THURSDAY, July 11, 2002 (HealthDayNews) -- A new drug that literally makes breathing easier has produced promising results in an early trial for newborn babies with a severe lung problem.
The drug treatment also holds hope for the millions of people with respiratory conditions such as asthma, the researchers report.
The treatment is based on a revision of the conventional wisdom about how the body controls breathing, says its developer, Dr. Jonathan Stamler, a professor of medicine at Duke University Medical Center. It has been thought that a simple molecule, nitric oxide, acts to relax airways in the lungs.
"We discovered about 10 years ago that a class of molecules in the lung provides most of this biological activity," Stamler says. "They are nitric oxide-like, not nitric oxide itself. Over the past 10 years, it has been increasingly accepted that these complexes are a novel class of molecules that reside in the lung and have a proven ability to make airways relax."
The molecules are called S-nitrosothiols (SNOs). Stamler and his colleagues spent years screening members of the family -- "there are tons of molecular structures out there in the chemical literature," he says -- until they found one that appears to produce the right response in the right place. It is O-nitrosoethanol, which they abbreviate as ENO.
The first medical trial used ENO to help seven newborns with a problem called persistent pulmonary hypertension. It creates high blood pressure in the lungs, causing blood vessels to constrict so much that the baby's heart can't pump oxygen-rich blood to the body.
Nitrogen oxide gas has been used to treat the condition, but it has major drawbacks, such as production of free radicals, which are reactive molecules that can damage the lungs. An alternative treatment uses a miniature version of the heart-lung machine, a cumbersome piece of equipment.
ENO treatment improved the flow of oxygen-rich blood to the body of the seven babies without the side effects of nitric oxide, says a report in tomorrow's edition of The Lancet.
Says Dr. Ronald Goldberg, chief of neonatal-perinatal medicine at Duke University, "What I can say is that in our limited clinical experience, the response has been very favorable in terms of improvement of oxygenation and a drop in pulmonary pressure."
"We have looked for free radicals in these babies and have not found them," Goldberg adds. "This summer, we will continue to study the medication in an increasing number of babies, looking at the safety issues."
Because Duke is a regional medical center, "We might see anywhere from one to three babies a month with this condition," Goldberg says. Larger studies would be needed to get U.S. Food and Drug Administration approval for use of ENO in newborns with such breathing problems.
Stamler already is looking beyond that application.
"I would argue that there is a good reason to try this in some other diseases that are characterized by depleted levels of oxygen, such as asthma and cystic fibrosis, and also in conditions that cause impairment of breathing, such as emphysema," he says.
ENO has been tested on animals, and "we have begun additional trials in humans," Stamler says. It's premature to discuss those trials because "we are just beginning." However, he cites other conditions, such as acute respiratory distress syndrome (ARDS), as possible candidates for ENO therapy.
"There is a possibility that you can improve well-being, and we are encouraged enough to say we should try it," Stamler says.
"There has been a lot of enthusiasm about nitric oxide for ARDS, but it produces lung toxicity," Stamler says. "Our test-tube model says ENO does not produce toxicity."
What To Do
You can learn more about asthma from the American Lung Association. For more on breathing problems in newborns, visit Cincinnati Children's Hospital Medical Center.
