Pharmacokinetics of fenbufen in man

The pharmacokinetics of fenbufen (3,4-biphenylcarbonyl proprionic acid) a new antiinflammatory agent, and its metabolites, gamma-hydroxy-4-biphenylbutyric acid and 4-biphenylacetic acid have been studied after oral administration to seven patients with rheumatoid arthritis. Fenbufen was administered as a single oral dose of 600 mg in hard gelatine capsules. A specific, sensitive gas chromatographic method was used to measure the concentration of the three compounds. A linear two-compartment open model appeared suitable to describe the course of the plasma level of fenbufen with time. This compound appeared in the blood after a lag time of 0.45 h and the peak plasma concentration of 5.97 micrograms/ml was observed after 1.19 h. The half-life of plasma disappearance was 10.26 h for fenbufen and 10.07 h and at 9.95 for metabolites II and III, respectively.