TY - JOUR
T1 - Determination of lorazepam in plasma from children by high-performance liquid chromatography with UV detection
AU - Muchohi, S. N.
AU - Obiero, K.
AU - Kokwaro, G. O.
AU - Ogutu, B. R.
AU - Githiga, I. M.
AU - Edwards, Geoffrey
AU - Newton, C. R. J. C.
PY - 2005/9/25
Y1 - 2005/9/25
N2 - 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.
AB - 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.
KW - Analysis in plasma
KW - Children
KW - High-performance liquid chromatography
KW - Lorazepam
KW - Pharmacokinetics
U2 - 10.1016/j.jchromb.2005.07.040
DO - 10.1016/j.jchromb.2005.07.040
M3 - Article
SN - 1570-0232
VL - 824
SP - 333
EP - 340
JO - Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences
JF - Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences
IS - 1-2
ER -
