Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial inflammation of the joints with high risk of disability. In recent years, remarkable progress has been made towards the diagnosis and treatment of RA, and the international RA guidelines have been also kept updated. Nevertheless, there are many challenges in China, especially inadequate number of rheumatologists and insufficient experience in the diagnosis and treatment of RA. Therefore, Chinese Rheumatology Association drafted the standardized diagnosis and treatment of RA based on the available evidence, so as to improve the management of RA patients in China.

Objective To assay the contents of acetaminophen with ultra high-performance liquid chromatography (UHPLC) method in the sustained-release tablets radiated by Gamma ray. Methods Acetaminophen sustained-release tablets were radiated by ⁶⁰Co. UHPLC equipped with the Shim-pack GISS-C₁₈（2.1 mm×50 mm, 1.9 μm）was used for the assay. The mobile phase was methanol-0.05 % ammonium acetate solution (15∶85). The flow rate was 0.3 ml/min with the detection wavelength at 245 nm. Results The acetaminophen showed good linear relationship within the range of 20-100 μg/ml (r=0.999 4). The RSD values of repeatability was 0.9 %. The average recovery was 97.9 %-104.9 %. Acetaminophen content was 96.2 %, 92.2 %, 91.8 %, 83.9 % at 0, 8, 50 and 80 kGy radiation, respectively. Conclusion This method is speedy and accurate. It can be used to assay the content of acetaminophen in the sustained-release tablets after radiation. The content of acetaminophen decreased after radiation.