Opioid Withdrawal Syndrome

Timeline runs off the half-life - Heroin withdrawal can start as little as five hours after the last dose; methadone may take two to three days. Symptoms last roughly three to ten days depending on the drug, and a protracted abstinence syndrome can run for weeks.

Score it, don't eyeball it - The Clinical Opiate Withdrawal Scale (COWS) is an 11-item scale scored 0 to 47: mild 5 to 12, moderate 13 to 24, moderately severe 25 to 36, severe above 37. Use it to document severity and to decide whether buprenorphine is safe to give.

Precipitated withdrawal is the one you cause - Buprenorphine is a high-affinity partial agonist. Give it to a dependent patient who is not already withdrawing and it displaces the full agonist, swaps full receptor activation for partial, and produces sudden severe withdrawal. It has to wait 12 to 18 hours after the last short-acting agonist such as heroin or oxycodone, and 24 to 48 hours after a long-acting agonist such as methadone. Transitioning from methadone, taper below 30 mg and wait at least 72 hours; after a fentanyl patch, wait 48 to 72 hours.

Antagonists do it faster - Naloxone and naltrexone strip the receptor outright. Naltrexone produces dysphoria, irritability, tachycardia, tremor, and sweating, and patients transitioning off buprenorphine or methadone onto it stay at risk for roughly 14 days. Injected buprenorphine/naloxone precipitates withdrawal too, because the naloxone that is inert sublingually is fully active IV.

Titrate naloxone - In a known opioid-dependent patient, 0.04 to 0.1 mg IV, aiming for respiratory drive rather than full reversal. A fully reversed dependent patient wakes up combative.

Treatment is replacement plus an alpha-2 - Methadone 10 mg PO or IV, repeatable every 4 to 6 hours while withdrawal persists; patients rarely need more than 40 mg in 24 hours. Sublingual buprenorphine 4 to 12 mg is the alternative once the timing window above has passed. Clonidine blunts the noradrenergic surge, and lofexidine, an alpha-2 agonist FDA-approved in 2018 for acute opioid discontinuation, can be used up to 14 days.

Symptomatic cover is worth the effort - Loperamide for diarrhea, promethazine for nausea and vomiting, ibuprofen for myalgia. Cheap, and the difference between a cooperative patient and an emergency you have to sedate.

Sort it from the other withdrawals - Sedative-hypnotic withdrawal looks similar but lacks lacrimation, rhinorrhea, and mydriasis, and it is the one that seizes. Hallucinogen and stimulant intoxication cause mydriasis without the nausea, vomiting, diarrhea, and rhinorrhea. Send a urine toxicology screen: most opioids are detectable for 12 to 36 hours, but methadone, buprenorphine, and LAAM will not show on a standard opiate panel and have to be ordered specifically.

Baseline labs before induction - ECG, CBC, blood alcohol level, and a basic metabolic panel are the standard workup. Vomiting and diarrhea leave these patients volume-depleted and electrolyte-deranged before you ever start.

Chronic mu stimulation suppresses endogenous endorphin production and drives adenylyl cyclase superactivation. Remove the exogenous opioid, by cessation or by giving a partial agonist or an antagonist, and the counter-regulatory machinery runs unopposed. The locus coeruleus at the base of the brain is the principal trigger site: its noradrenergic neurons carry a high density of opioid receptors and supply most of the noradrenergic innervation to the limbic system and cortex. Gray matter and the nucleus raphe magnus contribute.

What follows is a noradrenergic surge. Lacrimation, rhinorrhea, piloerection, myalgia, diarrhea, nausea and vomiting, mydriasis, photophobia, insomnia, yawning, and autonomic hyperactivity with tachypnea, hyperreflexia, tachycardia, sweating, hypertension, and hyperthermia. Fatalities are rare in an otherwise healthy adult, but it destabilizes hemodynamics and volume status and will derail an anesthetic.