What can be given to a patient with tachycardia, who is currently taking olanzapine (olanzapine) 10mg twice a day (bid)?

Management of Tachycardia in a Patient on Olanzapine 10mg BID

First, determine if this tachycardia represents hemodynamic instability requiring immediate cardioversion, or if the patient is stable enough for pharmacologic rate control—if the patient shows signs of shock, altered mental status, acute heart failure, or hypotension, proceed directly to synchronized cardioversion after sedation. 1

Initial Assessment and Stabilization

Before treating the tachycardia itself, you must determine whether this represents:

• Primary arrhythmia causing instability (requires immediate intervention)
• Secondary compensatory tachycardia from an underlying condition like dehydration, fever, or olanzapine toxicity (treat the cause) 1

Key clinical decision point: At heart rates of 122-125 bpm, symptoms are unlikely to be caused primarily by the tachycardia unless there is significant ventricular dysfunction—rates <150 bpm typically represent secondary tachycardia. 1

Critical First Steps

• Obtain a 12-lead ECG immediately to determine if this is narrow-complex (supraventricular) or wide-complex tachycardia, but do not delay treatment if the patient is unstable 1
• Assess for signs of instability: acute altered mental status, ischemic chest pain, acute heart failure, hypotension, or other signs of shock 1
• Provide supplemental oxygen and establish IV access 1
• Check olanzapine level if available, as toxic levels (>100 ng/mL) commonly cause tachycardia and other ECG abnormalities 2

If Patient is UNSTABLE (Immediate Action Required)

Proceed to immediate synchronized cardioversion after sedation in the conscious patient. 1

• Start with 100J, then 200J, then 360J if needed 1
• Have resuscitation equipment immediately available 1

If Patient is STABLE (Pharmacologic Management)

For Narrow-Complex Regular Tachycardia (Most Likely SVT)

First-line: Adenosine 6 mg IV rapid push followed by 20 mL saline flush; if no response after 1-2 minutes, give 12 mg IV push (can repeat 12 mg once more if needed). 1

• Critical caveat: Have a defibrillator immediately available, as adenosine may precipitate atrial fibrillation 1
• Contraindicated in asthma due to bronchospasm risk 1
• Adenosine will slow SVT and often allow identification of underlying rhythm, but has no effect on ventricular tachycardia 1

If adenosine fails or is contraindicated, use beta-blockers:

• Metoprolol 5 mg IV over 1-2 minutes, repeat every 5 minutes as needed to maximum 15 mg 1
• OR Esmolol (preferred if concerned about prolonged effects): 0.5 mg/kg IV loading dose over 1 minute, followed by 0.05 mg/kg/min infusion; can titrate up to 0.3 mg/kg/min 1

Avoid beta-blockers if: asthma, obstructive airway disease, decompensated heart failure, or pre-excited atrial fibrillation 1

Alternative: Calcium channel blockers (if beta-blockers contraindicated)

• Diltiazem 15-20 mg (0.25 mg/kg) IV over 2 minutes; can give additional 20-25 mg in 15 minutes if needed, followed by 5-15 mg/h maintenance infusion 1
• OR Verapamil 2.5-5 mg IV over 2 minutes; may repeat 5-10 mg every 15-30 minutes to total 20-30 mg 1

Critical warning: Only use calcium channel blockers for narrow-complex tachycardias; avoid in heart failure, pre-excited AF/flutter, or any rhythm consistent with VT 1

For Wide-Complex Tachycardia (Assume VT Until Proven Otherwise)

If hemodynamically stable monomorphic VT:

• Procainamide 20-50 mg/min until arrhythmia suppressed, hypotension develops, QRS widens by 50%, or total dose of 17 mg/kg given 1
• Avoid if QT prolongation or CHF present 1

Alternative: Amiodarone 150 mg IV over 10 minutes, can repeat if needed, followed by 1 mg/min infusion for 6 hours, then 0.5 mg/min (maximum 2.2 g/24 hours) 1

Special Considerations for Olanzapine-Induced Tachycardia

Olanzapine Toxicity Recognition

Olanzapine commonly causes tachycardia through multiple mechanisms:

• Sinus tachycardia is the most common ECG abnormality (22% of acute poisonings) 2
• QTc prolongation also occurs in 22% of cases, creating risk for torsades de pointes 2
• Atrial fibrillation can occur, though rare 3
• Hypotension and bradycardia paradoxically can occur, especially with rapid absorption 4

The dose of 10mg BID (20mg/day total) is at the upper end of the FDA-approved range, and maximal dosing is associated with substantial orthostatic hypotension. 5

Management Strategy for Olanzapine-Related Tachycardia

If tachycardia is secondary to olanzapine toxicity or side effects:

1. Hold the next olanzapine dose and reassess 5
2. Continuous ECG monitoring is mandatory due to risk of QTc prolongation and arrhythmias 2
3. Check orthostatic vital signs before any intervention, as olanzapine causes significant orthostatic hypotension 6, 7, 5
4. Supportive care with IV fluids if dehydrated or hypotensive 1
5. Consider dose reduction to 5-10 mg BID or switching to once-daily dosing 5

Common Pitfalls to Avoid

• Do not assume sinus tachycardia is benign—olanzapine can cause QTc prolongation leading to torsades de pointes, though this is rare 2
• Do not give verapamil for wide-complex tachycardia—it is contraindicated unless the rhythm is known to be supraventricular 1
• Do not use adenosine for irregular or polymorphic wide-complex tachycardia—it may cause degeneration to ventricular fibrillation 1
• Do not combine beta-blockers with calcium channel blockers—risk of profound bradycardia and hypotension 1
• Assess for orthostatic hypotension before giving additional intramuscular olanzapine if considering this route 5

When to Consult

Seek expert consultation if:

• Rhythm interpretation is uncertain 1
• Antiarrhythmic therapy fails 1
• Considering a second antiarrhythmic agent (contraindicated without expert input) 1
• Patient has prolonged QTc and you're considering procainamide or sotalol (both contraindicated) 1