The presently disclosed subject matter is directed to opioid antagonist formulations for use in mitigating opioid abuse and/or overdose in a subject. Particularly, the disclosed formulation comprises an immediate release opioid antagonist coupled with an extended release opioid antagonist. The disclosed opioid antagonists attenuate the activity of an opioid agonist and thus prevent or reverse the adverse effects of the agonist. Particularly, the immediate release component allows for immediate availability of the opioid antagonist to provide fast onset treatment, while the extended release component allows continued release of the opioid antagonist to further mitigate the opioid overdose. Thus, the disclosed formulation advantageously provides a fast-onset opioid antagonist in addition to a slow-release opioid antagonist, lasting up to 48 hours post administration.
