Formation of antibiotic, biodegradable/bioabsorbable polymers by processing with neomycin sulfate and its inclusion compound with ?-cyclodextrin

Samples of pure neomycin sulfate and its inclusion compound (IC) with β-cyclodextrin were implanted into films of poly(L-lactic acid) (PLLA) and poly(ε-caprolactone) (PCL). Both polymers have been widely used commercially to make sutures. The antibacterial activity of these films against Escherichia coli was tested. Films made by either solution casting or melt pressing were divided into the following three groups: (1) plain polymer films, (2) those embedded with pure neomycin sulfate, and (3) those embedded with neomycin sulfate-β-cyclodextrin IC. Filter paper treated with 1.5 μL of 10 mg/μL Kanamycin and neomycin were used as controls and resulted in 11- and 8-mm zones of inhibition/or antibacterial activity, respectively. Small discs (ca. 2% of total area) cut from solution-cast films of PLLA and PCL containing 50 wt % neomycin sulfate IC had 17- and 16-mm zones of inhibition, and PLLA and PCL containing 50 wt % pure neomycin sulfate deterred bacterial growth, resulting in 19-mm zones of inhibition. Melt-pressed films containing 10 wt % pure neomycin sulfate or its IC, showed 17- and 11-mm zones of inhibition for PLLA films, respectively, while PCL films showed 13- and 9-mm zones of inhibition, respectively. For melt-pressed films that contain 0.01 wt % pure neomycin sulfate or its IC, PLLA films showed 11- and 9.5-mm zones of inhibition, respectively, while PCL films showed 11- and 10-mm zones of inhibition, respectively. Since an antibiotic, bioabsorbable suture does not require surgical removal, implanting an inclusion compound in the suture might allow the slow release of antibiotic, thereby guarding against postsurgical infection and also protecting the antibiotic from degradation during the melt-spinning process used to make the suture.