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Association between hydroxychloroquine concentrations and its efficacy and safety in Japanese patients with
Hiroshi Takei1, Masayuki Hashiguchi2, Satoshi Takanashi1
1Division of Rheumatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan.
Objectives:
This study aims to evaluate the association between serum concentrations of hydroxychloroquine (HCQ) and its derivatives and clinical efficacy in Japanese patients with rheumatoid arthritis (RA).
Methods:
Patients with active RA despite conventional synthetic disease-modifying antirheumatic drugs were recruited, and HCQ was administered for 24 weeks in addition to the prior treatment. Serum concentrations of HCQ, desethylhydroxychloroquine (DHCQ), desethylchloroquine (DCQ), and bisdesethylchloroquine (BCQ) were measured at weeks 0, 4, 8, 12, 24, and 32. The association between each serum concentration and achievement of American College of Rheumatology (ACR) 20/50/70 was analysed.
Results:
Forty-nine patients whose sera were available were included in the analysis. The serum concentrations of HCQ, DHCQ, DCQ, and BCQ reached a plateau at Week 4 and remained at the stable levels during the 24 weeks. The concentrations of HCQ, DHCQ, DCQ, and BCQ at Week 24 were higher in patients who achieved ACR20 than in those who did not. Furthermore, higher serum concentrations of DHCQ and BCQ were also associated with the achievement of ACR50 and ACR70, while those of HCQ and DCQ were not.
Conclusions:
Serum concentrations of HCQ and its derivatives are associated with the clinical effectiveness of HCQ in Japanese patients with RA.
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