Randomized clinical comparisons of diclofenac concentration in the soft tissues and blood plasma between topical and oral applications

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT center dot Efficacy of oral administration of nonsteroidal anti-inflammatory drugs (NSAIDs) on the synovial and muscle tissues has been established. center dot However, efficacy of percutaneous administration of NSAIDs has not sufficiently been established because of lack of scientific data. WHAT THIS STUDY ADDS center dot The diclofenac concentration in the muscle and fat at 12 h after topical application with a pair of tapes containing a total of 30 mg diclofenac sodium was significantly higher than that after oral application of a capsule containing 37.5 mg diclofenac sodium, whereas there was no significant difference in the plasma diclofenac level between the two applications. center dot The concentration in the synovial membrane and fluid was significantly lower after topical application than after oral application. To compare tissue concentrations of diclofenac resulting from topical and oral applications of diclofenac according to clinically recommended prescriptions. Diclofenac sodium was applied to 14 subjects (four male and 10 female), who were scheduled to undergo knee arthroplasty due to osteoarthritis, according to the oral or topical prescription (a capsule containing 37.5 mg diclofenac sodium or two tapes containing a total of 30 mg diclofenac sodium). At 12 h after prescription, the diclofenac concentration in the fat, muscle and synovial tissues was measured with liquid chromatography and mass analysis. The diclofenac concentration in the muscle was significantly higher (P = 0.0196) after topical application (average 9.29 ng ml(-1)) than after oral application (0.66 ng ml(-1)), whereas there was no significant difference in the plasma diclofenac level (4.70 and 6.63 ng ml(-1)) between the two applications. The concentration in the synovial membrane was significantly (P = 0.0181) lower in the topical application (4.99 ng ml(-1)) than in the oral application (15.07 ng ml(-1)). Whereas plasma levels resulting from topical and oral applications of diclofenac according to clinically recommended prescriptions were comparable, concentration levels in the muscle and synovial tissues were different.