NEW DRUGS BEING TESTED FOR PAIN RELIEF

Mothers may feel that the pain of childbirth is the worst anyone can
endure, but pain specialists say other pain can be at least as severe, and
they are testing new drugs to control it.

The pains can be excruciating, unremitting and unrelieved even by opiates
like morphine, and the drugs now being tested in both animals and humans
are surprising in their nature.

Researchers, who described their work on pain relief in Philadelphia this
week at the annual meeting of the American Association for the Advancement
of Science, said there is real hope for sufferers of neuropathic pain --
the kind that often comes with severe diabetes, major injuries, the
nerve-damaging consequences of AIDS and conditions such as shingles
triggered by the same herpes virus that causes chicken pox. It can even
come as an agonizing ``phantom pain'' following amputation of a limb or the
deep-seated nerve injury that first makes itself known as a seemingly
ordinary low back pain.

According to Dr. Gary J. Bennet of Allegheny University of the Health
Sciences in Philadelphia, nearly 3 million Americans may suffer these types
of ``really terrible chronic pain.''

Bennet said he and his colleagues have been investigating three classes of
drugs that seem to show positive effects in laboratory rats that can serve
as a model for human neuropathic pain when a single sciatic nerve is
severed. He said ordinary painkillers do nothing for the animals' pain,
which is actually mild, but the compounds aimed at neuropathic pains do
work.

One of the drugs Bennet and his colleagues are testing is actually a
standard anti-convulsive compound used against epilepsy. Known
scientifically as gabapentin, it is marketed as Neurontin by Parke-Davis,
and although it is not ``a miracle solution'' to the pain problem, it does
appear to control the nervous system's response to severe pain signals and
is just beginning to be tested in humans.

Virtually every pharmaceutical company is now exploring another compound
that has been found to be useful in reducing nerve injury caused by
strokes, Bennet said. The compound, called n-mda, or n-methyl-d-aspartate,
appears to work by blocking the ability of brain cells to transmit pain
signals from severely injured parts of the body, he said.

A third class of new pain-killers, ironically, is derived from the
extremely painful and often deadly venom of a South Pacific shellfish
called the cone snail that snorkelers and skin divers often encounter and
occasionally step on to their misery.

The venom contains a protein called conopeptide, and scientists at Neurex
Corp. in Menlo Park have synthesized a portion of the conopeptide molecule
to create a drug called ziconotide. The compound has already been tested
against a variety of extremely severe neuropathic pain conditions in human
patients, and the company expects to seek approval for it from the U.S.
Food and Drug Administration later this year, said Dr. Robert Luther, drug
development director at Neurex.