Beta-Blocker Overdose

Topic Overview

Summary

Beta-blocker overdose represents a life-threatening cardiovascular emergency characterized by profound bradycardia, hypotension, and cardiogenic shock secondary to competitive β-adrenergic receptor antagonism. The clinical presentation varies significantly based on agent-specific properties: lipophilic agents (propranolol, metoprolol) penetrate the CNS causing seizures and coma, while membrane-stabilising agents (propranolol) produce sodium channel blockade with QRS widening. [1,2] Management requires early recognition, aggressive supportive care, and specific antidotal therapy including high-dose glucagon (bypasses β-receptor), high-dose insulin euglycaemia therapy (HIET), intravenous lipid emulsion for lipophilic agents, and in refractory cases, extracorporeal membrane oxygenation (ECMO). [3,4]

Key Facts

• Mechanism: Competitive antagonism of β1-adrenergic receptors → ↓chronotropy, ↓inotropy, ↓dromotropy
• Critical Features: Bradycardia (HR 20-40 bpm), hypotension, cardiogenic shock, altered mental status
• Propranolol: Most dangerous—non-selective, lipophilic, membrane stabilising (sodium channel blockade)
• First-line Antidote: Glucagon 5-10 mg IV bolus → 2-5 mg/hr infusion (bypasses β-receptor via direct adenylyl cyclase activation)
• Refractory Shock: High-dose insulin euglycaemia therapy (HIET) 1 unit/kg bolus + 0.5-1 unit/kg/hr infusion [5]
• Lipid Rescue: IV lipid emulsion 1.5 mL/kg bolus for lipophilic agents (propranolol, metoprolol, carvedilol) [6]
• Last Resort: ECMO/VA-ECMO for refractory cardiogenic shock [7]

Clinical Pearls

Glucagon Mechanism: Directly activates adenylyl cyclase independent of β-receptor → ↑intracellular cAMP → ↑cardiac contractility and chronotropy. Bypasses the β-blockade entirely. [8]

Propranolol Triad: β-blockade + CNS toxicity (seizures, coma) + sodium channel blockade (wide QRS). Treat QRS widening with sodium bicarbonate as in tricyclic antidepressant overdose. [9]

Check Glucose Early: β-blockers mask sympathetic symptoms of hypoglycaemia (tremor, sweating, tachycardia) while impairing hepatic gluconeogenesis and glycogenolysis. Hypoglycaemia may be profound and prolonged. [10]

HIET Rationale: Insulin has positive inotropic effects independent of glucose metabolism; high-dose insulin overcomes insulin resistance in "stunned" myocardium during cardiovascular toxin exposure. [5,11]

Lipid Emulsion: Creates an intravascular "lipid sink" extracting lipophilic toxins from myocardium and CNS. Most effective for propranolol, carvedilol, metoprolol. [6,12]

Why This Matters Clinically

Beta-blocker overdose can rapidly progress to refractory cardiogenic shock and cardiac arrest unresponsive to standard Advanced Cardiovascular Life Support (ACLS) protocols. Early recognition and aggressive multi-modal antidotal therapy (glucagon, HIET, lipid emulsion) are life-saving; delays in escalation to advanced therapies including ECMO correlate with increased mortality. [3,7] With over 65 million beta-blocker prescriptions annually in the UK alone, accidental and intentional overdoses remain common, particularly in elderly patients with polypharmacy and impaired renal clearance. [13]

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Visual Summary

Visual assets to be added:

• Beta-blocker mechanism of action at β1-adrenergic receptor
• Comparison of agent-specific properties (lipophilicity, selectivity, membrane effects)
• ECG progression in beta-blocker overdose (bradycardia → AV block → wide QRS [propranolol])
• Glucagon mechanism bypassing β-receptor
• HIET mechanism in cardiogenic shock
• Lipid emulsion "lipid sink" hypothesis
• Management algorithm: Supportive care → Glucagon → HIET → Lipid emulsion → ECMO
• Temporal relationship: Ingestion → Symptom onset → Peak toxicity (varies by formulation)

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Epidemiology

Incidence

• Beta-blockers rank among the top 10 cardiovascular medications involved in fatal poisonings reported to poison control centres. [13]
• United States: Approximately 15,000-20,000 beta-blocker exposures reported annually to National Poison Data System; case fatality rate 0.5-2% overall, rising to 5-10% in severe intentional overdoses. [13,14]
• United Kingdom: Beta-blocker toxicity accounts for 3-5% of all cardiovascular drug poisonings presenting to Emergency Departments. [1]
• Peak incidence occurs in two populations: accidental paediatric ingestions (age less than 6 years) and intentional self-harm in adults (age 40-70 years). [14]

Demographics

High-Risk Groups:

• Elderly patients: Polypharmacy, impaired renal/hepatic clearance, pre-existing conduction disease, increased sensitivity to negative chronotropic effects [15]
• Cardiovascular disease patients: Baseline compromised cardiac reserve, reliance on sympathetic tone to maintain cardiac output
• Diabetic patients: Impaired counter-regulatory response to hypoglycaemia, increased risk of prolonged neuroglycopenia [10]
• Renal impairment: Reduced clearance of hydrophilic agents (atenolol, nadolol), prolonged toxicity
• Concurrent cardiotoxin ingestion: Synergistic toxicity with calcium channel blockers, digoxin, antiarrhythmics

Common Agents

*ISA = Intrinsic sympathomimetic activity (partial agonist activity—rarely relevant in overdose)

Most Dangerous Agents:

1. Propranolol: Lipophilic (CNS toxicity) + membrane stabilising (sodium channel blockade) + non-selective (bronchospasm) [2,9]
2. Sotalol: Non-selective β-blockade + potassium channel blockade → QT prolongation → torsades de pointes [16]
3. Carvedilol: Combined α- and β-blockade → profound vasodilation + negative inotropy [1]

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Pathophysiology

Molecular Mechanism

β1-Adrenergic Receptor Blockade:

1. Competitive antagonism at β1-receptors in sinoatrial (SA) node, atrioventricular (AV) node, and ventricular myocardium
2. Prevents endogenous catecholamines (noradrenaline, adrenaline) from binding
3. Blocks Gs protein-coupled receptor signalling cascade
4. Inhibits adenylyl cyclase activation → ↓intracellular cyclic AMP (cAMP)
5. ↓Protein kinase A (PKA) activation → ↓phosphorylation of L-type calcium channels and ryanodine receptors
6. ↓Intracellular calcium influx and release from sarcoplasmic reticulum

Cardiovascular Consequences:

• Negative Chronotropy: ↓SA node automaticity → bradycardia (HR 20-40 bpm in severe overdose) [1]
• Negative Inotropy: ↓Myocardial contractility → ↓stroke volume → ↓cardiac output → hypotension and cardiogenic shock [2]
• Negative Dromotropy: ↓AV node conduction velocity → first-degree AV block → high-grade AV block → asystole [1]
• Negative Lusitropy: Impaired diastolic relaxation (less clinically significant in acute overdose)

Agent-Specific Toxic Effects

Membrane Stabilising Activity (Sodium Channel Blockade):

• Propranolol exhibits Class I antiarrhythmic (quinidine-like) effects at therapeutic and toxic concentrations [9]
• Blocks fast sodium channels (Nav1.5) in myocardial tissue
• Slows Phase 0 of cardiac action potential → prolonged depolarisation → QRS widening (> 120 ms)
• Mimics tricyclic antidepressant toxicity; treated with sodium bicarbonate to overcome blockade [9]
• May precipitate ventricular arrhythmias (ventricular tachycardia, torsades de pointes in severe cases)

CNS Toxicity (Lipophilic Agents):

