Signs and Symptoms
- SSRIs:
- Traditional SSRIs (fluoxetine, paroxetine, sertraline):
- Sedation
- Serotonin syndrome
- In single substance overdose, rarely will cause severe medical effects
- Citalopram/escitalopram:
- Somnolence, vomiting, tachycardia
- QTc prolongation
- Seizures (more common in citalopram)
- Exhibit delayed toxicity (up to 24 hr after ingestion)
- SNRIs:
- Duloxetine:
- Somnolence, vomiting, tachycardia
- Seizures rare
- Venlafaxine/desvenlafaxine:
- Atypical antidepressants:
- Bupropion
- Sedation
- Seizures
- QRS & QTc prolongation
- Trazodone:
- Sedation
- QTc prolongation
- Hypotension
- Priapism
- Mirtazapine:
- Sedation
- QTc prolongation
- Possible neutropenia in chronic dosing
- Atypical antipsychotics:
- Developed for fewer extrapyramidal symptoms (EPS), particularly tardive dyskinesia, than typical antipsychotics
- Most common symptoms in overdose include sedation, tachycardia, and miosis
- Clozapine:
- Agranulocytosis (in up to 1% taking chronically)
- Sialorrhea
- Cardiomyopathy
- Anticholinergic delirium
- Olanzapine:
- Anticholinergic delirium
- QTc prolongation
- Quetiapine:
- Hypotension from significant α1-antagonism
- QTc prolongation
- Anticholinergic delirium
- Ziprasidone:
- Sedation
- QTc prolongation → increased risk of torsade
- Aripiprazole:
- No QTc prolongation
- Hypotension
- Prolonged CNS dysfunction
Essential Workup
- Determine agents ingested, dose, and time of ingestion:
- Investigate for coingested drugs
- Rapid bedside glucose if altered mental status
Diagnostic Tests & Interpretation
Lab
- Specific drug levels of these medications rarely available and do not guide emergent management
- ECG:
- For evaluation of QTc and QRS width
- Urine pregnancy:
- In female patients of childbearing age
- Electrolytes, BUN, creatinine, glucose
- Urine drug of abuse screening:
- Rarely changes clinical management
- Salicylate and acetaminophen concentrations
- Very common coingestants in suicidal patients
- Serum ethanol:
- To evaluate ethanol intoxication as contributing to altered mental status
Imaging
- CT of brain if uncertain cause of depressed mental status
- CXR if intubated or hypoxic
Differential Diagnosis
- TCA overdose
- Ethanol overdose
- Isoniazid overdose
- Hypoglycemia
- Hypoxemia
- Hyponatremia
- Hypocalcemia
- Withdrawal syndromes
- Serotonin syndrome
- Head trauma
- Opioid intoxication
- Sedative-hypnotic overdose
- Mood stabilizer/antiepileptic overdose
- DKA
Prehospital
- In cases of suspected overdose, bring all medication bottles to hospital with patient
- ABCs
- 0.9% NS IV fluids as needed for hypotension
- Benzodiazepines as needed for seizures
Initial Stabilization/Therapy
- ABCs:
- Administer oxygen
- Place on cardiac monitor and measure pulse oximetry
- Establish IV access
- Intubate as needed for airway protection or respiratory status
- Rapid bedside glucose measurement
- Naloxone or D50W as indicated for altered mental status and rapid clinical evaluation:
- Flumazenil is not recommended for mixed-overdose patients, patients with underlying seizure disorder, or patients chronically on benzodiazepines
- May give diphenhydramine 25-50 mg IM/IV or Cogentin 1-mg IV for EPS
ED Treatment/Procedures
- GI decontamination:
- Do not attempt decontamination in a patient who cannot protect their airway
- Intubation solely for decontamination purposes, however, is not recommended
- Activated charcoal may be beneficial in early presenting overdoses
- For QRS widening, administer sodium bicarbonate IV push:
- Sodium bicarbonate infusion (i.e., “bicarb drip”) is NOT appropriate for use with QRS widening, as it is ineffective and potentially limits ability to provide sodium bicarbonate boluses
- Treat hypotension unresponsive to IV fluids with norepinephrine rather than dopamine owing to α1 receptor antagonism
- Treat seizures with:
- Initial therapy: benzodiazepines
- For refractory seizures: Barbiturates
- Treat symptoms of serotonin syndrome (fever, AMS, tachycardia, rigidity, hyperreflexia) with benzodiazepines and active cooling
Medication
- Activated charcoal: 50-75-g PO initial dose; better to give 10-g charcoal per 1 g ingested xenobiotic as tolerated up to 100-g PO
- Benztropine 1-mg PO/IV
- Diazepam: 5-10-mg IV bolus (peds: 0.1 mg/kg IV bolus or 0.5 mg/kg rectal)
- Diphenhydramine 25-50-mg IM/IV (peds 1 mg/kg)
- Lorazepam: 2-4 mg (peds: 0.03-0.05 mg/kg) IV bolus
- Naloxone: 0.4-2 mg (peds: 0.1 mg/kg) initial bolus; may repeat up to a total of 10 mg
- Norepinephrine: 0.5-2 mcg/kg IV infusion
- Phenobarbital: 15-20 mg/kg IV max dose is 2 g; caution: Likely to develop respiratory depression with IV loading doses
- Sodium bicarbonate: 1 mEq/kg IV bolus (adult 8.4%; peds: <50 kg, 4.2%)
Disposition
Admission Criteria
- 24 hr telemetry admission for ingestions of the following: Citalopram, escitalopram, venlafaxine, desvenlafaxine, bupropion
- Asymptomatic patients 6 hr after ingestion of other antidepressant medications do not require medical admission
- Coma
- Altered mental status
- Symptoms of serotonin syndrome
- Hemodynamic compromise
- ECG changes
- Suicidal patients should be on a 1:1 observation
Discharge Criteria
- Asymptomatic patients of less toxic antidepressants >6 hr after ingestion may be medically cleared for psychiatric admission
- Discharge only asymptomatic patients who are not suicidal (i.e., accidental exposure)
Follow-up Recommendations
Psychiatry referral for patients with intentional overdose
- BoyerEW, ShannonM. The serotonin syndrome . N Engl J Med. 2005;352(11):1112-1120.
- LevineMD, RuhaAM. Antidepressants. In: WallsRM, HockbergerRS, Gausche-HillM, et al., eds. Rosen's Emergency Medicine, 9th ed.Philadelphia, PA: Elsevier; 2018:1868-1875.
- NelsonJC, SpykerDA. Morbidity and mortality associated with medications used in the treatment of depression: an analysis of cases reported to U.S. poison control centers, 2000-2014 . Am J Psychiatry. 2017;174(5):438-450.
- StorkCM. Serotonin reuptake inhibitors and atypical antidepressants. In: HoffmanRS, Howland MA, LewinNA, et al., eds. Goldfrank's Toxicologic Emergencies. 10th ed.Chicago, IL: McGraw-Hill Medical; 2015.
See Also (Topic, Algorithm, Electronic Media Element)
Tricyclic Antidepressant Poisoning