8.1 Approach to the Poisoned Patient: Poison Centers, Toxidromes, Decontamination & Enhanced Elimination

8.1 Approach to the Poisoned Patient: Poison Centers, Toxidromes, Decontamination & Enhanced Elimination

Poison Centers and the Emergency Medicine Pharmacist

The United States has a single national Poison Help line, 1-800-222-1222, which routes callers to their regional center. According to the 2024 National Poison Data System (NPDS) report from America's Poison Centers, 55 US poison centers handled nearly 2.1 million human exposures that year, about one every 15 seconds. Most calls from homes are managed without an ED visit, and that triage is a large part of the network's value.

Poison centers are staffed by specialists in poison information, many of them pharmacists or nurses, with medical toxicologists on call. Calls from hospitals feed NPDS, the near real-time surveillance system that detects outbreaks of adulterated drugs, new psychoactive substances and product hazards.

Consult the poison center (or the institution's toxicology service) for:

• Every intentional or unknown ingestion, especially with sustained-release products or multiple agents.
• Unfamiliar substances: plants, mushrooms, household chemicals, veterinary drugs, foreign products.
• Antidote decisions with narrow indications, such as digoxin immune fab, physostigmine, high-dose insulin, lipid emulsion or antivenom.
• Decisions about decontamination and extracorporeal removal.

The emergency medicine pharmacist adds four practical contributions at the bedside:

1. Product identification: imprint codes, formulation (immediate- vs. extended-release), salt form and concentration of liquids.
2. Worst-case dose estimation: assume every missing tablet was taken and convert to mg/kg.
3. Antidote logistics: locating stock, calculating doses and preparing infusions (stocking standards appear in Section 18.5).
4. Timeline building: time of ingestion drives nomogram use, observation periods and decontamination decisions.

Structured Initial Assessment

Stabilize the airway, breathing and circulation first. Check a point-of-care glucose in every patient with altered mental status. Give naloxone in titrated doses for suspected opioid toxicity with respiratory depression (Section 8.4). Thiamine should never delay dextrose in a hypoglycemic patient.

The history covers five questions: what (agent and formulation), how much, when, by what route, and why (intentional, accidental or recreational). Ask about every medication in the home, not only the patient's own.

Screening Tests After an Intentional Ingestion

Limits of Urine Drug Screens

Immunoassay urine drug screens rarely change emergency management and often mislead:

• Fentanyl and its analogues are not detected by the standard opiate immunoassay, which targets morphine and codeine. Methadone, buprenorphine and often oxycodone also need separate assays.
• Benzodiazepine screens frequently miss clonazepam and lorazepam.
• Amphetamine screens can be falsely positive with bupropion, labetalol, pseudoephedrine and other drugs.
• A positive result shows exposure in the past days, not intoxication now.

Toxidrome Recognition

A toxidrome is a cluster of signs that points to a drug class before results return. Skin moisture and pupil size separate the most commonly confused patterns.

Gastrointestinal Decontamination

Decontamination is a risk-benefit decision for each patient, not a routine step. Position statements from the American Academy of Clinical Toxicology (AACT) and the European Association of Poisons Centres and Clinical Toxicologists (EAPCCT) shape current practice.

Single-Dose Activated Charcoal

• Dose: 1 g/kg orally or by tube; adults usually receive 50 g.
• Timing: benefit is most likely within about 1 hour of ingestion. Later use is reasonable for delayed absorption, such as with sustained-release or anticholinergic products.
• Withhold when: the airway is unprotected or mental status is declining (aspiration risk), there is bowel obstruction or perforation, or the ingestion is a caustic or hydrocarbon.
• Binds poorly: metals such as iron and lithium, alcohols and glycols, hydrocarbons, acids and alkalis.
• Avoid cathartics: sorbitol adds no proven benefit, and repeated doses can cause dehydration and hypernatremia, especially in children.

Multiple-Dose Activated Charcoal (MDAC)

MDAC interrupts enterohepatic and enteroenteric recirculation, sometimes called "gut dialysis." The 1999 AACT/EAPCCT position statement supports it for life-threatening ingestions of carbamazepine, dapsone, phenobarbital, quinine and theophylline. After the initial dose, adults commonly receive about 25 g every 2 hours or 50 g every 4 hours. Bowel sounds must be present, and an antiemetic improves tolerance.

Whole Bowel Irrigation (WBI)

WBI pushes unabsorbed drug through the gut with polyethylene glycol electrolyte solution (PEG-ELS) by nasogastric tube until the rectal effluent is clear:

Indications are sustained-release or enteric-coated products, iron, lithium, and packets of illicit drugs (body packers). Contraindications include ileus, obstruction or perforation, GI bleeding, an unprotected airway, hemodynamic instability and intractable vomiting. A ruptured cocaine packet with severe toxicity needs surgery, not more irrigation.

Gastric Lavage and Ipecac

Gastric lavage should not be used routinely. It risks aspiration, esophageal injury and hypoxia and has not been shown to improve outcomes. Syrup of ipecac has no role: the American Academy of Pediatrics advised against keeping it at home in 2003.

Enhanced Elimination

Urinary Alkalinization

Raising urine pH traps weak acids in the tubular lumen. The main indication is salicylate poisoning; others include chlorpropamide, methotrexate and chlorophenoxy herbicides. Aim for urine pH 7.5 to 8.0 while keeping serum pH no higher than about 7.55 and replacing potassium, because hypokalemia blocks urine alkalinization (Section 8.3).

Extracorporeal Treatment (ECTR)

The EXTRIP workgroup publishes poison-specific recommendations. Drugs are good candidates when they are:

• Small (below about 500 Da for conventional dialysis; high-flux membranes clear larger molecules).
• Water-soluble with a low volume of distribution (below about 1 L/kg).
• Poorly protein-bound, or saturating their binding sites at toxic concentrations, as salicylate and valproate do.
• Slowly cleared by the body.

Classic candidates include lithium, salicylates, methanol and ethylene glycol, metformin-associated lactic acidosis, valproate, carbamazepine, phenobarbital and theophylline. Intermittent hemodialysis gives the fastest clearance; continuous therapy is a fallback when the patient cannot tolerate it. Digoxin and tricyclic antidepressants are not removed meaningfully because of high tissue binding. Section 11.4 covers drug dialyzability in more detail.

Observation and Disposition

Some products can seriously harm a toddler after one or two tablets or a small swallow: opioids including buprenorphine, sulfonylureas, calcium channel blockers, tricyclic antidepressants, clonidine, methyl salicylate (oil of wintergreen), camphor and diphenoxylate-atropine. Treat any reported pediatric exposure to these agents as potentially serious.

After an intentional overdose, medical clearance is followed by a suicide risk assessment. The Joint Commission's 2026 National Performance Goals include a dedicated goal on reducing suicide risk.