Naloxone
"Naloxone has been used as an antidote to opioids for over 50 years, and the drug has been readily available as a parenteral formula. Naloxone acts as a pure μ-opioid receptor competitive antagonist and is instrumental in preventing accidental overdose of opioids. Due to its effectiveness in preventing death due to opioid overdose, the federal government has recommended that naloxone should be available over-the-counter at most pharmacies.