Daniel I. Palma, Elena M. Vega, María N. Gai

Abstract

Objective: A simple and rapid HPLC method with UV detection of the unbound concentration of ertapenem was developed for therapeutic drug monitoring (TDM) in the elderly inpatient. Methods: After ultracentrifugation, chromatographic separation of ertapenem in human plasma was achieved at 25°C with a C18 column and a mobile phase compounded by acetonitrile-phosphate buffer pH 6.5, 50 mM (14:86, v/v). Quantitative determination was performed by UV at 310 nm. The method was specific and validated with a limit of quantification of 0.24 mg/L for unbound concentration. Results: The intra- and inter-day coefficients of variation were between 0.56 and 2.32% and the accuracy was between 91.0 and 102.0 %. Ertapenem showed stability in all tests carried out in plasma samples. The performance of the developed method to determine ertapenem in plasma was validated and it was established that it is fast, accurate, precise, and reproducible over a clinically relevant calibration range. Conclusion: The method has been developed and validated for TDM in the elderly inpatient to evaluate the attainment of the pharmacokinetic/pharmacodynamic index of carbapenem antibiotics.