Opioid Toxicity Medication

Updated: Jun 06, 2020
  • Author: Everett Stephens, MD; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD  more...
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Medication Summary

Naloxone is a pure competitive antagonist of opioid receptors and lacks any agonist activity. Adverse effects are rare at therapeutic doses. Naloxone can be given by the intravenous (IV), intramuscular (IM), endotracheal (ET), or subcutaneous (SC) route. The use of intranasal naloxone has also been reported and holds promise, given the absence of need for intravenous access and reduced risk for needle stick to healthcare providers. [55]

By the IV or ET route, the onset of action of naloxone is 1-2 minutes. A second dose can be repeated every 2-3 minutes. With IM or SC administration, onset is 2-5 minutes.D iscontinue treatment as soon as the desired degree of opioid reversal is achieved. Higher doses may be necessary to reverse methadone, diphenoxylate, propoxyphene, butorphanol, pentazocine, nalbuphine, designer drugs, or veterinary tranquilizers.

Nalmefene (Revex) and naltrexone are newer opioid antagonists that have longer half-lives than naloxone (4-8 h and 8-12 h vs 1 h). The routine use of a long-acting antagonist in the patient who is unconscious for unknown reasons is not recommended. In addition, the fear of precipitating prolonged opioid withdrawal likely prevents the widespread use of these antagonists for emergency reversal of opiate intoxication.

In theory, nalmefene might be useful for persons with opiate addiction who accidentally overdose on heroin but refuse to stay for continued observation after an initial reversal dose of naloxone. However, this practice can be fatal to the patient who is discharged and then uses an excessive dose of opioids in order to counteract the withdrawal symptoms caused by the nalmefene. The routine use of this agent is not recommended.


Opioid Reversal Agents

Class Summary

These agents reduce or eliminate the effects of opioid agents on their receptors.

Naloxone (Narcan, Evzio)

Historically, the most commonly used opioid receptor antagonist in the United States. It is used to reverse opioid intoxication or overdose. Prevents or reverses opioid effects (hypotension, respiratory depression, sedation), possibly by displacing opiates from their receptors. Half-life is 1 h. The injectable solution is available in vials and syringes (0.4 mg/mL, 1 mg/mL) for IV/IM/SC administration by healthcare providers. It is also available as an autoinjector (delivers 0.4 mg IM/SC) for home use by family or caregivers.

If patients do not respond to multiple doses of naloxone, consider alternative causes of unconsciousness.

Naloxone intranasal (Narcan Nasal Spray)

Competitive opioid antagonist that antagonizes opioid effects by competing for the same receptor sites. The intranasal form is indicated for the emergency treatment of known or suspected opioid overdose, as manifested by respiratory and/or central nervous system depression.