For the drug that flopped in clinical trials, Viagra has subsequently been an extraordinary success story. When scientists first concocted the little blue pill more than 20 years ago, it was as a treatment for the heart condition angina.
The idea was that it would ease pain by dilating blood vessels around the heart.
The results were disappointing, until doctors noticed an extraordinary side-effect among male volunteers.
"Researchers knew they were on to something when patients refused to give the drugs back at the end of the trial," says Dr Mike Kirby, adviser to the Sexual Dysfunction Association.
Viagra generates sales of more than £1 billion a year and, as well as providing effective treatment for erectile dysfunction, is attracting interest as a potential remedy for a range of other illnesses from deadly lung disorders to cold hands.
The secret of Viagra, and other drugs in the same class, is that they allow blood to flow more freely by helping arteries to relax. They do this by blocking the effects of an enzyme called phosphodiesterase.
Evidence suggests it could even be used to combat jet lag.
Below, we examine other ways the modern day wonder-drug could help repair the damaged body. In most cases, research is still at an early stage and the drug is not yet being widely used. In others, such as the deadly lung disease pulmonary arterial hypertension, a form of the drug is already being used to save lives in Britain.
HEART ATTACKS
Giving Viagra after a heart attack could repair damaged muscle by restoring oxygen supplies. Researchers at Virginia Commonwealth University in the U.S. compared the antiimpotence drug with nitroglycerin, the standard treatment given to heart attack victims, and found Viagra was better at restoring bloodflow and helping tissue heal.
BREAST CANCER
Breast and colon tumours in mice shrank threefold when they were injected with the drug in experiments at Johns Hopkins University in the U.S. Scientists believe Viagra works by 'unmasking' cancer cells, so the immune system can recognise them as foreign and destroy them.
COLD HANDS
Raynaud's disease affects up to one in five people and is caused when blood supply to fingers and toes is interrupted. Most of the time they appear cold, white and look dead, but exposure to cold can trigger a burning sensation. Patients given 50mg of Viagra twice a day, for four weeks, had fewer and much shorter 'burning' attacks due to better bloodflow.
CROHN'S DISEASE
British researchers claim the sex pill could fight Crohn's disease, a debilitating condition, which often needs major surgery on the bowel. Tests at University College London showed the drug boosts bloodflow around the small intestine - the area most affected by the disease - and helps fight bacteria.
INFERTILITY
A woman's chances of becoming pregnant could improve, according to scientists. In some women, the lining of the uterus is too thin to sustain a pregnancy. The drug increases bloodflow to the uterus and stimulates growth of cells.
DIABETES
Three out of four diabetics suffer gastroparesis - when the stomach empties too slowly. It causes loss of appetite and dehydration. U.S. scientists found Viagra helped by relaxing stomach muscles.
PELVIC PAIN
Up to 50 per cent of men suffer pelvic pain, causing discomfort around the lower back and groin.
Viagra appears to help by dilating blood vessels in the pelvic area and boosting bloodflow, according to a trial at Washington University in the U.S..
STILL BIRTHS
Every year, about 600 babies in the UK are stillborn because of a pregnancy disorder called pre-eclampsia. But foetal deaths dropped sharply in pregnant mice given the Viagra. In pre-eclampsia, arteries feeding the placenta do not widen enough to deliver all the blood the baby needs. Viagra relaxes muscles in the artery walls.
LUNG DISEASE
Nobody knows what causes pulmonary arterial hypertension, a condition that affects about 4,000 people in the UK, often women in their 30s and 40s. But few sufferers survive beyond three to four years. Blood pressure becomes dangerously high in the pulmonary artery. A Viagra-based drug called Revatio is extending the lives of some sufferers by boosting blood flow to the lungs, reducing the workload on the heart.
PROSTATE PROBLEMS
The little blue pill can improve symptoms of benign prostatic hyperplasia. BPH is part of the natural ageing process and nothing to do with prostate cancer. But it does cause frequent urinating, bladder stones, depression and daytime tiredness due to constant broken sleep. Doctors at Northwestern University in Chicago tested the drug on 300 men - it had a good effect..
Tuesday, December 7, 2010
Happy birthday Viagra
Exactly 15 years ago, Michael Allen took a call from a doctor in a small Welsh town that gave the first hint of a revolution to come. The doctor had been running a small clinical trial testing a new drug to treat angina. The future for the drug, known as UK-92480. was looking bleak: other trials had showed that it did not have much impact on the disease, and indeed was less effective than existing treatments.
When the doctor gave his progress report to Allen, clinical project manager at drug giant Pfizer, he mentioned some side effects among the healthy volunteers in the trial in Merthyr Tydfil. These included indigestion, back pain – and, the doctor added, erections.
