Category:MAT for opioid use disorder

A medication for opioid use disorder (MOUD; the older term is "medication-assisted treatment" or MAT) is a medicine used to treat opioid use disorder, with the goal of stabilising the patient, reducing illicit-opioid use, reducing overdose mortality, and supporting recovery and social reintegration. The category is small but exceptionally consequential: three medicines (methadone, buprenorphine, extended-release naltrexone) are approved in the United States for the indication, and they are among the most-studied medicines in clinical pharmacology for any indication, with substantial mortality-reduction data that has driven a generational shift in addiction-medicine practice and a major regulatory loosening of access.

The conceptual founding event of MOUD was the 1965 study by Vincent Dole and Marie Nyswander at the Rockefeller Hospital in New York, who established the metabolic-disease model of opioid addiction and showed that daily oral methadone stabilised heroin-using patients into productive lives without ongoing illicit use.^[1] The Dole-Nyswander framework reframed opioid use disorder as a chronic medical condition treatable with daily long-term medicine, in deliberate contrast to the contemporary abstinence-based and morally framed treatment of addiction. Methadone maintenance was operationalised through the federally licensed Opioid Treatment Programmes (OTPs, originally Narcotic Treatment Programmes) that became the standard delivery model in the U.S. from 1972 onward; the daily clinic visit for observed dosing, with progressively earned take-home doses for patients in stable recovery, has remained the basic structure of methadone-based MOUD.

The transformative development of the past twenty years has been the office-based provision of buprenorphine. Buprenorphine is a partial mu-opioid receptor agonist with high receptor affinity but a ceiling on its analgesic and respiratory-depressant effects; its sublingual formulation, alone (Subutex) or combined with the abuse-deterrent naloxone (Suboxone), was approved by the U.S. FDA for office-based treatment of opioid use disorder in 2002 under the Drug Addiction Treatment Act of 2000.^[2] The DATA Act represented a substantial regulatory innovation: it permitted physicians who completed an 8-hour training course and obtained a DEA "X-waiver" to prescribe buprenorphine for opioid use disorder from a routine outpatient practice, in contrast to the OTP-restricted dispensing model of methadone. The X-waiver requirement was progressively expanded (mid-level providers including nurse practitioners and physician assistants gained the waiver in 2016; patient caps were raised; the training requirement was suspended in 2021) and was eliminated entirely in the Consolidated Appropriations Act of 2023: any practitioner with a standard DEA registration may now prescribe buprenorphine for opioid use disorder without additional waiver or training. The long-acting injectable buprenorphine formulations Sublocade (monthly subcutaneous, Indivior 2017) and Brixadi (weekly or monthly, Braeburn 2023) provide steady-state plasma concentrations for patients in whom daily sublingual dosing is difficult.

The third MOUD is extended-release naltrexone. Naltrexone is a full mu-opioid receptor antagonist; an opioid taken by a patient on naltrexone has no effect. The oral formulation (1984 for opioid use disorder; 1994 for alcohol use disorder) had limited utility because adherence was poor (the patient could simply stop taking the medicine before resuming opioid use), but the depot intramuscular naltrexone (Vivitrol, Alkermes 2010 for opioid use disorder) provides 28-day steady-state opioid receptor blockade and substantially better outcomes than oral naltrexone. Vivitrol requires complete opioid washout (7 to 14 days) before initiation, which limits its use to patients who can tolerate the washout (often inpatient or residential setting) and excludes the substantial fraction of patients who would otherwise initiate MOUD at the point of clinical contact.

The three MOUDs have different mechanism profiles and different patient-population fits. Methadone, as a full mu agonist, produces opioid effect and can be used by patients still in active opioid withdrawal; it is dispensed daily under observation in the OTP setting and requires the patient to come to the clinic every morning, which is structurally demanding but provides daily clinical contact and observed adherence. Buprenorphine, as a partial agonist with a ceiling effect, is safer in overdose (the ceiling on respiratory depression makes fatal overdose substantially harder than with methadone) and is dispensed from any DEA-registered outpatient prescriber, which has enabled rapid scale-up of access. Buprenorphine requires that the patient be in mild-to-moderate opioid withdrawal at initiation, because precipitated withdrawal occurs if buprenorphine is given to a fully opioid-saturated patient (the partial agonist displaces the full agonist from the receptor and reduces total opioid activity). Naltrexone, as a pure antagonist, prevents opioid effect but provides no agonist effect; it is best for highly motivated patients with substantial outside support and is the option that does not require interaction with the controlled-substance prescribing system.

The mortality-reduction data for MOUD are among the most robust in addiction-medicine pharmacology. Cohort studies and randomised trials show approximately 50-percent reduction in all-cause mortality in patients on methadone or buprenorphine compared to no medication, with similar effect on overdose-specific mortality. The cohort data also show that MOUD initiation in the immediate post-overdose period (in the emergency department, on hospital admission for opioid-related cause, at jail release) substantially reduces re-overdose mortality. The 2023 elimination of the X-waiver, the parallel introduction of buprenorphine vending machines and telemedicine prescribing, and the substantial expansion of harm-reduction services (naloxone distribution; supervised consumption sites in selected jurisdictions; fentanyl test strips) represent the contemporary public-health response to the opioid epidemic described under opioid analgesics and Schedule II controlled substances.

• Full mu-opioid receptor agonists:
  • Methadone (Dolophine, Methadose; daily oral; dispensed through DEA-licensed Opioid Treatment Programmes for the OUD indication)
• Partial mu-opioid receptor agonist:
  • Buprenorphine (Subutex; Suboxone with naloxone; Zubsolv; Sublocade monthly SC injection; Brixadi weekly or monthly SC injection); office-based prescribing under any DEA registration since 2023
• Mu-opioid receptor antagonists:
  • Oral naltrexone (ReVia; limited utility because of adherence)
  • Extended-release intramuscular naltrexone (Vivitrol; monthly IM; for adherent patients with complete opioid washout)
• Adjuncts and historical agents:
  • Naloxone (Narcan, Zimhi; intranasal and intramuscular formulations for opioid overdose reversal; foundational to MOUD-era community harm reduction; widely distributed since 2014 in the U.S.)
  • Lofexidine (Lucemyra), the alpha-2 agonist FDA-approved in 2018 for symptomatic management of opioid withdrawal; the related clonidine has off-label use for the same indication
  • Heroin-assisted treatment (diacetylmorphine maintenance, available in Switzerland, the Netherlands, Germany, Canada; not U.S.) is mentioned for completeness but is outside U.S. legal practice

The boundary of this category is "medicine prescribed for the chronic treatment of opioid use disorder." The medicines used for opioid overdose reversal (naloxone in its various formulations) are cross-listed under opioid antagonists separately, although naloxone is foundational to the contemporary harm-reduction infrastructure of MOUD. The medicines used for treatment of substance use disorders other than opioid (naltrexone and acamprosate and disulfiram for alcohol use disorder; bupropion and varenicline for tobacco use disorder; the absence of FDA-approved medicines for stimulant use disorder remains a current research focus) are listed under the respective substance-specific MAT pages. The medicines used in opioid withdrawal symptomatic management (clonidine, lofexidine, the antiemetics, the antidiarrhoeals, the symptomatic comfort medicines) are listed under their primary mechanism categories.

This category page is an encyclopedia article about its subject. The actual index of medicines belonging to the category is generated automatically by the wiki engine, from category-membership declarations on the individual medicine pages, and appears at the foot of the page below the references.