Tricyclic antidepressant overdoseMANAGEMENT

TOXICOLOGIC PRESENTATIONS · 12 SECTIONS

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492 items

☷ Legend

01Approach to the Critical Patient/attcp55

Immediate priorities

›Initial stabilization

›Airway risk

›Depressed mental status

›Recurrent seizures

›Severe agitation requiring control

›Breathing risk

›Hypoventilation

›Aspiration risk

›Circulation risk

›Hypotension

›Wide-complex tachycardia

›Ventricular dysrhythmia

›Monitoring and access

›Cardiac monitor

›12-lead ECG within 10 minutes

›IV access x2

›Temperature

›Point-of-care glucose

›Early tox strategy

›High-risk features

›QRS duration 100 ms or more

›Ventricular dysrhythmia

›Hypotension refractory to fluids

›Seizure

›Coma

›Early consultation triggers

›Poison centre

›Critical care

›Cardiology for refractory dysrhythmia

›ECMO-capable centre for refractory shock

ECG-first risk stratification

›ECG danger markers

›QRS widening

›QRS 100 ms or more predicts higher seizure risk

›QRS 160 ms or more predicts higher ventricular dysrhythmia risk

›aVR terminal R wave prominence

›R in aVR 3 mm or more

›R to S ratio in aVR greater than 0.7

›QTc prolongation

›Torsades risk context

›Rightward terminal QRS axis

›Terminal 40 ms axis rightward shift

Immediate bedside decision points

›Time-critical branching

›If QRS 100 ms or more

›Sodium bicarbonate bolus strategy

›pH target 7.50 to 7.55

›If seizure

›Benzodiazepine first-line

›Sodium bicarbonate if concurrent QRS widening or instability

›If hypotension

›Crystalloid bolus

›Norepinephrine early for refractory hypotension

›If ventricular dysrhythmia

›Sodium bicarbonate escalation

›Lidocaine consideration

›Avoid class Ia and Ic agents

02History/hx43

Focused tox history

›Ingestion details

›Substance

›Tricyclic antidepressant name

›Co-ingestants

›Dose estimate

›Number of tablets

›Strength per tablet

›Time of ingestion

›Time since ingestion

›Staggered ingestion possibility

›Formulation

›Immediate-release

›Sustained-release

›Symptoms timeline

›Neuro

›Somnolence

›Agitation or delirium

›Seizure

›Cardiorespiratory

›Palpitations

›Syncope

›Dyspnea

›Anticholinergic

›Dry mouth

›Blurred vision

›Urinary retention

›Risk modifiers

›Patient factors

›Cardiac disease

›Seizure disorder

›Renal impairment

›Hepatic impairment

›Medication factors

›Sodium-channel blockers

›QT-prolonging agents

›Serotonergic agents

›Context and safety

›Access to medications

›Home supply size

›Recent refill

›Supervision and supports

›Reliable caregiver availability

›Safe storage plan

03Physical Exam/exam44

Targeted exam

›Vital signs patterns

›Temperature

›Hyperthermia

›Heart rate

›Sinus tachycardia

›Bradycardia in severe toxicity

›Blood pressure

›Hypotension

›Respiratory status

›Hypoventilation

›Neurologic

›Mental status

›Somnolence

›Delirium

›Coma

›Seizure activity

›Ongoing convulsions

›Postictal state

›Pupillary size and reactivity

›Mydriasis

›Anticholinergic findings

›Mucous membranes

›Dryness

›Skin

›Dryness

›Flushing

›Bowel sounds

›Ileus

›Bladder

›Retention

›Cardiovascular

›Perfusion

›Capillary refill delay

›Cool extremities

›Rhythm evaluation

›Irregular pulse

›Respiratory

›Aspiration signs

›Crackles

›Hypoxia

PITFALLS

›Pitfalls

›Normal early vitals despite impending toxicity

›Rapid deterioration within first 2 hours after ingestion

›Agitation masking declining mental status

04Differential Diagnosis/ddx31

Life-threatening mimics

›Broad differential

›Sodium-channel blocker toxidrome

›Tricyclic antidepressant poisoning

›Diphenhydramine toxicity

›Cocaine toxicity

›Flecainide or propafenone toxicity

›Carbamazepine toxicity

›Anticholinergic toxidrome

