A validated LC–MS/MS method for the simultaneous determination of thalidomide and its two metabolites in human plasma: Application to a pharmacokinetic assay

An accurate and sensitive LC–MS/MS method for determining thalidomide, 5‐hydroxy thalidomide and 5′‐hydroxy thalidomide in human plasma was developed and validated using umbelliferone as an internal standard. The analytes were extracted from plasma (100 μL) by liquid–liquid extraction with ethyl acetate and then separated on a BETASIL C₁₈ column (4.6 × 150 mm, 5 μm) with mobile phase composed of methanol–water containing 0.1% formic acid (70:30, v/v) in isocratic mode at a flow rate of 0.5 mL/min. The detection was performed using an API triple quadrupole mass spectrometer in atmospheric pressure chemical ionization mode. The precursor‐to‐product ion transitions m/z 259.1 → 186.1 for thalidomide, m/z 273.2 → 161.3 for 5‐hydroxy thalidomide, m/z 273.2 → 146.1 for 5′‐hydroxy thalidomide and m/z 163.1 → 107.1 for umbelliferone (internal standard, IS) were used for quantification. The calibration curves were obtained in the concentrations of 10.0–2000.0 ng/mL for thalidomide, 0.2–50.0 ng/mL for 5‐hydroxy thalidomide and 1.0–200.0 ng/mL for 5′‐hydroxy thalidomide. The method was validated with respect to linear, within‐ and between‐batch precision and accuracy, extraction recovery, matrix effect and stability. Then it was successfully applied to estimate the concentration of thalidomide, 5‐hydroxy thalidomide and 5′‐hydroxy thalidomide in plasma samples collected from Crohn's disease patients after a single oral administration of thalidomide 100 mg.     

Rapid and sensitive LC‐MS/MS method for determination of megestrol acetate in human plasma: application to a human pharmacokinetic study

A rapid, simple and fully validated LC‐MS/MS method was developed and validated for the determination of megestrol acetate in human plasma using tolbutamide as an internal standard (IS) after one‐step liquid–liquid extraction with methyl‐tert‐butyl‐ether. Detection was performed using electrospray ionization in positive ion multiple reaction monitoring mode by monitoring the transitions m/z 385.5 → 267.1 for megestrol acetate and m/z 271.4 → 155.1 for IS. Chromatographic separation was performed on a YMC Hydrosphere C₁₈ column with an isocratic mobile phase, which consisted of 10 mm ammonium formate buffer (adjusted to pH 5.0 with formic acid)–methanol (60:40, v/v) at a flow rate of 0.4 mL/min. The achieved lower limit of quantitation (LLOQ) was 1 ng/mL (signal‐to‐noise ratio > 10) and the standard calibration curve for megestrol acetate was linear (r > 0.99) over the studied concentration range (1–2000 ng/mL). The proposed method was fully validated by determining its specificity, linearity, LLOQ, intra‐ and inter‐day precision and accuracy, recovery, matrix effect and stability. The validated LC‐MS/MS method was successfully applied for the evaluation of pharmacokinetic parameters of megestrol acetate after oral administration of a single dose 800 mg of megestrol acetate (Megace?) to five healthy Korean male volunteers under fed conditions. Copyright © 2012 John Wiley & Sons, Ltd.     

Development and validation of a rapid LC‐MS/MS method to quantify letrozole in human plasma and its application to therapeutic drug monitoring

A selective, rapid, and sensitive liquid chromatography–tandem mass spectrometry(LC‐MS/MS) method was developed and validated for the determination of letrozole (LTZ) in human plasma, using anastrozole as internal standard (IS). Sample preparation was performed by one‐step protein precipitation with methanol. The analyte and IS were chromatographed on a reversed‐phase YMC‐ODS‐C₁₈ column (2.0 × 100 mm i.d., 3 µm) with a flow rate of 0.3 mL/min. The mobile phase consisted of water containing 0.1% formic acid (v/v) and methanol containing 0.1% formic acid (v/v). The mass spectrometer was operated in selected reaction monitoring mode through electrospray ionization ion mode using the transitions of m/z 286.2 → 217.1 for LTZ and m/z 294.1 → 225.1 for IS, respectively. The method was validated for selectivity, linearity, lower limit of quantitation, precision, accuracy, matrix effects and stability in accordance with the US Food and Drug Administration guidelines. Linear calibration curves were 1.0–60.0 ng/mL. Intra‐ and inter‐batch precision (CV) for LTZ were <9.34%, and the accuracy ranged from 97.43 to 105.17%. This method was successfully used for the analysis of samples from patients treated with LTZ in the dose of 2.5 mg/day. It might be suitable for therapeutic drug monitoring of these patients and contribute to predict the risk of adverse reactions. Copyright © 2015 John Wiley & Sons, Ltd.     

