The kinetics of flurbiprofen in synovial fluid

Steady state plasma and synovial fluid flurbiprofen concentrations obtained from 26 rheumatoid arthritis patients receiving 100 mg of flurbiprofen b.i.d. were analyzed using the NONMEM program. Only one synovial fluid sample per patient was available. Population estimates for the plasma parameters, clearance, volume of distribution, and elimination half-life were 1.75 L hr-1, 11.9 L, and 4.8 hr, respectively, and the corresponding interindividual variances in these parameters were 29, 19 and 23%, respectively. The apparent elimination half-life from synovial fluid was 7.1 hr. After accounting for interindividual variability there was a residual variability of approximately 40% in both the plasma and synovial fluid concentrations.