Transsynovial kinetics of indoprofen in patients with rheumatoid arthritis and cyclooxygenase-inhibition in vitro.

Twenty-four patients suffering from rheumatoid arthritis and requiring articular punctures were treated with 200 mg of indoprofen thrice daily for four days. The subjects were divided into four groups each of six patients. Following the last dose, blood and synovial fluid samples were taken simultaneously according to different time schedules. Maximum plasma levels of 17.5 micrograms/ml were observed after 2.5 h. Peak synovial fluid concentrations amounted to 8.1 micrograms/ml 4 h following the last dose. Elimination from synovial fluid occurred at 10.6 h compared to 9.3 h from plasma. Free synovial fluid levels of approximately 50 ng/ml are in the range of concentrations necessary for cyclooxygenase inhibition in mouse peritoneal macrophages.