Clinical meaning
Advanced pharmacotherapy for substance use disorders involves complex clinical decision-making around medication selection, induction protocols, maintenance strategies, and management of treatment-resistant cases. Opioid agonist therapy (OAT) represents the most clinically complex pharmacotherapy: Buprenorphine microdosing (Bernese method) allows induction WHILE the patient continues full agonist use, avoiding the need for withdrawal before starting treatment. The protocol involves escalating low doses of buprenorphine (0.5 mg → 1 mg → 2 mg → 4 mg over days) while gradually discontinuing the full agonist. This avoids precipitated withdrawal by slowly occupying receptors without abruptly displacing the full agonist. Extended-release injectable buprenorphine (Sublocade) provides monthly subcutaneous depot injection (300 mg × 2 months, then 100 mg monthly), eliminating daily dosing and reducing diversion risk. Methadone pharmacology: full mu-agonist + NMDA receptor antagonist + serotonin/NE reuptake inhibitor; highly effective but requires observed daily dosing at federally licensed OTPs; long and variable half-life (15-60 hours) creates risk of accumulation and delayed respiratory depression, especially during induction (deaths cluster in the first 2 weeks). Naltrexone extended-release (Vivitrol) 380 mg IM monthly: complete opioid blockade; requires 7-10 days opioid-free; poor retention compared to buprenorphine/methadone but effective for motivated patients. For alcohol use disorder: naltrexone targets the opioid-mediated reinforcing effects of alcohol; the Sinclair method (taking naltrexone before drinking, not daily) uses pharmacological extinction to reduce craving over time. Gabapentin (off-label) at 900-1800 mg/day shows promise for AUD, particularly in patients with anxiety and insomnia. For stimulant use disorder: no FDA-approved medications, but mirtazapine, topiramate, and stimulant replacement (dextroamphetamine) are being studied; contingency management remains the most effective intervention.