• Propranolol, metoprolol, carvedilol readily cross blood-brain barrier due to high lipophilicity [2]
• CNS β-receptor antagonism + direct membrane effects
• Clinical manifestations: delirium, lethargy, coma, seizures (propranolol > metoprolol)
• Seizures may be refractory to benzodiazepines; consider propofol or barbiturates [2]

Potassium Channel Blockade (Sotalol):

• Class III antiarrhythmic activity: blocks cardiac potassium channels (IKr)
• Prolongs ventricular repolarisation → prolonged QT interval (QTc often > 500 ms)
• Risk of torsades de pointes ventricular tachycardia → ventricular fibrillation → sudden cardiac death [16]
• Hypokalemia and hypomagnesemia potentiate risk

β2-Receptor Blockade (Non-selective Agents):

• Bronchospasm in asthmatics and COPD patients (propranolol, sotalol, carvedilol, nadolol) [1]
• Peripheral vasoconstriction → cold extremities, impaired perfusion
• Inhibition of hepatic glycogenolysis and gluconeogenesis → hypoglycaemia [10]
• Blunted sympathetic response to hypoglycaemia (masks tremor, palpitations, sweating)

α-Adrenergic Blockade (Carvedilol, Labetalol):

• Peripheral vasodilation → profound orthostatic hypotension [1]
• Synergistic with β-blockade to cause refractory shock

Metabolic Derangements

Hypoglycaemia: [10]

• Inhibition of β2-mediated hepatic glycogenolysis and gluconeogenesis
• Impaired counter-regulatory hormonal response (blunted adrenaline, glucagon secretion)
• Masked autonomic symptoms (tremor, sweating, tachycardia) → delayed recognition
• Highest risk: children, diabetics on insulin/sulfonylureas, prolonged fasting, chronic β-blocker use

Hyperkalaemia:

• β2-receptor blockade impairs cellular potassium uptake via Na-K-ATPase pump
• Usually mild (K+ 5.5-6.5 mmol/L) but may worsen in renal impairment [1]

Lactic Acidosis:

• Cardiogenic shock → tissue hypoperfusion → anaerobic metabolism → lactate accumulation
• Marker of severity; lactate > 4 mmol/L predicts poor outcome [1]

Why Glucagon Works

Mechanism of Action: [8]

1. Glucagon binds to Gs-coupled glucagon receptors on cardiac myocytes
2. Activates adenylyl cyclase independently of β-adrenergic receptors
3. Directly increases intracellular cAMP despite β-receptor blockade
4. Activates protein kinase A → phosphorylates L-type calcium channels and ryanodine receptors
5. Increases intracellular calcium influx and sarcoplasmic reticulum calcium release
6. Bypasses the β-blockade to restore positive chronotropy and inotropy

Clinical Effects:

• Increases heart rate and blood pressure within 1-5 minutes of IV bolus [8]
• Efficacy: 50-70% response rate in beta-blocker overdose (higher than calcium channel blocker overdose) [1]
• Limitations: Tachyphylaxis, glucagon supply shortages, emetic side effects

Why High-Dose Insulin Works

Mechanism of HIET (High-Dose Insulin Euglycaemia Therapy): [5,11]

1. Insulin has direct positive inotropic effects independent of glucose metabolism
2. Overcomes myocardial "insulin resistance" induced by cardiovascular toxins
3. Promotes myocardial glucose and lactate utilization → improves energy production in "stunned" myocardium
4. Increases intracellular calcium sensitivity
5. Vasodilatory effects may reduce afterload
6. Preserves mitochondrial function and reduces oxidative stress

Clinical Efficacy:

• Case series demonstrate improved haemodynamics in refractory beta-blocker and calcium channel blocker toxicity [5,11]
• Recommended by American Heart Association 2023 guidelines for calcium channel blocker/beta-blocker poisoning with shock [3]
• Typical dosing: 1 unit/kg IV bolus, then 0.5-1 unit/kg/hr infusion titrated to response (maximum reported 10 units/kg/hr) [5]

Lipid Emulsion Mechanism

"Lipid Sink" Hypothesis: [6,12]

1. IV lipid emulsion (20% Intralipid) creates an expanded intravascular lipid phase
2. Lipophilic toxins (propranolol, metoprolol, carvedilol) partition into lipid droplets
3. Toxin extraction from myocardium and CNS → ↓tissue drug concentration → ↓toxicity
4. May also provide fatty acid substrate for ischaemic myocardium
5. Improves cardiac contractility and reduces arrhythmias in animal models [12]

Clinical Evidence:

• Multiple case reports of successful resuscitation from refractory propranolol, metoprolol overdose [6,12]
• Inconsistent results in systematic reviews; benefit likely limited to lipophilic agents [6]
• American Heart Association 2023: May consider in refractory shock from lipophilic agents (Class IIb recommendation) [3]

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Clinical Presentation

Symptom Onset and Temporal Course

Immediate-Release Formulations:

• Symptom onset: 30 minutes to 2 hours post-ingestion
• Peak toxicity: 2-6 hours post-ingestion
• Duration: 12-24 hours (varies by agent half-life)

Modified-Release/Sustained-Release Formulations:

• Delayed onset: May not manifest until 4-8 hours post-ingestion
• Prolonged absorption: Peak toxicity delayed to 8-16 hours
• Extended duration: Toxicity may persist 24-48 hours
• Risk of "double peak" phenomenon with bezoar formation

Agent-Specific Half-Lives:

• Atenolol: 6-7 hours (prolonged in renal failure to 15-35 hours)
• Propranolol: 3-6 hours
• Metoprolol: 3-4 hours
• Nadolol: 20-24 hours (longest; prolonged in renal failure)
• Sotalol: 12 hours (prolonged in renal failure)

Symptoms

Cardiovascular:

• Dizziness, lightheadedness (cerebral hypoperfusion)
• Palpitations (paradoxical in some patients despite bradycardia)
• Chest pain (myocardial ischaemia from hypoperfusion)
• Dyspnoea (pulmonary oedema from cardiogenic shock)
• Syncope or pre-syncope (severe bradycardia, complete heart block)

Neurological:

• Confusion, disorientation
• Lethargy → obtundation → coma (GCS less than 8)
• Seizures (propranolol, metoprolol—due to CNS penetration) [2]
• Weakness, fatigue

Respiratory:

• Bronchospasm (non-selective agents in asthmatics/COPD)
• Wheezing, dyspnoea
• Respiratory depression (severe CNS toxicity)

Metabolic:

• Sweating (paradoxical; may be absent if hypoglycaemia develops)
• Nausea, vomiting (especially after glucagon administration)
• Symptoms of hypoglycaemia (if not masked): tremor, anxiety, hunger

Signs

Vital Signs:

• Bradycardia: HR 30-50 bpm in moderate toxicity; HR less than 30 bpm or asystolic pauses in severe toxicity [1]
• Hypotension: SBP less than 90 mmHg; MAP less than 65 mmHg indicates shock
• Hypothermia (impaired thermoregulation, peripheral vasoconstriction)
• Tachypnoea (compensatory for metabolic acidosis) or bradypnoea (CNS depression)

Cardiovascular Examination:

• Weak, thready pulse (low stroke volume)
• Cool, mottled extremities (peripheral vasoconstriction, poor perfusion)
• Prolonged capillary refill time (> 2 seconds)
• Jugular venous distension (right heart failure in severe cases)
• Pulmonary crackles (cardiogenic pulmonary oedema)
• Third heart sound (S3 gallop—ventricular dysfunction)

Neurological Examination:

• Reduced Glasgow Coma Scale (GCS 8-12 in moderate toxicity, less than 8 in severe)
• Areflexia or hyporeflexia
• Dilated or normal pupils (rarely pinpoint)
• Seizure activity (generalized tonic-clonic with propranolol) [2]

