Fig. 2. Prostaglandin E²(PGE²) concentration in samples of dialytic perfusate collected from the surgical site of patients treated preoperatively with single oral doses of placebo, 50 mg rofecoxib, or 550 mg naproxen. Patients underwent impacted lower third molar removal and microdialysis probe implantation 1 h after drug administration, and dialytic samples were then collected from 60 to 240 min during the postoperative period. Each  point or  column indicates the mean value ± SD (  vertical bars ) obtained from 20 patients. *  P < 0.05, significant difference  versus placebo. ^a  P < 0.05, significant difference  versus naproxen.