2008-09-22 06:47:11Orderis
威而剛有助於患肺動脈高血壓的孩童
http://www.24drs.com/professional/list/content.asp?x_classno=10&;x_idno=161
藉由增加肺部一氧化氮濃度達到療效
根據波士頓兒童醫院與其他中心的研究人員表示，威而剛可能是患有肺動脈高血壓孩童的救命仙丹。Marshall L. Summar, MD，現任為凡德比克大學醫學中心醫學遺傳基因暨分子生理與生物物理學分部的助理教授表示：「很明顯地，無法產生適量的一氧化氮是導致肺動脈高血壓的主因，這是暫時型高血壓，而永久型高血壓則是另種情況。任何可以幫助一氧化氮生產的方法都可能具有療效。所以，可能還有更直接且便宜的方法能達到這目標，這也是我們所努力企求的；不過，就目前還言之過早，這是未來的事。」
Viagra a Breath of Fresh Air for Kids With Pulmonary Hypertension
Works by Upping Nitric Oxide Levels in Lungs
By Neil Osterweil
WebMD Medical News
Reviewed by Aman Shah, MD
Aug. 9, 2001 -- Sildenafil could be a life saver for kids with pulmonary hypertension, according to researchers at Boston Children's Hospital and other centers.
"It appears that inability to produce sufficient amounts of nitric oxide [NO] contributes to kids developing pulmonary hypertension -- this is the transient form; the persistent [form] is a different issue," says Marshall L. Summar, MD, associate professor of pediatrics in the division of medical genetics and molecular physiology and biophysics at Vanderbilt University Medical Center in Nashville, Tenn.
"Anything you can do to bolster NO production is probably going to be of some help. There are probably some more direct ways to get at it that are a lot cheaper that we're looking at, but that's for the future," Summar tells WebMD.
Children with pulmonary hypertension are typically treated with inhaled NO delivered through a ventilator; the gas helps the blood vessels in the lungs relax, allowing more blood to flow through them. Yet when physicians try to wean them off NO, the blood pressure can skyrocket again.
"The biggest problem with Viagra is that everyone seems to look at the enzyme capacity and production; they need to make sure that there's sufficient raw material in these patients, because most of them have very low arginine constituents, so they may not be able to generate sufficient nitric oxide even if you rev up the enzyme," says Summar.
He points out that the precursors for making nitric oxide -- arginine and its precursor citrulline -- are made out of the urea cycle. "Newborns particularly have vastly diminished urea cycle capacity compared to adults -- it's just not ramped up yet," he says, adding that under stress there are even lower levels of production. He says that he is getting ready to do a trial to see if giving these precursors can block or prevent the pulmonary hypertension from developing in the kids at risk.
But as David Wessel, MD, and Andrew Atz, MD, reported in the journal Anesthesiology in 1999, sildenafil, which works by preventing the premature release of NO from blood vessel walls and allowing the vessels to stay relaxed, may also help kids be eased off inhaled NO.
To date, Wessel and colleagues at Children's Hospital have successfully weaned 13 of 14 children off of inhaled NO, in some cases using sildenafil pills they crushed and delivered through feeding tubes. An additional 15-20 children have been treated at other centers with similar results, Wessel said in an interview with The Boston Globe last week.
However, the market for pulmonary hypertension drugs is very small compared with the multibillion dollar market for ED therapies, so it's not certain whether Pfizer would be willing to commit to the estimated $4 million to $10 million it would cost to test a reformulated drug in clinical trials.
"Our focus right now is on the medical possibilities," Pfizer spokesman Geoff Cook tells WebMD. "Anecdotally, there have been data out there that seem to show this potentially could be a very important treatment for a condition that really has no treatments. It's a crying medical need, and that's our focus."
© 2001 WebMD Corporation. All rights reserved.
藉由增加肺部一氧化氮濃度達到療效
根據波士頓兒童醫院與其他中心的研究人員表示，威而剛可能是患有肺動脈高血壓孩童的救命仙丹。Marshall L. Summar, MD，現任為凡德比克大學醫學中心醫學遺傳基因暨分子生理與生物物理學分部的助理教授表示：「很明顯地，無法產生適量的一氧化氮是導致肺動脈高血壓的主因，這是暫時型高血壓，而永久型高血壓則是另種情況。任何可以幫助一氧化氮生產的方法都可能具有療效。所以，可能還有更直接且便宜的方法能達到這目標，這也是我們所努力企求的；不過，就目前還言之過早，這是未來的事。」
Viagra a Breath of Fresh Air for Kids With Pulmonary Hypertension
Works by Upping Nitric Oxide Levels in Lungs
By Neil Osterweil
WebMD Medical News
Reviewed by Aman Shah, MD
Aug. 9, 2001 -- Sildenafil could be a life saver for kids with pulmonary hypertension, according to researchers at Boston Children's Hospital and other centers.
"It appears that inability to produce sufficient amounts of nitric oxide [NO] contributes to kids developing pulmonary hypertension -- this is the transient form; the persistent [form] is a different issue," says Marshall L. Summar, MD, associate professor of pediatrics in the division of medical genetics and molecular physiology and biophysics at Vanderbilt University Medical Center in Nashville, Tenn.
"Anything you can do to bolster NO production is probably going to be of some help. There are probably some more direct ways to get at it that are a lot cheaper that we're looking at, but that's for the future," Summar tells WebMD.
Children with pulmonary hypertension are typically treated with inhaled NO delivered through a ventilator; the gas helps the blood vessels in the lungs relax, allowing more blood to flow through them. Yet when physicians try to wean them off NO, the blood pressure can skyrocket again.
"The biggest problem with Viagra is that everyone seems to look at the enzyme capacity and production; they need to make sure that there's sufficient raw material in these patients, because most of them have very low arginine constituents, so they may not be able to generate sufficient nitric oxide even if you rev up the enzyme," says Summar.
He points out that the precursors for making nitric oxide -- arginine and its precursor citrulline -- are made out of the urea cycle. "Newborns particularly have vastly diminished urea cycle capacity compared to adults -- it's just not ramped up yet," he says, adding that under stress there are even lower levels of production. He says that he is getting ready to do a trial to see if giving these precursors can block or prevent the pulmonary hypertension from developing in the kids at risk.
But as David Wessel, MD, and Andrew Atz, MD, reported in the journal Anesthesiology in 1999, sildenafil, which works by preventing the premature release of NO from blood vessel walls and allowing the vessels to stay relaxed, may also help kids be eased off inhaled NO.
To date, Wessel and colleagues at Children's Hospital have successfully weaned 13 of 14 children off of inhaled NO, in some cases using sildenafil pills they crushed and delivered through feeding tubes. An additional 15-20 children have been treated at other centers with similar results, Wessel said in an interview with The Boston Globe last week.
However, the market for pulmonary hypertension drugs is very small compared with the multibillion dollar market for ED therapies, so it's not certain whether Pfizer would be willing to commit to the estimated $4 million to $10 million it would cost to test a reformulated drug in clinical trials.
"Our focus right now is on the medical possibilities," Pfizer spokesman Geoff Cook tells WebMD. "Anecdotally, there have been data out there that seem to show this potentially could be a very important treatment for a condition that really has no treatments. It's a crying medical need, and that's our focus."
© 2001 WebMD Corporation. All rights reserved.