Aug. 7 (Bloomberg) -- Scientists may have found the first effective antidote to nerve agents such as sarin, the deadly gas that terrorists used to attack Tokyo rail passengers in 1995.

An Alzheimer's disease drug and a generic anti-seizure medicine can combine to reverse the potentially lethal effects of chemicals called organophosphates, researchers said today in the Proceedings of the National Academy of Sciences.

Guinea pigs treated with the two drugs survived without showing life-threatening symptoms such as seizures, wrote scientists from the University of Maryland School of Medicine in Baltimore and the U.S. Army. The finding may help treat and save victims of chemical weapons and exposure to pesticides.

``This is extremely important, because for the first time we can resolve intoxication from insecticides and nerve agents,'' said Edson Albuquerque, chairman of the school's pharmacology department, in a telephone interview today. The study was funded by the Army, the National Institutes of Health and the National Institute of Environmental Health Sciences.

The finding may help soldiers survive chemical attacks. ``The Army was very receptive to this kind of research,'' Albuquerque said.

Guinea pigs -- which are rodents, not pigs -- have a nervous system similar to that of humans, and a treatment that works on these animals should also prove effective in humans, Albuquerque said.

Poison from organophosphates disrupts the nervous system and may strike people in a combat zone, in a terrorist attack or during the handling of insecticides, in which the chemicals are also used, the researchers wrote. The poisons disrupt the enzyme that regulates acetylcholine, a neurotransmitter. The result is too much stimulation of muscles and nerves.

Brain Damage

Exposure to the chemicals can cause brain damage, seizures, difficulty breathing, increased chewing and loss of motor coordination, or even death. In 1995, members of a religious group called Aum Shinrikyo used sarin to attack train lines under Tokyo, and a dozen people died.

Drugs that inhibit the enzyme called acetylcholinesterase are used to treat Alzheimer's disease, the most common form of senile dementia, as that disorder has been linked to a shortage of acetylcholine. The drug in the Alzheimer's study was galantamine, which is sold as Razadyne by New Brunswick, New Jersey-based Johnson & Johnson, the maker of thousands of health products.

Insecticides containing the poisons are soluble in fat, and thus are absorbed easily through the skin, according to the Web site of Pesticide Action Network UK, a London-based nonprofit that fights hazards from chemical control of pests.

``People use insecticides without precaution, particularly in Third World countries,'' Albuquerque said. ``This is very, very serious.''

Atropine

In the study, the generic drug atropine, an anti-seizure medicine, when used alone, failed to fully protect the guinea pigs against organophosphate poisoning from the nerve agents soman and sarin, and from paraoxon, an ingredient for insecticide.

Researchers found that treating the guinea pigs with a combination of atropine and galantamine safeguarded the animals from potentially lethal doses. The medicines were delivered either 30 minutes before or as much as five minutes after the exposure to organophosphates.

The atropine used in the study was supplied by St. Louis- based Sigma-Aldrich Corp., a seller of products for scientific research.

To contact the reporter on this story: Emily Brown in Washington at ebrown18@bloomberg.net.

Last Updated: August 7, 2006 17:06 EDT