Synovial fluid kinetics of non-steroidal anti-inflammatory drugs.

Synovial fluid kinetics of NSAIDs are still in a relatively nascent stage. These kinetics are determined by the biochemical characteristics of the drugs, the characteristics of the synovium, and the characteristics of the host. NSAIDs show a delayed peak concentration (relative to serum) in the synovial fluid, and their terminal synovial half-lifes generally parallel the serum half-life. Their intrasynovial concentrations are determined to a large extent by synovial fluid protein concentrations plus diffusional barriers to ingress and egress, although displacing substances (including other drugs), and disease, may complicate kinetics. The synovial pharmacodynamic of NSAIDs are understood very poorly. Hopefully a better understanding of synovial fluid and tissue kinetics will lead to more rational therapy with NSAIDs in the future.