Stimulant use disorder

Background

• A substance use disorder that includes cocaine (freebase, crack rock), methamphetamine (crystal meth, meth, crystal, jib, speed, ice, tina, side), and other amphetamine-like substances

Epidemiology

• Second-most commonly used illicit substance after marijuana

Pathophysiology

• All stimulants work on the dopamine system

Stimulant	Mechanism	Half-life	Routes of administration
Cocaine	decreased dopamine re-uptake	30 to 120 minutes	smoking, snorting, or injecting
Crack cocaine			smoked, but can be mixed with an acid and injected
Freebase			may explode when smoked
Methamphetamine	reverses dopamine reuptake, leading to increased excretion	wide variability, about 10 to 30 hours	powder can be snorted or pressed into a pill; base can be swallowed or injected; crystal meth can be smoked, dissolved and injected, or snorted

Clinical Manifestations

Acute intoxication

• Common symptoms include tachycardia or bradycardia, pupillary dilatation, high or low blood pressure, sweating, chills, nausea or vomiting, weight loss, psychomotor agitation or retardation, muscular weakness, respiratory depression, chest pain, arrhythmias, confusion, seizures, dyskinesia, dystonia, and coma
• Severe intoxication may cause mania, paranoia, severe delirium, hypertension, agitation, sweating, formication and skin picking, choreoathetosis, and ataxia

Stimulant-induced psychosis

• Schizophrenia complicates about 15 to 25% of chronic stimulant use within 2 to 5 years
• Unclear what the causal relationship is between stimulants and schizophrenia

Other sequelae

• Cardiovascular or cerebrovascular disease, including myocardial infarction, stroke, and acute kidney injury
• Psychiatric diseases including psychosis, depression, and suicidal ideation
• Increased risk of HIV and hepatitis C
• Death

Withdrawal

• Symptoms include depressed mood, vivid dreams, fatigue, insomnia, hypersomnia, cravings, psychomotor agitation or impairment, increased appetite, agitation, irritability, and cognitive impairment

Investigations

Urine drug screen

• Cocaine metabolites are detectable for about 3 to 5 days
  • False positives: none
• Methamphetamines may be detectable for 3 to 5 days, with some variability
  • False positives: nasal inhalers, ADHD medications, bupropion, trazodone, chlorpromazine, promethazine, ranitidine

Management

Intoxication

• Generally focussed on supportive care

Withdrawal

• Generally focussed on supportive care, including good nutrition
• Cognitive behavioural therapy and sleep hygiene may be helpful

Chronic treatment

• There is no good evidence in favour of any pharmacologic treatment, and medication-based treatment is generally not recommended
  • N-acetylcysteine may prevent relapse
  • Disulfiram may treat cocaine use disorders
  • Modafinil may be useful
• The main focus is on psychosocial treatments, including contingency management, cognitive behavioural therapy, motivational interviewing, relapse prevention, and psychodynamic therapy
  • Long-term abstinence is around 30 to 50% for people in treatment, with 40-50% dropout rate
  • Contingency planning with or without cognitive behavioural therapy seems to be the most promising