FORT LAUDERDALE, Fla--Interest in neurotoxins derived from marine cone snails has led to development of a calcium-channel blocking agent that could potentially be used as an alternative to opioid analgesics for patients with cancer pain. Early clinical studies with the agent (SNX-111, being developed by Neurex Corporation, Menlo Park, Calif) have found it to be more potent than morphine and free of opioid side effects, Richard W. Tsien, DPhil, said at a conference on gene technology organized by the University Biochemistry & Molecular Biology Foundation, Inc. and Bio/Technology Magazine.