Interaction between piroxicam and azithromycin during distribution to human periodontal tissues

Background: Non-steroidal anti-inflammatory drugs and antibiotics are impor tant in the prevention of infections and pain associated with periodontal s urgery as well as in the adjunctive therapy of periodontal disease. In this study, patients undergoing oral surgery were treated with piroxicam and az ithromycin to examine the interactions of these drugs on periodontal tissue s. Methods: Sixty-six patients were assigned to 3 groups and treated for 3 day s as follows: 1) piroxicam 20 mg/day; 2) azithromycin 500 mg/day; or 3) pir oxicam 20 mg/day plus azithromycin 500 mg/day. Samples of blood, saliva, gi ngiva, and alveolar bone were collected during surgery and at days 0.5, 2.5 , 4.5, and 6.5 after last dose. Piroxicam concentrations were assayed by hi gh-performance liquid chromatography and azithromycin concentrations by mic robiological assay. Results: In patients treated with piroxicam alone, the highest drug concent rations were found in plasma at each time point, but consistent piroxicam l evels were also detected in gingival samples up to 4.5 days. The combined t reatment with piroxicam plus azithromycin was associated with a reduction o f piroxicam concentrations in periodontal tissues. In patients receiving az ithromycin alone, high drug levels were measured in periodontal tissues up to 6.5 days. This distribution pattern did not vary in patients treated wit h piroxicam plus azithromycin. Conclusions: Treatment with piroxicam or azithromycin alone ensures a favor able distribution of these drugs into periodontal tissues. However, upon co mbined administration, azithromycin interferes negatively with the periodon tal disposition of piroxicam. This interaction might depend on the displace ment of piroxicam from acceptor sites at the level of periodontal tissues.