Azithromycin induces genotoxicity and cytostasis in human peripheral blood lymphocytes and apoptosis in HepG2 cells: An in vitro study

Azithromycin (AZM) is a second generation macrolide, a semi-synthetic derivative of erythromycin. AZM accumulates extensively in cells and tissues, making the evaluation of potential off-target effects relevant when cellular exposure is prolonged or elevated. This study characterized the in vitro genotoxic, cytostatic, metabolic, and apoptotic effects of AZM in primary human peripheral blood lymphocytes (PBLs) and HepG2 cells. PBL cultures from four healthy donors were exposed to 1.25–5.0 μg/mL AZM for 48 h and assessed using chromosome aberration (CA), micronucleus (MN), mitotic index (MI), and cytokinesis-block proliferation index (CBPI) analyses. HepG2 cells were evaluated using the MTT reduction assay after exposure to 0.312–40 μg/mL AZM for 24–72 h and by Annexin V-APC/7-AAD flow cytometry after 48 h. AZM increased chromosomal aberration and micronucleus frequencies and reduced MI and CBPI in PBLs. In HepG2 cells, AZM reduced MTT-derived metabolic activity in a concentration- and time-dependent manner (48-h IC 50 : 13.64 μg/mL) and increased apoptotic cell populations, while necrosis remained limited. These findings demonstrate concentration-dependent in vitro toxicological effects in both models.