Investigation of cytotoxic and genotoxic effects of the antihistaminic drug, loratadine, on human lymphocytes

Context: Loratadine (LOR) is a new generation antihistamine used in the treatment of allergic disorders. Objective: The aim of this study was to evaluate the cytogenotoxic effect of LOR on human peripheral blood lymphocytes. Materials and methods: We investigated the genotoxic effect of this drug in cultured human peripheral blood lymphocytes using sister chromatid exchange (SCE), chromosomal aberrations (CA) and micronucleus (MN) assay in culture conditions. Proliferation index (PI), mitotic index (MI) and nuclear division index (NDI) were also calculated to determine the cytotoxic/cytostatic effect. Cultures were treated with LOR at three concentrations (5, 15 and 25 mg/ml) for 48 h. Results: Although the MI significantly decreased at the higher concentrations (15 and 25 mg/ml) compared with negative (solvent) control, LOR indicated weaker cytotoxic potential in PI and NDI values at all the tested concentrations. LOR increased the frequencies of SCE, CA and MN in all lymphocyte cultures. However, significant increase was observed in MN at the medium and highest doses (15 and 25 mg/ml) and in CA at the medium dose (15 mg/ml) compared with negative (solvent) control culture. Our results indicate that LOR has cytotoxic and genotoxic effects on human peripheral blood lymphocyte cultures. Discussion: Although most of previously findings have shown that LOR does not reflect genotoxicity, our results indicated that it may be a genotoxic drug. Conclusion: More studies are necessary to elucidate the relationship between cytotoxic, genotoxic and apoptotic effects, and to make a possible risk assessment in patients receiving therapy with this drug.