Abstract: OBJECTIVE To establish HPLC method in the detection of plasma and displacement liquid of biapenem and to study pharmacokinetics of biapenem in the patients with continuous renal replacement therapy. METHODS HPLC column was ZORBAX Eclipse XDB-C₁₈(4.6 mm×150 mm, 5 μm)with the mobile phase of methanol(A)-0.1 mmol·L^-1sodium acetate solution(B)(0-6.5 min, 2%A; 6.5-7 min, 2%→60%A; 7-15 min, 60%A). The wavelength of detection was 300 nm. The internal standard was carbamazepine and the flow rate was 1.0 mL·min^-1. Ten cases of CRRT patients were given 0.3 g dose of biapenem with iv. 2 mL venous blood was collected after giving medicine at 0, 5, 15, 30, 45 min and 1, 2, 4, 6, 8 h, while 2 mL displacement liquid were collected. RESULTS Displacement liquid and plasma concetration of biapenem had a good linear relation in the range of 0.2-50 μg·mL^-1. The three different concentration(low, medium and high) plasma and displacement liquid sample's average recovery were (101.05±4.31)% and(101.09±2.72)%. The intra-and inter-day precision was both < 5%. The pharmacokinetics of biapenem best fitted to two-compartment model:C_max was (15.37±2.98)mg·L^-1;t_1/2β was (71.36±40.41)min, V₁ was (11.75±3.86)L, AUC_0-∞ was (0.64±0.15) mg·L^-1·min^-1. CONCLUSION The method of HPLC has the features of high sensitivity, excellent stability, strong selectivity and high precision. There is no obvious change on pharmacokinetics of biapenem in the patients with CRRT.