Researchers at Monash University in Australia have developed a new drug-delivery strategy that is able to block pain within nerve cells in what could be a major development in the search for an immediate and long-lasting treatment for pain.
More than 100 million Americans experience chronic pain, and this figure is expected to grow, driven by an increased life expectancy and by an increasing incidence of diabetes and cancer combined with better survival rates, often leaving patients with severe and poorly treated pain. The global market for nerve pain treatments in the U.S. is more than $600 billion, and yet current pain therapies are not completely effective and often cause adverse effects.
New research published in Science Translational Medicine describes how a target protein, long known to be associated with both chronic and acute pain, works within nerve cells. This protein is the NK1 receptor––the receptor of the neuropeptide substance P, which mediates pain transmission. Because of its association with pain and other diseases of the nervous system, many drug-development efforts have focused on inhibiting this receptor, but the efficacy of these treatments has been limited. The new research shows that such ineffectiveness could be partly because the treatments targeted the NK1 receptor on the surface of nerve cells.
The investigators found that the NK-1 receptor controls pain once it is inside the cell––therefore, drugs that block it when it is on the surface of the cell have little efficacy. Instead, this new research shows that, in animal models, if the NK-1 receptor is blocked once it enters nerve cells, it is possible to suppress pain more effectively.
Investigator Dr. Michelle Halls said that the new strategy of “targeting receptors inside the cell represents a new frontier in drug delivery and a novel therapeutic strategy for dealing with pain.”
Working with a multidisciplinary team of cell biologists, pharmacologists, physiologists, and drug-delivery experts, the researchers developed drugs that specifically target NK-1 receptors within nerve cells. Studies showed that using these drugs––which have an engineered lipid attachment that targets the drug to NK-1 receptors inside the cells––could block pain for extended periods in several animal models.
Co-investigator Dr. Meritxell Canals said: “This is a proof-of-concept study that shows that we can re-engineer current pain drugs and make them more effective. The challenge is now to translate the technology into human clinical trials. This is a complex and challenging path––but the ultimate benefits to patients with nerve pain are potentially highly significant.”
Source: Medical Xpress; May 31, 2017.