Thank you to Pharmacist Steve for reviewing and fact checking this post.
Most people in the chronic pain community seem to use the word opioid correctly and prefer it to opiate, but I’m not sure they know why. Also, When I read various state laws and saw the word opiate in their legislation, I became concerned because it could cause future legal problems. I’ve seen doctors misuse the term opiate, as well as people in the addiction and recovery community. It’s important for all of us to understand the differences between the words opiate and opioid, and among the terms opioid agonists and antagonists, and partial agonists, so we understand how they work or don’t work to treat pain and withdrawal symptoms. It’s important to know this stuff if you’re working on legislation, too, so that you can guide the language toward optimal availability of the best medicines for all patients. To that end, please allow me to throw down some knowledge. Please be warned that this post contains sexual references. This is a time-honored learning tradition used by medical students to help remember boring but important information.
First, a Little Cell Biology
All opioid and opiate pain relievers work basically the same way. They are molecules that have a specific shape and/or molecular affinity for another molecule that sits on the surface of the cells of the body called a receptor. Receptors are proteins that are embedded into the surface of cells all over your body. Opioid receptors are much more prevalent in brain and nerve tissue. There are three kinds of opioid receptors, mu, delta, and kappa, but the most potent medicines seem to fit into the mu receptors. When you read academic medical articles, you’ll see them referred to as MOP, DOP, and KOP, sometimes without spelling them out or defining them first. Receptors are connected to another molecule inside the cell wall called a G-protein. The G-protein inside the cell wall acts like a switch that activates other parts of the cell that interrupt the transmission of pain signals to the brain. Researchgate.net has a great illustration of the opioid molecule and the receptor in the cell walls of two neurons that’s helpful to visualize what I’m talking about. For the purpose of this post, you can ignore the chemical reactions illustrated inside the cells. Suffice it to say that the reactions caused by the opioid sitting in the receptor is what causes the cells to interrupt the transmission of pain signals to the brain.
Opioids versus Opiates
These two words are often used interchangeably, and they shouldn’t be, because they have different meanings. An opioid medication is a class of drugs that has a molecular affinity for opioid receptors. The term opioid is an umbrella term that includes all types of medicines, whether plant derived or synthetic. Opiates, on the other hand, are plant derived medicines. Examples of opiates include morphine, and codeine. You can, theoretically, grow and make your own at home. (But you should know that growing certain plants for other-than-ornamental purposes is illegal.) Some sources classify heroin as an opiate, others call it a semisynthetic opioid because you must chemically alter morphine to make it; however, you must first have a supply of plant-derived morphine to make it, thus the tendency to classify it as an opiate. Whereas opiates are considered to be plant-derived medicines, opioids include opiates as well as synthetic and semisynthetic lab-manufactured drugs that activate the opioid receptors. So now you know why you shouldn’t accept legislation that limits protections to opiates as opposed to opioids; because opiates is a far smaller subset of medicines than opioids. See Table 1. for a list of opioids, opiates, and the trade names of commonly prescribed medicines in each category.
Agonist, Antagonist, and Partial Agonist
Opioids have what pharmacists call biochemical affinity (strength of attraction; think of it as the strength of a magnet) for the cell’s opioid receptors and efficacy in terms of whether and how strongly they initiate action inside the cell. The words agonist, partial agonist, and antagonist actions describe variations in affinity and efficacy of the medications.
To simplify, I like to use analogies. It’s useful to think of opioid agonists as the on switch for pain relief and opioid antagonists as the off switch that deactivate the G-protein inside the cell. You already know what an antagonist is because you know what it means to be antagonized by someone; as in, some internet bro who wants to antagonize pain patients for not wanting to self-identify as addicted; some FaceBook troll who wants to draw you into a false conspiracy theory; as in some psychiatrist who tries to tell you opioids don’t work for chronic pain; as in some trend-sucking dilettante surgeon who tells you you’re an addict because you take opioid medication for chronic pain. Antagonizers have the opposite effect of agonists. They make pain worse pharmacologically and use social stigma to manipulate and control.
Antagonists are like chastity belts. Just like a selfish and lazy sexual partner, the antagonist molecule sits on the receptor and does not activate it. This pharmacologic mind-fuck reverses the action of opioid agonists. Naltrexone and naloxone are opioid antagonists. Some people will incorrectly call them opioids. They are more accurately called opioid antagonists because they reverse the effects of opioid drugs, even if they do fit inside the opioid receptor. When a doctor gives you an opioid antagonist and calls it an opioid, it is neuropharmacological rape. It’s like using a date rape drug, because if you don’t know, you do not have the capability to consent to the treatment.