›Antihistamine toxicity

›Antipsychotic toxicity

›Serotonin toxicity

›SSRI or SNRI toxicity

›MAOI interaction

›Sympathomimetic toxidrome

›Amphetamine toxicity

›CNS catastrophe

›Intracranial hemorrhage

›Meningoencephalitis

›Metabolic causes

›Hypoglycemia

›Severe hypoxia

›Severe hypercapnia

Coding

›Coding alignment

›ICD-10

›T43.011A poisoning by tricyclic antidepressants accidental

›T43.012A poisoning by tricyclic antidepressants intentional self-harm

›T43.014A poisoning by tricyclic antidepressants undetermined

›SNOMED CT concepts

›Tricyclic antidepressant poisoning

›Drug-induced wide QRS complex

›Drug-induced hypotension

05Laboratory Tests/lt36

Core labs

›Baseline labs

›Electrolytes

›Potassium for arrhythmia risk

›Sodium for hypertonic therapy planning

›Bicarbonate for alkalinization context

›Renal function

›Creatinine for clearance and shock

›Glucose

›Hypoglycemia exclusion

›Venous blood gas

›pH baseline

›PCO2 baseline in mmHg

›Lactate

›Shock marker

›Creatine kinase

›Seizure or rhabdomyolysis concern

›Co-ingestion screen

›Acetaminophen level

›Time-based repeat if early presentation

›Salicylate level

›Mixed toxidrome exclusion

›Ethanol level

›Sedation confounder

›Pregnancy test

›Management modifier

Monitoring labs during alkalinization

›Alkalinization safety labs

›Potassium

›Hypokalemia risk with alkalemia

›Ionized calcium

›Tetany or dysrhythmia risk in alkalemia

›Repeat blood gas

›pH target verification

›PCO2 trend in mmHg

PITFALLS

›Limitations

›Serum TCA concentrations poor correlation with severity

›Urine drug screen limited clinical utility for acute management

06Diagnostic Tests/dt42

Scoring Systems

›ECG-based risk tools

›QRS thresholds

›QRS 100 ms or more

›Higher seizure risk

›Sodium bicarbonate indication

›QRS 160 ms or more

›Higher ventricular dysrhythmia risk

›aVR criteria

›R wave in aVR 3 mm or more

›Predictive of severe toxicity

›R to S ratio in aVR greater than 0.7

›Predictive of seizures and dysrhythmia

›QTc prolongation

›Torsades risk context

›Magnesium readiness

MRI

›MRI role

›Indications

›Alternate neurologic diagnosis after stabilization

›Contraindications

›Hemodynamic instability

›Ongoing dysrhythmia

›Utility limits

›No role in diagnosing TCA toxicity

›CT role

›Head CT indications

›Persistent altered mental status after tox stabilization

›Focal neurologic deficit

›Significant head trauma from collapse

›Chest imaging indications

›Aspiration concern

›Hypoxia unexplained by tox course

›Utility limits

›No role in diagnosing TCA toxicity

Ultrasound

›Point-of-care ultrasound

›Shock evaluation

›LV systolic function estimate

›IVC assessment

›Pericardial effusion exclusion

›Procedural support

›Central venous access guidance

›Utility limits

›No direct diagnostic role for TCA poisoning

07Disposition/dispo26

Level of care

›Disposition framework

›ICU indications

›QRS 100 ms or more

›Any ventricular dysrhythmia

›Hypotension requiring vasopressors

›Seizure

›Need for bicarbonate infusion

›Need for mechanical ventilation

›Step-down or monitored bed criteria

›Mild symptoms resolving

›Normalizing ECG without bicarbonate infusion

›ED observation criteria

›Asymptomatic patient

›Normal ECG

›Reliable monitoring for minimum observation window

Observation duration

›Monitoring time

›Asymptomatic ingestion

›Continuous monitoring for at least 6 hours

›Repeat ECG prior to clearance

›Sustained-release formulation

›Extended observation

Transfer criteria

›Higher level of care triggers

›Refractory shock

›Refractory ventricular dysrhythmia

›Need for ECMO consideration

›Need for toxicology-guided lipid therapy

08Treatment/t117

Decontamination

›GI decontamination

›Activated charcoal

