OBJECTIVE: To explore the application and practice of pharmaceutical care network Europe（PCNE） classification system for proton pump inhibitors（PPI） drug-related problems（DRP） in outpatient and emergency department

so as to provide basis and practice mode for standardized application of PPI in outpatient and emergency departments. METHODS: The PPI prescriptions of outpatient and emergency departments were collected from Beijing Chaoyang Hospital（West Ward） Affiliated to Capital Medical University from Jan. to Jun. 2020

DRP were identified and intervened by the combination of Prescription Pre-review Software and manual pharmaceutical care

and PPI drug-related problems were identified and statistically analyzed based on the PCNE classification system. RESULTS: Among 6 044 cases of outpatients and emergency patients using PPI

451 cases of drug-related problems were identified

all of which were intervened

with 421 intervention acceptances and a 93.35% intervention acceptance rate. “Poor treatment outcome”（27.27%

123/451）

“（possible） adverse drug events”（29.93%

135/451） and “unnecessary drug therapy”（42.79%

193/451） were common DRP problems; one problem could have more causes（the total number of causes was 543）

among which the drug selection category（57.46%

312/543） was the main reason for the problem. CONCLUSIONS: DRP classification system can improve pharmacists’ ability to identify and deal with DRP and accurately discover the causes of DRP

which is of great significance for the normalization of rules of prescription audit

standardization of records of pharmaceutical care and systematization of comprehensive analysis of DRP.