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Antimicrobial Agents and Chemotherapy, March 2000, p. 533-539, Vol. 44, No. 3
Biotechnology Laboratory1 and Departments of
Biochemistry & Molecular Biology and Microbiology & Immunology3,
University of British Columbia, Vancouver, British Columbia, Canada V6T
1Z3, and Inex Pharmaceuticals
Corporation, Burnaby, British Columbia, Canada V5J
5J82
Received 26 January 1999/Returned for modification 20 September
1999/Accepted 1 December 1999
Encapsulation of gentamicin in liposomes can be used to achieve
intracellular delivery and broaden the clinical utility of this drug.
We have previously described a novel, rationally designed, pH-sensitive
liposomal carrier for gentamicin that has superior in vitro efficacy
against intracellular infections compared to the efficacies of both
free gentamicin and non-pH-sensitive liposomal controls. This liposomal
carrier demonstrated pH-sensitive fusion that was dependent on the
presence of unsaturated phosphatidylethanolamine (PE) and the
pH-sensitive lipid N-succinyldioleoyl-PE. The
pharmacokinetics and biodistribution of the free and liposomal
gentamicin were examined in mice bearing a systemic Salmonella
enterica serovar Typhimurium infection. Encapsulation of
gentamicin in pH-sensitive liposomes significantly increased the
concentrations of the drug in plasma compared to those of free
gentamicin. Furthermore, the levels of accumulation of drug in the
infected liver and spleen were increased by 153- and 437-fold,
respectively, as a result of liposomal encapsulation. The increased
accumulation of gentamicin in the liver and spleen effected by
liposomal delivery was associated with 104-fold greater
antibacterial activity than that associated with free gentamicin in a
murine salmonellosis model. These pH-sensitive liposomal antibiotic
carriers with enhanced in vitro activity could be used to improve both
in vivo intracellular drug delivery and biological activity.
0066-4804/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Antibacterial Efficacy of Gentamicin Encapsulated in pH-Sensitive
Liposomes against an In Vivo Salmonella enterica Serovar
Typhimurium Intracellular Infection Model


*
Corresponding author. Mailing address: Inex
Pharmaceuticals Corporation, 100-8900 Glenlyon Parkway, Burnaby, B.C.,
Canada V5J 5J8. Phone: (604) 419-3200. Fax: (604) 419-3201. E-mail:
mwebb{at}inexpharm.com.
Present address: QLT Phototherapeutics, Vancouver, British
Columbia, Canada V5T 4T5.
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