Published on 12 February 2019

The treatment of pain is a major medical issue. Morphine and synthetic opiates are today the most effective drugs despite their considerable side effects. A team of researchers from Université Paris-Sacla, directed by Patrick Couvreur (Institut Galien Paris-Sud), has just presented a nano-drug with a significant anti-pain effect in rats, without causing addiction. This study was published in Science Advances.

The use of endogenous neuropeptides, such as enkephalins or endorphins, is undoubtedly an interesting alternative to the use of morphine. Indeed, by acting mainly on the delta receptors of opiates (neurotransmitter receptors that modulate in particular the function of response to pain), these natural molecules do not induce these side effects. Unfortunately, after administration, these molecules are metabolized in minutes and are unable to trigger an analgesic effect.

The "Innovative Nanomedicines for the Treatment of Critical Illnesses" team led by Patrick Couvreur at the Institut Galien Paris-Sud (Paris-Sud University / CNRS) came up with the idea of ​​synthesizing nanoparticle samples made from leu-enkephalin coupled, at its amino or carboxyl terminus, to squalene. The chemical bond is effected via various chemical bonds, enzymatically activable. It has been shown that these nanomedicines induce, in the rat, a significant and prolonged pain-relieving effect with a sub-curve area greater than that of morphine, ie a greater efficiency.

Through the use of opiate receptor antagonists, which do not penetrate the blood-brain barrier, it has been observed that unlike morphine, leu-enkephalin-squalene nanoparticles spared brain tissue and acted exclusively at the level of the brain peripheral receivers. Imaging has, moreover, shown that the nanoparticles were capable of delivering the neuropeptide specifically at the level of the painful inflammatory zone; they thus avoid the central effects responsible for the phenomena of addiction.

The biochemical and histological investigations carried out on the level of the treated animals have, moreover, demonstrated that this new anti-pain medication does not induce any toxicity or side effect.

This study, published in the journal Science Advances, represents a breakthrough in the treatment of pain through nanomedicine.

The text below is taken from the french press release.