A rapid and sensitive determination of hypoxic radiosensitizer agent nimorazole in rat plasma by LC‐MS/MS and its application to a pharmacokinetic study

A highly sensitive, accurate and robust LC‐MS/MS method was developed and validated for determination of nimorazole (NMZ) in rat plasma using metronidazole (MNZ) as internal standard (IS). The analyte and IS were extracted from plasma by precipitating protein with acetonitrile and were chromatographed using an Agilent Poroshell 120, EC‐C₁₈ column. The mobile phase was composed of a mixture of acetonitrile and 0.1 % formic acid (85:15 v/v). The total run time was 1.5 min and injection volume was 5 μL. Multiple reaction monitoring mode using the transitions of m/z 227.1 → m/z 114.0 for MNZ and m/z 172.10 → m/z 128.1 for IS were monitored on a triple quadrupole mass spectrometer, operating in positive ion mode. The calibration curve was linear in the range of 0.25–200 ng/mL (r² > 0.9996) and the lower limit of quantification was 0.25 ng/mL in the rat plasma samples. Recoveries of NMZ ranged between 88.05 and 95.25%. The precision (intra‐day and inter‐day) and accuracy of the quality control samples were 1.25–8.20% and ?2.50–3.10, respectively. The analyte and IS were found to be stable during all sample storage and analysis procedures. The LC‐MS/MS method described here was validated and successfully applied to pharmacokinetic study in rats. Copyright © 2015 John Wiley & Sons, Ltd.     

UPLC‐MS/MS determination of voriconazole in human plasma and its application to a pharmacokinetic study

A sensitive and rapid ultra performance liquid chromatography tandem mass spectrometry (UPLC‐MS/MS) method was developed to determine voriconazole in human plasma. Sample preparation was accomplished through a simple one‐step protein precipitation with methanol. Chromatographic separation was carried out on an Acquity UPLC BEH C₁₈ column using an isocratic mobile phase system composed of acetonitrile and water containing 1% formic acid (45:55, v/v) at a flow rate of 0.50 mL/min. Mass spectrometric analysis was performed using a QTrap5500 mass spectrometer coupled with an electrospray ionization source in the positive ion mode. The multiple reaction monitoring transitions of m/z 351.0 → 281.5 and m/z 237.1 → 194.2 were used to quantify voriconazole and carbamazepine (internal standard), respectively. The linearity of this method was found to be within the concentration range of 2.0–1000 ng/mL with a lower limit of quantification of 2.0 ng/mL. Only 1.0 min was needed for an analytical run. This fully validated method was successfully applied to the pharmacokinetic study after oral administration of 200 mg voriconazole to 20 Chinese healthy male volunteers. Copyright © 2014 John Wiley & Sons, Ltd.     

Simultaneous quantification of hyperin,reynoutrin and guaijaverin in mice plasma by LC‐MS/MS: application to a pharmacokinetic study

A specific and sensitive LC‐MS/MS assay was developed to simultaneously quantify three structurally similar flavonoid glycosides – hyperin, reynoutrin and guaijaverin – in mouse plasma. Biosamples were prepared by solid‐phase extraction. Isocratic chromatographic separation was performed on an AichromBond‐AQ C₁₈ column (250 × 2.1 mm, 5 μm) with methanol–acetonitrile–water–formic acid (20:25:55:0.1) as the mobile phase. Detection of hyperin, reynoutrin, guaijaverin and internal standard [luteolin‐7‐O‐β‐d ‐apiofuranosyl‐(1 → 6)‐β‐d ‐glucopyranoside] was achieved by ESI‐MS/MS in the negative ion mode using m/z 463 → m/z 300, m/z 433 → m/z 300, m/z 433 → m/z 300 and m/z 579 → m/z 285 transitions, respectively. Linear concentration ranges of calibration curves were 4.0–800.0 ng/mL for hyperin and reynoutrin and 8.0–1600.0 ng/mL for guaijaverin when 100 μL of plasma was analyzed. We used this validated method to study the pharmacokinetics of hyperin, reynoutrin and guaijaverin in mice following oral and intravenous administration. All three quercetin‐3‐O‐glycosides showed poor oral absorption in mice, and the absolute bioavailability of hyperin after oral administration of 100 mg/kg was 1.2%. Pretreatment with verapamil increased the peak concentration and area under the concentration–time curve of hyperin, which were significantly higher than the control values. The half‐life of hyperin with verapamil was significantly prolonged compared with that of the control. Copyright © 2016 John Wiley & Sons, Ltd.     

