Determination of Imipenem in Human Plasma by HPLC

OBJECTIVE To establish an HPLC method for the detection of imipenem in human plasma. METHODS Samples were spiked with 0.5 mol·L^-1 urea as stabilizer solution, 5-bromine urea pyrimidine as internal standard, proteins were precipitated with acetonitrile followed by extraction with dichloromethane and the upper aquous phase was injected. Separation was achieved on an Atlantis C₁₈ column (4.6 mm×150 mm, 5 μm). The mobile phase composed of methanol and 10 mmol·L^-1 monopotassium phosphate (pH=6.0)(4∶96) with a flow rate of 1.0 mL·min^-1. The column temperature was 25 ℃. The UV detection wavelength was 300 nm. RESULTS Calibration curves of imipenem showed good linear regression in the range of 0.5-100 mg·L^-1(r=0.999 7). The lower limit of quantification of imipenem was 0.5 mg·L^-1. The mean absolute recovery was 82.72%, and the method recovery was 87.60%-96.36%. Intra- and inter-day variations were <10%. CONCLUSION The established method is simple, sensitive and accurate for determining imipenem in human plasma.