The Food and Drug Administration (FDA) has approved Purdue Pharma’s Nalmefene Hydrochloride Injection for the complete or partial reversal of opioid drug effects, including respiratory depression, induced by either natural or synthetic opioids, and in the management of known or suspected opioid overdose.

Nalmefene HCl was developed as an alternative to naloxone to reverse the effects of opioids, including respiratory depression, sedation, and hypotension. The drug was previously marketed under the brand name Revex (Baxter) but was discontinued in 2008.

Pharmacodynamic studies have shown that nalmefene has a longer duration of action than naloxone. Nalmefene HCl can be administered via the intravenous, intramuscular, or subcutaneous route.

The most common adverse reactions reported in clinical trials with nalmefene injection were nausea (18%), vomiting (9%), tachycardia (5%), hypertension (5%), postoperative pain (4%), fever (3%), and dizziness (3%). 

Nalmefene Hydrochloride Injection is supplied as a single-dose vial containing 2mg/2mL (1mg/mL) of nalmefene base in a carton of 10 vials.

The product is expected to be available by mid-2022. In a press release, Purdue stated that it will be distributing the drug for no profit.

“Nalmefene is an important part of our commitment to help abate the opioid crisis,” said Craig Landau, MD, CEO and president, Purdue Pharma. “This FDA approval is an example of our ongoing efforts to help provide much-needed treatment for patients and health care providers.”


  1. FDA approves Nalmefene HCl Injection, 2mg/2mL (1mg/1mL) for the treatment of known or suspected opioid overdose with natural or synthetic opioids. News release. Purdue Pharmaceuticals, LP. Accessed February 23, 2022.
  2. Nalmefene Hydrochloride Injection. Package insert. Purdue Pharmaceuticals, LP; 2022. Accessed February 23, 2022.