What are the mechanisms and treatment options for illicit drug use?

Mechanisms and Treatment Options for Illicit Drug Use

Substance use disorders are biopsychosocial conditions requiring comprehensive treatment that addresses both the underlying brain disease and behavioral/social components to effectively reduce morbidity and mortality.1

Mechanisms of Illicit Drug Use

Neurobiological Mechanisms

• Addiction involves changes in brain structure and function, particularly in reward pathways

• Drug users select substances with specific pharmacokinetic characteristics that increase positive reinforcement 2:

  • Rapid absorption
  • Rapid entry into central nervous system
  • High bioavailability
  • Short half-life
  • Small volume of distribution
  • High free drug clearance

• Routes of administration are chosen to optimize drug delivery to the brain:

  • Inhalation/smoking: Most rapid delivery to brain
  • Intravenous injection: Maximizes bioavailability
  • Each route carries specific risks (infection, mucosal damage, carcinogenesis)

Biopsychosocial Model

• The American Society of Addiction Medicine recognizes addiction as more than just a brain disease 1

• Key components include:

  • Genetic predisposition interacting with social exposure
  • Environmental factors (drug availability, social cues)
  • Psychological factors (coping mechanisms, mental health)

• Avoidant coping strategies are strongly associated with continued drug use in treatment populations 3

• Depression is a significant comorbidity that affects treatment outcomes 3

Diagnostic Criteria for Substance Use Disorders

According to DSM-5 criteria, substance dependence includes 1, 4:

1. Using more substance than intended
2. Inability to reduce use
3. Significant time spent seeking substances
4. Physical effects of use
5. Substance use replacing other activities
6. Continued use despite problems
7. Tolerance
8. Withdrawal symptoms
9. Use to avoid withdrawal symptoms

Treatment Options

Medication-Assisted Treatment

• Opioid Use Disorders:

  • Methadone: Long-acting opioid agonist that reduces withdrawal and cravings 5
  • Buprenorphine: Partial opioid agonist with lower overdose risk
  • Naltrexone: Opioid antagonist that blocks euphoric effects

• Alcohol Use Disorders:

  • FDA-approved medications include disulfiram, acamprosate, and naltrexone 1

• Stimulant and Cannabis Use Disorders:

  • No FDA-approved medications specifically for these disorders 4
  • Treatment relies primarily on behavioral interventions

Behavioral Interventions

• Evidence-based approaches 1:

  • Cognitive-behavioral therapy (including relapse prevention)
  • Motivational interviewing
  • Community reinforcement approaches
  • Contingency management

• Patients who achieve abstinence show decreased use of avoidant coping strategies 3

Screening and Brief Interventions

• SBIRT (Screening, Brief Intervention, Referral, and Treatment) is effective in primary care settings 1
• Goals of SBIRT:
  1. Encourage healthcare providers to screen and provide brief advice
  2. Reduce vulnerability to negative consequences
  3. Improve linkages between general healthcare and specialized treatment

Community-Based Approaches

• Peer outreach programs are effective for reaching individuals not ready for treatment 1
• Drug courts offer treatment alternatives to incarceration 1

Special Considerations

Mortality Risk

• Standardized mortality ratios vary by substance 6:

  • Cannabis: 4.9
  • Cocaine: 6.4
  • Amphetamine: 6.0
  • Heroin: 9.1
  • Other opioids: 7.7

• Injection drug use significantly increases mortality risk, particularly for opioid and stimulant users 6

Medical Complications

• Cardiovascular events including stroke are associated with many illicit drugs 7
• Opioid overdose deaths have increased 200% since 2000 1
• Drug interactions are common, particularly pharmacodynamic interactions affecting the CNS 2

Treatment Access Challenges

• Only about 18% of those needing treatment receive any form of intervention 1
• In prison populations, where substance use disorders affect approximately 65% of inmates, only about 11% receive professional treatment 1

Treatment Algorithm

1. Assessment:

   • Determine primary substance(s) of use
   • Evaluate for polysubstance use
   • Screen for psychiatric comorbidities (particularly depression)
   • Assess injection drug use status

2. Intervention Selection:

   • For opioid use disorders: Initiate medication-assisted treatment with methadone, buprenorphine, or naltrexone
   • For stimulant or cannabis use disorders: Focus on behavioral interventions
   • For all patients: Implement appropriate behavioral therapy (CBT, motivational interviewing)

3. Monitoring:

   • Regular toxicology screening
   • Assessment of coping strategies
   • Monitoring for depression and other psychiatric symptoms
   • Evaluation of cardiovascular health, particularly in stimulant users

4. Adjustments:

   • Intensify treatment for those showing continued use
   • Address avoidant coping strategies specifically
   • Treat comorbid psychiatric conditions

Pitfalls to Avoid

• Focusing solely on the neurobiological aspects while ignoring social and behavioral components 1
• Inadequate treatment of comorbid psychiatric conditions, especially depression 3
• Failing to address injection drug use, which significantly increases mortality risk 6
• Overlooking potential drug interactions between illicit substances and prescribed medications 2
• Discharging patients from treatment programs for continued use rather than intensifying treatment