What are the initial medication regimens and doses for an adult patient with substance use disorder, a history of mental health issues, and potential medical comorbidities?

Initial Medication Management for Substance Use Disorder

For opioid use disorder, initiate buprenorphine 4-8 mg sublingual based on withdrawal severity (COWS >8), targeting 16 mg total on day one, then prescribe 16 mg daily of buprenorphine/naloxone for ongoing treatment. 1

Opioid Use Disorder: First-Line Treatment

Confirm Patient is in Active Withdrawal

• Must wait appropriate time since last use to avoid precipitated withdrawal 1:
  • Short-acting opioids (heroin, morphine IR): >12 hours
  • Extended-release formulations (OxyContin): >24 hours
  • Methadone maintenance: >72 hours (consider methadone instead)
• Use Clinical Opiate Withdrawal Scale (COWS) to assess severity 1

Buprenorphine Induction Protocol

• If COWS <8 (mild withdrawal): No buprenorphine indicated; reassess in 1-2 hours 1
• If COWS ≥8 (moderate-severe withdrawal): Give buprenorphine 4-8 mg sublingual based on severity 1
• Reassess after 30-60 minutes and titrate to target of 16 mg total on day one 1
• Maintenance dosing: Prescribe buprenorphine/naloxone 16 mg sublingual daily 1, 2
• Instruct patients to hold medication under tongue for 5-10 minutes until dissolved 2

Alternative Opioid Use Disorder Medications

• Naltrexone: 50 mg daily oral, or 100 mg Monday/Wednesday and 150 mg Friday, or 380 mg monthly injection 1
  • Best for motivated patients who prefer not to take opioid agonist therapy 1
  • Requires baseline and periodic (every 3-6 months) liver function monitoring 1
  • Cannot be used if patient requires opioids for pain management 1
• Methadone: Refer to specialized treatment program; not typically initiated in primary care 1

Alcohol Use Disorder

Pharmacotherapy Options

• Naltrexone: 50 mg daily oral or 380 mg monthly injection 1, 3
  • Most effective anticraving agent for alcohol use disorder in patients with severe mental illness 3
  • Monitor liver function at baseline and every 3-6 months 1

Tobacco/Nicotine Use Disorder

Medication Options

• Varenicline: Shows promise in patients with severe mental illness who smoke 3
• Bupropion: Effective for tobacco cessation in adolescents and young adults 4

Benzodiazepine Use Disorder

Critical Management Considerations

• Refer to specialist when possible due to risks of tapering including seizures, increased anxiety/depression, and altered mental status 1
• Avoid abrupt discontinuation 1

Stimulant Use Disorder (Cocaine, Methamphetamine)

Current Evidence

• No pharmacologic treatment can be recommended for primary care setting 1
• Behavioral therapies are the mainstay of treatment 1

Co-occurring Mental Health Disorders

Integrated Treatment Approach

• Treat both conditions simultaneously with integrated treatment plans, which is consistently superior to treating disorders separately 5
• For schizophrenia with substance use disorder: Clozapine is more efficacious than other antipsychotics 3
• For bipolar disorder with substance use disorder: Valproate remains treatment of choice; lithium and quetiapine may not be effective 3

Antidepressant Considerations

• Initial dosing for tricyclics 1:
  • Desipramine: 10-25 mg morning, maximum 150 mg (activating, reduces apathy)
  • Nortriptyline: 10 mg bedtime, maximum 40 mg daily (more sedating, useful for agitated depression)
• SSRIs 1:
  • Fluoxetine: 10 mg every other morning, maximum 20 mg daily
  • Paroxetine: 10 mg daily, maximum 40 mg daily
• Allow 4-8 weeks for full therapeutic trial 1

Essential Harm Reduction Measures

Universal Interventions

• Provide naloxone kit for overdose prevention 1
• Screen for hepatitis C and HIV 1
• Offer reproductive health counseling 1

Critical Pitfalls to Avoid

• Never give buprenorphine to patients not in active withdrawal - high binding affinity causes precipitated withdrawal 1
• Exercise extreme caution transitioning from methadone to buprenorphine - risk of severe, prolonged precipitated withdrawal 1
• Do not use naltrexone in patients requiring opioid pain management - blocks analgesic effects 1
• Avoid benzodiazepines for anxiety in substance use disorder patients - risk of tolerance, addiction, and cognitive impairment 1
• Screen for substance use disorder before prescribing long-term opioids for chronic pain, as these patients receive higher doses and are at increased risk 6

Follow-up and Monitoring

• Combine all pharmacotherapy with counseling and behavioral therapies - medication alone is insufficient 2, 1
• Arrange follow-up within 3-7 days of buprenorphine initiation 1
• Monitor for treatment adherence and consider long-acting injectable formulations if adherence is uncertain 1