Neurex Corp. has moved into a Phase II/III study with SNX-111, aneuron-specific calcium channel blocker derived from a snail toxin,for relief of severe chronic pain in cancer and AIDS patients.

The study involving 200 patients at 30 U.S. medical centers is themost advanced clinical trial with the drug. SNX-111 is a chemicallysynthesized peptide based on naturally occurring calcium channelblockers in the venom of cone snails found in the Philippines.

The peptide, an N-type neuronal and voltage sensitive calciumblocker, is pumped into the spinal chord to inhibit pain sensationsfrom reaching the brain. Neurex, of Menlo Park, Calif., iscollaborating on the pain remedy with Medtronic Inc., ofMinneapolis, which makes the implantable device used to deliver thedrug.

Neurex also is evaluating SNX-111 in Phase II trials for preventingbrain damage associated with ischemia in head trauma and stroke.The company is collaborating with Warner-Lambert Co., of MorrisPlains, N.J. on those studies.

In treating pain and ischemic complications, SNX-111 blockspresynaptic calcium channels, inhibiting nerve cell communicationsand the release of overexcited neurotransmitters.

While the drug deadens pain sensations by keeping them fromtraveling up the spinal chord to the brain, it attempts to offsetischemic-related brain damage by preventing oxygen-starved neuronsfrom becoming highly agitated.

Paul Goddard, chairman and CEO of Neurex, said endpoints for thepain trials include symptomatic relief as measured by FDA-acceptedscales, elimination of the use of other analgesics and reduction ofneuropathic pain, which causes a burning sensation of the skin.

The blinded trials are expected to take a year to complete. Goddardsaid an interim analysis of the data will be performed halfwaythrough the studies in the third quarter of this year.

Phase I/II trials of SNX-111 demonstrated the compound has thepotential to provide symptomatic relief of pain without the sideeffects of opiates, such as morphine. Patients in those studies werenon-responsive to opiates, but experienced significant reductions inpain with Neurex's compound.

Neurex's other most advanced drug candidate is Corlopam(fenoldopam), which the company licensed from London-basedSmithKline Beecham plc. The drug is being developed for control ofblood pressure during surgery and for treatment of malignanthypertension.

Goddard said Neurex expects to file a new drug application with theFDA for Corlopam this year.

Neurex's stock (NASDAQ:NXCO) closed Tuesday at $9.25, up 12cents. n

-- Charles Craig

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