1-Oxo Fexofenadine-d10 Methyl Ester is the labeled analogue of 1-Oxo Fexofenadine Methyl Ester (O870040), an intermediate in the preparation of Fexofenadine (F322470). It can also be used for the synthesis of an oxidation metabolite of Terfenadine (T114500),a H1-receptor antagonist.