A 32-year-old man from Delhi presents to the emergency department with severe anxiety, body aches, sweating, and insomnia for the past 36 hours. He reports last using heroin 2 days ago and is now requesting immediate relief. Vital signs show: HR 110/min, BP 145/92 mmHg, RR 20/min, temperature 37.8°C. Pupil size is 4 mm bilaterally. Which of the following is the most appropriate immediate pharmacological intervention?

Explanation

## Clinical Assessment This patient presents with **opioid withdrawal syndrome** (anxiety, myalgias, diaphoresis, insomnia, tachycardia, hypertension, mydriasis) occurring 36 hours after last heroin use — consistent with the typical 8–24 hour onset in short-acting opioids. ## Why Buprenorphine Is Correct **Key Point:** Buprenorphine is the first-line agent for opioid withdrawal management in acute settings because it: - Has a **partial agonist** activity at μ-opioid receptors (vs. full agonists like methadone) - Produces a **ceiling effect** on respiratory depression, making it safer in overdose - Can be initiated **immediately** during active withdrawal without waiting for peak withdrawal (unlike methadone, which requires careful induction) - Rapidly relieves withdrawal symptoms within 30–60 minutes - Has a **long half-life** (24–72 hours), allowing once-daily or alternate-day dosing **High-Yield:** In India, buprenorphine is increasingly preferred over methadone for opioid substitution therapy (OST) due to superior safety profile and lower abuse potential. ## Mechanism of Symptom Relief Buprenorphine's partial agonism: 1. Displaces heroin from μ-receptors (higher receptor affinity) 2. Provides enough agonist activity to suppress withdrawal symptoms 3. Avoids the "high" that full agonists produce, reducing reinforcement and relapse risk **Clinical Pearl:** Buprenorphine can be safely given **even if the patient is still in early withdrawal** — it will not precipitate acute withdrawal as it is a partial agonist. Naltrexone, by contrast, would cause severe precipitated withdrawal if given now. ## Maintenance and Monitoring - Initial dose: 8 mg sublingual (as in this case) - Titrate by 2–4 mg increments every 1–3 days - Maintenance range: 8–32 mg/day (up to 32 mg in severe cases) - Counsel on: - Sublingual dissolution (not swallowing) - Avoiding concurrent benzodiazepines (respiratory risk) - Regular clinic attendance for monitoring **Mnemonic: BUPE = Buprenorphine Useful Partial agonist for Early withdrawal** [cite:Harrison 21e Ch 395; DSM-5-TR]