Naloxone Injection 0.4 mg Vials, Single-Dose 10/Box by Pfizer (RX)Naloxone Injection 0. 4 mg Vials are used as an emergency treatment to rapidly reverse the effects of opioid overdose, including life threatening symptoms such as respiratory depression, sedation, and loss of consciousness. Naloxone is an opioid antagonist that works by displacing opioids from their receptors in the brain, quickly restoring normal breathing and consciousness. It is vital in emergency medical situations and is administered by