What are the potential interactions between Abilify (aripiprazole) and Strattera (atomoxetine)?

Interactions Between Abilify (Aripiprazole) and Strattera (Atomoxetine)

When combining Abilify (aripiprazole) and Strattera (atomoxetine), monitor for potential drug-drug interactions related to CYP2D6 metabolism, as both medications are metabolized through this pathway, which may lead to increased side effects. 1

Pharmacokinetic Interactions

• Atomoxetine is primarily metabolized through the cytochrome P450 2D6 (CYP2D6) pathway, which can be affected by other medications that use the same metabolic pathway 1
• Aripiprazole is a substrate of both cytochrome P450 isoenzymes 3A4 and 2D6, creating potential for drug interactions affecting its metabolism 2
• Approximately 7% of the population are poor metabolizers of atomoxetine, resulting in significantly higher plasma levels and longer half-lives, which may increase the risk of adverse effects when combined with aripiprazole 1
• The combination may lead to competitive inhibition of the CYP2D6 pathway, potentially increasing blood levels of one or both medications 1

Potential Side Effects to Monitor

• The combination may increase the risk of:
  • Sedation/somnolence (atomoxetine commonly causes somnolence) 3
  • Cardiovascular effects - both medications can affect heart rate and blood pressure 3
  • Extrapyramidal symptoms - aripiprazole can cause these effects, which might be exacerbated by the combination 4, 5
  • Cognitive impairment - antipsychotic polypharmacy has been associated with cognitive effects 1
  • Increased global side-effect burden 1

Clinical Management Recommendations

• Start with lower doses of both medications when using them in combination and titrate slowly while monitoring for side effects 6
• Monitor vital signs regularly, particularly blood pressure and heart rate, as both medications can affect cardiovascular parameters 3
• Be vigilant for signs of increased side effects that might indicate elevated blood levels of either medication 1
• Consider genetic testing for CYP2D6 metabolizer status before initiating this combination, especially in patients with previous adverse reactions to either medication 1
• Monitor for mental status changes, which could indicate adverse effects from the combination 6

Special Considerations

• This combination may be beneficial in certain cases where monotherapy with either agent has provided insufficient symptom control 7
• The combination of these medications has not been extensively studied, so careful monitoring is essential 7
• If adverse effects occur, consider dose reduction of one or both medications before discontinuing the combination 6
• Neither medication should be combined with monoamine oxidase inhibitors (MAOIs) due to risk of serious adverse effects 1
• Be aware that discontinuation of atomoxetine may lead to discontinuation syndrome in some patients 1

Contraindications

• Avoid this combination in patients with:
  • Significant cardiac abnormalities or cardiovascular disease 1
  • History of seizures, as both medications may lower seizure threshold 6
  • Severe hepatic insufficiency, as this can increase exposure to atomoxetine 3
  • Concurrent use of other medications that strongly inhibit or induce CYP2D6 1