What’s the Difference Between Opioids and Opiates?
The terms “opioid” and “opiate” are often used interchangeably to describe the entire class of pain-relieving drugs that bind to opioid receptors, whether they’re natural, synthetic or semi-synthetic.
In medical circles, “opioid” traditionally refers to the synthetic and semi-synthetic drugs in this class, while “opiate” traditionally refers to opium alkaloids, or the natural derivatives. But according to The National Alliance of Advocates for Buprenorphine Treatment, the term “opioid” has recently come to apply to all opioids and opiates. The National Institute on Drug Abuse also classifies all of the drugs that act on opiate receptors as “opioids,” regardless of how they’re produced.
Four Classes of Opioids
Using the term “opioid” to mean any of the drugs that bind to opioid receptors, there are four classes of opioids:
- Endogenous opioids, which are produced by the body
- Opium alkaloids, or natural opiates, which include codeine and morphine
- Semi-synthetic opioids, which include hydrocodone, oxycodone and buprenorphine
- Fully synthetic opioids, which include Fentanyl, methadone and naloxone.
Opioids are prescribed for mild to severe pain. When they attach to the opioid receptors in the body, they send signals to the brain to reduce the severity of the pain. They also slow breathing, produce a sense of calm and well-being and often have euphoric effects.
Different Ways to Categorize Opioids
Opioids can be categorized in a number of ways. They can be classified based on their typical use, such as anesthesia (Fentanyl), treating severe pain (morphine), treating moderate or chronic pain (hydromorphone), treating mild pain or cough (codeine) and treating diarrhea (loperamide).
An opioid can also be categorized based on how it interacts with opioid receptors. In this case, the classifications are full agonist, partial agonist or antagonist.
Agonist opioids fully activate the opioid receptors and produce the full opioid effect. Agonists include heroin, oxycodone, methadone and morphine.
Partial agonist opioids activate the opioid receptors, but to a much lesser degree than full agonists, producing far weaker effects. Partial agonists include buprenorphine, which is used to treat an addiction to opioids by staving off cravings and withdrawal symptoms without producing the intense effects of drugs like heroin and oxycodone.
Antagonist opioids attach to the opioid receptors without activating them. These drugs don’t cause any opioid effects, and they block agonist opioids from attaching to the receptors. Naltrexone and naloxone are both antagonists. Naloxone can be used to reverse a heroin overdose, and it’s available to the general public by prescription as a hand-held, single-use injector known as Evzio. When it’s injected into muscle, it reverses the action of the agonist opioid on the receptor to restore respiratory function until medical personnel arrive.
Opioids are highly addictive due to their extremely euphoric effects, and dependence can develop in a short period of time due to the fact that opioids produce a high degree of tolerance very quickly. This means that as the brain changes the way it functions in order to compensate for the presence of the opioid, increasingly higher doses are needed to get the desired effects.
Over time, a shift in brain function and structure may occur, and the brain will begin to operate more “normally” when the opioid is in the system than when it’s not. As a result, withdrawal symptoms will set in when the drug use is discontinued. These symptoms can be excruciating, and withdrawal typically requires a medical detox program that uses various medications as needed to relieve the intensity of symptoms and reduce the duration of the detox process.