Five years and much research later, Pfizer applied for marketing approval for the drug – not for angina, but for male impotence. Ten years on, and Viagra has been used by more than 30 million men worldwide for erectile dysfunction.
It is also finding a host of new uses, too. The drug that nearly didn't make it is being used or investigated for the treatment of more than a dozen diseases and health problems. Researchers say it could turn out to be as versatile as Aspirin.
Conditions being assessed for treatment with Viagra include jet lag, heart failure, premature ejaculation, diabetes symptoms, multiple sclerosis, pain, premature birth, chronic pelvic pain, memory loss, Reynaud's phenomenon, and strokes.
In Egypt, Viagra has been used to save unconsummated marriages; in Argentina, it has been investigated as a new therapy for jet lag; in Israel, researchers have found that it can help cut flowers survive for longer.
Jet lag
Viagra may speed up recovery from jet lag, according to research at the Universidad Nacional de Quilmes in Buenos Aires. The brain's master clock controls the sleep-wake cycle by releasing hormones and neurotransmitters that regulate a wide range of functions. It's thought that an enzyme called cGMP plays a role in the regulation of the clock; Viagra boosts its effects by stopping it from being broken down by another enzyme, PDE5. The researchers found that animals injected with the drug adapted faster to light changes, suggesting that Viagra speeds up the time it takes the body clock to adapt to jet lag.
Erectile dysfunction
Now approved by regulatory authorities in more than 20 countries, Viagra was the first effective oral therapy available to men with erectile dysfunction. Until its release, the mainstays of therapy were injections and vacuum erection devices. In men with the condition, the nerves or blood vessels that play a part in the erection process don't work properly. The drug works by increasing the blood flow to the penis. According to a report from Auburn University in Alabama, the drug can combat impotence resulting from a wide range of causes, including side effects from other drugs, psychological problems, ageing, and diseases like type-2 diabetes, Parkinson's disease, depression and kidney failure.
Stroke
More than 80 stroke patients are being given Viagra in a trial starting this month in Detroit. Doctors believe that if given within three days of a stroke, the drug could help both men and women regain and improve movement, speech and thinking via its effect on the molecule cGMP, which is thought to create new cells in the brain. The trial follows successful work with animals and a small number of patients. "What we found is that we can use Viagra to create new brain cells," said Dr Michael Chopp, scientific director of the Neuroscience Institute at the hospital. "When animals with stroke are treated with Viagra, the drug provides very significant neurological functional benefit. They do much better."
Underweight babies
Doctors have been using Viagra in a trial with pregnant women as a therapy for intrauterine growth restriction, in which the fetus is smaller than expected for the number of weeks of the pregnancy. The condition is estimated to affect around 5 per cent of births in the UK. It's thought that the drug increases blood supply to the womb and placenta so that more nutrients and oxygen get through to the fetus, which can then carry on growing in the womb and is not born as prematurely as it might otherwise have been. Viagra works in this case by acting on an enzyme called PDE-5, which allows blood vessels to expand and increases blood flow to the baby.
In Israel, a trial is underway where pregnant women will be given 25mg of Viagra. If doing so allows the babies to spend just a few more days in the womb, this could make a big difference to the child's long-term health.
Multiple sclerosis
Estimated to affect more than 85,000 people in the UK – twice as many women as men – MS is the most common disabling disease of the central nervous system in young adults. MS is thought to be caused when the immune system attacks the sheaths that protect our nerves. The damage caused disrupts the way that messages are carried to and from the brain, interfering with a wide range of body functions.
An Auburn University report suggested that Viagra may protect against some degeneration: "It has been shown to protect multiple sclerosis patients from neurodegeneration through increased grey matter perfusion in the brain," the researchers said.
Memory and learning
A number of studies have suggested that taking Viagra can boost memory and learning skills. Just how it does so, however, it not clear. One theory is that it triggers increased blood flow and improved glucose processing in the brain; another is that levels of cGMP, which Viagra increases, have to be kept high for peak learning ability.
Production of cGMP decreases with age and may contribute to age-related memory decline, according to Auburn University researchers: "Viagra offers a new strategy for memory improvement and a novel therapy for Alzheimer's disease in the future," they say.
Unconsummated marriages
Doctors at Cairo University Hospital have successful used Viagra to tackle the tricky problem of unconsummated marriages. Of the 35 patients in one study, 32 were able to overcome their marital problems after taking Viagra. In all, 23 patients needed the drug for less than a month, five for up to three months and four for longer than that. "The aim was to evaluate the effectiveness of short-term use in the management of unconsummated marriages diagnosed to be mainly psychogenic in origin," said the researchers. "Viagra is effective as a short-term treatment option in the management of unconsummated marriages."
