Chronotherapy for rheumatoid arthritis: current perspectives

Abstract

Chronotherapy for rheumatoid arthritis: current perspectives Hideto To Department of Medical Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences for Research, University of Toyama, Toyama, Japan Abstract: Rheumatoid arthritis (RA) is an autoimmune disorder of unknown etiology. Morning stiffness, a characteristic feature of RA, shows a 24-hour rhythm. Cytokines, which are considered to play an important role in the pathogenesis of RA, also exhibit a 24-hour rhythm, with a peak in the early morning. These rhythms have been attributed to the endogenous hormone balance and changes in expression levels of clock-related genes. Chronotherapy based on the 24-hour rhythm of RA has been performed using glucocorticoids and disease-modifying antirheumatic drugs. In a previous study, it was reported that modified-release prednisone tablets were administered to patients with RA at night, which demonstrated that the severity of morning stiffness was markedly less than that in patients receiving the standard treatment. Methotrexate (MTX) is the most frequently used RA drug worldwide. In a basic study, cytokines and inflammatory responses in RA model animals showed 24-hour rhythms, based on which MTX was administered and exerted dosing time-dependent antirheumatic effects. Plasma C-reactive protein and cytokine levels also exhibit 24-hour rhythms in patients with RA, with peaks occurring in the early morning. MTX has been shown to markedly inhibit the exacerbation of arthritis in patients with RA when it is administered as inflammatory responses and tumor necrosis factor-α levels begin to increase. Tacrolimus (TAC) is an immunosuppressive agent that is administered to patients who undergo organ transplants. Since one of the mechanisms of action of TAC is the inhibition of inflammatory cytokine production, it is used as an RA therapeutic drug. When TAC was previously administered in the early light or early dark phase to RA model animals, the group treated in the early light phase had notably inhibited increase in arthritis scores compared with that in the early dark phase. The selection of an optimal dosing time associated with 24-hour rhythms in RA symptoms may lead to more effective and safer treatments for RA using glucocorticoids and disease-modifying antirheumatic drugs. Keywords: methotrexate, steroid, circadian rhythm, cytokines