Loratadine and Fluoxetine Concomitant Use
Loratadine (Claritin) is generally considered safe to use concomitantly with fluoxetine (Prozac). Evidence from a pharmacokinetic/pharmacodynamic study of desloratadine (the active metabolite of loratadine) with fluoxetine showed no clinically important changes in fluoxetine pharmacokinetics and no significant electrocardiographic effects. [1]
Drug-Interaction Profile
Fluoxetine is a potent inhibitor of CYP2D6. [1] Desloratadine pharmacokinetics were not associated with clinically relevant changes during coadministration with fluoxetine in healthy volunteers. [1] In that study, desloratadine coadministered with fluoxetine did not produce clinically important ECG or ventricular rate changes. [1]
Pharmacokinetic Evidence Supporting Lack of Clinically Meaningful Interaction
In healthy volunteers receiving desloratadine 5 mg with fluoxetine 20 mg, desloratadine exposure showed a small increase in Cmax (15%) without an increase in AUC. [1] Fluoxetine pharmacokinetics were not changed in a clinically meaningful way during coadministration with desloratadine. [1]
Electrocardiographic Safety Evidence
Desloratadine plus fluoxetine caused no significant changes in ECGs or ventricular rate in the study population. [1]
Clinical Implications for Loratadine Use
Direct loratadine–fluoxetine interaction data were not identified in the cited evidence base. [1] Because the available evidence involves desloratadine with fluoxetine and desloratadine is the active metabolite of loratadine, lack of clinically meaningful interaction with desloratadine supports low likelihood of a clinically important interaction with loratadine. [1]
Monitoring Considerations
Routine additional monitoring is not indicated based on the available interaction study findings. [1] Common adverse events observed in the desloratadine plus fluoxetine study included headache. [1]
Common Pitfalls to Avoid
Avoid assuming absence of interaction for other antihistamines that have different metabolic pathways or greater cardiotoxic potential. [1] Avoid extrapolating from this interaction study to non-allergic indications or higher-than-labeled dosing. [1]
Practical Concomitant-Use Recommendation
Concomitant use of loratadine with fluoxetine is recommended when an antihistamine effect is indicated. [1]