These preliminary data conform earlier results in the international literature that diclofenac penetrates rapidly into synovial fluid, peaks in concentration at three to four hours after a single oral dose, and is present in substantially higher concentrations in synovial fluid than in plasma at four hours after dosing and beyond. In addition, it appears that diclofenac does not accumulate in the plasma over a one-week period of a twice-daily dose of 75 mg. Higher synovial fluid levels are sustained, however, for periods up to 12 hours after single or multiple dosing. These results suggest that, despite a short half-life in plasma, diclofenac persists at the site of inflammation, and this may help explain this extended duration of therapeutic effect after plasma levels have decreased. Persistence of diclofenac in the synovial fluid at 12 hours may account for its effectiveness on a twice-daily dosing regimen and may justify this recommendation.
ASJC Scopus subject areas
- Anesthesiology and Pain Medicine