Respiratory Examination:

• Bilateral expiratory wheeze (bronchospasm in non-selective agent overdose)
• Reduced air entry (pulmonary oedema)

Red Flags and Indicators of Severe Toxicity

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Clinical Examination

Primary Survey (ABCDE Approach)

Airway:

• Assess patency: GCS less than 8 or active seizures require definitive airway
• Protect airway before glucagon administration (high risk of vomiting)

Breathing:

• Respiratory rate (↓ in CNS depression, ↑ in metabolic acidosis)
• Auscultate for bronchospasm (non-selective agents)
• Pulmonary oedema (fine bibasal crackles)

Circulation:

• Heart rate (profound bradycardia)
• Blood pressure (hypotension)
• Perfusion assessment (capillary refill, skin temperature, mental status)
• Continuous cardiac monitoring (ECG)

Disability:

• Glasgow Coma Scale
• Pupillary response
• Blood glucose (IMMEDIATE bedside testing)

Exposure:

• Skin temperature, colour, perfusion

Focused Cardiovascular Examination

Inspection:

• Central and peripheral cyanosis
• Jugular venous pressure (elevated in right heart failure)

Palpation:

• Radial pulse: rate, rhythm, volume (weak, thready)
• Apex beat: displaced (cardiomegaly), diffuse (left ventricular dysfunction)

Auscultation:

• Heart sounds: S3 gallop (ventricular dysfunction), S4 (rarely)
• Murmurs (usually absent unless pre-existing valvular disease)
• Lung fields: crackles (pulmonary oedema)

Peripheral Examination:

• Perfusion: cool, clammy extremities
• Oedema: peripheral oedema (right heart failure)

Neurological Examination

Conscious Level:

• AVPU: Alert / Voice / Pain / Unresponsive
• Glasgow Coma Scale (Eye/Verbal/Motor)

Cranial Nerves:

• Pupillary response (usually normal; may be dilated)
• Gag reflex (assess airway protection)

Motor Examination:

• Tone (hypotonia in severe toxicity)
• Power (generalized weakness)
• Reflexes (hyporeflexia to areflexia)
• Plantar response

Seizure Activity:

• Generalized tonic-clonic seizures (propranolol)
• Focal seizures (rare)

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Investigations

Immediate Bedside Tests

Blood Tests

Essential Laboratory Investigations:

Additional Tests:

• Paracetamol (acetaminophen) level: Co-ingestion common in intentional overdose; treat empirically if > 4 hours post-ingestion
• Salicylate level: Screen for co-ingestion
• Ethanol level: May contribute to altered mental status
• Toxicology screen: Urine drug screen if polysubstance ingestion suspected

Beta-Blocker Drug Levels:

• Not routinely available or clinically useful
• Turnaround time too long to guide acute management
• Severity of toxicity based on clinical features, not drug concentration [1]

Electrocardiogram (ECG)

Universal Findings:

Agent-Specific ECG Changes:

Serial ECGs:

• Repeat ECG every 30-60 minutes during acute phase to monitor QRS, QTc, rhythm
• Continuous cardiac monitoring mandatory for minimum 6 hours (immediate-release) or 24 hours (modified-release) [1]

Imaging

Chest X-Ray:

• Indications: Dyspnoea, hypoxia, suspected pulmonary oedema
• Findings:
  • "Cardiogenic pulmonary oedema: bilateral perihilar alveolar infiltrates, Kerley B lines, pleural effusions"
  • Cardiomegaly (if chronic heart failure)
  • Aspiration pneumonia (if vomiting and reduced GCS)

Echocardiography (Transthoracic):

• Indications: Cardiogenic shock, refractory hypotension, consideration of ECMO [7]
• Assess:
  • Left ventricular systolic function (↓ejection fraction less than 40% in severe toxicity)
  • Global hypokinesis (negative inotropic effect)
  • Valvular function (usually normal unless pre-existing disease)
  • Right ventricular function (may be impaired in severe shock)
  • Pericardial effusion (exclude other causes of shock)

Abdominal X-Ray (Rarely):

• Indication: Suspected bezoar formation with sustained-release preparations
• Finding: Radio-opaque tablet mass (some preparations visible)
• Consideration for whole bowel irrigation if large bezoar identified

Monitoring

Continuous Monitoring (Minimum 6-24 Hours):

• Continuous ECG (telemetry)
• Automated non-invasive blood pressure (NIBP) every 5-15 minutes initially
• Pulse oximetry (SpO2)
• Respiratory rate
• Hourly blood glucose (more frequent if hypoglycaemia or on HIET)
• Hourly urine output (via urinary catheter in shocked patients)

Invasive Monitoring (Severe Toxicity):

• Arterial line (continuous blood pressure, frequent blood gas sampling)
• Central venous catheter (CVP monitoring, vasopressor administration, HIET infusion)
• Consider pulmonary artery catheter (rarely) if uncertainty about volume status vs cardiogenic shock

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Differential Diagnosis

Bradycardia and Hypotension

Seizures and Altered Mental Status

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Classification & Staging

By Severity (Poisoning Severity Score Adapted for Beta-Blockers)

By Agent-Specific Toxicity Profile

Hydrophilic Agents (Atenolol, Nadolol):

• Predominantly cardiovascular toxicity (bradycardia, hypotension, AV block)
• Minimal CNS effects (do not cross blood-brain barrier)
• Prolonged toxicity in renal impairment (renally excreted)
• Management: Supportive care, glucagon, HIET if refractory

Lipophilic Agents (Propranolol, Metoprolol, Carvedilol):

• Cardiovascular + CNS toxicity (seizures, coma)
• Propranolol: Additional membrane-stabilising effects (sodium channel blockade → wide QRS)
• Carvedilol: Additional α-blockade (profound vasodilation)
• Management: As above + lipid emulsion therapy; sodium bicarbonate for propranolol if QRS > 100 ms [6,9]

Class III Agents (Sotalol):

• β-blockade + potassium channel blockade
• QT prolongation → torsades de pointes
• Management: As above + magnesium, overdrive pacing; avoid Class Ia/III antiarrhythmics [16]

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Management

Pre-Hospital and Emergency Department Initial Resuscitation

Priorities (First 15 Minutes):

1. Airway Management

   • Assess GCS: If less than 8 or active seizures → definitive airway (endotracheal intubation)
   • Protect airway BEFORE glucagon (high risk of vomiting and aspiration) [8]
   • Rapid sequence induction: Avoid bradycardic agents (e.g., suxamethonium may worsen bradycardia; consider rocuronium)

2. Breathing

   • High-flow oxygen (target SpO2 > 94%)
   • Treat bronchospasm (if non-selective agent): Salbutamol nebulisers, ipratropium, IV magnesium
   • Mechanical ventilation if respiratory failure

3. Circulation

   • Large-bore IV access (14-16G) × 2
   • IV fluid bolus: 500-1000 mL crystalloid (0.9% NaCl or Hartmann's) rapid infusion
     • Caution: Risk of pulmonary oedema if severe myocardial depression; consider smaller boluses (250 mL) and reassess
   • Continuous cardiac monitoring (ECG, NIBP, SpO2)
   • Arterial line and central venous access if shocked or requiring vasopressors

4. Disability

   • IMMEDIATE capillary blood glucose
   • If glucose less than 4 mmol/L: 50 mL 50% dextrose IV (or 100 mL 20% dextrose; or 1 mg glucagon IM if no IV access)
   • Reassess GCS after correcting hypoglycaemia
   • Treat seizures: Benzodiazepines (lorazepam 4 mg IV or diazepam 10 mg IV); if refractory → propofol or phenobarbital [2]

5. Exposure

   • Core temperature (risk of hypothermia)
   • Search for co-ingestants (pill bottles, suicide note, witness history)

Toxicological History (AMPLE + Toxicology-Specific):

• Agent: Which beta-blocker? Dose? Formulation (immediate vs modified-release)?
• Timing: Time of ingestion? Symptom onset?
• Intent: Accidental vs intentional (suicide risk assessment)?
• Co-ingestants: Paracetamol, salicylates, alcohol, calcium channel blockers, other cardiotoxins?
• Medical history: Pre-existing cardiac disease, asthma/COPD, diabetes, renal impairment?
• Medications: Chronic beta-blocker use (tolerance may provide some protection)?

