Single and repeated dose pharmacokinetics of dexketoprofen trometamol in young and elderly subjects.

Dexketoprofen trometamol, a high water-soluble salt of the active enantiomer of rac-ketoprofen, is a nonsteroidal antiinflammatory drug (NSAID) widely used for pain relief. This study was conducted to determine the pharmacokinetics of this analgesic agent in elderly subjects and to compare them with young volunteers following single and repeated oral doses. Twelve healthy young and 12 elderly subjects received 25 mg oral dexketo- profen (equivalent to 37 mg of its tromethamine salt) as a single dose (day 1) and 3-day repeated doses (1 dose every 8 h for a total of 10 doses). Serial concentrations of dexketoprofen were determined in plasma and urine by a reverse-phase HPLC/ultraviolet procedure over 24 h on day 1 and after the last 10th repeated t.i.d. dose. Compared to young subjects, elderly subjects showed significant increases in AUC and t1/2,z and decreases in CL/F following single and repeated doses. After single dosing, the corresponding mean +/- SD values were 5106.6 +/- 1873.0 vs. 3605.4 +/- 897.9 ng.h/ml (p = 0.015); 1.59 +/- 0.40 vs. 1.12 +/- 0.20 h (p < 0.001); and 1.11 +/- 0.29 vs. 1.63 +/- 0.36 ml/min/kg (p < 0.001). After the repeated dose, AUC, t1/2,z and CL/F averaged 5067.8 +/- 1373.4 vs. 3194.4 +/- 694.3 ng.h/ml (p < 0.001); 1.65 +/- 0.44 vs. 1.11 +/- 0.29 h (p < 0.005); and 1.12 +/- 0.23 vs. 1.87 +/- 0.42 ml/min/kg (p < 0.001). Median tmax was 0.5 h. Cumulative excretions in urine up to 24 h of unbound, conjugated and total dexketoprofen were similar among the groups. These results suggest that dexketoprofen elimination is reduced in the elderly. Although no drug accumulation in plasma was observed after single and repeated dosing, the renal function decline in elderly patients calls for a cautious dose-adjustment in this population.