Opioid antagonists: Uses, most common brand names, and safety information

Medically reviewed by  Jamie Winn, PharmD

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Opioid use disorder (OUD) is a chronic condition that can lead to serious consequences including opioid dependence, hospitalization, or death. It was estimated by the National Survey on Drug Use and Health that approximately 2 million adults in the United States had an OUD involving prescription opioids or heroin in 2016. In 2019, over 70% of drug overdoses were opioid-related. Opioid antagonists such as Narcan (naloxone) can be used to reverse life-threatening opioid overdoses as well as side effects due to opioid-induced constipation, slowed breathing, or sedation. These medications are often used to manage and prevent opioid addiction and help patients stop taking opioids without severe withdrawal symptoms.

The list below includes opioid antagonists approved by the U.S. Food and Drug Administration (FDA) and their pricing:

List of opioid antagonists

Purdue Pharmaceuticals was granted FDA approval in 2022 to bring another opioid antagonist, nalmefene back to the US market. There are several combination medications that contain opioid antagonists, including:

• Targiniq ER (oxycodone/naloxone)
• Contrave (bupropion/naltrexone)

What are opioid antagonists?

Opioid receptor antagonists are a class of medications that block one or more opioid receptors to reverse the effects of opioids in your peripheral and central nervous system (CNS). Treatment with an opioid receptor agonist (methadone), partial agonist (buprenorphine), or long-acting injection formulation of the opioid antagonist Vivitrol (naltrexone) is an effective treatment for substance abuse disorders such as opioid and alcohol dependence.

How do opioid antagonists work?

Synthetically made opioids or opiates derived from plants are potent and addictive medications that are used for their analgesic effects. They work by binding and activating one or more of the 4 types of opioid receptors (mu, delta, kappa, and opioid-receptor like-1). These receptors play an important part in pain transmission and are found throughout the body including the brain, spinal cord, and GI tract. Mu-opioid receptor activation by opioid agonists leads to side effects such as respiratory depression and sedation. Activation of the kappa and delta receptors leads to potent analgesia (pain relief). Opioids are typically classified based on how they interact with opioid receptors:

• Full agonists such as Duragesic (fentanyl), Roxicodone (oxycodone), Dolophine (methadone), Roxanol (morphine), and heroin strongly bind to opioid receptors and activate their functions. These medications produce strong pain-relieving effects as well as the potential for serious adverse reactions.
• Partial agonists such as Suboxone (buprenorphine) and Ultram (tramadol) do not activate opioid receptors as potently as full agonists. At low doses, partial agonists can provide similar analgesic effects as full agonists. When you increase the dose of partial agonists, you will get a limited increase in effectiveness while significantly increasing the side effects.
• Antagonists such as Narcan (naloxone) block or decrease the effects of opioids by inhibiting them from binding to one or more of the opioid receptors.
• Mixed agonist/antagonists such as Nubain (nalbuphine) can activate or block opioid receptors depending on the receptor and dose. These medications typically produce fewer side effects such as nausea and vomiting when compared to full agonists.

What conditions are opioid antagonists used to treat?

Opioid antagonists are a class of medications used in the treatment of the following:

• Opioid overdose or reversal of serious adverse effects of opioid use
• As part of a treatment program to prevent relapse from opioid or alcohol dependence
• Manage opioid effects such as shallow breathing or constipation.

Are opioid antagonists safe?

The use of opioid antagonists is relatively safe and effective when taken as prescribed. Certain conditions can worsen with the use of opioid antagonists, including seizures and heart disease. They can also cause acute cases of opioid withdrawal, especially if you were taking high doses of opioids. More specifically, Entereg (alvimopan) was shown to cause an increased risk of a heart attack when compared to patients who took a placebo in a clinical trial and Relistor (methylnaltrexone) should not be used in patients who have a known obstruction in their gastrointestinal tract.

What are the common side effects of opioid antagonists?

The adverse effects you experience from opioid antagonists will depend on several factors including the medication and dose. The most common adverse effects include:

• Nausea
• Vomiting
• Rapid heart rate (tachycardia)
• High blood pressure
• Injection site reaction from intravenous or subcutaneous formulations
• Headache
• Opioid withdrawal symptoms
• Fever
• Dizziness
• Insomnia
• Decreased appetite
• Diarrhea
• Insomnia
• Anxiety
• Dysphoria (general discomfort)
• Erectile dysfunction

This is not a complete list of side effects and we encourage you to consult with your healthcare professional or prescribing physician for medical advice about any possible side effects.

What is an opioid agonist/antagonist?

Opioid agonist/antagonist activity depends on the receptor type it affects. They can act as an agonist (stimulator) for one type of opioid receptor while working as an antagonist (inhibitor) for a different receptor. They are typically used in pain management.

What is the difference between opioid antagonists and agonists?

When opioid agonists interact with a receptor it produces a response such as pain relief. When opioid antagonists bind to a receptor it does not cause a response, but it does block opioid analgesics from binding to that receptor.

How much do opioid antagonists cost?

Opioid antagonists are very expensive with an average cost of up to around $5,000 per year.

You can purchase opioid antagonists for $49 per month from NiceRx if eligible for assistance. Prices at the pharmacy vary by location, strength, and quantity, as well as your insurance status.

Related resources for opioid antagonists

• https://www.ncbi.nlm.nih.gov/books/NBK537079/
• https://www.hcrcenters.com/blog/what-is-an-opioid-antagonist/
• https://www.webmd.com/connect-to-care/addiction-treatment-recovery/prescription/what-is-an-opioid-antagonist
• https://www.sciencedirect.com/topics/neuroscience/opioid-antagonist
• https://www.mass.gov/doc/article-antagonists-in-the-medical-management-of-opioid-use-disorders/download
• https://www.jpsmjournal.com/article/S0885-3924(02)00424-4/fulltext#secd23146249e1253
• https://www.cambridge.org/core/journals/cambridge-quarterly-of-healthcare-ethics/article/abs/birth-of-naloxone-an-intellectual-history-of-an-ambivalent-opioid/488D6075073599B12A2EFCDF6AE7F7BA