OBJECTIVEGelanxinning capsule (GXSC) is a Chinese medicine to cure coronary artery disease (CAD) and a compound of Pueraria lobata, hawthorn extract, and gypenosides. However, whether GXSC could improve coronary microvascular dysfunction (CMD) is unknown. We aimed to demonstrate the therapeutic effect of GXSC on CMD and its underlying mechanisms in CAD patients.PATIENTS AND METHODSThis was a single-center, randomized control trial. A total of 78 patients diagnosed by selective coronary angiography (CAG) participated in this study. Patients' demographics, medical history, medications, and results of laboratory testing were collected. The index of microcirculatory resistance (IMR) and coronary flow reserve (CFR) were obtained by CAG and single-photon emission computed tomography (SPECT) separately. Fasting blood samples were obtained on the morning following the admission day. Concentrations of several molecules of inflammation, endothelial function, and coronary microvascular function were measured by ELISA. Patients were followed-up two months after discharge and fasting blood samples were also acquired.RESULTSAll patients were randomly divided into 2 groups: GXSC, 38 (48.7%), and control, 40 (51.3%). The intergroup comparison revealed no significant differences with respect to all baseline variables. As for inflammation biomarkers, proinflammatory NOD-like receptor thermal protein domain associated protein 3 (NLRP3) and interleukin (IL)-1 were significantly decreased in GXSC compared with the control group (0.71±0.08 vs. 1.04±0.07, p<0.01 and 7.16±0.59 vs. 10.93±1.04, p<0.01). Anti-inflammatory adropin was increased in the GXSC group (7.75±0.59 vs. 5.71±0.68, p=0.03). As for indexes of endothelial function, the concentrations of syndecan (SDC) 1, SDC4 and heparan sulphates (HS) were significantly downregulated in 2 months GXSC treatment (3.31±0.28 vs. 4.85±0.43, p<0.01, 3.79±0.56 vs. 5.69±0.68, p=0.03 and 21.31±2.79 vs. 35.18±4.11 p<0.01). In addition, the level of SIRTUIN 1 (SIRT1), which is a vascular protective protein, was upregulated in GXSC group (5.63±0.30 vs. 4.22±0.37, p<0.01). As for molecules of coronary microvascular function, endocan, soluble urokinase plasminogen activator receptor (suPAR), and growth differentiation factor (GDF)-15 were significantly decreased consistently in GXSC compared with the control group (0.09±0.01 vs. 0.19±0.03, p<0.01, 4.44±0.40 vs. 5.73±0.40, p=0.03 and 2.08±0.17 vs. 2.69±0.18, p=0.02).CONCLUSIONSIn conclusion, GXSC could improve CMD by inhibiting inflammation and restoring endothelial function. GXSC might be an effective drug in CAD patients without obstructive epicardial coronary arteries but suffering from angina.