Abstract
Mechanisms how anti-rheumatic agents work in patients with rheumatoid arthritis have not been well clarified. We determined urinary excretion of bucillamine (SA 96) and its methylated metabolite (SA 679) in patients with rheumatoid arthritis, and attempted to find the relationship between the metabolism of bucillamine and its clinical effectiveness.
After taking 100 mg bucillamine orally, SA 96 and SA 679 were excreted into urine 0.3 to 26.0 mg, and 2.7 to 32.3 mg, respectively in 4 hours. Thus, the mode of excretion of bucillamine and its metabolite showed great heterogeneity in patients with rheumatoid arthritis. This was the case with SA 679/SA 96 ratio which represented methylation rate of bucillamine. There was no association between the excretion of SA 96 and SA 679 with age, disease duration, renal function, and total dosage of administered bucillamine.
No significant association was found between the mode of urinary excretion of SA 96 and SA 679 and clinical responsiveness, but some patients responded effectively to bucillamine even though relatively low urinary excretion of SA 96 and SA 679.
In summary, individual differences in the extent of methylation of bucillamine were present in patients with rheumatoid arthritis, however, are unlikely to be directly related to the clinical responsiveness of this anti-rheumatic drug.