Development and application of a LC–MS/MS assay for the simultaneous quantification of edaravone and taurine in beagle plasma

An LC–MS/MS method was developed and validated for the simultaneous quantification of edaravone and taurine in beagle plasma. The plasma sample was deproteinized using acetonitrile containing formic acid. Chromatographic separations were achieved on an Agilent Zorbax SB‐Aq (100 × 2.1 mm, 3.5 μm) column, with a gradient of water (containing 0.03% formic acid) and methanol as the mobile phase at a flow rate of 0.3 mL/min. The analyte detection was carried out in multiple reaction monitoring mode and the optimized precursor‐to‐product transitions of m/z [M+H]⁺ 175.1 → 133.0 (edaravone), m/z [M+H]⁺ 189.1 → 147.0 (3‐methyl‐1‐p‐tolyl‐5‐pyrazolone, internal standard, IS), m/z [M–H]^? 124.1→80.0 (taurine), and m/z [M–H]^? 172.0 → 80.0 (sulfanilic acid, IS) were employed to quantify edaravone, taurine, and their corresponding ISs, respectively. The LOD and the lower LOQ were 0.01 and 0.05 μg/mL for edaravone and 0.66 and 2 μg/mL for taurine, respectively. The calibration curves of these two analytes demonstrated good linearity (r ＞ 0.99). All the validation data including the specificity, precision, recovery, and stability conformed to the acceptable requirements. This validated method has successfully been applied in the pharmacokinetic study of edaravone and taurine mixture in beagle dogs.     

Determination of sunitinib and its active metabolite,N‐desethyl sunitinib in mouse plasma and tissues by UPLC‐MS/MS: assay development and application to pharmacokinetic and tissue distribution studies

A simple, sensitive and specific method using ultraperformance liquid chromatography/tandem mass spectrometry (UPLC‐MS/MS) was developed to determine sunitinib and N‐desethyl sunitinib in mouse plasma and tissues. The analytes were separated by an isocratic mobile phase consisting of acetonitrile and buffer solution (water with 0.1% formic acid and 5 m m ammonium acetate; 40: 60, v/v) running at a flow rate of 0.35 mL/min for 2 min. Quantification was performed using a mass spectrometer by multiple reaction monitoring in positive electrospray ionization mode. The transition was monitored at m/z 399 → 283, m/z 371 → 283 and m/z 327 → 270 for sunitinib, N‐desethyl sunitinib and internal standard, respectively. Calibration curves were linear over concentration ranges of 2–500, 0.5–50 and 1–250 ng/mL for plasma, heart and other biosamples. The method was successfully applied to animal experiments. The pharmacokinetic study indicated that sunitinib was eliminated quickly in mice with a half‐life of 1.2 h; tissue distribution data showed more sunitinib and its metabolite in liver, spleen and lung, which provided reference for further study. Copyright © 2014 John Wiley & Sons, Ltd.     

Determination of tigecycline in human plasma by LC–MS/MS and its application to population pharmacokinetics study in Chinese patients with hospital‐acquired pneumonia

A selective, sensitive and rapid liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for the determination of tigecycline (TGC) in human plasma, using tigecycline‐d₉ as an internal standard (IS). Analytical samples were prepared using a protein precipitation method coupled with a concentration process. The analyte and IS were separated on a reversed‐phase Waters Acquity UPLC^® BEH‐C₁₈ column (2.1 × 50 mm i.d., 1.7 μm) with a flow rate of 0.25 mL/min. The mobile phase consisted of water, containing 0.2% formic acid (v/v) with 10 mm ammonium formate (A) and acetonitrile (B). The mass spectrometer was operated in selected reaction monitoring mode through electrospray ionization ion mode using the transitions of m/z 586.2 → 513.1 and m/z 595.1 → 514.0 for TGC and IS, respectively. The linearity of the method was in the range of 10–5000 ng/mL. Intra‐ and inter‐batch precision (CV) for TGC was <9.27%, and the accuracy ranged from 90.06 to 107.13%. This method was successfully applied to the analysis of samples from hospital‐acquired pneumonia patients treated with TGC, and a validated population pharmacokinetic model was established. This developed method could be useful to predict pharmacokinetics parameters and valuable for further pharmacokinetics/pharmacodynamics studies.     

