A scientist at the National Institutes of Health has developed the first practical method of making opiates artificially. His success culminates 50 years of research by chemists looking for a way to make the opiate drugs without the poppy plant.

The discovery by Kenner C. Rice is of great importance to research on pain, drug addiction and the operation of the human nervous system.

Its significance is heightened because the United States obtains its entire supply of opiates for widely used pain killing drugs--including codeine, morphine and Percodan--from foreign suppliers, chiefly India.

Bad weather or adverse politics abroad consequently can mean a sudden, unpredictable shortage of the critical drugs. Development of the artificial opiate could allow the manufacture of a backup supply.

Rice announced his discovery at the national meeting of the American Chemical Society in Las Vegas.

A severe shortage of opiate pain killers occurred in this country between 1973 and 1975, forcing the government to release nearly half the country's strategic stockpile of opium for private use.

Opiate drugs, including the illegal ones such as heroin and opium, are made from the sap of the poppy plant. Rice said his technique is complex enough that it could not be copied by home chemistry buffs, but could be made readily in the laboratory of a pharmaceutical firm.

Opiates are pain killers because they mimic the brain's natural pain killing system, which uses a substance called endorphins to stop pain.

Opiates are chemically similar to the endorphins, and so mimic their pain killing effects.