Is it safe to combine Vyvanse (lisdexamfetamine) and Pristiq (desvenlafaxine)?

Safety of Combining Vyvanse (Lisdexamfetamine) and Pristiq (Desvenlafaxine)

The combination of Vyvanse (lisdexamfetamine) and Pristiq (desvenlafaxine) can be used together safely with appropriate monitoring, though caution is warranted due to potential additive effects on blood pressure and heart rate.

Pharmacological Considerations

• Lisdexamfetamine is a prodrug stimulant that is converted to dextroamphetamine after ingestion, used primarily for ADHD treatment 1
• Desvenlafaxine is a serotonin-norepinephrine reuptake inhibitor (SNRI) and is the active metabolite of venlafaxine, used for depression 2
• When used together, these medications do not significantly alter each other's metabolism - studies show that d-amphetamine exposure remains bioequivalent when lisdexamfetamine is combined with venlafaxine (the parent drug of desvenlafaxine) 3

Safety Profile of the Combination

• The primary concern when combining these medications is their additive cardiovascular effects 3:

  • When used alone, each medication causes modest increases in pulse rate (+8.73 to 12.76 beats/min) and blood pressure
  • When combined, more significant increases were observed: pulse rate (+17.67 to 20.85 beats/min), systolic BP (+12.96 to 13.78 mmHg), and diastolic BP (+12.09 to 12.46 mmHg) 3

• While neither medication alone significantly increases serotonin syndrome risk, caution should be exercised when combining serotonergic medications 4

Monitoring Recommendations

• Regular monitoring of vital signs is essential, with particular attention to:

  • Blood pressure and heart rate at baseline and with each dose adjustment 3
  • Signs of excessive CNS stimulation (insomnia, anxiety, agitation) 5

• Patients should be monitored for potential drug-related adverse effects:

  • Most common side effects of lisdexamfetamine include decreased appetite (25-39% of patients), insomnia (11-19%), and mild cardiovascular effects 5
  • Common side effects of desvenlafaxine include insomnia, somnolence, dizziness, and nausea 2

Special Considerations

• The combination may exacerbate insomnia, which is a common side effect of both medications 2, 5
• Patients with pre-existing cardiovascular conditions, hypertension, or arrhythmias should be monitored more closely or potentially avoid this combination 3
• Start with lower doses of both medications when initiating combination therapy and titrate slowly while monitoring for side effects 3

Conclusion

• The combination of lisdexamfetamine and desvenlafaxine can be used safely in most patients, but requires appropriate cardiovascular monitoring 3
• The most significant concern is the additive effect on blood pressure and heart rate, which necessitates regular monitoring 3
• Patients should be educated about potential side effects and instructed to report significant cardiovascular symptoms or severe insomnia 5