Read More Opioid Agonists, Partial Agonists, and Antagonists: What are They?

" />

Opioid Agonists, Partial Agonists, and Antagonists: What are They?

As of January 2019, 130-plus people die in the United States per day after overdosing on opioids.


Opioid addictions manifest themselves through an array of substances, from heroin, synthetic opioids (e.g., fentanyl) to prescription pain relievers (e.g., oxycodone).


In the US, opioid dependency has steadily grown into a national crisis. The ramifications adversely affect spheres such as public health along with socioeconomic welfare.  


According to research performed by the Center for Disease Control and Prevention, the US loses $78.5 billion per year due to opioid misuse. This ‘economic burden’ is caused by expenditures on healthcare, lost productivity, addiction treatment, and criminal justice spending.


Why Did Opioid Addictions Become So Prevalent?


During the 1990s, the medical community, collectively, was duped into believing that opioids weren’t overly addictive. The insurance companies were insistent that the positives of symptom relief would vastly outweigh the negative side effects.


So, doctors began handing out opioid prescriptions with reckless abandon, having been successfully sold a bill of goods. Unfortunately, opioids did turn out to be highly addictive, and people began to misuse them at an increasingly rampant rate.


Treating Opioid Addictions


With the alarming rise of opioid addictions affecting the US so dramatically, comes a need to provide effective treatments.


Part of that involves understanding the substances themselves and how they’re unique from one another. After all, it’s critical to understand what a person faces when attempting to recover from opiate dependency. That knowledge allows a proactive plan to be formed to stay one step ahead of the various challenges that recovering addicts will face.


For instance, the following three terms are crucial to understanding when treating opiate addictions:


• Opioid agonist

• Partial Agonists

• Antagonists


Below is a breakdown of these terms and what they mean concerning rehab treatments for opiate addictions.


What is an Opioid Agonist?


Heroin, methadone, and all other opioids are referred to as agonists. They stimulate the opioid receptors and possess analgesic properties. For this reason, opioid agonists (e.g., morphine, codeine, dihydrocodeine, oxycodone, hydrocodone, and fentanyl) are regularly prescribed for pain management purposes.


What is a Partial Agonist?


For some context, as part of the μ opioid receptor subtype, buprenorphine is a partial agonist.


The term partial agonist means that the system doesn’t experience full stimulation despite the potential of all the receptors to be occupied. Also, this ensures that these kinds of opiates are less likely to cause respiratory depression.


Buprenorphine possesses a superior safety profile when taken alone, primarily due to this muted effect. Also, since buprenorphine is an antagonist at the κ receptor as well, it’s less conducive to lowering the mood of treatment users, when compared to agonists.


A drug such as tramadol is more complicated to explain since its pharmacology hasn’t been fully explored. However, it is known that tramadol can act as either a low potency μ agonist or a partial agonist. Generally, it’s prescribed by doctors for pain relief purposes.


Partial agonists in the vain of buprenorphine can displace a full agonist because it has a higher affinity at the μ opioid receptor. Still, it only leads to partial stimulation. The most common example of this shift is when people start methadone treatments to counteract heroin addiction. It’s a treatment method that offsets the harsher symptoms of heroin withdrawal.


In the absence of an agonist, partial agonists act as an agonist. Only when there are high levels of an opioid agonist will it act as an antagonist.


What Are Antagonists?


Naltrexone or naloxone are both antagonists that don’t stimulate receptors but bind to them. Both pharmaceutical substances contain a high affinity with opioid receptors. They will displace current agonists while stopping any future agonists from binding to the receptors.


To clarify, antagonists will prevent any heroin, methadone, or any other agonist stimulation if they’re present in the receptors. This reaction causes abrupt withdrawals.


In most cases, naloxone is utilized during emergency medical interventions to reverse opioid overdoses.


Whereas naltrexone is often prescribed as a maintenance treatment to offset the potential for opioid relapsing in detoxified service users.


Knowledge is Power with Opioid Addiction Recovery


Somewhere in between 21%-29% of patients who’ve been prescribed opiates end up abusing them. On top of that, somewhere around 8%-12% of these patients end up with an opioid use disorder (OUD). Furthermore, approximately 6% of those who are misusing opioids escalate into using heroin.


These are all alarming statistics, compounded by the fact that sometimes there are few other legal options without opiates to treat pain symptoms. Although doctors were poorly disciplined with their prescription pad in the 1990s, plenty of patients experience enough that it’d be inhumane not to provide a prescription.


Given these various challenges, the US population must obtain a firmer grasp on how to help those experiencing OUD recover and rehabilitate. Acquiring the knowledge offered in this article about agonists, partial agonists, and antagonists is one way to gain a pivotal window into providing effective treatments for OUD.



About the Author

Paula Nicola, M.D.
Dr. Nicola is the Facility Director at Renu. She is a trained and board certified medical doctor with specialized training in addiction medicine.

Tag Cloud

Related Posts