Yes, Suboxone blocks methadone.
Methadone and Suboxone are both opioid medications. Methadone is a full opioid agonist, meaning it fully activates opioid receptors. Suboxone is a partial opioid agonist, so it partially turns opioid receptors on.
However, “agonism” is a slightly different concept than “receptor affinity.” Receptor affinity refers to how tightly a drug binds to a receptor. Even though methadone “turns on” opioid receptors more than Suboxone, Suboxone actually binds “more tightly” to opioid receptors.
If Suboxone enters the body after methadone, it abruptly “kicks methadone off” the opioid receptors and binds instead. This leads to immediate less agonism of the opioid receptors which causes withdrawal symptoms.
Methadone and Suboxone can both prevent opioid withdrawal, but should not be used together for the reasons described above. If a person is switching from methadone to Suboxone, we usually recommend two days off of methadone prior to starting Suboxone to ensure that Suboxone does not “kick” any methadone off the body’s receptors and cause withdrawal.
If you are considering a switch from Suboxone to methadone or vice versa, talk to your doctor about the best way to proceed.