Scientific Presentation Abstracts 2009 American College of Veterinary Surgeons Veterinary Symposium October 8-10, Washington, DC

Osteomyelitis is an infective process characterized by chronic morbidity. The persistence of this disease despite antimicrobial therapy may be attributed to poor tissue concentration, impaired local immune response, biofilm formation, changes in rate of bacterial growth and their quorum sensing abilities, and intracellular localization of pathogens. Therefore, the development of a new strategy for targeting antimicrobial agents to bone tissues is urgent. Liposomes have been extensively used as carriers of antimicrobial and antineoplastic drugs. Liposomes are phospholipid nanoparticles that extravasate at sites of increased vascular permeability, such as sites of infection. Liposomal encapsulation of antimicrobials is a drug delivery system that increases the therapeutic index of these drugs by increasing their concentration at the site of infection and reducing potential negative side effects. This study is the first to describe the intravenous administration of 99mTc-labelled polyethylene-glycol PEG) coated liposomes in horses. There were minimal adverse effects associated with intravenous administration of 99mTc labeled liposomes in healthy adult horses. This study establishes normal scintigraphic findings after administration of 99mTc PEG liposomes to which clinical images can be compared, with the goal of utilizing 99mTc-PEG liposomes as a diagnostic aid. Liposomes have significant potential in horses, as a diagnostic tool and for targeted drug delivery in the management of refractory infections and neoplasia. Having addressed safety issues associated with intravenous liposome administration in horses, we now plan to study distribution patterns and efficacy of intravenous liposome administration for targeted delivery of drugs in the treatment of refractory orthopedic and soft tissue infections.