Development and validation of an UPLC method for the quantification of ethambutol in rat plasma

Abstract

Background: The effective monitoring of antitubercular drugs, including ethambutol (EMB), is important for the control of multiple drug resistance. The development of fast, facile, and inexpensive methods for the detection of low concentrations of EMB, especially near its minimum inhibitory concentration, is also important. Results: An UPLC method for estimating EMB in rat plasma was developed and validated. The method uses a small injection volume (1 μl) and elutes EMB at 3.18 min, with 0.070 μg ml⁻¹ and 0.250 μg ml⁻¹ as the limits of detection and quantification, respectively. The intra- and interday accuracy was 106.01–108.82% and 107.80–109.00%, respectively, with a precision of <5% in both cases. The mean extraction recovery of EMB from rat plasma was >97% at three concentration levels, establishing the consistency and reproducibility (n = 6) of the method. EMB was found to be stable in plasma under different storage and processing conditions. Conclusion: This paper presents a highly sensitive and specific isocratic UPLC method for the rapid quantization of EMB for use in pharmacokinetics and therapeutic drug monitoring.