History

•  Timing, quantity of ingestion/exposure, access to household chemicals/other meds, coingestions, enteric-coated/extended-release substances

Physical Exam

•  VS, pupils, skin, neuro findings (AMS, nystagmus, myoclonus, tremor), peristalsis, smell

Evaluation

•  ECG, FSG, CBC, chemistries, LFT’s, UA, ABG, hCG, osmolar/anion gap

•  Drug levels

•  Exposures for which drug level is useful: APAP, salicylates, theophylline, lithium, digoxin, EtOH, carboxyhemoglobin, methemoglobin, iron, methanol, ethylene glycol, lead, mercury, arsenic, organophosphate, anticonvulsants

Treatment

Dermal Decontamination

•  Irrigation w/ copious volumes of H₂O (unless metallic Na, K, or phosphorus)

Ocular Decontamination

•  Irrigation w/ copious volumes of H₂O

Enhanced Elimination

•  Urinary alkalinization w/ NaHCO₃ (eg, salicylates, phenobarbital, formic acid)

•  HD (eg, ethylene glycol, methanol, lithium, salicylates)

Disposition

•  Admit for any significant ingestion/exposure; consider transfer for complex presentations & inadequate hospital resources

Pearl

•  Hospital tox screens vary → learn your hospital’s screen to guide your practice

ANTICHOLINERGIC INGESTION

Definition

•  Antagonists @ muscarinic cholinergic receptor → inhibit parasymp system

History

•  Blurred vision, dry mouth, fever, AMS, flushing; “blind as a bat, dry as a bone, hot as a hare, mad as a hatter, red as a beet”

Differential

•  Sympathomimetic OD, EtOH/benzo withdrawal, thyroid storm, sepsis/meningitis

Findings

•  ↑ HR, ↑ temp, dilated pupils, dry MM/skin, ↓ bowel sounds, urinary retention, myotonic activity, choreoathetosis, confusion/delirium, szs

Evaluation

•  ECG (≠ QT_c Æ TCAs, neuroleptics); electrolytes; total CK (rhabdomyolysis); tox screen → r/o other ingestions; pulse ox; Tele

Treatment

•  Supportive: IV hydration, external cooling

•  Decontamination/elimination: Activated charcoal (1 dose, w/in 1–2 h), HD

•  BZD (IV): For agitation, szs

•  Physostigmine (IV): Reverses anticholinergic effects via acetylcholinesterase inhibition

•  NOT for routine use due to risk of intractable szs, AV block, asystole

Disposition

•  Admit; ICU for pts w/ cardiac instability or szs

Pearl

•  Rarely fatal unless significant hyperthermia is present

PSYCHOPHARMACOLOGIC INGESTION

Selective Serotonin Reuptake Inhibitors and Serotonin Syndrome

Approach

•  Spectrum for serotonin intoxication ranges from mild lethargy to serotonin syndrome

•  Consider serotonin syndrome for anyone on meds w/ serotonin activity, esp ≥2 agents

•  Greatest risk w/i min, h after starting new med or increasing dose of old med

Definition

•  SSRI: Selective serotonin reuptake inhibitors; SRIs: Serotonin reuptake inhibitors (also activity on epinephrine, norepinephrine, dopamine)

History

•  Akathisia, AMS, szs

Findings

•  ↑ HR, ↑ temp, ↑ reflexes, diaphoresis, mydriasis, ↑ ↓ BP, tremor, clonus, neuromuscular rigidity, ataxia

Evaluation

•  VS, CBC, chem 7, CK (rhabdo), ECG (↑ QRS, ↑ QT_c, torsades), pulse ox, Tele

Treatment

Acute overdose

•  Activated charcoal, admit for monitoring

Serotonin Syndrome

•  Supportive: IV fluids, electrolyte correction, external cooling (may require sedation/paralysis for severe hypothermia)

•  Benzos (IV): For agitation, rigidity, szs

•  (Anecdotal evidence) Cyproheptadine (12 mg initially, 4 mg PO q1h), chlorpromazine 25–50 mg IV for severe sxs

Pearl

NEUROLEPTICS, NEUROLEPTIC MALIGNANT SYNDROME

Definition

•  Characterized by D₂ antagonism ± serotonin receptor antagonism

History

•  Slurred speech, sedation, anticholinergic toxidrome, extrapyramidal sxs (dystonia, akathisia, parkinsonism, tardive dyskinesia)

•  NMS: ↑ HR, rigidity, AMS, szs, autonomic instability, metabolic acidosis, rhabdomyolysis