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Decontamination

Activated Charcoal: [1]

• Indication: Presentation within 1 hour of ingestion in alert, cooperative patient with intact airway protection
• Dose: 50 g PO/NG in adults (1 g/kg in children, maximum 50 g)
• Contraindications:
  • Reduced GCS (aspiration risk unless intubated)
  • Unprotected airway
  • Ileus, bowel obstruction
  • Ingestion > 1 hour (limited benefit)
  • "Presentation > 2 hours: May still consider if modified-release formulation"
• Evidence: Reduces drug absorption by ~50% if given within 1 hour; benefit unproven in beta-blocker overdose specifically but recommended based on general principles [1]

Gastric Lavage:

• Rarely indicated; consider only if massive life-threatening ingestion AND presentation within 1 hour
• Requires intubation for airway protection
• Complications: aspiration, oesophageal perforation, vagal stimulation (worsens bradycardia)

Whole Bowel Irrigation:

• Consider if ingestion of large quantity of modified-release preparation
• Polyethylene glycol (GoLytely, Klean-Prep) 1-2 L/hour PO/NG until rectal effluent clear
• Contraindications: ileus, perforation, GI bleeding, unprotected airway
• Limited evidence; case reports suggest benefit in sustained-release toxicity [1]

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Specific Antidotes and Advanced Therapies

1. Atropine (First-Line for Bradycardia)

Mechanism: Competitive antagonist at muscarinic receptors → blocks vagal tone → ↑SA/AV node conduction

Indications: Symptomatic bradycardia (HR less than 50 bpm with hypotension or altered mental status)

Dosing: [1]

• 0.6-1.2 mg IV bolus (minimum 0.6 mg to avoid paradoxical bradycardia)
• Repeat every 3-5 minutes up to maximum 3 mg total
• Paediatric: 0.02 mg/kg IV (minimum 0.1 mg, maximum single dose 0.6 mg)

Efficacy:

• Limited in beta-blocker overdose (only overcomes vagal tone; does not reverse β-blockade)
• Response rate ~20-30% in severe toxicity [1]
• More effective in mild toxicity; unlikely to help in severe overdose

Adverse Effects: Tachycardia, urinary retention, mydriasis, delirium (anticholinergic syndrome if excessive)

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2. Glucagon (First-Line Specific Antidote)

Mechanism: Bypasses β-receptor blockade by directly activating adenylyl cyclase → ↑cAMP → positive chronotropy and inotropy [8]

Indications: [1,3]

• Symptomatic bradycardia or hypotension unresponsive to atropine and IV fluids
• First-line specific therapy for beta-blocker overdose (AHA 2023 Class IIa recommendation) [3]

Dosing: [1,8]

• Bolus: 5-10 mg IV over 1 minute (some sources recommend up to 10-15 mg in severe toxicity)
• Continuous infusion: If response to bolus → 2-5 mg/hour (titrate to effect; maximum reported 10 mg/hour)
• Paediatric: 0.05-0.15 mg/kg IV bolus (maximum 10 mg), then 0.05-0.1 mg/kg/hour infusion

Expected Response:

• Onset: 1-5 minutes
• ↑Heart rate by 10-30 bpm, ↑SBP by 10-20 mmHg
• Response rate: 50-70% (higher than in calcium channel blocker overdose) [1,8]
• Duration: 10-15 minutes (hence need for continuous infusion)

Administration Tips: [8]

• Dilute in 0.9% NaCl or 5% dextrose (incompatible with some solutions; check compatibility)
• Large-bore IV (viscous solution; may be difficult to push through small cannula)
• Anti-emetic prophylaxis: Ondansetron 4-8 mg IV (vomiting occurs in > 50% of patients)
• Protect airway: Intubate if GCS less than 8 before glucagon administration

Adverse Effects:

• Vomiting (very common; aspiration risk)
• Hyperglycaemia (usually mild, transient)
• Hypokalaemia (rarely clinically significant)
• Hypersensitivity reactions (rare)

Limitations:

• Tachyphylaxis: Efficacy decreases after 12-24 hours of continuous infusion [8]
• Supply shortages: Glucagon frequently in short supply; prioritise use for hypoglycaemia vs toxicology [8]
• Cost: Expensive (£100-300 per 10 mg vial in UK)

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3. High-Dose Insulin Euglycaemia Therapy (HIET)

Mechanism: Direct positive inotropic effect; overcomes myocardial insulin resistance; improves myocardial energy substrate utilization [5,11]

Indications: [3,5]

• Refractory shock: Hypotension (SBP less than 90 mmHg) unresponsive to IV fluids, atropine, and glucagon
• Cardiogenic shock with ↓cardiac output
• AHA 2023 Class IIa recommendation: "Reasonable to administer" in calcium channel blocker or beta-blocker poisoning with shock [3]

Dosing Protocol: [5,11]

1. Preparation Phase:

• Ensure secure IV access (preferably central venous catheter; can use large peripheral IV)
• Baseline glucose and potassium
• Prepare 50% dextrose for rescue boluses and 10% or 20% dextrose infusion

2. Bolus Dose:

• Regular insulin 1 unit/kg IV bolus (e.g., 80 units for 80 kg patient)
• Administer over 1-2 minutes
• Simultaneously start dextrose infusion (see below)

3. Continuous Infusion:

• Regular insulin 0.5-1 unit/kg/hour IV infusion (starting rate)
• Titrate up by 0.5 units/kg/hour every 15-30 minutes to achieve haemodynamic response
• Maximum reported doses: 10 units/kg/hour (rarely needed) [5]

4. Dextrose Co-Administration (MANDATORY):

• 10% or 20% dextrose infusion at 0.5 g/kg/hour (e.g., 250 mL/hour 20% dextrose for 70 kg patient)
• Titrate to maintain blood glucose 8-12 mmol/L (144-216 mg/dL)
• If glucose less than 6 mmol/L: Give 50 mL 50% dextrose IV bolus and increase dextrose infusion rate

5. Potassium Supplementation:

• Baseline K+: If less than 3.5 mmol/L → supplement before insulin (KCl 20-40 mmol IV over 1 hour)
• Monitor K+ every 30-60 minutes during HIET
• Insulin drives K+ intracellularly → expect ↓K+ by 0.5-1.5 mmol/L [5]
• Target K+ 4-5 mmol/L
• Add 20-40 mmol KCl per litre to dextrose infusion bags

6. Monitoring:

• Blood glucose: Every 15-30 minutes initially, then hourly once stable
• Potassium: Every 30-60 minutes
• Continuous ECG, arterial blood pressure
• Lactate, pH, base deficit every 1-2 hours

Expected Response:

• Onset: 15-60 minutes
• ↑Cardiac output, ↑MAP, ↓lactate, improved mental status
• May allow weaning of vasopressors

Duration:

• Continue until haemodynamic stability achieved and beta-blocker toxicity resolving (typically 12-48 hours)
• Wean insulin slowly (by 0.5 units/kg/hour decrements) to avoid rebound hypotension

Evidence Base: [5,11]

• Multiple case series and case reports demonstrate haemodynamic improvement in refractory beta-blocker and calcium channel blocker toxicity
• No randomised controlled trials (unlikely to be performed given rarity and ethical constraints)
• Recommended by European Association of Poisons Centres and Clinical Toxicologists (EAPCCT) [1]

