COMPARISON OF THE BACTERICIDAL ACTIVITY OF AMIKACIN IN FREE AND LIPOSOMAL FORMULATION AGAINST GRAM-NEGATIVE AND GRAM-POSITIVE BACTERIA

The most common problems limiting the medical use of aminoglycosides have been the nephro- and oto-toxicities and the increasing bacterial resistance. It has been shown that encapsulation of drugs into liposomes enhances their efficacy while reducing their toxicities. The aim of this study was designated to evaluate the antimicrobial activity of free and liposomal amikacin. Encapsulated amikacin into liposome prepared by sonication. The drug contained in the liposome was measured by HPLC after lysis of vesicles by 0.2% Triton X-100. Release kinetics of amikacin from liposomes in presence of normal human pooled plasma were also evaluated. The MICs of this drug for P. aeruginosa (ATCC 27853), E. coli (ATCC 25922), S. faecalis (ATCC 29212) and S. aureus (ATCC 29213) were determined and compared to those the respective free drug using a broth dilution method.

In the presence of plasma, liposomal retention of amikacin was 80.25 ± 0.55% after 1 h of incubation and then remained nearly constant over period of 24 h period of the study. The encapsulation efficiency of liposomal preparation was 24.36% ± 1.14 of the initial amount of the drug in solution. The MICs of liposomal amikacin against all bacterial strains tested were lower than MICs of free amikacin. Our data suggest that liposome-entrapped amikacin could successfully resolve infections caused by all Gram-positive and Gram-negative bacterial studied and should be developed for further evaluation in in vivo experimental studies