Buprenorphine’s mechanism of action is that it binds to the brain’s mu-opioid receptors, reducing opioid cravings, preventing withdrawal symptoms, and blocking the effects of other opioids. 
Because of buprenorphine’s MOA, it has been shown in many studies to be an effective Medication for Addiction Treatment (MAT) for opioid use disorder (OUD) and acute opioid withdrawal syndrome. It is one of three medications approved by the Food and Drug Administration (FDA) to treat OUD. 
What Is Buprenorphine?
Buprenorphine is an FDA-approved medication for the treatment of opioid use disorder (OUD) as well as the management of opioid withdrawal.
Buprenorphine is useful for a number of reasons, including its ability to suppress opioid cravings and eliminate withdrawal symptoms without producing a euphoric high. While it has some misuse potential, it is far lower than that associated with “full” opioids people typically misuse. 
What Does Mechanism of Action Mean?
A substance’s mechanism of action (MOA) is the way in which it works or produces an effect on the body. If we understand how a drug works in the body, we can better understand what effects it will have at different doses and what side effects it may cause.
What Is Buprenorphine’s Mechanism of Action?
Buprenorphine is a partial opioid agonist that has a high affinity for the mu-opioid receptors in the brain, attaching to them and resulting in: 
- Reduced opioid withdrawal symptoms
- Decreased opioid cravings
- Reduced risk of relapse
- An ability to block other opioids at the receptor site
- Improved quality of life
It is also a delta receptor antagonist and a weak kappa receptor antagonist. 
Because it is only a partial agonist, it has a weaker effect than full opioid agonists like methadone and opioids of misuse, such as heroin and prescription painkillers. As a result, opioid-dependent people will not experience a euphoric high when taking buprenorphine.
Additionally, since buprenorphine has a high affinity for mu-opioid receptors but weaker activity, it displaces all other opioids at the receptor site—this means if someone relapses while taking buprenorphine, they won’t experience a rush or a high. They’ll only experience precipitated withdrawal symptoms, such as nausea, vomiting, diarrhea, anxiety, body aches and sweating.
Buprenorphine’s mechanism of action is unique because of its partial opioid properties. For example, its pain-relieving effects plateau at high doses, and it also has a “ceiling effect” for respiratory depression. This means that high doses of buprenorphine won’t result in stopped breathing or overdose, making it an extremely safe option for MAT. 
Buprenorphine has poor bioavailability when swallowed, which is why buprenorphine and Suboxone doses are intended to be dissolved under the tongue and absorbed sublingually. Once a person takes buprenorphine, it has a relatively slow onset of action and lasts longer than opioids of misuse, making it a great choice for treating OUD. 
Buprenorphine Receptor Action
|Mu-opioid receptor||Partial opioid agonist|
|Kappa opioid receptor||Antagonist|
|Delta opioid receptor||Antagonist|
Buprenorphine vs Suboxone Mechanism of Action
Suboxone is a combination medication for opioid use disorder, comprised of buprenorphine and naloxone, which is an opioid antagonist.
The buprenorphine works exactly the same in Suboxone as buprenorphine on its own. The only difference when it comes to the mechanism of action is the addition of naloxone, which can help prevent misuse and overdose.
The naloxone is inactive when a person takes Suboxone sublingually as prescribed—it only becomes active if someone attempts to misuse the medication by injecting it or snorting it, causing immediate precipitated withdrawal symptoms.
Buprenorphine’s Effect on the Body
Buprenorphine can cause a mild euphoria and low level of respiratory depression in opioid-naïve users. However, these side effects are less common in “opioid-experienced” patients whose bodies are already accustomed to opioid medications.
There are a few common side effects associated with buprenorphine use, including these:
- Constipation, nausea, and vomiting
- Disturbance in attention
- Drowsiness and fatigue
- Dry mouth
- Inability to sleep
- Tooth decay
It is sometimes difficult for people new to buprenorphine treatment to differentiate between the effects of their MAT and the general stress of opioid withdrawal, which can also cause a lot of these overlapping symptoms.
In general, if a person taking buprenorphine or any other medication experiences a symptom (whether on the list above or not) that seems like it may be serious or is impacting their quality of life, they should talk with a doctor. Often, small adjustments can be made to their treatment to lessen the severity of unwanted symptoms.
Also bear in mind that, just like with any new medication, many of these side effects will be temporary and will abate as your body gets used to the medication.
Effectiveness of Buprenorphine Treatment for OUD
Buprenorphine treatment for OUD has been shown to successfully treat OUD, including reducing the risk of relapse, overdose and death.
For example, one Swedish study found that patients treated with Suboxone are 1.82 times more likely (almost twice as likely) to stay in treatment and avoid opioid use as compared to patients that did not take Suboxone.  Suboxone also decreased the rate of opioid-positive drug tests by 14.2%.
Suboxone is known to be so effective for treating OUD that it was approved by the FDA for this use in 2002. Currently, it is one of three FDA-approved medications to treat OUD.
Reviewed By Peter Manza, PhD
Peter Manza, PhD received his BA in Psychology and Biology from the University of Rochester and his PhD in Integrative Neuroscience at Stony Brook University. He is currently working as a research scientist in Washington, DC. His research focuses on the role ... Read More
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