Effect of gingivitis on azithromycin concentrations in gingival crevicular fluid.
BACKGROUND
Macrolide antibiotics yield high concentrations in inflamed tissue, suggesting that their levels in gingival crevicular fluid (GCF) could be increased at gingivitis sites. However, the increased volume of GCF associated with gingivitis could potentially dilute macrolides. To determine whether these assumptions are correct, the bioavailability of systemically administered azithromycin was compared in GCF from healthy and gingivitis sites.


METHODS
Experimental gingivitis was induced in one maxillary posterior sextant in nine healthy individuals. Contralateral healthy sextants served as controls. Participants ingested 500 mg azithromycin, followed by a 250-mg dose 24 hours later. Four hours after the second dose, plaque was removed from experimental sites. GCF was collected from eight surfaces in both the experimental and control sextants and pooled separately. GCF samples were subsequently collected on days 2, 3, 8, and 15, and azithromycin content was determined by agar diffusion bioassay.


RESULTS
On days 2 and 3, the pooled GCF volume at experimental sites was significantly higher than at control sites (P <0.01), and the total azithromycin mass in 30-second GCF samples pooled from experimental sites was significantly higher than at control sites (P <0.02). However, there were no significant differences in azithromycin concentration between the experimental and control pools at any point. Concentrations exceeded 7.3 μg/mL on day 2 and 2.5 μg/mL on day 15.


CONCLUSIONS
Azithromycin concentrations are similar in GCF from gingivitis sites and healthy sites, suggesting that the processes that regulate GCF azithromycin concentration can compensate for local inflammatory changes.
Division of Periodontology, College of Dentistry, The Ohio State University Health Sciences Center, Columbus, OH, USA.
Nidhi
N
Jain
Pin-Chuang
PC
Lai
John D
JD
Walters
D000284:Administration, Oral; D000328:Adult; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D017963:Azithromycin / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D001682:Biological Availability; D003773:Dental Plaque / Q000378:metabolism; D003774:Dental Plaque Index; D005260:Female; D005500:Follow-Up Studies; D005883:Gingival Crevicular Fluid / Q000737:chemistry*; D005891:Gingivitis / Q000378:metabolism*; D006801:Humans; D008297:Male; D010512:Periodontal Index; D011446:Prospective Studies
D000900:Anti-Bacterial Agents; D017963:Azithromycin