Enhanced effectiveness of intraperitoneal antibiotics administered via liposomal carrier.

The local application of antibiotics to treat intraperitoneal contamination has been used with variable results. Liposomes are not rapidly absorbed from the peritoneal cavity, offering a potential delivery system for intraperitoneal antibiotics. The effects of liposome-incorporated antibiotic administration in a fecal peritonitis model were compared with the effects of conventional intraperitoneal and intramuscular antibiotics. Rats were divided into four groups: untreated, intramuscular cefoxitin, intraperitoneal cefoxitin, and intraperitoneal liposome-incorporated cefoxitin. Quantitative blood cultures were drawn at 4 and 24 hours. Liposome delivery of cefoxitin significantly reduced mortality and bacteremia at 4 and 24 hours compared with control subjects and conventional antibiotic groups. Peritoneal abscess formation tended to decrease in the liposome antibiotic group (mean +/- SEM, 6.86 +/- 0.79) compared with the group receiving free intraperitoneal administration of antibiotics (10.33 +/- 1.63). We conclude that liposomal delivery significantly enhances the effectiveness of cefoxitin in this model of peritonitis.