Substance Use Disorders

BASICS

Definition: Any pattern of substance use causing significant physical, mental, or social dysfunction.
Substances of abuse:
Alcohol
Cannabis (marijuana, hashish, oil, extracts)
Club drugs: MDMA, PMMA, GHB, flunitrazepam
Dissociative drugs: ketamine, PCP, TCP
Hallucinogens: LSD, salvia, DMT, ayahuasca
Inhalants: glue, paint thinners, nitrous oxide
Opioids: fentanyl, heroin, kratom, Krokodil, carfentanil, U-47700
Prescription meds: barbiturates, benzodiazepines, hypnotics, stimulants, dextromethorphan
Stimulants: amphetamines, cocaine, methamphetamine, khat
Synthetics: synthetic cannabinoids (Spice, K2), synthetic cathinones ("bath salts", Flakka)
Tobacco

Prevalence:
61.2 million (21.9%) Americans reported illicit drug use in 2021
14.1% of 12–17-year-olds; 38% of 18–25-year-olds
35.4% young adults used marijuana in past year
ALERT:
Opioid overdose is leading cause of death in ages 26–38 in the US; >82% from synthetic opioids
Xylazine-mixed synthetic opioids: not reversed by naloxone
Many states require naloxone prescription for patients at overdose risk (≥50 morphine mg equivalents/day, co-prescribed benzos, history of substance abuse)

Neurobiology: Substances affect dopamine & other neurotransmitter receptors; genetics influence susceptibility.
Risk Factors:
Academic problems, dropout
Criminal involvement
Depression, anxiety
Family dysfunction/trauma, family history
Peer/family use or approval
Unemployment, low SES

DSM-5-TR Substance Use Disorder: ≥2 of below in past year (severity by # criteria):
Use > intended
Failed attempts to quit
Time spent obtaining/using/recovering
Craving
Failed obligations
Continued use despite social/interpersonal problems
Interference with activities
Use in hazardous situations
Continued use despite health problems
Tolerance
Withdrawal

Psychiatric: anxiety, depression, psychosis
Frequent ER visits, blackouts, mood swings, insomnia
Chronic pain, repeated trauma, infections (endocarditis, hepatitis, HIV, TB, STI, pneumonia)
Incarceration, social/occupational problems

Metabolic delirium (hypoxia, hypoglycemia, infection, thiamine deficiency, thyroid disorders, toxicity)
Mood, anxiety, personality disorders

USPSTF: Screen all adults ≥18 yrs if diagnosis/treatment is available.
Screening tools:
Single-question screen: "How many times in the past year have you used an illegal drug or used a prescription medication for nonmedical reasons?"
Substance Use Brief Screen (SUBS)
CRAFFT (teens): Car, Relax, Alone, Forget, Family/Friends, Trouble
S2BI, BSTAD (adolescents)
Labs:
Blood alcohol
Urine drug screen (note: may miss synthetics)
HIV, hepatitis B/C
LFTs
Detection times (approximate):
Alcohol: 6–10 hrs; cocaine: 2–3 days; marijuana: 1–7 days (chronic: up to 1 month); opioids: 1–3 days; others as per substance

General: Combine pharmacotherapy & behavioral therapy (CBT or other evidence-based modalities)
Motivational interviewing and brief intervention can promote change.
Community reinforcement: Self-help (AA, NA), support groups for family

Benzodiazepine/barbiturate withdrawal: Gradual taper, consider long-acting agents (clonazepam, phenobarbital)
Opioid dependence:
Buprenorphine: 8–24 mg SL daily (SC monthly or 6-month implant forms available)
Buprenorphine/naloxone: 2/0.5 mg to 16/4 mg SL daily
Methadone: 10–40 mg PO/day (inpatient/licensed clinics only)
Naltrexone: 50 mg PO daily (must be opioid-free ≥7–10 days), or 380 mg IM q4wks
Naloxone: 0.4–2 mg IV/IM/SC, repeat q2–3min as needed (intranasal 4–8 mg)
Opioid withdrawal adjuncts: Clonidine 0.1–0.2 mg PO BID/TID, tramadol ER (off-label), antiemetics, nonaddictive analgesics
Mental health: Antidepressants, mood stabilizers, nonhabituating anxiolytics as indicated
Contraindications/precautions:
Buprenorphine: avoid in breastfeeding/hepatic impairment
Methadone: hepatic impairment
Naltrexone: pregnancy, breastfeeding, hepatic impairment
Clonidine: hypotension risk

Indications: severe withdrawal, mental status change, threat of harm, monitoring obstacles, comorbid illness, pregnancy
Monitor for infections (endocarditis, etc.)
Discharge when detox complete & rehab plan in place

F18.951: Inhalant use, unspecified with inhalant-induced psychotic disorder with hallucinations
F11.120: Opioid abuse with intoxication, uncomplicated
F17.201: Nicotine dependence, unspecified, in remission

Substance use disorders are prevalent, serious, and frequently underdiagnosed.
Comorbid psychiatric disorders are common.
Dysfunction in family, work, social, legal, or physical domains distinguishes substance abuse.
Dependence: tolerance, withdrawal, compulsive/repeated use.
Combined CBT and pharmacotherapy is best practice.
Refer opioid-dependent patients to an addiction specialist or certified program.