Pharmacokinetics of ketoprofen in rabbit after a single topical application

Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used by topical application in management of joint pain and inflammation. Little is known, however, about their pharmacokinetics, especially in the synovial compartme nt versus the plasma compartment, following topical administration. Ketoprofen, a NSAID, was delivered by a single topical application (KETUM ( R) 2.5% gel) on the rabbit knee-joint region of one hind limb. Concentratio ns of ketoprofen were measured in plasma, synovial fluid, joint capsule and synovial fat tissue at 2, 4, 6 and 12 hours after application. Whatever th e time period after application, ketoprofen concentrations in synovial flui d were much higher than in plasma. The time-course of the decrease in ketop rofen plasma concentrations was more rapid than that in synovial fluid. Sim ilarly, concentrations in joint capsule were higher than those found in syn ovial fat tissue. Finally, while ketoprofen concentrations decreased rapidl y in plasma and in synovial fat tissue, concentrations in joint capsule and particularly in synovial fluid were more sustained. The increase in reside nce time of ketoprofen in synovial fluid could be in favour of its efficien cy in the management of joint pain and inflammation.