Article Figures & Data
Figures
- Fig. 1.
Pharmacokinetics of free and liposomal gentamicin after i.v. administration of free and liposomal gentamicin in mice bearing anS. enterica serovar Typhimurium infection. Plasma lipid concentrations (A), plasma gentamicin/lipid ratios (B), and plasma gentamicin concentrations (C) are shown for free gentamicin (●) and for gentamicin encapsulated in liposomes composed of DPPC-chol (55/45; ■) or DOPE–N-succinyl-DOPE–chol–PEG-ceramide (35/30/30/5; ▵). Data are means ± standard deviations for three animals. Error bars are plotted for all datum points; where error bars are not visible, they are smaller than the size of the symbol.
- Fig. 2.
Accumulation of gentamicin and lipid in tissues after i.v. administration of free and liposomal gentamicin in mice bearing anS. enterica serovar Typhimurium infection. The proportion of the injected dose of gentamicin (●, ■, ▴) and lipid (□, ▵) in the liver (A), spleen (B), and kidneys (C) after the i.v. administration of free gentamicin (●) or gentamicin encapsulated in liposomes composed of either DPPC-chol (55/45; ■, □) or DOPE–N-succinyl-DOPE–chol–PEG-ceramide (35/30/30/5; ▴, ▵) are shown. Data are means ± standard deviations for three animals. Error bars are plotted for all datum points; where error bars are not visible, they are smaller than the size of the symbol.
- Fig. 3.
In vivo antibacterial activity of free and liposomal gentamicin against an intracellular S. enterica serovar Typhimurium infection in the spleen. The numbers of bacteria surviving in the spleen are shown for no-treatment controls (○) or for mice receiving either free gentamicin (●) or gentamicin encapsulated in DOPE–N-succinyl-DOPE–chol–PEG-ceramide (35/30/30/5 mol%; □) liposomes. Values represent the mean ± standard error numbers of CFU from duplicate assays with three or four mice per group. Results were analyzed by one-way analysis of variance on ranks and pairwise multiple comparison methods as described in Materials and Methods.
- Fig. 4.
In vivo antibacterial activity of free and liposomal gentamicin against a intracellular S. enterica serovar Typhimurium infection in the spleen. The numbers of bacteria surviving in the spleen are shown for no-treatment controls or for mice receiving a single administration of gentamicin at 5 mg/kg. Data are presented for free gentamicin or gentamicin encapsulated in liposomes of DOPE–N-succinyl-DOPE–chol–PEG-ceramide (35/30/30/5 mol%), DOPC–N-succinyl-DOPE–chol–PEG-ceramide (35/30/30/5), or DPPC-chol (55/45 mol%). Values represent the mean ± standard error numbers of CFU from duplicate assays with three or four mice per group. Results were analyzed by one-way analysis of variance on ranks and pairwise multiple comparison methods as described in Materials and Methods. Statistically significant pairwise comparisons between each liposomal gentamicin formulation and either the no-treatment control (★) or the free gentamicin control (∗) for which P was <0.05 are indicated by matching symbols. For all other pairwise comparisons P was >0.05.
- Fig. 5.
pH dependence of the lipid demixing of DOPE–N-succinyl-DOPE–chol–PEG-ceramide (39.5/30/30/0.5) (●) and DOPC–N-succinyl-DOPE–chol–PEG-ceramide (39.5/30/30/0.5) (○) liposomes. Liposomes encapsulating gentamicin and containing 1 mol% each NBD-PE and Rh-PE were mixed with a 10-fold excess of identical liposomes lacking fluorescent lipids and encapsulated drug at a final Ca2+ concentration of 20 mM and a pH of 6.93. The pH was adjusted and the percent dequenching was calculated at 2 min after the pH reduction as described in Materials and Methods.
Tables
- Table 1.
Biodistributions of free and liposomal gentamicin in liver, kidneys, and spleen of BALB/c mice infected with S. enterica serovar Typhimurium after i.v. administrationa
Parameter and formulation Organ Liver Kidney Spleen Gentamicin AUC (μg · h/g)b Free gentamicin 8.1 573 3.7 DPPC-chol 648 170 1,833 DOPE–N-succinyl-DOPE–chol–PEG-ceramide 1,244 194 1,611 Lipid AUC (μg · h/g)b DPPC-chol 1.64 × 104 1.75 × 103 5.59 × 104 DOPE–N-succinyl-DOPE–chol–PEG-ceramide 1.44 × 104 146 1.71 × 104 Liposomal AUC/free AUC DPPC-chol 80 0.30 497 DOPE–N-succinyl-DOPE–chol–PEG-ceramide 153 0.34 437 Gentamicin AUC/lipid AUC DPPC-chol 0.040 0.097 0.033 DOPE–N-succinyl-DOPE–chol–PEG-ceramide 0.086 1.33 0.094 ↵a The overall effect of liposomal encapsulation on the accumulation of gentamicin in the liver, kidneys, and spleen is summarized by the liposomal AUC/free AUC ratio. The drug/lipid ratio for the organs, which is an indicator of the propensity of the tissue to accumulate free drug that has leaked from the liposomes (higher ratio) or intact liposomes (unchanged ratio), is presented as the gentamicin AUC/lipid AUC ratio. Note that the drug/lipid ratios upon i.v. administration were 0.04 and 0.10 for DPPC-chol and DOPE–N-succinyl-DOPE–chol–PEG-ceramide, respectively.
↵b Linear-trapezoidal AUCs were calculated over the period from 0 to 24 h postadministration for liposomal gentamicin and over the period from 0 to 3 h postadministration for free gentamicin, as described in Materials and Methods.
