Biodegradable drug delivery systems for gentamicin release and treatment of synovial membrane infection

Objective-This study investigated two biodegradable drug delivery systems ( BDDS) for elution of gentamicin and elimination of synovial membrane infect ion. Study Design-The effect of BDDS on control and infected synovial explants w as determined. Animals or Sample Population-Synovial explants from four adult equine cadav ers. Methods-First, BDDS were placed in phosphate buffered saline for 14 days. F luent was tested for gentamicin concentration (G) and bioactivity. Second, synovial explants were divided into four groups (n = 14/group): Group 1 (co ntrol); Group 2 (infected control) 405 cfu Staphylococcus aureus added at 6 hours; Group 3 (antibiotic BDDS [Ab-BDDS]) Ab-BDDS added at 24 hours; Grou p 4 (infected Ab-BDDS) 405 cfu S. aureus added at 6 hours, Ab-BDDS added at 24 hours. Both types of Ab-BDDS were used (n = 7/type/group). Explants wer e incubated in standard medium for 4 days. Medium was cultured and analyzed for (G) and hyaluronic acid concentration (HA). Explants were analyzed for viability and morphologic changes. Results-The Ab-BDDS released >500 mu g/mL of active gentamicin for 10 days. In Group 3, infection was eliminated within 24 hours, but histologic score s did not return to normal. Viability was significantly reduced by infectio n, but if eliminated, viability tended to return to normal. In Group 3, the Ab-BDDS had no significant effect on viability or (HA). Histopathologic sc ores were significantly higher for infected synovium. Infection, even if tr eated, significantly reduced (HA). Conclusions-Both Ab-BDDS eliminated infection within 24 hours. However, syn ovial morphology, viability and function did not return to normal. Clinical Relevance-The Ab-BDDS may be useful for treatment of synovial memb rane infection. (C)Copyright 1999 by The American College of Veterinary Sur geons.