Short-term effects of four antibiotics on DNA synthesis in endothelial cells

The irritating effect of parenterally administered antibiotics on vessels i s a common clinical problem. In a previous study we found that solutions of three commonly used antibiotics, cefuroxime, erythromycin and dicloxacilli n, exerted cytotoxic effects on endothelial cells after 24 hr exposure. Tn contrast benzylpenicillin did not have such effects. in the present study, endothelial cells of different origin were exposed to these Four antibiotic s at higher concentrations than in the previous investigation but only for 5, 30 and 60 min. Incorporation of H-3-thymidine in the cells as a measurem ent of DNA synthesis was used as cytotoxic assay. A concentration-dependent and time-related inhibition was found after exposure to erythromycin and d icloxacillin but not after exposure to cefuroxime and benzylpenicallin. The effects were similar on the three different cell types used in the experim ents. This study demonstrates that the cytotoxic effects differ even after short-term exposure to the antibiotics. In contrast to the previous study, cefuroxime lacks cytotoxicity when endothelial cells are exposed for Less t han one hour. The short-term exposition model used in this study should be more predictive as it mimics in vivo conditions better.