Evaluation of Injectable Naloxone-Releasing Hydrogels

The opioid epidemic in the United States is a serious public health crisis affecting over 1.7 million Americans. In the last two decades, almost 450 000 people have died from an opioid overdose, with nearly 20% of these deaths occurring in 2017 and 2018 alone. During an overdose, overstimulation of the μ-opioid receptor leads to severe and potentially fatal respiratory depression. Naloxone is a competitive μ-opioid-receptor antagonist that is widely used to displace opioids and rescue from an overdose. Here, we describe the development of a slow-release, subcutaneous naloxone formulation for potential management of opioid overdose, chronic pain, and opioid-induced constipation. Naloxone is loaded into self-assembling peptide hydrogels for controlled drug release. The mechanical, chemical, and structural properties of the nanofibrous hydrogel enable subcutaneous administration and slow, diffusion-based release kinetics of naloxone over 30 days in vitro. The naloxone hydrogel scaffold showed cytocompatibility and did not alter the β-sheet secondary structure or thixotropic properties characteristic of self-assembling peptide hydrogels. Our results show that this biocompatible and injectable self-assembling peptide hydrogel may be useful as a vehicle for tunable, sustained release of therapeutic naloxone. This therapy may be particularly suited for preventing renarcotization in patients who refuse additional medical assistance following an overdose.