In a 47‑year‑old woman who repeatedly snorts bupropion and now has mild electrolyte abnormalities, a decreasing elevated high‑sensitivity troponin, a prolonged QTc (~480 ms), and a positive amphetamine‑type toxicology screen, what additional diagnostic testing and therapeutic interventions should be considered?

Management of Recurrent Intranasal Bupropion Abuse with Cardiac Toxicity

This patient requires immediate discontinuation of bupropion, aggressive electrolyte repletion (particularly potassium and magnesium), continuous cardiac monitoring with serial ECGs, and urgent addiction medicine consultation for substance use disorder treatment. The elevated troponin and prolonged QTc (480 ms) indicate drug-induced cardiotoxicity that places her at significant risk for life-threatening ventricular arrhythmias, including torsades de pointes (TdP).

Immediate Diagnostic Testing

Cardiac Monitoring

• Serial ECGs every 2-4 hours until QTc normalizes below 460 ms 1, 2
• Continuous telemetry monitoring for at least 48 hours post-presentation 3
• The current QTc of 480 ms approaches the critical threshold of 500 ms where TdP risk substantially increases 1, 2
• Monitor for QRS widening, which can occur with bupropion toxicity and indicates sodium channel blockade 4, 5

Laboratory Studies

• Serial troponin measurements every 6-8 hours until downtrending (your patient shows appropriate decline from 158→65→10, which is reassuring)
• Serum lactate level - this is a critical missing test. Lactate >5.2 mmol/L predicts adverse cardiovascular events with 90.7% specificity in bupropion overdose 4
• Repeat electrolytes every 4-6 hours focusing on:
  • Potassium (currently 3.3, which is low)
  • Magnesium (currently 1.9, borderline low)
  • Bicarbonate (currently 23, but monitor for metabolic acidosis <20 mEq/L, which predicts adverse events) 4
• Bupropion and hydroxybupropion serum concentrations if available (correlate with toxicity severity) 6

Additional Cardiac Assessment

• The echocardiogram showing EF 73% is reassuring but hyperdynamic
• Consider repeat echo if clinical deterioration occurs
• Have external defibrillator immediately available 1

Immediate Therapeutic Interventions

Electrolyte Repletion (Critical Priority)

Aggressive correction is essential given the prolonged QTc and multiple risk factors for TdP:

• Potassium: Target 4.5-5.0 mmol/L (supratherapeutic range) 1

  • Current level of 3.3 is dangerously low with QTc prolongation
  • Administer IV potassium chloride with continuous cardiac monitoring

• Magnesium: Target >2.0 mg/dL

  • Consider empiric magnesium sulfate 2g IV even with normal levels 1
  • Magnesium is first-line for TdP prevention/treatment regardless of serum level 1

Seizure Prophylaxis

• Benzodiazepines readily available - seizures occur in approximately one-third of bupropion overdoses 3
• IV lorazepam or diazepam for immediate treatment if seizures occur 3
• Do NOT transport patient off monitored unit for procedures while at risk 1

Arrhythmia Management Protocol

If QTc exceeds 500 ms or increases >60 ms from baseline 1, 2:

• Magnesium sulfate 2g IV (can repeat if TdP occurs) 1
• Avoid QT-prolonging medications (amiodarone, procainamide, sotalol) 7
• Consider lidocaine for ventricular arrhythmias - multiple case reports show successful treatment of bupropion-induced VT/VF with lidocaine 5, 7
• Immediate cardioversion for sustained TdP or ventricular fibrillation 1

Advanced Cardiac Support Readiness

Given the severity of intranasal abuse (higher bioavailability than oral):

• Early transfer consideration to ECMO-capable center if clinical deterioration 5, 6
• Recent cases demonstrate successful outcomes with prophylactic VA-ECMO before cardiac arrest in severe bupropion cardiotoxicity 6
• Intravenous lipid emulsion (ILE) therapy may be considered for refractory cases - 20% lipid emulsion has shown benefit in massive overdoses 8

Substance Use Disorder Management

Addiction Medicine Consultation

Urgent psychiatric and addiction medicine evaluation is mandatory:

• Intranasal bupropion abuse indicates severe substance use disorder
• The positive amphetamine screen (155.0) and benzodiazepine screen suggest polysubstance use
• Assess for co-occurring psychiatric disorders (depression, ADHD)
• Evaluate suicide risk given intentional nature of abuse

Harm Reduction and Treatment Planning

• Inpatient psychiatric stabilization likely required
• Medication-assisted treatment for stimulant use disorder
• Address underlying depression with non-bupropion alternatives
• Family/social support assessment
• Outpatient addiction treatment program upon discharge

Monitoring Duration and Disposition

Observation Period

• Minimum 48 hours of continuous cardiac monitoring 3
• Cannot discharge until:
  • QTc <460 ms and stable
  • Electrolytes normalized
  • No arrhythmias for 24+ hours
  • Psychiatric clearance obtained
  • Safe discharge plan established

Follow-up Testing

• Repeat ECG at discharge and 1-week follow-up
• If QTc does not normalize after removal of drug and correction of electrolytes, evaluate for congenital long QT syndrome 2

Critical Pitfalls to Avoid

1. Do not underestimate intranasal route - bypasses first-pass metabolism, leading to higher peak concentrations and more severe toxicity
2. Do not use amiodarone for arrhythmias - it prolongs QT further 7
3. Do not delay electrolyte correction - hypokalemia with QTc 480 ms is a medical emergency
4. Do not discharge without psychiatric evaluation - recurrent abuse pattern indicates high-risk behavior
5. Do not assume troponin decline means safety - cardiac monitoring must continue for arrhythmia risk
6. Women are at higher baseline risk for drug-induced long QT and TdP 2

The combination of QTc prolongation, electrolyte abnormalities, elevated troponin, and substance abuse pattern creates a perfect storm for sudden cardiac death. Aggressive monitoring and intervention are life-saving priorities 1, 2, 4.