Pharmacokinetics and Efficacy of Low-dose Ketoprofen in Postoperative Dental Pain

A double-blind, randomised trial was carried out to investigate the relationship between efficacy and various pharmacokinetic variables after single doses of racemic ketoprofen 12.5 and 25mg in patients with postoperative pain after third molar surgery over a 4-hour investigation period. Serial venous blood samples were obtained at 0, 0.25, 0.5, 0.75, 1, 1.5, 2, 3 and 4 hours after administration for subsequent determination of R(-) and S(+) ketoprofen. The relationship between the R(-) and S(+) ketoprofen concentrations and pain experience was summarised for each patient by the slope of the regression line for that individual. There was no significant difference (p > 0.05) between the two doses of ketoprofen for any of the efficacy measures. Peak plasma concentrations of both R(-) and S(+) ketoprofen were observed between 60 and 90 minutes after dosage. A significant negative correlation (p < 0.002) was observed between the decrease in pain scores and plasma concentrations of both R(-) and S(+) ketoprofen after each dose. However, the amount of variability in each patient's response makes it difficult to identify a causal relationship between these parameters. Low doses of ketoprofen provide satisfactory pain relief in the early postoperative period after third molar surgery. Efficacy of this analgesic does not appear to be dose related or directly related to plasma concentrations of either R(-) or S(+) enantiomers.