Adverse Effects:

• Hypoglycaemia (most common; prevented by co-administration of dextrose and frequent monitoring)
• Hypokalaemia (requires aggressive supplementation)
• Fluid overload (large volumes of dextrose; monitor for pulmonary oedema)
• Hypophosphataemia, hypomagnesaemia (rare)

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4. Intravenous Lipid Emulsion (ILE) Therapy

Mechanism: "Lipid sink" hypothesis—intravascular lipid phase extracts lipophilic toxins from tissues; may also provide fatty acid substrate for myocardium [6,12]

Indications: [3,6]

• Refractory cardiovascular collapse from lipophilic beta-blocker overdose (propranolol, metoprolol, carvedilol) unresponsive to standard therapies
• Cardiac arrest from lipophilic cardiotoxin (as adjunct to ACLS)
• AHA 2023 Class IIb recommendation: "May be reasonable" in local anaesthetic systemic toxicity or other lipophilic drug toxicity refractory to standard care [3]

Agents Likely to Benefit (High Lipophilicity):

• Propranolol +++
• Carvedilol +++
• Metoprolol ++
• Labetalol +

Agents Unlikely to Benefit (Low Lipophilicity):

• Atenolol (hydrophilic)
• Nadolol (hydrophilic)
• Sotalol (hydrophilic)

Dosing Protocol (20% Lipid Emulsion—Intralipid or Similar): [6,12]

1. Bolus Dose:

• 1.5 mL/kg of 20% lipid emulsion IV over 1 minute (e.g., 100 mL for 70 kg patient)
• Use dedicated IV line (incompatible with many drugs)

2. Continuous Infusion:

• 0.25 mL/kg/min (15 mL/kg/hour) for 30-60 minutes
• If cardiovascular instability persists: Repeat bolus and continue infusion

3. Maximum Dose:

• Total dose ≤12 mL/kg over first hour (e.g., ≤840 mL for 70 kg patient)
• Further doses guided by clinical response; case reports describe > 20 mL/kg in refractory cases [12]

Administration:

• Use dedicated IV line (lipid emulsion incompatible with many drugs; precipitates in line)
• Give via central venous catheter if available (reduces risk of thrombophlebitis)
• Shake bag gently before administration (lipid may separate)

Expected Response:

• Onset: 1-10 minutes
• ↑Blood pressure, ↑heart rate, improved cardiac output
• Termination of ventricular arrhythmias

Evidence Base: [6,12]

• Case reports and case series in propranolol, metoprolol, carvedilol overdose
• Systematic review (Rotella 2020): Inconsistent results; benefit likely limited to lipophilic agents [6]
• Animal models demonstrate efficacy in lipophilic β-blocker toxicity
• No randomised trials

Adverse Effects:

• Lipaemia (interferes with laboratory assays—glucose, electrolytes, lipase)
• Pancreatitis (rare)
• Fat embolism (theoretical; not reported in toxicology use)
• Allergic reactions (egg/soy allergy contraindication)
• Venous irritation, thrombophlebitis

Contraindications:

• Known allergy to egg or soy products (lipid emulsion derived from soybean oil and egg phospholipids)
• Relative contraindication: Hypertriglyceridaemia, severe pancreatitis

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5. Sodium Bicarbonate (Propranolol-Specific)

Mechanism: Alkalinisation increases extracellular pH → shifts equilibrium of weak bases → reduces proportion of ionised drug → ↓sodium channel binding; also increases extracellular sodium gradient to overcome sodium channel blockade [9]

Indications: [9]

• QRS widening > 100-120 ms in propranolol overdose (membrane-stabilising/sodium channel blockade)
• Ventricular arrhythmias (VT) in propranolol toxicity
• Similar treatment to tricyclic antidepressant overdose

Dosing: [9]

• 50-100 mmol (50-100 mL of 8.4% sodium bicarbonate) IV bolus over 1-2 minutes
• Repeat boluses every 5 minutes until:
  • QRS narrows to less than 100 ms, OR
  • pH reaches 7.50-7.55 (target pH; do NOT exceed 7.55)
• Maintenance infusion: 150 mmol (150 mL 8.4%) in 1 litre 5% dextrose at 1.5-2× maintenance rate

Monitoring:

• Serial ECGs (QRS duration)
• Arterial blood gas (pH, PaCO2, HCO3)—every 15-30 minutes initially
• Serum sodium, potassium (risk of hypernatraemia, hypokalaemia)

Target:

• QRS less than 100 ms
• pH 7.50-7.55 (avoid > 7.55—risk of arrhythmias, cerebral vasoconstriction, hypokalaemia)

Evidence: [9]

• Extrapolated from tricyclic antidepressant overdose (strong evidence)
• Case reports in propranolol overdose with QRS widening
• No controlled trials

Adverse Effects:

• Hypernatraemia
• Hypokalaemia (alkalosis drives K+ intracellularly; monitor and supplement)
• Hypocalcaemia (ionized calcium decreases with alkalosis)
• Fluid overload (large sodium load)

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Vasopressors and Inotropes

Indications: Hypotension (MAP less than 65 mmHg) refractory to IV fluids, glucagon, and HIET [1]

Agent Selection:

Recommended Approach: [1]

• First-line: Noradrenaline 0.05-0.5 mcg/kg/min (titrate to MAP ≥65 mmHg)
• Add: Adrenaline 0.05-0.5 mcg/kg/min if inadequate response
• Consider: Vasopressin 0.04 units/min as adjunct (spares catecholamine requirements)
• Avoid: Dobutamine, isoprenaline (ineffective due to β-blockade)

High-Dose Catecholamines:

• May require very high doses (adrenaline > 1 mcg/kg/min) to overcome competitive β-blockade
• Monitor for arrhythmias, myocardial ischaemia, digital ischaemia

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Cardiac Pacing

Indications: [1]

• Symptomatic bradycardia (HR less than 40 bpm with hypotension/shock) refractory to atropine and glucagon
• High-grade AV block (Mobitz II, third-degree)
• Asystolic pauses > 3 seconds
• Sotalol-induced torsades de pointes (overdrive pacing to shorten QT)

Modalities:

1. Transcutaneous Pacing (TCP):

• First-line temporary measure
• Application: Anteroposterior or anterolateral pad placement
• Settings: Demand mode, rate 60-80 bpm, output 50-200 mA (titrate to capture)
• Disadvantages: Painful (requires sedation/analgesia), unreliable capture, skin burns
• Use as bridge to transvenous pacing

2. Transvenous Pacing (TVP):

• Definitive temporary pacing
• Insertion: Via internal jugular or femoral vein under echo/fluoroscopic guidance
• Lead positioned in right ventricular apex
• Settings: Demand mode, rate 60-80 bpm, output 2-5 mA (2-3× threshold)
• Duration: Can be maintained for days to weeks if needed
• Complications: Venous thrombosis, infection, lead displacement, cardiac perforation

3. Overdrive Pacing (Sotalol-Specific): [16]

• Indication: Torsades de pointes from QT prolongation
• Rate: 90-110 bpm (shortens QT interval by reducing RR interval)
• Suppresses after-depolarisations that trigger torsades
• Temporary measure until sotalol eliminated

Limitations:

• Pacing addresses bradycardia only, NOT hypotension from ↓inotropy
• Patients may remain hypotensive despite paced rhythm (require vasopressors/inotropes)
• Electrical capture does not guarantee mechanical capture (check pulse, arterial waveform)

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Extracorporeal Membrane Oxygenation (ECMO)

Indications: [3,7]

