Purpose: The purpose of this study was to investigate the percutaneous absorption of ketoprofen applied topically to different anatomical sites on the body.
Methods: The study design was a randomized, four-way crossover in 24 healthy male subjects. One gram of ketoprofen 3% gel (30 mg dose) was applied every six hours for 25 doses over a 100 cm2 of the back, arm, and knee. A 0.5 ml of ketoprofen solution (60 mg/ml) was applied to the back as a reference treatment. Plasma and urine samples were obtained for the assay of racemic ketoprofen and ketoprofen enantiomers (S and R), respectively.
Results: The relative bioavailabilities of ketoprofen gel were 0.90 +/- 0.50, 1.08 +/- 0.63, and 0.74 +/- 0.38 when applied to the back, arm, and knee, respectively. The plasma ketoprofen C(max) for gel applied to the back and arm are similar (p > 0.05) but C(max) was lower when applied to the knee (p < 0.05). The time to C(max) ranged from 2.7 to 4.0 hours and was similar for gel treatments on the back and arm, but no longer for the knee treatment. The fraction of dose excreted in urine as total S and R enantiomers ranged from 5.41 to 9.10%.
Conclusions: The percutaneous absorption of ketoprofen was similar when applied to either the back or arm but was lower when applied to the knee.