How Do Opioid Antagonists Work?

Reviewed on 10/21/2021

How do opioid antagonists work?

Opioid antagonists are medications used to reverse opioid effects from opioid dependence, overdose, or therapeutic administrations such as anesthesia. Opioid antagonists bind to opioid receptors and block them from being stimulated by opioid agonists, which are drugs that enhance the activity of opioid receptors.

Opioid receptors are protein molecules on nerve cell (neuron) membranes in the central and peripheral nervous systems. Opioid receptors mediate the body’s response to most neurotransmitters, chemicals that neurons release to communicate with each other.

Some of the functions of opioid receptors include modulating pain, stress response, mood, and emotions. Most opioid antagonists work by blocking mu-opioid receptors, a type of opioid receptors responsible for the feeling of euphoria, pain relief, and dependence, in addition to other functions.

Some opioid antagonists block the opioid receptors on certain neurons known as pro-opiomelanocortin (POMC), which prevents the feedback of hunger sensation from the body and is used to treat obesity. Some of the opioid antagonists are combined with other classes of medications for eliciting dual effects, which include:

  • Partial opioid agonists: Partial opioid agonists have partial effects because they work as agonists in some receptors and antagonists in others. Opioid antagonists combined with partial agonists are used for pain relief while blocking euphoric effects, useful when treating opioid dependence.
  • Dopamine reuptake inhibitors: Dopamine reuptake inhibitors increase the levels of dopamine, a neurotransmitter that regulates pleasure sensation and appetite. Dopamine stimulates POMC neurons, which reduces appetite and increases energy expenditure. The combination with opioid antagonists regulates the dopamine reward system and reduces food cravings.


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How are opioid antagonists used?

Opioid antagonists may be administered through many routes including:

Opioid antagonists and opioid antagonist combinations are used to treating conditions that include:


Orphan designation

Pending FDA approval

  • Major depressive disorder

What are side effects of opioid antagonists?

Side effects of opioid antagonists may include the following:

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

What are names of some opioid antagonist drugs?

Generic and brand names of opioid antagonist drugs include:


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