Development of a rapid and sensitive SPE-LC-MS/MS method for the simultaneous estimation of fluoxetine and olanzapine in human plasma

A high‐performance liquid chromatographic assay with tandem mass spectrometric detection was developed to simultaneously quantify fluoxetine and olanzapine in human plasma. The analytes and the internal standard (IS) duloxetine were extracted from 500 μL aliquots of human plasma through solid‐phase extraction. Chromatographic separation was achieved in a run time of 4.0 min on a Hypersil Gold C₁₈ column (50 × 4.6 mm, 5 µm) using isocratic mobile phase consisting of acetonitrile–water containing 2% formic acid (70:30, v/v), at a flow‐rate of 0.5 mL/min. Detection of analytes and internal standard was performed by electrospray ionization tandem mass spectrometry, operating in positive‐ion and multiple reaction monitoring acquisition mode. The protonated precursor to product ion transitions monitored for fluoxetine, olanzapine and IS were m/z 310.01 → 147.69, 313.15 → 256.14 and 298.1 → 153.97, respectively. The method was validated over the concentration range of 1.00–150.20 ng/mL for fluoxetine and 0.12–25.03 ng/mL for olanzapine in human plasma. The intra‐batch and inter‐batch precision (%CV) across four quality control levels was ≤6.28% for both the analytes. In conclusion, a simple and sensitive analytical method was developed and validated in human plasma. This method is suitable for measuring accurate plasma concentration in bioequivalence study and therapeutic drug monitoring as well, following combined administration. Copyright © 2011 John Wiley & Sons, Ltd.     

An improved LC‐MS/MS method for quantitation of indapamide in whole blood: application for a bioequivalence study

An improved LC‐MS/MS method for the quantitation of indapamide in human whole blood was developed and validated. Indapamide‐d3 was used as internal standard (IS) and liquid–liquid extraction was employed for sample preparation. LC separation was performed on Synergi Polar RP‐column (50 × 4.6 mm i.d.; 4 µm) and mobile phase composed of methanol and 5 mm aqueous ammonium acetate containing 1 mm formic acid (60:40), at flow rate of 1 mL/min. The run time was 3.0 min and the injection volume was 20 μL. Mass spectrometric detection was performed using electrospray ion source in negative ionization mode, using the transitions m/z 364.0 → m/z 188.9 and m/z 367.0 → m/z 188.9 for indapamide and IS, respectively. Calibration curve was constructed over the range 0.25–50 ng/mL. The method was precise and accurate, and provided recovery rates >80% for indapamide and IS. The method was applied to determine blood concentrations of indapamide in a bioequivalence study with two sustained release tablet formulations. The 90% confidence interval for the geometric mean ratios for maximum concentration was 95.78% and for the area under the concentration–time curve it was 97.91%. The tested indapamide tablets (Eurofarma Laboratórios S.A.) were bioequivalent to Natrilix®, according to the rate and extent of absorption. Copyright © 2014 John Wiley & Sons, Ltd.     

Rapid quantitative analysis of etoricoxib in human plasma by UPLC‐MS/MS and application to a pharmacokinetic study in Chinese healthy volunteers

A selective and sensitive liquid chromatography–tandem mass spectrometry method was developed for simultaneous determination of etoricoxib in human plasma. Chromatography was performed on an Acquity UPLC HSS T3 column (1.8 μm, 50 × 2.1 mm), with a flow rate of 0.600 mL/min, using a gradient elution with acetonitrile and water which contained 2 mm ammonium acetate as the mobile phase. Detection was carried out on Triple QuadTM 5500 mass spectrometer under positive‐ion multiple reaction monitoring mode. The respective mass transitions used for quantification of etoricoxib and etoricoxib‐d3 were m/z 359.0 → 280.1 and m/z 362.0 → 280.2. Calibration curves were linear over the concentration range of 5–5000 ng/mL. The validated method was applied in the pharmacokinetic study of etoricoxib in Chinese healthy volunteers under fed and fasted conditions. After a single oral dose of 120 mg, the main pharmacokinetic parameters of etoricoxib in fasted and fed groups were respectively as follows: peak concentration, 2364.78 ± 538.01 and 1874.55 ± 367.90 ng/mL; area under the concentration–time curve from 0 to 120 h, 44,605.53 ± 15,266.66 and 43,516.33 ± 12,425.91 ng h/mL; time to peak concentration, 2.00 and 2.50 h; and half‐life, 24.08 ± 10.06 and 23.64± 6.72 h. High‐fat food significantly reduced the peak concentration of etoricoxib (p = 0.001) but had no effect on the area under the concentration–time curve.     