Evaluation

•  CBC, chem 20, CK (rhabdo), ECG (↑QT_c, torsades), UA (myoglobin)

Treatment

•  Dystonia/akathisia: Diphenhydramine, benztropine, BZD

•  NMS: Cooling, IV fluids, benzos, nondepolarizing neuromuscular blockade, dantrolene, bromocriptine, amantadine

LITHIUM

History

•  Acute tox: GI sxs initially; neurologic findings may develop later

•  Chronic tox: Neurologic sxs

Evaluation

•  VS, ECG, CBC, chem7, Ca, Mg, PO4, TSH, free T4, UA

•  Lithium level: Not useful in acute ingestion (development of neurologic sx is better reflection of tox); in chronic tox, level >1.5 mEq is significant

•  Assess for causes of decreased lithium clearance: Eg, dehydration, renal failure

Treatment

•  IV fluids: Decreases tox & promotes Li excretion, NS bolus then ½ NS

•  GI decontamination: Activated charcoal ineffective, whole bowel irrigation may be useful

•  Sodium polystyrene sulfonate (Kayexalate), consider thiazides, indomethacin, or amiloride for nephrogenic DI

•  BZD for szs (avoid phenytoin, which ↓ Li renal excretion)

•  HD: For pts w/ severe neurologic sxs &/or clinical deterioration

Disposition

•  Admit all pts w/ sustained release ingestions, lithium level >1.5 mEq, or new neurologic signs; lesser ingestions can be treated & observed 4–6 h → re√ level ± psychiatry eval

Pearl

•  Li has narrow therapeutic window; consider Li tox in pts w/ ARF/↓ UOP

TRICYCLIC ANTIDEPRESSANTS

Approach

•  Sxs of overdose almost always occur w/in 6 h of ingestion

Evaluation

•  ECG, CBC, chem 7, Ca/Mg/PO4, CK, UA tox screen, pulse ox, Tele

Treatment

•  Supportive: IV fluids

•  GI decontamination/elimination: Activated charcoal ± gastric lavage, intralipid for clomipramine

•  Sodium bicarbonate: 1–2 mEq/kg boluses titrated to pH 7.45–7.55

•  Indications: QRS >100, new RAD, ↓ BP, &/or ventricular dysrhythmia

•  BZD: For szs

•  Lidocaine: For ventricular dysrhythmias refractory to NaHCO_3, avoid procainamide or other type Ia or Ic antiarrhythmics

Disposition

•  Admit all pts w/ e/o cardiotoxicity or sz; d/c pts w/o sxs at 6 h after ingestion

Pearl

•  Antimuscarinic effects are absent in many cases of TCA overdose

ALCOHOLS

Definition

•  Ingestions of toxic alcohols

Approach

•  History

•  Type of alcohol ingested, time of ingestion, coingestants

•  PE: Monitor for airway protection, occult trauma (head injury)

•  Labs: Bedside glucose test (may be all that’s needed), BAL (declines 20 mg/dL/h), anion gap, serum/urine tox screen (if coingestants suspected), osmolar gap for alcohols other than EtOH

•  Osmol calc = 2 × Na + BUN/2.8 + glucose/18 + EtOH/4.6

•  Osmol gap = Osmol measured − osmol calc

•  Tx: Charcoal doesn’t bind alcohol, ± thiamine/folate

ETHANOL

History

•  EtOH ingestion, found down, lethargy, nausea, vomiting, ± associated trauma, ± aspiration, gastritis

Physical Findings

•  CNS, respiratory depression, slurred speech, ataxia, nystagmus

Evaluation

•  Bedside glucose (hypoglycemia common in alcoholics), ± BAL (if ingestion uncertain), ± CBC/BMP/LFTs/lipase, ± ECG (if pulse if irregular), ± magnesium level

Treatment

•  Maintain airway, serial exams, ± IVF/thiamine/folate (given but may not be necessary)

Disposition

•  Ambulating w/o ataxia + speaking clearly → d/c

Pearls

•  R/o head trauma, CNS infection, Wernicke encephalopathy, alcoholic ketoacidosis, hypoglycemia, alcohol withdrawal/DT, coingestions, SI/HI

•  Known EtOH ingestion/intoxication in pt w/ h/o same does not require lab & can be observed until clinically sober

METHANOL

Definition

•  Ingestion of methanol (peak levels 30–60 min, 24–30 h ½ life, hepatic metabolism)

History

•  Drinking: Paint solvents/antifreeze/windshield-washing fluid/canned fuels/gasoline additives, shellac/copy machine fluid/home heating fuels

