URINARY 6b-HYDROXYCORTISOL EXCRETION IN RHEUMATOID ARTHRITIS

The objective was to analyse whether the activity of the cytochrome P450 isoenzyme CYP3A4 is altered by disease activity of rheumatoid arthritis (RA). Urinary 6b-hydroxycortisol excretion, expressed as a fraction of the urinary creatinine output, was measured in 21 patients with RA treated with three different disease-modifying anti-rheumatic drugs (DMARDs) over 24 weeks. There were no correlations between urinary 6b-hydroxycortisol/creatinine (6b-OHC/Creat) ratio and measurements of disease activity such as plasma viscosity, Ritchie articular index and early morning stiffness. In addition, the three DMARDs sulphasalazine, sodium aurothiomalate and -penicillamine, smoking and the intake of various CYP3A4 substrates had no consistent detectable effect on the 6b-OHC/Creat ratio. There is no evidence that the dosage of drugs metabolized by the CYP3A4 isoenzyme needs to be adjusted for disease activity in RA.