Opioid medications are commonly prescribed to patients to relieve moderate to severe pain. Opioids are effective and often fast-acting drugs that directly influence how the brain responds to pain. In a high dosage, opioid drugs — including codeine, oxycodone, morphine and methadone — can create a state of euphoria for people. However, the high is short-lived causing people to abuse opiates more frequently and at higher doses to induce the same effects.

Frequent opioid abuse increases the risk of tolerance and opioid addiction. Though some people attempt to quit cold turkey, doctors usually strongly advise people to gradually taper off of the medication to alleviate withdrawal symptoms and to ease into recovery.

One of the most effective forms of addiction treatment is medication-assisted treatment. Medication-assisted treatment consists of opioid replacement therapy with the buprenorphine-naloxone combination drug or methadone. These medications alleviate withdrawal symptoms while preventing people from getting high.  called opioid antagonist, or opiate blocker therapy. Within this treatment, users are tapered off of abused opiates with counteracting drugs that help to prevent a high.

Opioid Agonist vs. Opioid Antagonist

Opioid Agonists

Opioid agonist treatment acts as a catalyst in the brain. Agonist drugs — morphine, heroin and oxycodone — are substances that attach themselves to pleasure and pain receptors in the brain and produce a chemical reaction. This chemical reaction is what produces the feeling of euphoria. In large doses, agonist drugs can become addictive.

In opioid agonist therapy, doctors use drugs producing the same effects as common opiate drugs. The agonist drugs used in treatment are long-acting and help alleviate withdrawal symptoms and cravings for up to 36 hours. People in agonist therapy can quickly develop a tolerance to the medication, but without the high. They are also at risk of developing a physiological dependence.

Opioid Antagonists

When people refer to opioid blockers, they’re talking about opioid antagonists. Opioid antagonists are not used in medically assisted detox treatment. Opioid antagonist therapy does the opposite of medication-assisted treatment. Opioid antagonists cause people to experience a very uncomfortable withdrawal. That’s why they’re only used for emergencies like an overdose, and in combination with buprenorphine (i.e. a buprenorphine-naloxone combination drug) to prevent a person from dissolving the film and shooting it up.

Opioid antagonists prevent chemical reactions in brain receptors. Antagonist drugs — naltrexone and naloxone — also referred to as opiate blockers, block addictive drugs from triggering brain receptors and prevent a high. Unlike people who are participating in agonist therapy, antagonist treatment patients are less likely to develop a tolerance to the medication. Antagonist drugs are effective but not addictive. Antagonist drugs protect people from the adverse side effects of opiate addiction and can help prevent drug cravings.

How Do Opioid Blockers Work?

Opiate blockers, or antagonist drugs, bind to opiate receptors in the brain that regulate pleasure and pain. Unlike agonist drugs, opiate blockers are stronger and do not stimulate brain receptors to produce a feeling of euphoria.

There are two different opiate blockers used for antagonist treatment: naloxone and naltrexone. Naloxone is used most frequently in a medical emergency to reverse or prevent opiate overdose. If a person overdoses, they will be given a naloxone shot, nasal spray or intravenous injection to counteract effects of the drug. Naloxone and other opioid blockers are not addictive.

Naltrexone is commonly used to treat opioid addiction, but should only be used while in recovery. This drug is not to be used during withdrawal because it can intensify symptoms. Taking naltrexone during recovery can help to block drug-induced highs and can decrease the urge to use drugs.

Because naltrexone and naloxone are so effective, they will block pain-relief effects when used in combination with other opioid drugs.

Examples of Opioid Blockers

Opioid blockers come in a variety of forms. While some are effective in only one injection, others are consumed monthly. Some of the most common types of opioid blockers include:

  • Naltrexone: This prescription antagonist drug comes in the form of a shot and an oral tablet. The liquid, Vivitrol, is injected into the muscle monthly. However, the opiate blocker pill is taken once a day. Patients should not start taking naltrexone until they have been off of opioids for seven to 10 days to make sure all traces of opioids are cleared from their systems. The monthly shot of Vivitrol is thought to be more effective than the tablet because many people do not adhere to the prescribed tablet regimen.
  • Naloxone: This antagonist drug commonly known as Narcan can be injected or inhaled through the nose during a medical emergency to reverse overdose effects. Once administered, opioid withdrawal symptoms will occur.
  • Buprenorphine-Naloxone Combination Drug: Buprenorphine itself is an opioid, a partial agonist. On its own, it is not a blocker, but it is when it is combined with naloxone, as is the case with buprenorphine-naloxone combination drugs. Buprenorphine most commonly comes in the forms of buccal film (Bunavail), dissolvable tablets (Zubsolv) and a dissolvable film (Suboxone). Buprenorphine is also available on its own, but the combination with naloxone is now preferred because it is harder for people to abuse it. All of these forms are mixed with naloxone to prevent the temptation to abuse the drug by injecting it. If a person attempts to inject these drugs, the naloxone will prevent them from getting high.  

Getting Addiction Help

If you or someone you know is struggling with opiate addiction, the medical professionals at The Recovery Village are available to help you. Through support and individualized opioid addiction treatment options, you will be one step closer to living the healthier life you deserve. Don’t wait another day to seek help.

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Editor – Camille Renzoni
Cami Renzoni is a creative writer and editor for The Recovery Village. As an advocate for behavioral health, Cami is certified in mental health first aid and encourages people who face substance use disorders to ask for the help they deserve. Read more
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Medically Reviewed By – Dr. Jessica Pyhtila, PharmD
Dr. Jessica Pyhtila is a Clinical Pharmacy Specialist based in Baltimore, Maryland with practice sites in inpatient palliative care and outpatient primary care at the Department of Veteran Affairs. Read more
Medical Disclaimer

The Recovery Village aims to improve the quality of life for people struggling with substance use or mental health disorder with fact-based content about the nature of behavioral health conditions, treatment options and their related outcomes. We publish material that is researched, cited, edited and reviewed by licensed medical professionals. The information we provide is not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be used in place of the advice of your physician or other qualified healthcare providers.