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By K K Jain MD

Ziconotide, the synthetic form of cone snail peptide pi (variant) conotoxin MVIIA, is a neuron-specific N-type calcium channel blocker that has been under development for the treatment of severe chronic pain and ischemia. The snail has been used in medicine since antiquity and prepared according to several formulations. Pliny considered the snail to be "a sovereign remedy to treat pain related to burns, abscesses and other wounds” (Bonnemain 2005).

Pi (variant) peptides that block voltage-sensitive calcium channels were isolated from a species of conus snails in 1991 (Olivera et al 1991). Development of SNX-111 (now ziconotide) for cerebral ischemia and traumatic brain injury began in 1993, and clinical trials for chronic pain started in 1995. Intrathecal ziconotide for pain was approved by the FDA in 2004.