What are the potential interactions between Strattera (atomoxetine) and Lexapro (escitalopram)?

Potential Interactions Between Strattera (Atomoxetine) and Lexapro (Escitalopram)

The combination of atomoxetine (Strattera) and escitalopram (Lexapro) may lead to increased escitalopram elimination, potentially reducing its efficacy, and requires careful monitoring for potential serotonergic effects. 1, 2

Pharmacokinetic Interactions

• Atomoxetine is primarily metabolized by the CYP2D6 enzyme system, while escitalopram is metabolized by multiple CYP enzymes including CYP3A4, CYP2C19, and to a lesser extent CYP2D6 3, 4

• According to the French Association for the Study of the Liver, protease inhibitors can increase the elimination of escitalopram, leading to lower plasma concentrations and potentially reduced efficacy 1

• While atomoxetine itself is not a strong CYP inhibitor, it may compete with escitalopram for metabolism through the CYP2D6 pathway, potentially affecting drug levels 3, 4

Pharmacodynamic Interactions

• Atomoxetine is a selective norepinephrine reuptake inhibitor (SNRI) that primarily affects norepinephrine but may have minor serotonergic effects 2, 3

• Escitalopram is a selective serotonin reuptake inhibitor (SSRI) that increases serotonin levels 2, 5

• The American Academy of Child and Adolescent Psychiatry advises caution when combining two medications that may affect serotonin levels due to the risk of serotonin syndrome 2

• Symptoms of serotonin syndrome include mental status changes (confusion, agitation), neuromuscular hyperactivity, and autonomic hyperactivity 2

Cardiovascular Considerations

• Both medications can individually affect cardiovascular parameters 6, 4

• Atomoxetine has been associated with statistically (though not always clinically) significant increases in heart rate and blood pressure 3

• Monitoring of cardiovascular parameters (heart rate, blood pressure) is recommended when using either medication, and particularly when using them in combination 3, 6

Clinical Management Recommendations

• If the combination is clinically necessary, start the second medication at a low dose and increase slowly while monitoring for adverse effects 2

• Monitor closely for symptoms of serotonin syndrome, especially in the first 24-48 hours after initiating therapy or changing doses 2

• Be aware that escitalopram's efficacy may be reduced when used with atomoxetine due to increased elimination 1

• Consider monitoring for:

  • Mental status changes (confusion, agitation, anxiety) 2
  • Neuromuscular symptoms (tremor, rigidity, myoclonus) 2
  • Autonomic nervous system effects (tachycardia, blood pressure changes) 2, 6

• The combination should be avoided in patients with a history of seizures, as both medications can lower the seizure threshold 2

Special Considerations

• Atomoxetine may be beneficial for patients with ADHD and comorbid anxiety, as studies have shown it can reduce anxiety symptoms 7

• If a patient is taking this combination and experiences reduced efficacy of escitalopram, dosage adjustments may be necessary 1, 2

• Neither medication should be combined with monoamine oxidase inhibitors (MAOIs) due to significantly increased risk of serotonin syndrome 2, 5

• Be aware of potential discontinuation syndrome if escitalopram is stopped abruptly 2