Since COVID-19 infection,many infected patients have developed multiple systemic symptoms that persist long after 3 months of infection,which is called Long COVID.Numerous studies have shown that fatigue is the most common symptom among the many symptoms of Long COVID that has severely impacted the quality of their life.Therefore,it is particularly important to understand the mechanisms by which Long COVID causes fatigue symptoms.This article summarizes the possible mechanisms of Long COVID fatigue,including immune response,oxidative stress,and affecting the central nervous system,by combing through the relevant literature,aiming to increase clinical awareness of fatigue induced by Long COVID and to provide certain ideas for its treatment.

Objective::To investigate the processing purpose of Morindae Officinalis Radix (MO), Euodiae Fructus (EF) and Polygalae Radix (PR) processed by Glycyrrhizae Radix et Rhizoma (Gly). Method::The content of dapsone in rat plasma was determined by high performance liquid chromatography (HPLC), the mobile phase was acetonitrile (A)-water (B) for gradient elution (0-5 min, 10%-25%A; 5-20 min, 25%A) and detection wavelength was set at 292 nm. PK Solution 2.0 software was used to simulate pharmacokinetic parameters. Result::Within 300 min after dapsone was administrated, compared with the control (CTL) group, the elimination of dapsone was slowed down and its plasma concentration was increased in the unprocessed product of MO (UMO) group. The elimination of dapsone was accelerated and its peak concentration (C_max) was decreased in the processed products of MO with Gly (GMO) groups, and they had positive correlation with proportion of Gly in GMO. Compared with the CTL group, the elimination of dapsone was slowed down, and its plasma concentration was increased and its peak time (T_max) was postponed in the unprocessed product of EF (UEF) group, while their C_max and T_max were changed in the processed products of EF with Gly (GEF) groups. Compared with the CTL group, the elimination of dapsone was slowed down and its plasma concentration was increased in the unprocessed product of PR (UPR) group, while the elimination was accelerated and its plasma concentration was decreased in the processed products of PR with Gly (GPR) groups. Conclusion::The elimination of dapsone is slowed down in rats administered with UMO, UEF and UPR, while its elimination is accelerated in rats administered with the processed products of these three herbs with different proportions of Gly. Among the proportions, effect of processed products of these three herbs with 100∶6 (ratio of unprocessed product-Gly) on pharmacokinetics of dapsone is not significant.