›Within 1 to 2 hours of ingestion

›Protected airway requirement

›Ileus risk consideration

›Whole bowel irrigation

›Large sustained-release ingestion consideration

›Toxicology-guided decision

Seizure and agitation control

›Neurotoxicity management

›Benzodiazepines

›Lorazepam IV 0.1 mg/kg

›Maximum single dose 4 mg

›Repeat every 5 to 10 minutes as needed

›Diazepam IV 0.15 mg/kg

›Maximum single dose 10 mg

›Repeat every 5 to 10 minutes as needed

›Refractory seizures

›Propofol infusion in intubated patient

›ICU titration protocol

›Phenobarbital IV 10 to 20 mg/kg

›Slow infusion monitoring

›Avoidance

›Phenytoin for TCA-induced seizures

›Flumazenil in mixed overdose risk

Sodium bicarbonate alkalinization

›Alkalinization strategy

›Indications

›QRS 100 ms or more

›Ventricular dysrhythmia

›Hypotension with suspected TCA toxicity

›Seizure with suspected TCA toxicity

›Bolus dosing

›Sodium bicarbonate 8.4% IV 1 to 2 mEq/kg

›Repeat bolus every 3 to 5 minutes until effect

›Stop boluses if pH 7.55 or more

›Infusion dosing

›Sodium bicarbonate 100 to 150 mEq in 1 L D5W

›Infusion rate 150 to 250 mL/hour

›Titration to ECG and pH targets

›Targets

›QRS less than 100 ms

›pH 7.50 to 7.55

›Potassium in normal range

›Monitoring during therapy

›ECG every 15 to 30 minutes during escalation

›Blood gas every 30 to 60 minutes during escalation

›Potassium every 1 to 2 hours during escalation

›Complications

›Hypokalemia

›Potassium replacement guided by serial labs

›Hypernatremia

›Sodium trend monitoring

›Volume overload

›Infusion rate adjustment

Ventilation and pH control

›Ventilation strategy

›Intubation indications

›Inability to protect airway

›Recurrent seizures

›Refractory agitation

›Refractory acidosis or rising PCO2 in mmHg

›Post-intubation goals

›Avoid hypoventilation

›Target pH 7.50 to 7.55 via controlled ventilation

›Avoid excessive alkalemia

Dysrhythmia management

›Arrhythmia approach

›First-line

›Sodium bicarbonate escalation

›Repeat boluses until QRS narrows

›Lidocaine

›Lidocaine IV 1 to 1.5 mg/kg bolus

›Repeat 0.5 to 0.75 mg/kg every 5 to 10 minutes

›Maximum 3 mg/kg total loading

›Lidocaine infusion 1 to 4 mg/min

›Titration to rhythm control

›Torsades management

›Magnesium sulfate IV 2 g

›Repeat as needed

›Avoidance of harmful antiarrhythmics

›Procainamide

›Quinidine

›Flecainide

›Amiodarone for sodium-channel blockade context

Hypotension and shock

›Hemodynamic support

›Fluids

›Isotonic crystalloid bolus 10 to 20 mL/kg

›Reassessment after each bolus

›Vasopressors

›Norepinephrine infusion

›Start 0.05 to 0.1 mcg/kg/min

›Titration to MAP target

›Epinephrine infusion

›Consideration if refractory

›Inotropy assessment

›POCUS LV function guidance

Rescue therapies

›Refractory toxicity options

›Hypertonic saline

›Indication

›Persistent QRS widening despite alkalinization

›Sodium chloride 3% IV 2 to 4 mL/kg bolus

›Repeat guided by toxicology and sodium level

›Intravenous lipid emulsion 20%

›Indication

›Refractory shock

›Refractory ventricular dysrhythmia

›Bolus 1.5 mL/kg over 2 to 3 minutes

›Repeat bolus once if persistent instability

›Infusion 0.25 mL/kg/min for 30 to 60 minutes

›Maximum total dose 10 mL/kg

›ECMO

›Indication

›Refractory cardiogenic shock despite maximal therapy

Evidence and guideline alignment

›Evidence levels

›Sodium bicarbonate for life-threatening sodium-channel blocker toxicity

›Class I recommendation in toxicology-focused resuscitation guidance

›Benzodiazepines for toxin-induced seizures

›Standard of care consensus

›Norepinephrine for vasodilatory shock

›Class I recommendation in shock management frameworks

09Special Populations/sp26

Pregnancy

›Pregnancy considerations

›Maternal priorities

