Is it safe to combine Lexapro (escitalopram) 20 mg and Strattera (atomoxetine) 40 mg?

Safety of Combining Lexapro 20 mg and Strattera 40 mg

The combination of Lexapro (escitalopram) 20 mg and Strattera (atomoxetine) 40 mg can be used together with caution, but requires monitoring for potential drug interactions and side effects.

Mechanism of Action and Interaction Potential

Lexapro (escitalopram) is a selective serotonin reuptake inhibitor (SSRI) that works primarily by inhibiting the reuptake of serotonin in the central nervous system 1. Strattera (atomoxetine) is a selective norepinephrine reuptake inhibitor that works by inhibiting presynaptic norepinephrine transporters in the prefrontal cortex 2.

These medications have different primary mechanisms of action:

• Lexapro: Primarily affects serotonin
• Strattera: Primarily affects norepinephrine

Safety Considerations

Pharmacokinetic Interactions

• Atomoxetine is metabolized primarily by CYP2D6 2
• Escitalopram has minimal inhibitory effects on CYP isoenzymes, suggesting a lower risk of pharmacokinetic drug interactions than some other antidepressants 3
• This combination is less concerning than combinations involving paroxetine (a strong CYP2D6 inhibitor) with atomoxetine

Pharmacodynamic Considerations

1. Cardiovascular Effects:

   • Atomoxetine can cause statistically (but not usually clinically) significant increases in heart rate and blood pressure 2
   • Escitalopram has minimal cardiovascular effects in most patients 3
   • Monitor vital signs regularly, especially during initial combination therapy

2. Risk of Serotonin Syndrome:

   • While atomoxetine primarily affects norepinephrine, there is a theoretical risk of serotonin syndrome when combined with SSRIs
   • Serotonin syndrome is characterized by confusion, fever, shivering, diaphoresis, ataxia, hyperreflexia, myoclonus, or diarrhea 4
   • Cases of serotonin syndrome have been reported with escitalopram, though it's rare 5
   • Monitor for early signs of serotonin syndrome, especially during initiation or dose changes

3. Side Effect Profile Overlap:

   • Both medications can cause nausea, insomnia, somnolence, and decreased appetite 1, 2
   • Combined therapy may potentially increase the risk or severity of these overlapping side effects

Monitoring Recommendations

When using this combination:

1. Initial Period (First 1-2 Weeks):

   • Monitor closely for signs of serotonin syndrome
   • Check blood pressure and heart rate
   • Assess for exacerbation of common side effects (nausea, insomnia, etc.)

2. Regular Follow-up:

   • The American College of Physicians recommends assessing patient status, therapeutic response, and adverse effects beginning within 1-2 weeks of initiation of therapy 6
   • Continue monitoring vital signs at regular intervals
   • Evaluate for emergence of any new side effects

Clinical Practice Guidance

The American Academy of Child and Adolescent Psychiatry acknowledges that medication combinations are commonly used to treat multiple disorders in the same patient (e.g., a stimulant and an SSRI for ADHD and anxiety) 6. This suggests that the combination of Lexapro and Strattera may be clinically appropriate when a patient has both conditions requiring these medications.

Conclusion

While there are no specific contraindications to using Lexapro 20 mg and Strattera 40 mg together, this combination should be used with appropriate monitoring. The theoretical risk of serotonin syndrome and potential for overlapping side effects warrants careful patient education and regular follow-up, particularly during the initial period of combined therapy.

If side effects become problematic, consider:

• Adjusting the timing of medication administration
• Temporary dose reduction of one or both medications
• More frequent monitoring until stable