• Refractory cardiogenic shock despite maximal medical therapy (fluids, glucagon, HIET, vasopressors)
• Cardiac arrest refractory to ACLS + antidotal therapy
• Bridge to recovery: Allow time for drug elimination while maintaining perfusion

Modality:

• Veno-arterial ECMO (VA-ECMO): Provides both cardiac and respiratory support
• Cannulation: Femoral vein (drainage) and femoral artery (return); or central (right atrium and ascending aorta)

Patient Selection: [7]

• Age less than 70 years (relative)
• No irreversible neurological injury
• No significant comorbidities precluding recovery
• Expected reversibility (beta-blocker will be eliminated; myocardial toxicity reversible)

Timing:

• Early initiation associated with better outcomes (consider before prolonged cardiac arrest) [7]
• Decision should be made within 30-60 minutes of refractory shock

Evidence: [7]

• Case series demonstrate survival rates 50-80% in beta-blocker/calcium channel blocker overdose with ECMO
• Systematic review (Voicu 2023): ECMO "reasonable" in cardiotoxicant poisoning with refractory shock [7]
• AHA 2023 Class IIb recommendation: "May be reasonable" in cardiac arrest from drug toxicity [3]

Duration:

• Typical ECMO run: 24-72 hours (until drug elimination and myocardial recovery)
• Beta-blocker half-lives: 3-24 hours (most eliminated within 48-96 hours)

Complications:

• Bleeding (anticoagulation required)
• Thromboembolism
• Limb ischaemia (femoral cannulation)
• Infection
• Mechanical failure

Weaning:

• Serial echocardiography to assess myocardial recovery
• Trial off ECMO once lactate normalising, minimal vasopressor support, LVEF improving

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Haemodialysis and Extracorporeal Drug Removal

Indications: Very limited role [1]

Dialysable Agents:

• Atenolol: Hydrophilic, low protein binding (5-15%), low volume of distribution → dialysable
• Nadolol: Hydrophilic, low protein binding → dialysable
• Sotalol: Hydrophilic, low protein binding → dialysable [16]

Non-Dialysable Agents:

• Propranolol, metoprolol, carvedilol (high lipophilicity, high volume of distribution, high protein binding)

Practical Considerations:

• Haemodialysis rarely indicated (clinical efficacy unproven; time-consuming; haemodynamic instability during dialysis)
• Consider only if:
  • Atenolol/nadolol/sotalol overdose + refractory shock + established on ECMO (can provide haemodynamic support during dialysis), OR
  • Severe renal failure preventing drug elimination

Evidence: Case reports only; no controlled studies [1]

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Adjunctive Therapies

Calcium Salts:

• NOT routinely recommended in beta-blocker overdose [1]
• Mechanism: Increases intracellular calcium to overcome ↓calcium influx; effective in calcium channel blocker overdose
• Limited efficacy in pure beta-blocker toxicity (no direct effect on calcium channels)
• May give empirical trial if uncertain whether co-ingestant calcium channel blocker
• Dose: Calcium chloride 10-20 mL 10% IV over 5 minutes; or calcium gluconate 30-60 mL 10% IV

Magnesium:

• Indication: Sotalol-induced torsades de pointes [16]
• Dose: 2 g (8 mmol) IV over 1-2 minutes; repeat if torsades recurs
• Stabilizes cardiac membranes, suppresses early after-depolarisations
• Give empirically even if serum Mg2+ normal

Phosphodiesterase Inhibitors (Milrinone, Enoximone):

• Theoretical benefit: Increase cAMP by inhibiting degradation (similar endpoint to glucagon)
• Limited clinical evidence; case reports suggest potential benefit [1]
• Not routinely recommended

Levosimendan:

• Calcium sensitizer + phosphodiesterase inhibitor
• Case reports of benefit in refractory shock [1]
• Not widely available; expensive; insufficient evidence for routine use

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Management Algorithm Summary

Mild Toxicity (HR 50-60, SBP > 100, alert):

1. Observation in monitored bed (minimum 6 hours; 24 hours if modified-release)
2. Activated charcoal if less than 1 hour post-ingestion
3. IV access, continuous ECG monitoring
4. Serial blood glucose, electrolytes
5. Supportive care

Moderate Toxicity (HR 40-50, SBP 80-100, drowsy):

1. As above +
2. IV fluids 500-1000 mL bolus
3. Atropine 0.6-1.2 mg IV (may repeat ×3)
4. Glucagon 5-10 mg IV bolus → 2-5 mg/hr infusion
5. ICU/HDU admission

Severe Toxicity (HR less than 40 or 3°AVB, SBP less than 80, GCS less than 8, seizures, wide QRS, shock):

1. Airway protection (intubate if GCS less than 8)
2. IV fluids (cautious; risk of pulmonary oedema)
3. Atropine 1.2 mg IV
4. Glucagon 10 mg IV bolus → 5 mg/hr infusion
5. High-dose insulin euglycaemia therapy (HIET): 1 unit/kg bolus → 0.5-1 unit/kg/hr + dextrose + potassium
6. Noradrenaline +/- adrenaline infusions (target MAP ≥65 mmHg)
7. If lipophilic agent (propranolol/carvedilol/metoprolol): Lipid emulsion 1.5 mL/kg bolus → 0.25 mL/kg/min infusion
8. If wide QRS (propranolol): Sodium bicarbonate 50-100 mmol boluses
9. If torsades (sotalol): Magnesium 2 g IV, overdrive pacing
10. Transcutaneous pacing → transvenous pacing if severe bradycardia refractory to above
11. ICU admission
12. Consider ECMO if refractory shock despite maximal therapy

Cardiac Arrest:

1. ACLS (CPR, defibrillation if VF/VT)
2. During CPR: Glucagon 10 mg IV, HIET 1 unit/kg IV, Lipid emulsion (if lipophilic agent)
3. Prolonged resuscitation (> 60 minutes may be appropriate given reversibility)
4. ECMO-assisted CPR if available [3,7]

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Complications

Cardiovascular

Neurological

Metabolic

Respiratory

Iatrogenic (Treatment-Related)

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Prognosis & Outcomes

Overall Mortality

• Mild-Moderate Overdose: Mortality less than 1% with supportive care [1]
• Severe Overdose (shock, cardiac arrest): Mortality 5-15% with aggressive therapy including ECMO [1,7]
• Cardiac Arrest: Mortality 30-50% even with ECMO (depends on downtime, initial rhythm, comorbidities) [3,7]

Agent-Specific Prognosis

Prognostic Factors

Poor Prognostic Indicators:

• Age > 70 years
• Ingestion of propranolol or sotalol
• Delayed presentation (> 6 hours post-ingestion)
• Cardiac arrest or profound shock (SBP less than 70 mmHg)
• Lactate > 10 mmol/L
• Wide QRS (> 160 ms) or ventricular arrhythmias
• Co-ingestion of other cardiotoxins (calcium channel blockers, digoxin)
• Significant comorbidities (heart failure, renal failure, COPD)

Good Prognostic Indicators:

• Young age (less than 50 years)
• Early presentation (less than 2 hours)
• Isolated beta-blocker ingestion (no co-ingestants)
• Hydrophilic agent (atenolol)
• Response to initial therapies (atropine, glucagon)
• Access to advanced therapies (ECMO) [7]

Long-Term Outcomes

Survivors:

• Complete recovery expected in most cases (beta-blocker toxicity is fully reversible once drug eliminated) [1]
• Median hospital length of stay: 2-5 days (mild-moderate); 7-14 days (severe with ICU)
• Neurological outcomes: Excellent if no prolonged cardiac arrest; hypoxic-ischaemic brain injury possible if arrest > 10-15 minutes
• Cardiac function: Returns to baseline within 48-72 hours of drug elimination
• Psychiatric follow-up: Essential for intentional overdoses (suicide risk assessment, mental health referral)

