Cone snails are extremely dangerous marine molluscs that pose enormous threats due to the toxic venom they release. These conotoxins are contained in a microscopic harpoon, which is released through the proboscis, a tongue-like structure. After approximately 30 seconds the ejected harpoon is replaced from an internal harpoon sac and a new harpoon is reloaded and ready to fire. These toxins cause prey to go into excitotoxic shock, where the venom causes muscles to contract and lock, making movement impossible. Conotoxins may also cause flaccid paralysis, where the prey’s muscles become completely limp. Cone snails are not only dangerous to fish and other molluscs, but to shell collectors also. Be aware next time you’re shell hunting and make sure that a nice shell is void of inhabitants.
Due to the research of biochemists and pharmacologists, the venom of the magician’s cone, or Conus magus, has been synthesized into a chronic pain suppressant. The drug Ziconotide, marketed as Prialt, is the first ω-conotoxin to be utilized safely and effectively in medicines for humans suffering from chronic pain. Prialt is delivered intrathecally, or directly into the spinal cord, opposite of common pain medication that is delivered orally. It cannot be ingested orally due to the high temperature and acidity in the stomach. Stomach and digestive enzymes will immediately break down peptides if taken orally. However, medication injected straight into the spinal cord is not subjected to harsh stomach conditions. Also, intrathecal injections provide maximum pain reducing effects along with reduced possibility of side effects. Ziconotide works by reducing or blocking pain signals traveling to the brain.
Prialt has become a very successful and powerful drug. While on Prialt, each dosage is long lasting and reduces pain almost completely. However, doses in high concentration proved to cause many adverse side effects. During clinical trials, subjects reported dizziness, nausea, memory impairment, confusion, blurred vision, slurred speech, and sedation. However, those who experienced any or none of these side effects reported that complete pain relief was achieved.
Below is a short clip of a cone snail feeding, enjoy!
-by Halle Nowak
McGivern, J.G. (2007) Ziconotide: a review of its pharmacology and use in the treatment of pain. Neuropsychiatric Disease and Treatment. 3:69-85.
Olivera, B.M. (2002) Conus venom peptides: Reflections from the biology of clades and species. Annual Review of Ecology and Systematics. 33: 25-47.