[The distribution of benorylate in plasma, synovial fluid and synovial tissue in rheumatoid arthritis].

The authors report on the drug benorylate which is available in the Federal Republic under the name of Benortan (4-acetamidophenyl-2-acetoxybenzoat). Numerous examinations have shown that it is well tolerated by mouth and that it has beneficial clinical effects with few side effects. Benorylate is a neutral, fat-soluble, water-insoluble substance which upon absorption is almost completely hydrolyzed into salicylate and paracetamol. 6 patients with classical seropositive rheumatoid arthritis and with a highly active synovialitis of one or both knee joints not previously treated received 4 g of a 40% benorylate suspension orally twice daily over a period of 9-14 days. On different days at exactly determined times of drug administration blood, and on the day of synovectomy synovial fluid and synovial tissue, were taken and frozen to - 70 degrees C and subsequently examined as to the content of salicylate, paracetamol, and unchanged benorylate. The plasma levels of salicylate and paracetamol were generally distinctly higher than the concentrations of these metabolites in the synovial fluid. Benorylate which is practically not detectable in blood is found in the synovial tissue and is detectable in greatest quantities in the most inflamed synovial villi. Benorylate can probably penetrate into the synovial membrane like its metabolites salicylate and paracetamol; it remains, however, to be examined whether the metabolites are distributed differently in different synovial areas (active inflamed and unattacked synovial tissue, respectively) in the same way as benorylate per se.