Pharmacokinetic Interaction Between Atomoxetine and Fluoxetine

Mechanism of Interaction

• Fluoxetine potently inhibits CYP2D6, the primary metabolic pathway for atomoxetine, leading to a marked reduction in atomoxetine clearance. 1, 2, 3, 4

Pharmacokinetic Consequences

• Co‑administration of fluoxetine with atomoxetine produces approximately a 10‑fold increase in atomoxetine area‑under‑the‑curve (AUC) and a 5‑fold increase in peak plasma concentration (Cmax), substantially elevating the risk of adverse drug reactions. 1, 3, 4

Safety Monitoring Recommendations

• Patients receiving the combination should be closely observed for common adverse effects such as nausea, vomiting, fatigue, decreased appetite, abdominal discomfort, and somnolence. 1, 3, 4

Suicidality Considerations

• In children and adolescents treated with atomoxetine, there is an increased risk of suicidality that warrants vigilant monitoring, especially during the initial treatment months or after dose adjustments. 1, 3, 4