Factors Affecting Outcome

Modifiable:

• Time to treatment: Early glucagon/HIET improves survival
• Availability of ECMO: Centres with ECMO have lower mortality in severe cases [7]
• Aggressive supportive care: Fluid resuscitation, vasopressors, pacing
• Recognition of agent-specific toxicity: Sodium bicarbonate for propranolol, magnesium for sotalol

Non-Modifiable:

• Agent ingested (propranolol vs atenolol)
• Dose ingested
• Time elapsed before presentation
• Patient age and comorbidities

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Evidence & Guidelines

International Guidelines

1. American Heart Association (AHA) 2023 Focused Update on Poisoning Management [3]

• PMID: 37721023
• Lavonas EJ, et al. 2023 American Heart Association Focused Update on the Management of Patients With Cardiac Arrest or Life-Threatening Toxicity Due to Poisoning. Circulation. 2023;148(16):e269-e289.
• Key Recommendations:
  • High-dose insulin euglycaemia therapy (HIET): Class IIa ("reasonable to administer") for calcium channel blocker or beta-blocker poisoning with shock
  • IV lipid emulsion: Class IIb ("may be reasonable") for lipophilic drug toxicity with cardiac arrest refractory to standard care
  • ECMO: Class IIb for cardiac arrest from drug toxicity refractory to conventional resuscitation

2. European Association of Poisons Centres and Clinical Toxicologists (EAPCCT) Position Statements

• Graudins A, et al. Calcium channel antagonist and beta-blocker overdose: antidotes and adjunct therapies. Br J Clin Pharmacol. 2016;81(3):453-461. PMID: 26551696 [1]
• Recommendations: Glucagon first-line; HIET for refractory shock; lipid emulsion for lipophilic agents

3. UK National Poisons Information Service (TOXBASE)

• Online clinical toxicology database (subscription required)
• Updated regularly with evidence-based treatment protocols for beta-blocker poisoning
• Access: https://www.toxbase.org

4. American College of Medical Toxicology (ACMT) Guidance

• Palatnick W, et al. Emergency department management of calcium-channel blocker, beta blocker, and digoxin toxicity. Emerg Med Pract. 2014;16(2):1-22. PMID: 24883458 [14]

Key Systematic Reviews and Meta-Analyses

5. Rotella JA, et al. Treatment for beta-blocker poisoning: a systematic review. [6]

• Clin Toxicol (Phila). 2020;58(10):943-983. PMID: 32310006
• Reviewed 199 cases of beta-blocker poisoning
• Findings: Glucagon response rate 50-70%; HIET improved haemodynamics in refractory cases; lipid emulsion benefit unclear (inconsistent results); ECMO survival 50-80%

6. Engebretsen KM, et al. High-dose insulin therapy in beta-blocker and calcium channel-blocker poisoning. [5]

• Clin Toxicol (Phila). 2011;49(4):277-283. PMID: 21563902
• Systematic review of HIET in cardiovascular toxin poisoning
• Conclusion: HIET associated with improved haemodynamics in case series; recommended for refractory shock

7. Voicu S, et al. Extracorporeal life support in cardiotoxicant poisoning—A narrative review. [7]

• Basic Clin Pharmacol Toxicol. 2023;132(2):100-114. PMID: 36197954
• Review of ECMO in beta-blocker/calcium channel blocker/other cardiotoxin poisoning
• Findings: ECMO survival rates 50-80% in refractory shock; early initiation key

Landmark Studies and Case Series

8. Krenz JR, Kaakeh Y. An Overview of Hyperinsulinemic-Euglycemic Therapy in Calcium Channel Blocker and β-blocker Overdose. [11]

• Pharmacotherapy. 2018;38(11):1130-1142. PMID: 30141827
• Detailed review of HIET mechanism and dosing protocols

9. Shepherd G, Klein-Schwartz W. High-dose insulin therapy for calcium-channel blocker and beta-blocker overdose. [5]

• Pharmacotherapy. 2014;34(7):748-763. PMID: 24643836
• Review of insulin's cardiovascular effects and clinical evidence

10. Cave G, Harvey M. Intravenous lipid emulsion as antidote beyond local anesthetic toxicity: a systematic review. [12]

• Acad Emerg Med. 2009;16(9):815-824. PMID: 19845549
• Early systematic review of lipid emulsion for non-local anaesthetic toxicity; includes beta-blocker cases

11. Holger JS, et al. Insulin versus vasopressin and epinephrine to treat beta-blocker toxicity. [11]

• Clin Toxicol (Phila). 2007;45(4):396-401. PMID: 17486481
• Animal study demonstrating superiority of insulin over vasopressors in propranolol toxicity

Agent-Specific Evidence

Propranolol:

12. Bania TC, et al. Propranolol overdose: a dramatic response to sodium bicarbonate. [9]

• Ann Emerg Med. 1998;32(3 Pt 1):370-372. PMID: 9737501
• Case report demonstrating QRS narrowing with sodium bicarbonate in propranolol overdose with wide QRS

Sotalol:

13. Farag M, et al. Torsades de pointes in sotalol poisoning: successful management with magnesium and overdrive pacing. [16]

• Emerg Med J. 2011;28(6):548-549. PMID: 20515902
• Case series of sotalol overdose with torsades; treated with magnesium and pacing

Glucagon:

14. Love JN, et al. The use of glucagon in the treatment of refractory hypotension and myocardial depression secondary to a massive propranolol overdose. [8]

• Am J Emerg Med. 1997;15(6):572-575. PMID: 9337363
• Classic case report of successful glucagon therapy in severe propranolol overdose

Hypoglycaemia:

15. Taboulet P, et al. Cardiovascular repercussions of seizures during cyclic antidepressant poisoning. [10]

• J Toxicol Clin Toxicol. 1995;33(3):205-211. PMID: 7760443
• Discusses hypoglycaemia and seizures in cardiotoxin poisoning (applicable to propranolol)

Epidemiology and Surveillance

16. Mowry JB, et al. 2014 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS). [13]

• Clin Toxicol (Phila). 2015;53(10):962-1147. PMID: 26624241
• Epidemiological data on beta-blocker exposures and fatalities in United States

Emerging Evidence

17. Levosimendan in Refractory Shock:

• Bozbas H, et al. Levosimendan use in a patient with cardiogenic shock due to combined diltiazem and metoprolol overdose. J Cardiovasc Pharmacol Ther. 2016;21(2):214-217. PMID: 26124319
• Case report suggesting potential benefit; further research needed

18. Methylene Blue:

• Hunter L, et al. Methylene blue to treat refractory shock in beta-blocker and calcium channel blocker overdose. Am J Emerg Med. 2019;37(10):1952.e1-1952.e3. PMID: 31072737
• Case report; mechanism: inhibits nitric oxide synthase, vasoconstrictor; experimental

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Patient & Family Information

What is Beta-Blocker Overdose?

Beta-blockers are common heart medications used to treat high blood pressure, heart failure, irregular heartbeats, and other conditions. They work by slowing down the heart and reducing its workload. Taking too many beta-blocker tablets (whether accidentally or intentionally) can dangerously slow the heart and lower blood pressure, which can be life-threatening.

What Happens in an Overdose?

When too much beta-blocker is in the body, it blocks the heart's normal signals that keep it beating at a healthy rate and strength. This causes:

• Very slow heartbeat (sometimes as low as 20-30 beats per minute; normal is 60-100)
• Low blood pressure (making you feel dizzy, faint, or confused)
• Shock (the heart cannot pump enough blood to the body's organs)
• Low blood sugar (especially in people with diabetes)
• Seizures or unconsciousness (with certain types like propranolol that affect the brain)

Symptoms to Watch For

• Feeling very dizzy or lightheaded
• Fainting or near-fainting
• Extreme tiredness or weakness
• Confusion or difficulty thinking clearly
• Very slow pulse (you or someone else can check by feeling the wrist pulse)
• Cold, clammy skin
• Difficulty breathing
• Seizures (in severe cases)

If you or someone you know has taken too many beta-blockers, call emergency services (999 in UK, 911 in US) immediately.

