Scientists at Harvard Medical School have successfully created a painkiller from the deadly toxin found in pufferfish and porcupinefish. The painkiller has been tested on rats and could potentially replace opioids, which are known to cause addiction in patients. Opioids are typically prescribed to individuals suffering from chronic pain in the back, head, or joints, when conventional painkillers no longer work. While opioids can alleviate pain by blocking receptors in the brain and spinal cord that transmit pain signals, they can also be highly addictive and fatal in cases of overdose. The opioid epidemic in the United States has led researchers to search for a safer alternative.
The nerve toxin tetrodotoxin, produced by pufferfish and porcupinefish, is lethal in small doses as it causes paralysis. Just one or two milligrams of the toxin can kill an adult human. However, tetrodotoxin has a similar effect to opioids as it blocks the transmission of pain signals in sodium channels. The challenge for scientists was to create a painkiller from the deadly toxin. Researchers led by Chao Zhao have developed a method to slowly release tetrodotoxin in tiny doses in the body. The tetrodotoxin used for the painkiller was combined with a biodegradable polymer that suppresses its toxic effects. The polymer breaks down in the body after administration, releasing small amounts of tetrodotoxin that are safe for humans.
Tests on rats that were given doses of tetrodotoxin that would normally be lethal were successful, with no abnormal behavior observed after administration. To further minimize safety risks, the researchers added a penetration enhancer to the tetrodotoxin-polymer combination, which allows the substance to be better absorbed by the nervous system. The pain-relieving effect was achieved with even lower doses of the combination, and tissue damage was not observed in the rats. Further studies will be conducted to confirm the safety of the procedure before clinical trials with human patients can begin. The researchers hope to increase the duration of the pain-relieving effect to several weeks with the development of a new medication.
