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Determination of lorazepam in plasma from children by high-performance liquid chromatography with UV detection

Muchohi, S. N., Obiero, K., Kokwaro, G. O., Ogutu, B. R., Githiga, I. M., Edwards, Geoffrey and Newton, C. R. J. C. (2005) 'Determination of lorazepam in plasma from children by high-performance liquid chromatography with UV detection'. Journal of Chromatography B-Analytical Technologies in the Biomedical and Life Sciences, Vol 824, Issue 1-2, pp. 333-340.

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Abstract

A simple, sensitive, selective, and reproducible reversed-phase high-performance liquid chromatographic (HPLC) method with UV detection was developed for the determination of lorazepam (LZP) in human plasma, using oxazepam (OZP) as internal standard. LZP and OZP were extracted from alkalinized (pH 9.5) spiked and clinical plasma samples using a single step liquid-liquid extraction with a mixture of n-hexane-dichloromethane (70:30%; v/v). Chromatographic separation was performed on a reversed-phase Synergi (R) Max RP analytical column (150 mm x 4.6 mm i.d.; 4 mu m particle size), using an aqueous mobile phase (10 mM KH2PO4 buffer (pH 2.4)-acetonitrile; 65:35%, v/v) delivered at a flow-rate of 2.5 ml/min. Retention times for OZP and LZP were 10.2 and 11.9 min, respectively. Calibration curves were linear from 10 to 300ng with correlation coefficients (r(2)) better than 0.99. The limits of detection (LOD) and quantification (LOQ) were 2.5 and 10 ng/ml, respectively, using 0.5 ml samples. The mean relative recoveries at 20 and 300 ng/ml were 84.1 +/- 5.5% (n = 6) and 72.4 +/- 5.9% (n = 7), respectively; for OZP at 200 ng the value was 68.2 +/- 6.8% (n = 14). The intra-assay relative standard deviations (R.S.D.) at 20, 150 and 270 ng/ml of LZP were 7.8%, 9.8% (n = 7 in all cases) and 6.6% (n = 8), respectively. The inter-assay R.S.D. at the above concentrations were 15.9%, 7.7% and 8.4% (n=7 in all cases), respectively. Intra- and inter-assay accuracy data were within the acceptance interval of +/- 20% of the nominal values. There was no interference from other commonly co-administered anticonvulsant, antimicrobial, antipyretic, and antimalarial drugs. The method has been successfully applied to a pharmacokinetic study of LZP in children with severe malaria and convulsions following administration of a single intravenous dose (0.1 mg/kg body weight) of LZR Crown Copyright (c) 2005 Published by Elsevier B.V. All rights reserved.

Item Type: Article
Uncontrolled Keywords: lorazepam high-performance liquid chromatography analysis in plasma pharmacokinetics children childhood cerebral malaria solid-phase extraction status epilepticus mass-spectrometry electron-capture whole-blood benzodiazepines seizures diazepam column
Subjects: QV Pharmacology > QV 4 General works
WS Pediatrics > Diseases of Children and Adolescents > General Diseases > WS 200 General works
Faculty: Department: Groups (2002 - 2012) > Molecular & Biochemical Parasitology Group
Digital Object Identifer (DOI): https://doi.org/10.1016/j.jchromb.2005.07.040
Depositing User: Ms Julia Martin
Date Deposited: 08 Sep 2011 15:15
Last Modified: 06 Feb 2018 13:02
URI: http://archive.lstmed.ac.uk/id/eprint/1913

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