methadone include the patient's opioid tolerance, the time since last opioid use, the type of opioid used (long-acting vs. short-acting), and the risk of methadone toxicity.Methadone is a full-opioid agonist used for both opioid overuse treatment and for chronic pain. It is the most commonly prescribed medication for addiction. Methadone comes in a different forms: tablet, oral solution, or an injection. One of methadone's benefits is that it can last up to 56 hours in the body, so if a patient misses one of their daily doses (~24 hrs.), they will not typically struggle with withdrawal symptoms. Other advantages of methadone include reduction in infectious disease related to injection drug use and reduced mortality. When patients taking MAT improve and want to refrain from taking methadone, they must be properly weaned off the medication, which must be done under medical observation. Methadone has a number of serious side effects, including slowed breathing, nausea, vomiting, restlessness, and headache. Dosages can be adjusted after 1–2 days, or another medication may be recommended for your situation if you experience side effects. Lung and breathing complications are possible long-term side effects of methadone use. Methadone, as an opiate, has the potential to be addictive. Many opponents believe that replacement drugs only substitute one addiction with another, and that methadone can be manipulated and exploited in some cases. BuprenorphineImportant considerations when initiating buprenorphine include withdrawal symptom severity, the time since last opioid use, and the type of opioid used (long-acting vs. short-acting). Initiating buprenorphine too soon can lead to rapidly-triggered withdrawal symptoms (i.e., precipitated withdrawal). This is because buprenorphine has a high affinity for opioid receptors and is only a partial opioid agonist, meaning that as buprenorphine displaces full opioid agonists, a much weaker analgesic and euphoric effect is produced.Buprenorphine is a partial opioid receptor agonist. Unlike methadone and other full opioid receptor agonists, buprenorphine is less likely to cause respiratory depression due to its ceiling effect. This is because buprenorphine's effects do not increase linearly past moderate doses. Buprenorphine is known to be more at a risk of misuse or overdose compared to buprenorphine-naloxone and methadone, but treatment with buprenorphine may be associated with reduced mortality. Buprenorphine under the tongue is often used to manage opioid dependence. Preparations were approved for this use in the United States in 2002. A month-long injectable version of buprenorphine was approved by the FDA in 2017. Buprenorphine/NaloxoneImportant considerations