Journal of Analytical & Bioanalytical Techniques
Open Access

Research Article

Determination of Total and Free Concentrations of Flucloxacillin and Cefazolin in Human Plasma by Liquid Chromatography/Tandem Mass Spectrometry

¹Department of Medicine, University of Otago−Christchurch, Christchurch, New Zealand

²Toxicology, Canterbury Health Laboratories, Christchurch, New Zealand

³Infectious Diseases Specialist and Medical Microbiologist, Nelson Bays Primary Health, Nelson, New Zealand

*Corresponding Author:

Dr. Mei Zhang
Clinical Pharmacology, Department of Medicine
University of Otago - Christchurch/Toxicology
Canterbury Health Laboratories, Christchurch, New Zealand
Tel: 0064 3 364 0640 ext 89746
Fax: 0064 3 364 1003
E-mail: mei.zhang@cdhb.health.nz

Received date: January 23, 2014; Accepted date: February 15, 2014; Published date: February 18, 2014

Citation: Zhang M, Moore GA, Everts R, Begg EJ (2014) Determination of Total and Free Concentrations of Flucloxacillin and Cefazolin in Human Plasma by Liquid Chromatography/Tandem Mass Spectrometry. J Anal Bioanal Tech 5:182. doi: 10.4172/2155-9872.1000182

Copyright: © 2014 Zhang M, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

A rapid, simple and sensitive liquid chromatography/tandem mass spectrometry (LC-MS/MS) assay was developed for the determination of total and free concentrations of flucloxacillin and cefazolin in human plasma. Free flucloxacillin and cefazolin were separated from bound drug by ultra filtration. Samples of plasma and plasma ultra filtrate were pre-treated with acetonitrile (sample: acetonitrile = 1:4). Flucloxacillin, cefazolin and butobarbitone, the internal standard, were then resolved on a C18 (2)column using gradient elution of 0.05% formic acid and methanol. The three compounds were detected using electrospray ionisation in the positive mode. Standard curves were linear over the concentration range 0.2 to 100 mg/L (r>0.99) in plasma and 0.005 to 10 mg/L (r>0.99) in plasma ultra filtrate for both flucloxacillin and cefazolin. For both total and free flucloxacillin and cefazolin, bias was <±10%, and intra- and inter-day coefficients of variation (imprecision) were <10%. The limit of quantification was 0.2 mg/L for both flucloxacillin and cefazolin in plasma. The limit of quantification was 0.005 mg/L for both flucloxacillin and cefazolin in plasma ultra filtrate. The assay has been used successfully in a clinical pharmacokinetic study of flucloxacillin, and in clinical practice to enhance the effective use of flucloxacillin and cefazolin.

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