Raynaud's phenomenon
A common, painful condition, caused by an interruption of blood flow to the fingers or other extremities, in severe cases Raynaud's phenomenon can lead to gangrene. A number of trials have shown that Viagra can be highly effective in treating it, both for men and women. One trial showed a halving of symptoms; in another, the symptoms of some patients disappeared altogether. "I have successfully treated 10 patients with Raynaud's phenomenon, using Viagra," said Dr Jack Lichtenstein, who carried out his study in Maryland. "In all patients, the results ranged from an excellent response to complete relief of symptoms." It is thought that Viagra works here by increasing blood flow and returning circulation to the affected areas.
Heart failure
Research in Italy suggested that Viagra improves the ability of patients with heart failure to exercise. The drug increased oxygen uptake, reduced pressure in the arteries, and improved the working of the lungs, said the Milan University researchers. Again, it's thought that the drugs does so by increasing levels of nitric oxide.
Wilting flowers
When researchers at Bar-Ilan University in Israel put cut flowers in a weak solution of Viagra – one-fiftieth the amount taken by men for impotence – the flowers survived for two weeks instead of one. They suspect the Viagra works through its effects on nitric oxide, which is also how the drug treats erectile dysfunction.
Pain
"Viagra has been shown to have immense potential for the treatment of pain in animals and humans," said pharmacologists at Auburn University.
Diabetes
Research on 40 men at the Instituto Mexicano del Seguro Social in Mexico showed that Viagra lowered levels of compounds associated with heart disease in patients with type-2 diabetes. The drug also improved glucose control.
When the doctor gave his progress report to Allen, clinical project manager at drug giant Pfizer, he mentioned some side effects among the healthy volunteers in the trial in Merthyr Tydfil. These included indigestion, back pain – and, the doctor added, erections.
Five years and much research later, Pfizer applied for marketing approval for the drug – not for angina, but for male impotence. Ten years on, and Viagra has been used by more than 30 million men worldwide for erectile dysfunction.
It is also finding a host of new uses, too. The drug that nearly didn't make it is being used or investigated for the treatment of more than a dozen diseases and health problems. Researchers say it could turn out to be as versatile as Aspirin.
Conditions being assessed for treatment with Viagra include jet lag, heart failure, premature ejaculation, diabetes symptoms, multiple sclerosis, pain, premature birth, chronic pelvic pain, memory loss, Reynaud's phenomenon, and strokes.
In Egypt, Viagra has been used to save unconsummated marriages; in Argentina, it has been investigated as a new therapy for jet lag; in Israel, researchers have found that it can help cut flowers survive for longer.
Jet lag
Viagra may speed up recovery from jet lag, according to research at the Universidad Nacional de Quilmes in Buenos Aires. The brain's master clock controls the sleep-wake cycle by releasing hormones and neurotransmitters that regulate a wide range of functions. It's thought that an enzyme called cGMP plays a role in the regulation of the clock; Viagra boosts its effects by stopping it from being broken down by another enzyme, PDE5. The researchers found that animals injected with the drug adapted faster to light changes, suggesting that Viagra speeds up the time it takes the body clock to adapt to jet lag.
Erectile dysfunction
Now approved by regulatory authorities in more than 20 countries, Viagra was the first effective oral therapy available to men with erectile dysfunction. Until its release, the mainstays of therapy were injections and vacuum erection devices. In men with the condition, the nerves or blood vessels that play a part in the erection process don't work properly. The drug works by increasing the blood flow to the penis. According to a report from Auburn University in Alabama, the drug can combat impotence resulting from a wide range of causes, including side effects from other drugs, psychological problems, ageing, and diseases like type-2 diabetes, Parkinson's disease, depression and kidney failure.
Stroke
More than 80 stroke patients are being given Viagra in a trial starting this month in Detroit. Doctors believe that if given within three days of a stroke, the drug could help both men and women regain and improve movement, speech and thinking via its effect on the molecule cGMP, which is thought to create new cells in the brain. The trial follows successful work with animals and a small number of patients. "What we found is that we can use Viagra to create new brain cells," said Dr Michael Chopp, scientific director of the Neuroscience Institute at the hospital. "When animals with stroke are treated with Viagra, the drug provides very significant neurological functional benefit. They do much better."
