nobel Prize in Physiology or Medicine for showing that nitric oxide acts as a signaling device between cardiovascular cells. See NobelPrize.org: The Nobel Prize in Physiology or Medicine 1998 to learn more. Viagra uses method No. 3 — it eliminates the PDE that is decomposing the cGMP, so cGMP builds up in the penis and has a larger effect on the artery walls. The greater the amount of cGMP the greater the blood flow, and the greater the blood flow the greater the degree of the erection. Viagra contains sildenafil citrate packaged as a pill. When a man takes a Viagra pill, the sildenafil citrate flows throughout his body, but it really only affects the PDE5 enzyme in the penis. The drug stays in the bloodstream for about four hours, and then it is washed out of the blood by the liver and kidneys. And that’s the end of the "how it works" part of the Viagra story: " A man takes a Viagra pill. " The sildenafil citrate enters his bloodstream and flows throughout his body. " The sildenafil citrate attaches to the PDE5 enzyme in his penis and disables most of it. " When the man becomes sexually aroused, the brain sends the normal message to the NANC cells in his penis, which produce nitric oxide as usual. " The nitric oxide creates cGMP, which starts relaxing the arteries in his penis. " Since the PDE5 has been disabled, the cGMP in the penis does not break down. Instead, it builds up and lets the arteries in the penis fully dilate. " His penis inflates with blood, and the man gets a full erection. This works perfectly for the majority of men.

In November, the Supreme Court will have the chance to lower cheap valtrex prices, spur innovation and increase patient access to innovative new therapies by ruling in favor of Food and Drug Administration "pre-emption." It can do so by giving federal regulators, not judges and juries in 50 different states, the ability to make authoritative national rulings as to the warnings that should be included on drug labels. This would be a long-overdue change. Currently, the tort system allows individual class-action lawyers, judges, and juries to second-guess FDA labeling decisions in emotionally fraught cases that penalize companies for behavior the FDA either allows or even mandates. Litigation pushes drug companies to flood labels with dubious warnings in the hopes of warding off lawsuits, and to abandon developing medicines for some diseases that are particularly litigation-prone, such as drugs for pregnant women.

FDA Wants Men on ED Drugs to Listen Up Erectile dysfunction drugs Viagra, Levitra and Cialis can, in rare cases, cause sudden hearing loss; users who find their hearing impaired should stop taking the drugs and call their doctor. The Food and Drug Administration has asked makers of the drugs to put a warning to that effect on product labels. The alert comes two years after the drugs were linked to rare cases of vision loss, caused by a disruption in blood supply to the optic nerve. The latest alert was prompted by a case report in the Journal of Laryngology & Otology of sudden hearing loss in a man taking Viagra. A search of FDA records found 29 similar reports involving ED drug users and a few people who took the drugs during clinical trials. Although hearing loss is common in men in their 50s — the age group most likely to take ED drugs — age-related loss tends to be gradual, unlike the kind tied to the warning. The FDA has also issued a hearing-loss warning on Revatio, a blood pressure drug in the same class. Revatio users who experience hearing problems should stay on the drug until they have checked with their doctor. ED drugs, on the market for more than a decade, generally have an excellent safety record. More-common problems include flushing and muscle soreness.

Erection dysfunction may help to treat Crohn’s disease Researchers found evidence that suggests Crohn’s disease is caused by a weak immune response. The study, published in The Lancet, also suggest that Viagra might help in the treatment of the disease. Crohn’s disease is a chronic inflammatory disorder that causes ulcerations in the small and large intestines. Many researchers consider Crohn’s to be an autoimmune disease — an illness that occurs when the body tissues are attacked by its own immune system. However, Anthony Segal, at University College London, UK, and colleagues found that the inflammation in Crohn’s arises due to a weak immune response. The investigators looked at the quantities of neutrophils that patients with Crohn’s disease produce in response to trauma at sites in the bowel and on the skin surface. They found that in response to trauma, Crohn’s disease patients produced much lower quantities of neutrophils and inflammatory mediators when compared with healthy individuals. Cultured blood cells were also abnormal in the patients. To test the inflammatory response to bacteria, the team also measured local inflammatory and blood flow changes in participants after injecting a harmless form of Escherichia Coli under their skin. In the healthy controls, blood flow in the area of inflammation increased approximately ten-fold by 24 hours. Crohn’s disease patients, however, had much lower blood flow than controls. The researchers found that the abnormally low blood flow in Crohn’s patients could be corrected by treatment with Sildenafil, indicating a possible role for the drug in the treatment of the disease. The authors believe that in Crohn’s disease, reduced or delayed recruitment of neutrophils to sites at which bacteria penetrate the intestinal wall might lead to the persistence of bacteria and other organic debris in the tissue. The body may respond to this build up of bacteria by secreting inflammatory molecules, which accumulate and lead to the development of chronic inflammation typical of Crohn’s. Segal states: " Our investigations identified defective innate immunity in Crohn’s disease… In Crohn’s disease, a constitutionally weak immune response predisposes to accumulation of intestinal contents that breach the mucosal barrier of the bowel wall, resulting in granuloma formation and chronic inflammation."