Objective To investigate the compatible stability of esketamine hydrochloride,sufentanil citrate,butorphanol tartrate,and metoclopramide in 0.9%sodium chloride injection,and to provide a reference for the rational use of medication for postoperative analgesia.Methods The four drugs were compounded by simulating the clinical concentrations of the drugs,and the samples were taken at 0,4,8,12,24 and 48 h under light-shielded and light-exposed conditions at room temperature.The appearance,pH value,relative drug content,and insoluble particles were determined.Results The appearance of esketamine hydrochloride,sufentanil citrate,butorphanol tartrate,and metoclopramide concoction was clear at 48 h.The pH values were in the range of 4.69 to 4.79,and the relative drug content of the four drugs were in the range of 95%to 105%.The number of insoluble particles exceeded the specified range in the Chinese Pharmacopoeia(2020 edition)at 4 h and 8 h.Conclusions Under light-shielded and light-exposed conditions at room temperature,the appearance,pH value and relative drug content of the compounded solution remained stable for 48 h.However,the number of insoluble particles exceeded the specified standard.Therefore,it is not recommended to mix the above 4 drugs with 0.9%sodium chloride injection for use in analgesic pumps.