Underweight babies
Doctors have been using Viagra in a trial with pregnant women as a therapy for intrauterine growth restriction, in which the fetus is smaller than expected for the number of weeks of the pregnancy. The condition is estimated to affect around 5 per cent of births in the UK. It's thought that the drug increases blood supply to the womb and placenta so that more nutrients and oxygen get through to the fetus, which can then carry on growing in the womb and is not born as prematurely as it might otherwise have been. Viagra works in this case by acting on an enzyme called PDE-5, which allows blood vessels to expand and increases blood flow to the baby.
In Israel, a trial is underway where pregnant women will be given 25mg of Viagra. If doing so allows the babies to spend just a few more days in the womb, this could make a big difference to the child's long-term health.
Multiple sclerosis
Estimated to affect more than 85,000 people in the UK – twice as many women as men – MS is the most common disabling disease of the central nervous system in young adults. MS is thought to be caused when the immune system attacks the sheaths that protect our nerves. The damage caused disrupts the way that messages are carried to and from the brain, interfering with a wide range of body functions.
An Auburn University report suggested that Viagra may protect against some degeneration: "It has been shown to protect multiple sclerosis patients from neurodegeneration through increased grey matter perfusion in the brain," the researchers said.
Memory and learning
A number of studies have suggested that taking Viagra can boost memory and learning skills. Just how it does so, however, it not clear. One theory is that it triggers increased blood flow and improved glucose processing in the brain; another is that levels of cGMP, which Viagra increases, have to be kept high for peak learning ability.
Production of cGMP decreases with age and may contribute to age-related memory decline, according to Auburn University researchers: "Viagra offers a new strategy for memory improvement and a novel therapy for Alzheimer's disease in the future," they say.
Unconsummated marriages
Doctors at Cairo University Hospital have successful used Viagra to tackle the tricky problem of unconsummated marriages. Of the 35 patients in one study, 32 were able to overcome their marital problems after taking Viagra. In all, 23 patients needed the drug for less than a month, five for up to three months and four for longer than that. "The aim was to evaluate the effectiveness of short-term use in the management of unconsummated marriages diagnosed to be mainly psychogenic in origin," said the researchers. "Viagra is effective as a short-term treatment option in the management of unconsummated marriages."
Raynaud's phenomenon
A common, painful condition, caused by an interruption of blood flow to the fingers or other extremities, in severe cases Raynaud's phenomenon can lead to gangrene. A number of trials have shown that Viagra can be highly effective in treating it, both for men and women. One trial showed a halving of symptoms; in another, the symptoms of some patients disappeared altogether. "I have successfully treated 10 patients with Raynaud's phenomenon, using Viagra," said Dr Jack Lichtenstein, who carried out his study in Maryland. "In all patients, the results ranged from an excellent response to complete relief of symptoms." It is thought that Viagra works here by increasing blood flow and returning circulation to the affected areas.
Heart failure
Research in Italy suggested that Viagra improves the ability of patients with heart failure to exercise. The drug increased oxygen uptake, reduced pressure in the arteries, and improved the working of the lungs, said the Milan University researchers. Again, it's thought that the drugs does so by increasing levels of nitric oxide.
Wilting flowers
When researchers at Bar-Ilan University in Israel put cut flowers in a weak solution of Viagra – one-fiftieth the amount taken by men for impotence – the flowers survived for two weeks instead of one. They suspect the Viagra works through its effects on nitric oxide, which is also how the drug treats erectile dysfunction.
Pain
"Viagra has been shown to have immense potential for the treatment of pain in animals and humans," said pharmacologists at Auburn University.
Diabetes
Research on 40 men at the Instituto Mexicano del Seguro Social in Mexico showed that Viagra lowered levels of compounds associated with heart disease in patients with type-2 diabetes. The drug also improved glucose control.
Viagra boosts feel-good 'love' hormone
Impotence drugs such as Viagra may do more than help men physically have sex -- they may also boost levels of a hormone linked with feelings of love, U.S. researchers reported Thursday.
Viagra and related drugs seem to act on the part of the brain that controls release of the hormone oxytocin.
Viagra, known generically as sildenafil, raised levels of the hormone oxytocin in rats, the team at the University of Wisconsin-Madison said in a report published in the Journal of Physiology.
This hormone is involved in nursing and childbirth but also in orgasm and feelings of sexual pleasure.
And it seems Viagra and related drugs act on the part of the brain that controls release of oxytocin, said Wisconsin physiology professor Meyer Jackson.
"This is one piece in a puzzle in which many pieces are still not available," Jackson said in a statement. "But it raises the possibility that erectile dysfunction drugs could be doing more than just affecting erectile dysfunction."
Viagra is an inhibitor of an enzyme called phosphodiesterase type 5. Related drugs such as Eli Lilly and Co.'s Cialis, known generically as tadalafil, and Levitra or vardenafil, sold by GlaxoSmithKline, Bayer AG and Schering-Plough, are also PDE-5 inhibitors.