Partial agonists (in red boldface in Table 1, below), are like shitty dildos that may be too small, or which have weak batteries and can’t finish the job. Partial opioid agonists only partially activate the opioid receptors and only partially relieve pain. They are still useful, however, for mild to moderate pain, and are thought to have a much lower abuse potential.
An agonist is the opposite of antagonist. It relieves your pain. Full or strong opioid agonists are like dildos that are fully charged and which are the correct size. They get the job done, and they are the best in class for severe, intense pain relief. Just like great sex, if it’s going to work well, the opioid must hit the G-protein just so to have full effect inside the cell.
Class | Common or Generic Name | Trade Names1 |
|---|---|---|
| Opiates | kratom (partial agonist) | NA |
| codeine
(partial agonist) |
usually sold only in combination with acetaminophen and caffeine | |
| morphine | Apokyn, Arymo, Avinza, DepoDur, Duramorph, Embeda, Infumorph, Kadian, Kynmobi, Mitigo, Morphabond, MS-Contin, Paregoric, Roxanol, Statex | |
| thebaine (paramorphine) | NA | |
| Semi-synthetic opioids | buprenorpine (partial agonist) | Buprenex, Subutex, Belbuca, Brixadi, Butrans, Probuphine, Sublocade |
| heroin (diacetylmorphine) | NA, illicit in the US, Schedule I | |
| hyrdromorphone | Dilaudid, Exalgo, Palladone | |
| hydrocodone | Hysingla, Vantrela, Zohydro | |
| oxycodone | Oxaydo, Oxecta, Oxycontin, Roxicodone, Roxybond | |
| oxymorphone | Numorphan, Opana | |
| Synthetic opioids | alfentanil | Alfenta |
| dextropropoxyphene | NA | |
| fentanyl | Duragesic, Abstral, Actiq, Fentora, Ionsys, Lazanda, Onsolis, Sublimaze, Subsys | |
| methadone | Dolophine | |
| meperidine | Demerol | |
| pethidine | NA | |
| remifentanil | Ultiva | |
| tapentadol | Nycynta ER | |
| tramadol (partial agonist) | Ultram | |
| 1Trade names are according to whatever I found on RXlist.com. This is not an exhaustive list of commercially available opioids. |
The few weak or partial agonists include kratom (an opiate), codeine (an opiate), buprenorphine (semisynthetic opioid), and tramadol (synthetic opioid). They are all available over the counter in many parts of the world; kratom, here in the US; codeine, mixed with acetaminophen and caffeine in Canada; and tramadol in Mexico. But they are not going to do the job for people with severe, chronic, intractable pain, especially from past trauma, or for people with severe IBD flares accompanied by vomiting and diarrhea that require IV opioids, because when you’re constantly vomiting, you can’t keep an oral medication down long enough for it to be effective. Partial agonists don’t really cut it for kidney stones, either.
Knowledge is power, and knowing what this language means is critical for chronic pain patients, people in rehab, and their advocates for the following reasons:
- Patients need to know these basics when discussing medications with their doctors. If you’re already on a full agonist, for example, and it isn’t working that well, switching to a partial agonist, or worse, a partial agonist mixed with an antagonist that’s meant to treat addiction probably isn’t going to help you. We cannot let clinicians try to snow-job us into accepting a new medication (buprenorphine and Suboxone, I’m talking about you) that won’t be as effective for our pain just because it either makes more money for the doctor, or is just easier to prescribe, politically or legally; these are not medically justified decisions and are straight up malpractice.
- It’s also critical that, when working on changing legislation, you understand these nuances so you can work toward passing laws that don’t leave out a whole class of medications.
- It’s important to understand when someone uses the word heroin to fear monger. Heroin is used in European countries, Canada and Australia medicinally. It’s a legitimate, useful medication. US law is simply behind the times, stuck in a medieval hellscape.
- Everyone needs to understand why it’s a bad idea to let people who don’t know these basics (ie, politicians, people whose kids overdosed, and cops) to make and enforce laws about using these medicines.
I hope readers find this useful. Stay tuned for other KNOW YOUR DRUGS posts about combination drugs and what I call punitive medication. Questions? Comments? Cries of anguish? Email me at ChronicPainPariah@gmail.com.
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