ObjectiveTo investigate the situation of off-label drug use in dose (OLDUD) of ambroxol hydrochloride injection (AHI) in perioperative period among patients for stanford type A aortic dissection in Guangdong General Hospital, so as to provide references for the rational application of AHI in clinical practice. MethodsAll medical orders of AHI for patients had aortic arch replacement for Stanford type A aortic dissection in Guangdong General Hospital between January 2005 and December 2014 were included. The patients were divided into a mild OLDUD ( < 450 mg) group, a moderate OLDUD (450 mg≤OLDUD < 900 mg) group, and a high OLDUD (≥900 mg)group. The preoperative and postoperative features, incidence of PPCs, mortality, incidence of reintubation, time of mechanical ventilation, time stay in ICU, time stay in hospital and the overall costs among three groups were compared by SPSS 22.0 software. Resultsa) A total of 549 patients were included. The incidence of OLDUD was 99.82%. The most common PMDDs were 450 mg (n=358) and 900 mg (n=88). b) The three groups were well matched for perioperative and operative variables. c) The incidence of preoperative drug use was 8.6%. The incidences (5.5% vs. 7.7% vs. 15.7%, P=0.022) and maximum doses (180 mg vs. 300 mg vs. 450 mg, P=0.014) of preoperative drug use were statistically different in mild OLDUD, moderate OLDUD and high OLDUD groups. The days of preoperative drug use were not different (3 d vs. 2.5 d vs. 2 d, P=0.307). The days of postoperative drug use (9.5 d vs. 13 d vs. 19 d, P < 0.001) and postoperative drug use in maximum doses (7 d vs. 8 d vs. 7 d, P=0.005) were different. d) The incidence of PPCs was 100%, and the mortality (8.2% vs. 6.6% vs. 9.0%, P=0.696) was not statistically different among mild OLDUD, moderate OLDUD and high OLDUD groups. However the incidence of reintubation (14.3% vs. 13.8% vs. 27%, P=0.009), time of mechanical ventilation (37 h vs. 50 h vs. 114 h, P < 0.001), time stay in ICU (138 h vs. 178.5 h vs. 316 h, P < 0.001), time stay in hospital (25 d vs. 27 d vs. 34 d, P=0.001) and the overall costs (¥ 0.17 million vs. ¥ 0.19 million vs. ¥ 0.25 million, P < 0.001) were different among three groups. Moreover, they were all increasing along with the dose of AHI. ConclusionAHI cannot improve the prognosis of patients having aortic arch replacement for Stanford Type A Aortic Dissection in a dose-dependent manner. Further well-designed prospective studies should be conducted to verification or falsification.