ETHNOPHARMACOLOGICAL RELEVANCEChildren's Zibei Xuanfei syrup is an herbal preparation from a lifetime professor, famous old Chinese doctor, and postgraduate supervisor of medical doctor of Shandong University of Traditional Chinese Medicine. This herbal preparation promotes lung health, relieves cough, reduces phlegm, and benefits pharynx.AIM OF THE STUDYTo verify the clinical efficacy and safety of Zibei Xuanfei syrup for children in treatment of acute trachea bronchitis with wind-heat invading lung syndrome.MATERIALS AND METHODSThis was an age-stratified, block randomized, double-blind, extremely low dose parallel control, multi-center clinical trial. A total of 453 pediatric patients diagnosed with acute tracheal bronchitis in Western medicine and cough due to exogenous factors with wind-heat invading lung syndrome in Chinese medicine were enrolled. They were divided into three subgroups based on age 1∼3, 4-7, and 8-14 years old, and randomly assigned to children's Zibei Xuanfei syrup and extremely low doses of children's Zibei Xuanfei syrup (control) in a 3:1 ratio. The primary outcome was the decreased values of cough Visual Analogue Scale (VAS) score after 7 days of administration. Secondary outcomes included a decrease in cough VAS score after 3 and 5 days of the administration, and the total score of Traditional Chinese Medicine(TCM) syndrome after 3, 5, and 7 days of treatment. The chest X-ray and blood C-reactive protein were examined during screening. The safety assessment included blood urine, and stool routine, liver and kidney function of laboratory tests, and an electrocardiogram at the screening and the last visit.RESULTSThe subjects of two groups had high administration adherence (completion over 80%) (299/323, 92.6% in children's Zibei Xuanfei syrup group vs 103/107, 96.3% in the control group; p > 0.05). The children's Zibei Xuanfei syrup group was significantly better than the control group in the decreased values of cough VAS score after 7 days of administration(6.35 ± 3.45 vs 3.73 ± 3.98, p < 0.001). The subgroup analysis of the decreased value of cough VAS scores aged 1-3 years old were 5.80 ± 3.43 vs 3.75 ± 4.38 (P = 0.003), 4-7 years old was 6.30 ± 3.69 vs 2.73 ± 3.65 (P < 0.001), and 8-14 years old were 6.91 ± 3.12 vs 4.69 ± 3.75(P = 0.001)respectively. The secondary outcomes decrease values of cough VAS score of children's Zibei Xuanfei syrup group vs control group after 5 days of administration were 5.88 ± 2.90 vs 3.55 ± 3.41(P < 0.001), after 3 days of administration were 3.61 ± 2.53 vs 2.43 ± 2.56 (P < 0.001). The effective rate of the TCM symptom total score of children's Zibei Xuanfei syrup group vs control group was 91.38% vs 54.95%after 7 days of the administration, 86.93% vs 50.94% after 5 days of the administration, and 64.78% vs 40.19% after 3 days administration(each p < 0.001). There was no significant difference in Adverse Event between the two groups (59/331, 17.82% vs 15/111, 13.51%, P > 0.05). The children's Zibei Xuanfei syrup group had 5 Serious Adverse Events (incidence rate 1.21%), all of which were unrelated to the trial drug.CONCLUSIONChildren's Zibei Xuanfei syrup appears to be extremely effective and safe in the treatment of acute trachea bronchitis with wind-heat invading lung syndrome. Future studies with large sample sizes will need to collect more safety data use for children.