Application of polylactic acid polymer in the treatment of acute maxillary sinusitis in rabbits.

To evaluate the therapeutic effects of topical antibiotic delivered by polylactic acid (PLA) polymer on paranasal sinusitis, we induced maxillary sinusitis in 32 New Zealand white rabbits by obstructing the maxillary sinus ostium and inoculating the sinus cavity with Streptococcus pneumoniae. The rabbits were divided into three groups: a control group (group 1) treated only by reopening the ostium, a group (group 2) treated by both reopening the ostium and injecting ampicillin (40 mg/kg/day), and a group (group 3) in which ampicillin in the PLA carrier (0.326 mg) was placed within the sinus after ostial patency was reestablished. The number of colony forming units (CFU) was lowest in group 3, followed by groups 2 and 1. Ampicillin concentration in the maxillary sinus secretion of group 3 was significantly higher than in group 2. The results suggest that treatment with PLA-ampicillin polymer may maintain high therapeutic concentrations of ampicillin in maxillary sinus secretion.