Relevant pharmacokinetics, bioavailability, and bioequivalence studies on Chlorpheniramine maleate (various species): a review.

Introduction: Chlorpheniramine maleate (CPM) is a first-generation H1-antihistamine widely used for allergic conditions, yet its pharmacokinetic (PK) and bioavailability profiles across species remain poorly characterized. Understanding interspecies variability is critical for translational applications and the development of novel formulations. This review aims to summarize and critically evaluate the pharmacokinetics, bioavailability, species-specific behavior, mechanistic insights, and formulation-dependent variability of CPM, with emphasis on intranasal and buccal administration routes and their translational potential. Methods: We conducted a scoping review in accordance with PRISMA-ScR 2018 Guidelines on studies assessing CPM pharmacokinetics in hu-mans and animal models. The identification phases consisted of keyword terms mesh in PubMed: Search 1: Chlorpheniramine Bioavailability (n = 38), Search 2: Chlorpheniramine Bioequivalency (n = 14), and Search 3: Intranasal Chlorpheniramine (n = 54). Repeated or irrelevant studies were excluded, with a total of 22 studies analyzed, from which 13 are included in the final report. Results: CPM exhibits moderate oral bioavailability (25%-50%) and extensive tissue distribution, with a long elimination half-life (∼20 h). Intranasal and buccal routes demonstrate faster absorption and partial hepatic bypass. Bioequivalence studies reveal significant formulation-dependent variability, influenced by excipient design, release profiles, and stereochemistry. Conclusion: CPM remains a pharmacologically valuable molecule with underexplored delivery routes and applications. Standardization of formulations, population-specific pharmacokinetics, and further trials are warranted to unlock the full therapeutic potential of this approach beyond classical allergy treatment.