Circadian Variation in Plasma IL-6 and the Role of Modified-Release Prednisone in Polymyalgia Rheumatica

Aims: To investigate the circadian variation in IL-6 and effects of morning and night time glucocorticoids in polymyalgia rheumatica. Methods: Cytokines were measured in newly diagnosed polymyalgia rheumatica over two 24-h periods, 2 weeks apart during which they received 7 mg/day of modified-release prednisone at night or morning prednisolone. All patients then received 15 mg/day morning prednisolone. Morning IL-6 concentrations were measured after 2 weeks. Morning stiffness, changes in peak IL-6 levels and area under the curve were compared. Results: IL-6 followed a circadian rhythm with a peak at 04h00. Modified-release prednisone caused greater reduction of IL-6 and area under the curve. Conclusion: IL-6 showed marked circadian variation. The possibility that modified-release prednisone offers a treatment advantage over standard therapy should be tested in a larger study.