A modified method for determination of lumefantrine in human plasma by HPLC-UV and combination of protein precipitation and solid-phase extraction: application to a pharmacokinetic study.

An HPLC-UV method was developed and validated for the determination of lumefantrine in human plasma. Lumefantrine and its internal standard halofantrine were extracted from plasma samples using protein precipitation with acetonitrile (0.2% perchloric acid) followed by solid-phase extraction with Hypersep C(8) cartridges.

Development and validation of a high-performance liquid chromatography/tandem mass spectrometry method for the determination of artemether and its active metabolite dihydroartemisinin in human plasma.

To study the pharmacokinetic profile of artemether in children and in the context of antiviral drugs for HIV infected patients co-infected with malaria, an LC-MS/MS method was developed and validated to simultaneously determine artemether and its metabolite dihydroartemisinin in human plasma. Using artemisinin as the internal standard, 0.5 mL samples were processed with solid phase extraction (Waters Oasis HLB column), the elutes were directly injected onto a C18 LC column (Waters, Symmetry, 150 mm x 4.

Development and validation of a hydrophilic interaction liquid chromatography-tandem mass spectrometry method for determination of isoniazid in human plasma.

An LC-MS/MS method for the determination of isoniazid in human plasma was developed and validated. Human plasma aliquots of 100 microL were used for analysis. The assay used nialamide as the internal standard.

An LC-MS-MS method for the determination of nevirapine, a non-nucleoside reverse transcriptase inhibitor, in human plasma.

A sensitive and rapid liquid chromatography tandem mass spectrometry (LC-MS-MS) method has been developed to measure the levels of the HIV-1 non-nucleoside reverse transcriptase inhibitor nevirapine (NVP) in human plasma. The analyte and internal standard (IS) are isolated from plasma by a simple perchloric acid precipitation of plasma proteins followed by centrifugation. LC-MS-MS in positive mode used pairs of ions at m/z of 267/226 for NVP and 628/421 for the IS, respectively.

Simultaneous determination of five HIV protease inhibitors nelfinavir, indinavir, ritonavir, saquinavir and amprenavir in human plasma by LC/MS/MS.

A sensitive and rapid liquid chromatography tandem mass spectrometry (LC-MS-MS) method has been developed to measure the levels of five HIV protease inhibitors nelfinavir (NFV), indinavir (IDV), ritonavir (RTV), saquinavir (SQV) and amprenavir (APV) in human plasma. The analytes and internal standard are isolated from plasma by a simple acetonitrile precipitation of plasma proteins followed by centrifugation. LC-MS-MS in positive mode used pairs of ions at m/z of 568.

Determination of nelfinavir free drug concentrations in plasma by equilibrium dialysis and liquid chromatography/tandem mass spectrometry: important factors for method optimization.

A method was developed and validated for measuring the free fraction of nelfinavir in plasma employing equilibrium dialysis for the separation of free (unbound) drug and liquid chromatography/tandem mass spectrometry for quantitation. Nelfinavir, widely used to treat HIV infection, is a highly bound HIV protease inhibitor with the fraction bound in plasma being greater than 98%. Thus variations in the free fraction may be clinically important when interpreting total drug concentrations.