They block this enzyme, which in turn breaks down other compounds. This increases blood flow in the muscles but it also affects a brain structure known as the posterior pituitary.
This, in turn, boosts oxytocin, at least in the rats. It probably does the same thing in people, Jackson said.
"It does the same thing it does in smooth muscle -- instead of (levels) coming down in a minute or two, they stay up a little longer," Jackson said in a telephone interview.
Oxytocin was known for years to be involved in labor and it is the hormone that causes the "let-down" of milk in breastfeeding babies. Only in recent decades has it been found to have a function in men -- in sexual arousal and function.
This could suggest other uses for Viagra and related drugs, Jackson said -- perhaps promoting social bonding.
"What I hope is that people read our paper who can test these ideas in animals and humans," Jackson said.
"I hope that this doesn't cause some wild orgy of inappropriate recreational use."
Some groups have complained that people use the impotence drugs for fun, instead of using them as prescribed for sexual dysfunction caused by low blood flow to the genitals.
Viagra and related drugs seem to act on the part of the brain that controls release of the hormone oxytocin.
Viagra, known generically as sildenafil, raised levels of the hormone oxytocin in rats, the team at the University of Wisconsin-Madison said in a report published in the Journal of Physiology.
This hormone is involved in nursing and childbirth but also in orgasm and feelings of sexual pleasure.
And it seems Viagra and related drugs act on the part of the brain that controls release of oxytocin, said Wisconsin physiology professor Meyer Jackson.
"This is one piece in a puzzle in which many pieces are still not available," Jackson said in a statement. "But it raises the possibility that erectile dysfunction drugs could be doing more than just affecting erectile dysfunction."
Viagra is an inhibitor of an enzyme called phosphodiesterase type 5. Related drugs such as Eli Lilly and Co.'s Cialis, known generically as tadalafil, and Levitra or vardenafil, sold by GlaxoSmithKline, Bayer AG and Schering-Plough, are also PDE-5 inhibitors.
They block this enzyme, which in turn breaks down other compounds. This increases blood flow in the muscles but it also affects a brain structure known as the posterior pituitary.
This, in turn, boosts oxytocin, at least in the rats. It probably does the same thing in people, Jackson said.
"It does the same thing it does in smooth muscle -- instead of (levels) coming down in a minute or two, they stay up a little longer," Jackson said in a telephone interview.
Oxytocin was known for years to be involved in labor and it is the hormone that causes the "let-down" of milk in breastfeeding babies. Only in recent decades has it been found to have a function in men -- in sexual arousal and function.
This could suggest other uses for Viagra and related drugs, Jackson said -- perhaps promoting social bonding.
"What I hope is that people read our paper who can test these ideas in animals and humans," Jackson said.
"I hope that this doesn't cause some wild orgy of inappropriate recreational use."
Some groups have complained that people use the impotence drugs for fun, instead of using them as prescribed for sexual dysfunction caused by low blood flow to the genitals.
Viagra can treat pulmonary hypertension
Viagra is being used to treat not only erectile dysfunction, but also pulmonary hypertension, according to a U.S. researcher.
The drug may have potential for treating several other conditions such as mountain sickness and Raynaud's phenomenon, reports the August issue of Harvard Men's Health Watch.
Viagra is now marketed under the name Revatio for pulmonary hypertension -- an uncommon but serious disorder of high pressure in the blood vessels leading to the lungs, the newsletter said.
Viagra can reduce pulmonary artery pressure at high altitude and improve the ability to exercise in low oxygen conditions.
The three erectile dysfunction medications currently on the market -- Viagra, Levitra and Cialis -- all work by the same means, and they have similar side effects. The most common are headaches and facial flushing, which occur in 15 percent of men, as well as nasal congestion, indigestion and back pain, but these side effects are often mild and temporary, the newsletter said.
The drug may have potential for treating several other conditions such as mountain sickness and Raynaud's phenomenon, reports the August issue of Harvard Men's Health Watch.
Viagra is now marketed under the name Revatio for pulmonary hypertension -- an uncommon but serious disorder of high pressure in the blood vessels leading to the lungs, the newsletter said.
Viagra can reduce pulmonary artery pressure at high altitude and improve the ability to exercise in low oxygen conditions.
The three erectile dysfunction medications currently on the market -- Viagra, Levitra and Cialis -- all work by the same means, and they have similar side effects. The most common are headaches and facial flushing, which occur in 15 percent of men, as well as nasal congestion, indigestion and back pain, but these side effects are often mild and temporary, the newsletter said.
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