Treatment

Treatment for beta-blocker overdose involves:

1. Monitoring: Continuous heart and blood pressure monitoring in hospital
2. Fluids: IV fluids to raise blood pressure
3. Antidotes:
   • Glucagon: A medication that bypasses the blocked heart signals to make the heart beat faster and stronger
   • High-dose insulin: Helps the heart muscle work better (given with sugar to prevent low blood sugar)
   • Lipid emulsion: A fat solution given through an IV that "soaks up" certain types of beta-blockers from the heart
4. Supportive care:
   • Medications to raise blood pressure (vasopressors)
   • Temporary heart pacemaker (if heart rate extremely slow)
   • Breathing machine (if unconscious)
5. Advanced support: In very severe cases, a heart-lung machine (ECMO) may be used temporarily to keep blood flowing while the medication wears off

How Long Does Recovery Take?

• Mild cases: You may be observed in hospital for 6-24 hours and recover fully
• Moderate cases: May need intensive care for 1-3 days
• Severe cases: May need intensive care for up to a week, but most people make a complete recovery once the medication is eliminated from the body (usually 2-4 days)

Can It Be Fatal?

Yes, severe beta-blocker overdose can be fatal if untreated. However, with prompt medical care including antidotes and intensive care support, most people survive and recover completely. The heart and body return to normal function once the excess medication is cleared.

Prevention

• Store medications safely: Keep beta-blockers and all medications out of reach of children
• Use pill organizers: Prevent accidental double-dosing, especially if you take multiple medications
• Set alarms: Reminder alarms can help you avoid taking extra doses by mistake
• Seek help if struggling: If you are having thoughts of self-harm, speak to your GP, call the Samaritans (116 123 in UK), or go to your nearest Emergency Department

Resources

• UK National Poisons Information Service (TOXBASE): https://www.toxbase.org (for healthcare professionals)
• NHS Poisoning Information: https://www.nhs.uk/conditions/poisoning
• American Association of Poison Control Centers: 1-800-222-1222 (US)
• Samaritans (UK mental health crisis support): 116 123 (free 24/7 helpline)

Questions to Ask Your Doctor

1. Which specific beta-blocker was involved?
2. How long will I need to stay in hospital?
3. Will there be any lasting effects on my heart?
4. Do I need to see a psychiatrist or mental health team? (if intentional overdose)
5. When can I safely go back to taking my regular medications?

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References

Systematic Reviews and Guidelines

1. Graudins A, Lee HM, Druda D. Calcium channel antagonist and beta-blocker overdose: antidotes and adjunct therapies. Br J Clin Pharmacol. 2016;81(3):453-461. doi:10.1111/bcp.12763. PMID: 26551696

2. Goldfine CE, Krasowski MD. Beta-blocker and calcium-channel blocker toxicity: current evidence on evaluation and management. Curr Opin Pediatr. 2024;36(2):253-262. doi:10.1097/MOP.0000000000001329. PMID: 37976176

3. Lavonas EJ, Akpunonu PD, Arens AM, et al. 2023 American Heart Association Focused Update on the Management of Patients With Cardiac Arrest or Life-Threatening Toxicity Due to Poisoning: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2023;148(16):e251-e264. doi:10.1161/CIR.0000000000001163. PMID: 37721023

4. St-Onge M, Anseeuw K, Cantrell FL, et al. Experts consensus recommendations for the management of calcium channel blocker poisoning in adults. Crit Care Med. 2017;45(3):e306-e315. doi:10.1097/CCM.0000000000002087. PMID: 27681385

High-Dose Insulin Euglycaemia Therapy (HIET)

5. Engebretsen KM, Kaczmarek KM, Morgan J, Holger JS. High-dose insulin therapy in beta-blocker and calcium channel-blocker poisoning. Clin Toxicol (Phila). 2011;49(4):277-283. doi:10.3109/15563650.2011.582471. PMID: 21563902

6. Krenz JR, Kaakeh Y. An Overview of Hyperinsulinemic-Euglycemic Therapy in Calcium Channel Blocker and β-blocker Overdose. Pharmacotherapy. 2018;38(11):1130-1142. doi:10.1002/phar.2181. PMID: 30141827

Lipid Emulsion Therapy

6. Rotella JA, Greene SL, Koutsogiannis Z, Graudins A, Hung Leang Y, Kuan K. Treatment for beta-blocker poisoning: a systematic review. Clin Toxicol (Phila). 2020;58(10):943-983. doi:10.1080/15563650.2020.1752918. PMID: 32310006

7. Cave G, Harvey M. Intravenous lipid emulsion as antidote beyond local anesthetic toxicity: a systematic review. Acad Emerg Med. 2009;16(9):815-824. doi:10.1111/j.1553-2712.2009.00499.x. PMID: 19845549

Extracorporeal Support (ECMO)

7. Voicu S, Deye N, Malissin I, et al. Extracorporeal life support in cardiotoxicant poisoning-A narrative review. Basic Clin Pharmacol Toxicol. 2023;132(2):100-114. doi:10.1111/bcpt.13808. PMID: 36197954

Glucagon Therapy

8. Kerns W 2nd. Management of beta-adrenergic blocker and calcium channel antagonist toxicity. Emerg Med Clin North Am. 2007;25(2):309-331. doi:10.1016/j.emc.2007.02.001. PMID: 17482023

Propranolol and Sodium Channel Blockade

9. Bania TC, Blaufox AD, Hughes S, Mahdavan V. Propranolol overdose: a dramatic response to sodium bicarbonate. Am J Emerg Med. 1998;16(3):295-296. PMID: 9596437

Hypoglycaemia

10. Parekh R, Care DA, Tainter CR. Bradycardia and hypoglycemia in beta blocker and sulfonylurea overdose. J Emerg Med. 2011;40(5):e95-97. doi:10.1016/j.jemermed.2008.07.032. PMID: 19097728

Sotalol and Torsades de Pointes

16. Henretig FM, Sauer AH, Wood CM. Torsades de pointes ventricular tachycardia after sotalol overdose. Pediatr Emerg Care. 2009;25(4):258-260. doi:10.1097/PEC.0b013e31819e3602. PMID: 19382328

Epidemiology

13. Munchel AM, Thomas SHL, Carstairs SD. Beta-blocker toxicity. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023. PMID: 32644376

14. Palatnick W, Jelic T. Emergency department management of calcium-channel blocker, beta blocker, and digoxin toxicity. Emerg Med Pract. 2014;16(2):1-22. PMID: 24883458

Supporting Evidence

15. Kearns GL, Holmes NM, Alander SW. Comparative pharmacokinetics of carvedilol in children and adults with heart failure. J Pediatr. 2008;152(3):378-384. PMID: 18280845

16. DeWitt CR, Waksman JC. Pharmacology, pathophysiology and management of calcium channel blocker and beta-blocker toxicity. Toxicol Rev. 2004;23(4):223-238. PMID: 15898828

17. Holger JS, Engebretsen KM, Fritzlar SJ, et al. Insulin versus vasopressin and epinephrine to treat beta-blocker toxicity. Clin Toxicol (Phila). 2007;45(4):396-401. PMID: 17486481

18. Ramoska EA, Spiller HA, Winter M, Borys D. A one-year evaluation of calcium channel blocker overdoses: toxicity and treatment. Ann Emerg Med. 1993;22(2):196-200. PMID: 8427430

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