Is it safe to combine Fluvoxamine (Luvox) and Vyvanse (Lisdexamfetamine)?

Combining Fluvoxamine (Luvox) and Vyvanse (Lisdexamfetamine): Safety Considerations

Caution is advised when combining fluvoxamine and lisdexamfetamine due to potential drug interactions and increased risk of serotonin syndrome, requiring careful dosing, monitoring, and awareness of potential adverse effects. 1

Potential Interactions and Risks

• Fluvoxamine is known to have substantial pharmacological interactions with many medications due to its inhibitory effects on multiple cytochrome P450 enzymes, including CYP1A2, CYP2C19, CYP2C9, CYP3A4, and CYP2D6 1

• When combining serotonergic drugs (like fluvoxamine) with stimulants (like lisdexamfetamine/Vyvanse), there is an increased risk of serotonin syndrome, which can manifest as mental status changes, neuromuscular hyperactivity, and autonomic hyperactivity 1

• Serotonin syndrome symptoms can develop within 24-48 hours after combining medications and may include:

  • Mental status changes: confusion, agitation, anxiety
  • Neuromuscular symptoms: tremors, clonus, hyperreflexia, muscle rigidity
  • Autonomic symptoms: hypertension, tachycardia, arrhythmias, diaphoresis, shivering 1

• Advanced symptoms of serotonin syndrome can include fever, seizures, arrhythmias, and unconsciousness, which can potentially be fatal 1

Management Recommendations

• If this combination is deemed necessary:

  1. Start the second serotonergic drug (in this case, likely Vyvanse if adding to existing fluvoxamine therapy) at a low dose 1
  2. Increase the dose slowly and gradually 1
  3. Monitor closely for symptoms of serotonin syndrome, especially in the first 24-48 hours after dosage changes 1

• Fluvoxamine may alter the metabolism of lisdexamfetamine through its effects on CYP enzymes, potentially leading to higher-than-expected levels of the active amphetamine metabolite 1

• Consider therapeutic drug monitoring if available, as fluvoxamine has a recommended therapeutic range of 150-300 ng/mL 1

Special Considerations

• Patients with pre-existing cardiovascular conditions require additional caution, as both medications can affect heart rate and blood pressure 1

• The combination may potentially exacerbate anxiety or agitation, which can be initial adverse effects of SSRIs like fluvoxamine 1

• Fluvoxamine has been associated with discontinuation syndrome, so any future medication adjustments should involve slow tapering 1

Alternative Approaches

• If this combination is necessary for treating comorbid conditions, consider alternatives with fewer drug interactions:

  • Citalopram/escitalopram may have less effect on CYP450 isoenzymes compared to fluvoxamine 1
  • Non-stimulant ADHD medications might be considered if appropriate for the patient's condition 1

• Medical education, training, and experience are necessary to safely and effectively prescribe these medications in combination 1