Should you hold Dexedrine (dextroamphetamine) and Adderall (amphetamine and dextroamphetamine) in the presence of tachycardia?

Should You Hold Dexedrine and Adderall in the Presence of Tachycardia?

Yes, you should hold Dexedrine (dextroamphetamine) and Adderall (amphetamine/dextroamphetamine) when tachycardia is present, as these stimulants cause β-adrenergic receptor stimulation leading to increased heart rate and stroke volume, which will worsen existing tachycardia and potentially precipitate life-threatening arrhythmias.

Mechanism of Cardiovascular Risk

Amphetamines work by stimulating the release of norepinephrine, affecting both α- and β-adrenergic receptors 1:

• β-Adrenergic stimulation directly increases heart rate, stroke volume, and skeletal muscle blood flow 1
• α-Adrenergic stimulation causes vasoconstriction and increases total peripheral resistance 1
• These combined effects will exacerbate pre-existing tachycardia and increase myocardial oxygen demand

Clinical Evidence of Cardiovascular Toxicity

Documented cardiovascular complications from amphetamine medications include 2:

• Acute myocardial infarction
• Cardiac arrhythmias
• Sudden cardiac death
• Cardiomyopathy (with chronic abuse)

Acute toxicity presentations consistently demonstrate 1:

• Tachycardia as a primary clinical sign
• Tachypnea
• Hyperthermia
• Potential progression to seizures

Management Algorithm When Tachycardia is Present

Immediate Actions:

1. Discontinue the stimulant medication immediately 1
2. Assess hemodynamic stability - determine if the tachycardia is causing symptoms (altered mental status, chest pain, hypotension, acute heart failure) 3, 4
3. Obtain 12-lead ECG to differentiate the tachycardia mechanism 4

If Hemodynamically Unstable:

• Proceed directly to synchronized cardioversion (Class I recommendation) 3, 4
• Do not delay for pharmacologic interventions 4

If Hemodynamically Stable:

• Treat the tachycardia based on mechanism 4:
  • For SVT: vagal maneuvers, then adenosine, then AV nodal blockers 5, 4
  • For ventricular tachycardia: antiarrhythmic drugs or cardioversion 6
• Manage amphetamine toxicity supportively 1:
  • Intravenous fluids for hyperthermia and renal protection
  • Benzodiazepines for agitation or seizures
  • β-blockers (propranolol) for persistent tachyarrhythmias 1

Critical Caveats

Do not use AV nodal blocking agents (beta blockers, calcium channel blockers, adenosine, digoxin) if there is any suspicion of pre-excited atrial fibrillation or Wolff-Parkinson-White syndrome, as this may precipitate ventricular fibrillation 4, 3.

Avoid verapamil or diltiazem if ventricular tachycardia cannot be excluded, as this may cause hemodynamic collapse 4.

Long-Term Considerations

Before restarting stimulant therapy, you must 2:

• Identify and treat the underlying cause of tachycardia
• Ensure cardiovascular stability
• Consider alternative ADHD treatments if cardiovascular risk factors persist
• Recognize that adults with ADHD on CNS stimulants face greater cardiovascular risk than pediatric populations 2

Tolerance considerations: While some cardiovascular tolerance develops with chronic stimulant use in controlled therapeutic dosing 7, acute tachycardia represents either toxicity or an underlying cardiac condition that contraindicates continued use until fully evaluated.