›Maternal stabilization as fetal stabilization

›Left lateral tilt in late pregnancy

›Monitoring

›Fetal monitoring after maternal stabilization when viable gestation

›Medications

›Sodium bicarbonate use acceptable when indicated

›Benzodiazepines risk benefit in life-threatening seizures

›Disposition

›Obstetrics consultation for viable gestation

Geriatric

›Older adult considerations

›Higher baseline conduction disease prevalence

›Lower threshold for ICU

›Medication effects

›Increased anticholinergic sensitivity

›Fluid strategy

›Lower bolus volumes with frequent reassessment

Pediatrics

›Pediatric considerations

›Rapid deterioration risk

›Early PICU involvement

›Weight-based dosing

›Sodium bicarbonate 1 to 2 mEq/kg bolus

›Benzodiazepines weight-based dosing

›Observation

›Minimum 6 hour monitoring for asymptomatic ingestion with normal ECG

10Background/b40

Epidemiology

›Epidemiology

›Exposure patterns

›Common cause of life-threatening antidepressant poisoning despite reduced prescribing

›Time course

›Onset typically within 1 to 2 hours after ingestion

›Highest risk window within first 6 hours

›Morbidity drivers

›Ventricular dysrhythmia

›Refractory hypotension

›Seizures

Pathophysiology

›Mechanisms

›Fast sodium-channel blockade

›QRS widening

›Ventricular dysrhythmia

›Potassium-channel effects

›QT prolongation

›Alpha-1 blockade

›Hypotension

›Anticholinergic effects

›Delirium

›Ileus

›Hyperthermia

›GABA antagonism

›Seizures

›High protein binding and large volume of distribution

›Limited dialyzability

Therapeutic Considerations

›Rationale for alkalinization

›Increased extracellular sodium concentration

›Competitive relief of sodium-channel blockade

›Serum alkalemia

›Reduced free fraction of TCA

›Reduced binding to sodium channels

›Target pH 7.50 to 7.55

›Balance of efficacy and alkalemia risk

›Why certain therapies are avoided

›Class Ia and Ic antiarrhythmics worsen sodium-channel blockade

›Physostigmine risk in TCA cardiotoxicity

›Phenytoin may worsen dysrhythmia in sodium-channel blockade

›Dialysis limitations

›Ineffective due to high protein binding and tissue distribution

11Patient Discharge Instructions/pdi19

copy discharge instructions

›Discharge guidance

›What happened

›Medication overdose can affect heart rhythm and brain function

›What to do now

›Take medicines only as prescribed

›Store medicines locked and out of reach

›Avoid alcohol and sedating drugs unless prescribed

›Follow-up

›Primary care follow-up within 1 to 3 days

›Mental health follow-up if overdose was intentional or unclear

›Return to ED now if

›Fainting or near-fainting

›Seizure

›New confusion

›Chest pain

›Fast or irregular heartbeat

›Trouble breathing

›Persistent vomiting

›Severe weakness

12References/r13

Clinical guidelines and key sources

›Core references

›American Heart Association focused update on poisoning and envenomation in resuscitation

›Sodium bicarbonate for life-threatening sodium-channel blocker toxicity

›GEMNet guideline for management of tricyclic antidepressant overdose

›Sodium bicarbonate bolus strategies

›Ontario Poison Centre sodium-channel blocker QRS widening treatment sheet

›NaHCO3 1 to 2 mEq/kg for QRS greater than 100 ms

›Royal Children’s Hospital clinical guideline for TCA poisoning

›Sodium bicarbonate 2 mmol/kg for QRS widening or ventricular arrhythmia

›Boehnert and Lovejoy tricyclic antidepressant poisoning ECG predictors

›QRS duration association with seizures and dysrhythmia

›Review of sodium bicarbonate use in sodium-channel blocker poisoning

›Evidence synthesis for QRS narrowing effect

Evidence & Review

Reviewed by SymptomDx Medical Team · Last reviewed June 16, 2026

SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.