Advances in High-Resolution MS and Hepatocyte Models Solve A Long-Standing Metabolism Challenge: The Loratadine Story

Abstract

Background: Loratadine (LOR, Claritin^®) is a long-acting antihistamine used to treat allergic rhinitis. The major active human metabolite, desloratadine (DL, Clarinex^®), is extensively metabolized to 3-hydroxydesloratadine (3-OH-DL) (M40) and subsequently glucuronidated before elimination. This study revealed the ability of a novel, long-term hepatocyte micropatterned co-culture (MPCC) model to generate in vivo metabolites. Metabolites were detected and characterized using non-targeted MS/MS^ALL with SWATH™ acquisition by a UHPLC-Q-TOF system. Results & methodology: Human MPCCs extensively metabolized LOR and formed 3-OH-DL-glucuronide (M13). Cross-species comparisons revealed monkey- and rat-specific metabolites with gender-specific DL-pyridine-N-oxide formation in male rats. These results demonstrate a first for an in vitro hepatocyte model to generate circulating metabolites of LOR and detect species-specific differences. Early focus on human metabolites could have spared characterization of nonhuman metabolites in preclinical species.

Keywords::

• LC–MS
• metabolism
• SWATH

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.

Ethical conduct of research

The authors state that they have obtained appropriate institutional review board approval or have followed the principles outlined in the Declaration of Helsinki for all human or animal experimental investigations. In addition, for investigations involving human subjects, informed consent has been obtained from the participants involved.

Acknowledgements

The authors acknowledge Jeannemarie Gaffney and Jared Broberg for manufacturing long-term hepatocyte micropatterned co-cultures (MPCC) for incubation studies using loratadine. The authors also thank QPS, LLC colleagues Lakshmi Ramanathan and Cornelia Smith for helping with loratadine hepatocyte suspension and MPCC incubations. Caroline Lee, Helen Shen and Zamas Lam provided several helpful suggestions. Insightful assistance with Sciex MetabolitePilot Software was provided by Suma Ramagiri, Keith Goodman and Eva Duchoslav.