Evaluation of Dose-dependent Interactions of Antibiotics using RBC Membrane Model Systems

Background: The present study aims to understand the membrane interactions of three different antibiotics widely used for non-specific viral diseases. Methods: The dose-dependent membrane interactions of the selected antibiotics were elucidated using octanol: water partition coefficient and hemolysis assay. Results: Our octanol: water partition coefficient experiments indicated that among the three antibiotics (Azithromycin, Erythromycin, and Amoxicillin), azithromycin and erythromycin were more hydrophobic compared to amoxicillin. This finding also correlated with hypotonic hemolysis assay experiments where the membrane stabilization effects of both azithromycin and erythromycin were reduced in a dose-dependent manner compared to amoxicillin. Conclusion: This may be attributed to the hydrophobic nature of azithromycin, and erythromycin penetrates deeper into the RBC membrane to the extent of the hydrophobic core compared to amoxicillin. The result is also concurrent with the observations from the hemolysis assay in the isotonic conditions. To conclude, among the three antibiotics, azithromycin, erythromycin localized on the hydrophobic core of the lipid membrane, and amoxicillin localized on the outer surface and slight penetration to the outer leaflet of the membrane.