Descrição
Fluconazole inhibits CYP3A4-mediated metabolism of loratadine, modestly increasing loratadine plasma concentrations; however, loratadine's poor CNS penetration limits the clinical consequence.
Mecanismo
Loratadine is metabolised by CYP3A4 (and CYP2D6) to its active metabolite desloratadine; fluconazole's CYP3A4 inhibition raises loratadine AUC moderately without meaningfully altering QTc in most patients.
Significância Clínica
Pharmacokinetic studies show a modest (~40%) increase in loratadine exposure; unlike terfenadine or astemizole, loratadine does not prolong the QT interval at elevated concentrations under normal circumstances.
Conduta
No dose adjustment is required for most patients; use caution in patients with pre-existing cardiac conduction abnormalities or QT prolongation risk factors.