Physical Findings

•  CNS depression, vomiting, papilledema/hyperemia, visual changes/loss, gastritis

Evaluation

•  ↑ Methanol level, ↑ Osmol gap, ↑ anion gap (profound), chemistries, ABG

Treatment

•  Based presumptive Dx if levels delayed, maintain airway

•  Fomepizole: Loading dose (15 mg/kg in 100 mL D₅W over 30 min) → maintenance (10 mg/kg q12h × 4 doses → 15 mg/kg q12 to methanol concentration <20/dL)

•  Folate 50 mg IV q4h until resolution of acidemia (cofactor to convert formic acid → CO₂ + H₂O)

•  Dialysis: Absolute indications → visual impairment + detectible methanol level or >50 mL/dL, osmol gap >10, ingestion >1 mg/kg, severe acidosis, renal failure

Disposition

•  Admit

ETHYLENE GLYCOL

Definition

•  Ingestion of ethylene glycol (peak levels 30–180 min, 3–7 h ½ life, 70% hepatic metabolism)

History

•  Drinking: Antifreeze, coolants, paint, polishes, detergents, fire extinguishers

Physical Findings

•  3 phases: <12 h → ↓ CNS (like EtOH), gastritis; 12–24 h → ↑ HR/RR/BP/SOB; >12 h → ATN (oxylate crystal deposition)

Evaluation

•  Ethylene glycol level, ↑ osmol gap, ↑ AG, calcium oxylate crystals in urine, beta-hydroxybutyrate (used to distinguish from alcoholic ketoacidosis)

Treatment

•  Based presumptive Dx if levels delayed, maintain airway

•  Fomepizole: Loading dose (15 mg/kg in 100 mL D₅W over 30 min) → maintenance (10 mg/kg q12h × 4 doses → 15 mg/kg q12h to methanol concentration <20/dL)

•  Folate/thiamine 100 mg IV q6h/pyridoxine 50 mg IV q6h until resolution of acidemia (cofactors in oxalic acid metabolism)

•  HD: Severe acidosis (pH <7.25) + osmol gap >10, renal failure (Cr >1.2 mg/dL), ethylene glycol level >50 mg/dL, deterioration despite supportive care

Disposition

•  Admit

Clinical Pearl

•  Urine/gastric contents fluorescence w/ Woods lamp due to antifreeze additives (early)

ISOPROPYL ALCOHOL

Definition

•  Ingestion of isopropyl alcohol (peak levels 30–180 min, 3–7 h ½ life, 80% hepatic metabolism, lethal dose 2–4 mL/kg)

History

•  Drinking: Rubbing alcohol, paint thinner, solvents, skin/hair products, nail polish remover

Physical Findings

•  Profound ↓ CNS (2–4 × EtOH), fruity odor on breath, respiratory depression, ↓ BP, gastritis

Evaluation

•  Chemistries, UA, FSG, isopropyl level, nl AG, ↑ osmol gap, falsely ↑ Cr (from acetone)

Treatment

•  Based presumptive Dx if levels delayed

•  Supportive (rarely lethal)

•  Dialysis: Refractory hypotension, levels >500 mg/dL

Disposition

•  Admit

ALCOHOL WITHDRAWAL

Definition

•  Abrupt cessation or significant reduction in alcohol intake (begins 6–24 h/peaks 48–72 h after last drink)

History

•  Heavy alcohol use w/ cessation, insomnia, anorexia, nausea, vomiting, restlessness, diaphoresis, sz

Physical Findings

•  Tremulousness, szs (25% of pts at 6–48 h), delirium, hallucinations (visual > auditory), autonomic hyperactivity (tachycardia, HTN, irritability, hyperreflexia), delirium tremens (rare/serious, 24 h–5 d after last drink): Tremor/autonomic hyperactivity/confusion/hallucinations/low-grade fever

Evaluation

•  Bedside glucose testing, CBC, BMP, LFTs/coags (if liver Dysfxn suspected), BAL

Treatment

•  Glucose (if hypoglycemic), thiamine, lorazepam 2 mg IV for sz, IV/IM/PO long-acting BZD (ie, lorazepam 1–4 mg IV q10–30min to sedation, diazepam 5 mg IV q5–10min to sedation, chlordiazepoxide), phenobarbital as 2nd-line

Disposition

•  Admit for if requiring IV medication/DTs ± ICU

Clinical Pearls

•  Rarely fatal (increased w/ aspiration due to sz) when treated appropriately

•  May require very large doses of IV BZD to control/treat

DRUGS OF ABUSE

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