Nitrogen is a big part of the air we breathe, but too much can kill.
Researchers at Johns Hopkins University reviewed 25 years of studies on using sodium phenylacetate and sodium benzoate to help eliminate excess nitrogen, which can generate ammonia in the blood of children with urea-cycle disorders. This causes brain damage, retardation, coma and even death.
“In all my years I never came across another disease where patients come in near-comatose and you stick a needle in them and lo and behold, they wake up ? just like that. It was just astonishing,” said Dr. Saul Brusilow, professor emeritus of pediatrics at Hopkins and the first to use the treatment in 1980.
The body produces sodium phenylacetate and sodium benzoate in small amounts to help regulate nitrogen, but in some cases can?t produce enough, according to Brusilow?s report in this week?s New England Journal of Medicine. Most patients hospitalized for ammonia poisoning are children.
“Sodium phenylacetate and sodium benzoate already know how to eliminate nitrogen in urine, so having more in the body carries more nitrogen out and reduces the toxic effects of excess nitrogen accumulation,” Dr. Ada Hamosh, clinical director of the McKusick-Nathans Institute of Genetic Medicine, said in a statement.
Nitrogen is generated when the body breaks down proteins into amino acids, Hamosh said. It binds to these sodium compounds to form urea, which is a component of urine.
Despite the immediate clinical success of the treatment, the U.S. Food and Drug Administration finally approved the drug combination in 2005.
Hamosh estimated one in 40,000 children is born with a urea-cycle disorder.
“We?re teaching all medical students at Hopkins to consider hyperammonemia and immediately do blood tests when they see a combative, lethargic or comatose newborn or child,” she said. “The longer the hyperammonemia lasts, the higher the risk for brain damage.”
Treatment consists of high-doses of intravenous sodium phenylacetate and sodium benzoate for two hours followed by maintenance infusions until blood ammonia levels are normal, according to the article. Overall, 84 percent of patients survived, and 96 percent survived individual episodes of severe ammonia poisoning.
For older children and adults, a protein-restricted diet and maintenance medications usually control the disorder, Hamosh said.
