[Detection of cutaneously administered flufenamic acid in the inner space of the knee joint].

Ten patients who were scheduled for surgery due to an internal damage of the knee joint, were treated 2 days before operation 3 times daily with an ointment containing flufenamic acid (Mobilisin spezial). At the time of operation, plasma and synovial fluid, tissue samples from the synovial membrane, Hoffa's fat pad and-- as far as possible--meniscus and articular cartilage were taken. Until 72 h after the operation, urine samples were collected. The flufenamic acid level was determined by means of high pressure liquid chromatography associated with fluorometric detection. Flufenamic acid was detected in all tissues of the knee joint and in the synovial fluid. The highest concentration of flufenamic acid was found in the synovial membrane.