Fast and reliable HPLC method for determination of cefuroxime in human serum : application to optimization of dosing regimen in patients with lower respiratory tract infection

A rapid and inexpensive high-performance liquid chromatography method with UV detection for determination of cefuroxime (CFU) in small human serum samples was developed and validated. In this method, serum samples were spiked with an internal standard and proteins were precipitated by 0.4 M perchloric acid. Separation was carried out on an RP-18 column with a mobile phase composed of 20 mM potassium dihydrogen phosphate buffer and methanol (85 : 15; v/v), pH 4.5. In order to assess the usefulness of newly developed method in CFU dosage design, CFU concentrations in serum from 6 patients with lower respiratory tract infections ranging in age from 43 to 91 years were determined. The antibiotic was administered intravenously at a dose of 1500 mg every 8 hours for 10-14 days. Pharmacokinetic analysis and simulations were performed using Phoenix WinNonlin. Dosage optimization was based on pharmacokinetic pharmacodynamic (PK/PD) indices. The lower limit of quantification of the assay was 0.25 μg/mL and the calibration curve was linear at the concentration range from 0.25 to 300 μg/mL. The method was characterized by an excellent precision (≤ 6.4%) and accuracy (≤ 9.0%). Recoveries ranged from 92% to 96%. CFU in serum samples was stable when stored at -30OC for at least 10 days, at room temperature (+22OC) for up to 6 h, and during three freezeñthaw cycles, when stored at -30OC and thawed to room temperature. Pharmacokinetic analysis showed significant differences in pharmacokinetic parameters of CFU in the studied patients: volume of distribution was from 8.9 to 20.6 L, terminal elimination half-life from 1.3 to 5.3 h, and total body clearance from 31 to 232 mL/min. In the elderly patients studied dosage optimization was required. These results suggest that our simple and rapid HPLC method may be useful to monitor serum CFU concentrations in patients on standard dosages and to support determination of CFU dosage regimens based on the PK/PD indices