Opioid use disorder is a chronic, relapsing disease with physical and psychiatric components. It is associated with economic hardship, social isolation, incarceration, increased rates of blood-borne infections such as HIV and viral hepatitis, adverse pregnancy outcomes, and increased mortality. According to the NIH, there were 80,411 deaths involving an opioid in the US in 2021, more than in any previous year. Several guidelines on the management of opioid use disorder are available; all recommend maintenance pharmacotherapy as the standard of care.

The FDA has approved a generic injectable formulation of the opioid antagonist nalmefene (Purdue) for the management of known or suspected opioid overdose. Revex, the reference product, was withdrawn from the market in 2008 for commercial reasons.

The FDA has approved a higher-dose injectable formulation of the opioid antagonist naloxone (Zimhi – Adamis) for emergency treatment of opioid overdose. A single IM or SC injection of the new formulation delivers 5 mg of naloxone; injectable formulations that deliver 0.4 mg or 2 mg of the drug have been available for years. Naloxone is also available in intranasal formulations for the same indication (see Table 1).