THREE TYPES OF OPIOID DRUG—RECEPTOR INTERACTIONS
Not all opioids are the same. There are three types of opioids that are classified by the effect that they have on the endorphin receptors. They are the full agonist, the partial agonist and the antagonist.
FULL ENDORPHIN AGONIST
As used here, an agonist is something that stimulates or produces an effect. Agonist is derived from the Late Latin agnista which means contender, which is derived from the Greek agonists which also means contestant which came from agon meaning contest. An agonist is a chemical contestant or contender.
Full agonists are drugs that bind to endorphin receptors in the brain and cause them to produce endorphins which give analgesic (pain) relief and, depending on the dose and frequency, addictive effects and feelings of euphoria. Unless an individual’s metabolism and DNA prevent it, the larger the dose of a full agonist, the more receptors are activated and the larger the effects. Examples of full agonists are oxycodone, methadone, codeine, heroin and morphine.
Partial agonists are drugs that bind primarily to endorphin opioid receptors and cause them to produce endorphins but to a much lesser extent than full agonists. Buprenorphine, Suboxone and Subutex are partial agonists. When the dosage of a full agonist is increased, the opioids will activate more receptors and create more endorphins. When the dosage of a partial agonist is increased, there is only a small increase, if any, in the production of endorphins.
COMPARING EFFECTS OF FULL AGONIST AND PARTIAL AGONIST
One way of viewing the difference between a full agonist and a partial agonist is to compare it to the operation of an elevator that requires a code that must be entered for someone to use the elevator to reach a specific floor.
Each time a person takes a full agonist it contains a code, unless significantly modified by the DNA and the way the full agonist is metabolized, which will allow the elevator to reach a certain floor. In low doses, the elevator code (number of endorphins created) may only allow the elevator to reach the second floor. However, as the full agonist dosage increases, the elevator code can now rise to higher floors and eventually to the tenth floor.
A partial agonist, like buprenorphine, will only stimulate the receptors to produce a certain amount of endorphins. Using our elevator example, when an individual takes a partial agonist in small doses it may contain a code that allows the elevator to rise to the second floor. However, no matter how much the dosage of the partial agonist increases, the code in the partial agonist will not allow the elevator to rise above the fourth floor.
This is why it is much harder to abuse a partial agonist than a full agonist, but this is also why a partial agonist like burprenorphine is very helpful as we medically detox someone from opioids.
For our purposes here, an antagonist is something that blocks an effect. Antagonist is derived from antagonize which is derived from the Greek antagonizesthal which means to struggle against, which is derived from agonizesthal which means to struggle which is derived from agon (contest).
Antagonists are drugs that bind to the same endorphin receptors but don’t stimulate the production of endorphins. What they do is occupy the receptors and prevent the receptors from being stimulated and reduce the amount of endorphins being created. This is why someone who is taking oxycodone (the active ingredient in OxyContin) to stimulate endorphin production can go into withdrawal if they take an antagonist. The antagonist blocks the receptors and does not allow the oxycodone to stimulate the receptors to produce endorphins. Naloxone and naltrexone are antagonists.
Antagonists are used in emergency rooms to try to counteract the effects of opioid overdose by causing the receptors to immediately give up the opioids.
From one of our patients:
“While at Novus through conversations with staff and counselors, I have come to realize that I have the strength to overcome my addiction to opiates. Many of the counselors related to my fears and experiences of fighting my dependency to drugs. I now feel like there is hope for a normal, sober life.”
If you want information about Suboxone or Subutex detoxification, call Novus Medical Detox Center.
Our detox advisors are available 7 days a week.