Opioid Receptor Agonists
Opioid receptor agonists include:
- buprenorphine (Brixadi, Subutex, Suboxone, Zubsolv, Sublocade)
- methadone (Methadose, Dolophine)
“Buprenorphine is a partial agonist of the opioid receptor. This means that it only partially turns on the opioid receptors, which are primarily located in the brain,” explains Sarah Leitz, MD, national physician lead for harm reduction and addiction medicine at Kaiser Permanente. “It also attaches really tightly to the opioid receptor, which makes it hard for other substances like heroin, fentanyl, or other opioids to knock it off. This helps an individual who is in a lot of withdrawal to start to feel better and less sick with fewer cravings to use.”
Dr. Leitz also cleared up some key differences between methadone and buprenorphine. “Methadone, in contrast to buprenorphine, fully turns on the opioid receptor, but it also is slow to onset, binds tightly, and stays attached for a long time,” Leitz says. “So, by gradually starting methadone and taking it once daily, individuals will find that their withdrawal symptoms improve and their cravings to use decrease. They also don’t get any ‘high’ or euphoria because the onset is so gradual.”
Opioid Antagonists
- naltrexone (Depade, ReVia)
Naltrexone is available in a daily pill form and as a long-lasting monthly injection, and any healthcare professional can administer it. Usually, people start taking naltrexone after completely stopping opioid use for 7 to 14 days, to prevent withdrawal symptoms, which can make it more challenging to start than methadone or buprenorphine.
“We typically recommend taking these medications for at least 6 to 12 months, but many people choose to take them for longer,” Leitz says. “Once someone has found stability with their medication and feels that their opioid use disorder is not an active part of their lives, they may want to try reducing or stopping their OUD medication.”
Centrally Acting Alpha-2 Adrenergic Agonists
“To explore a dose reduction or stopping buprenorphine or methadone, it is recommended that the individual meet with their addiction medicine prescriber and their addiction counselor and discuss a taper plan,” advises Leitz. “These taper plans can be adjusted throughout the process, but having an idea of what it might look like to start is a good idea. It is also important to set up regular check-ins to see how the taper is going.”
A typical taper involves dose changes, check-ins, and flexibility. “I like to make changes in the dose every two to four weeks and to speak with patients about every three to four weeks while they are tapering down,” Leitz says. “Often, the individual increases withdrawal symptoms or cravings for one to two weeks after a dose decrease, but that should stabilize.”
Leitz affirms that the need to slow or stop the tapering process doesn’t indicate failure. It just means that the dose needs to be adjusted to ensure success.
The goal is to prevent a relapse. The danger of a relapse, Leitz explains, is that they may have built up a high tolerance during their previous period of use that they no longer have. Tolerance means needing to take more of a substance to experience the same effect that a lower dose gave someone before.
“If a person returns to substance use, specifically with fentanyl or heroin, they may attempt to use the same amount they previously used,” says Leitz. “However, this dosage is often far too high for their tolerance level at that point. This can lead to an unintentional overdose, which can be fatal.”
Leitz emphasizes that it’s extremely important to ensure that naloxone (Narcan), a medication for treating overdoses, is always available, especially if a person has stopped medications for OUD, and that individuals returning to opioid use remember not to use alone.