High-throughput protein precipitation method with 96-well plate for determination of doxepin and nordoxepin in human plasma using LC–MS/MS

The aim of this study was to establish a high-throughput and sensitive LC–MS/MS method for the determination of doxepin and its major active metabolite nordoxepin in human plasma. It has been designed for bioequivalence study for formulations containing 25 mg of doxepin. Doxepin and nordoxepin were extracted from human plasma samples by protein precipitation with acetonitrile by using protein precipitation 96-well plates. The analyte was separated using a Phenomenex Kinetex Biphenyl column (100 × 2.1 mm, 2.6 μm) using isocratic elution with a mobile phase of 20 mM ammonium formate (30%) and acetonitrile:methanol 3:7 v:v (70%) at a flow rate of 0.5 mL/min and an injection volume of 10 μL. The detection was performed using a triple quadrupole mass spectrometer by multiple reaction monitoring mode to monitor the precursor-to-product ion transitions of m/z 280.4 → 107.0 and 283.4 → 235.0 for doxepin and doxepin-D3, respectively, and 266.3 → 106.9 and 269.3 → 235.0 for nordoxepin and nordoxepin-D3, respectively, in positive electrospray ionization mode. The total run time was 3.5 min. The method was validated over a concentration range of 50–10,000 pg/mL using a Triple Quad 4500 MS System (Sciex) for both analytes. The developed and validated method can be successfully used to study the bioequivalence/pharmacokinetics of doxepin and nordoxepin.     

A validated HPLC‐MS/MS method for the quantification of caderofloxacin in human plasma and its application to a clinical pharmacokinetic study

A simple, selective and rapid HPLC‐MS/MS method was developed and validated for the determination of caderofloxacin in human plasma. Sparfloxacin was used as the internal standard (IS). After precipitation with methanol and dilution with the mobile phase, the samples were injected into the HPLC‐MS/MS system. The chromatographic separation was performed on a Zorbax XDB Eclipse C₁₈ column (150 × 4.6 mm, 5 µm) with a mobile phase of ammonium acetate buffer (20 mm, pH 3.0)–methanol, 45:55 (v/v). The MS/MS analysis was done in positive mode. The multiple reaction monitoring transitions monitored were m/z 412.3 → 297.1 for caderofloxacin and m/z 393.2 → 292.2 for the IS. The calibration curve was linear over the range of 50.0–8000 ng/mL with an aliquot of 100 μL plasma. The precision of the assay was 2.0–9.4 and 6.6–11.5% for the intra‐ and inter‐run variability, respectively. The intra‐ and inter‐run accuracy (relative error) was 4.4–10.0 and ?1.2–4.0%. The total run time was 3.5 min. The assay was fully validated in accordance with the US Food and Drug Administration guidance. It was successfully applied to a pharmacokinetic study of caderofloxacin in healthy Chinese volunteers. Copyright © 2015 John Wiley & Sons, Ltd.     

Simultaneous determination of tapentadol and its carbamate prodrug in rat plasma by UPLC‐MS/MS and its application to a pharmacokinetic study

A prodrug of tapentadol, namely tapentadol carbamate (WWJ01), was synthesized to improve the bioavailability of tapentadol owing to its extensive first‐pass metabolism. In this study, a highly rapid and sensitive UPLC‐MS/MS method was developed and validated for the simultaneous determination of tapentadol and WWJ01 in rat plasma with fluconazole as an internal standard. The analytes and internal standard were treated by methanol and then separated on a Phenomenex Kinetex® XB‐C₁₈ (2.1 × 50 mm × 2.6 μm) column at a flow rate of 0.3 mL/min. The mobile phase comprised methanol and water with a gradient elution. The mass transition ion‐pairs were m/z 222.2 → 107.0, m/z 293.2 → 71.9 and m/z 307.1 → 220.0 for tapentadol, WWJ01 and IS, respectively. Excellent linearity was observed over the concentration range of 2–1250 ng/mL (r = 0.995) with a lower limit of quantification of 2 ng/mL for both tapentadol and WWJ01. The intra‐ and inter‐day accuracy and precision for all quality control samples were within ±15%. The validated method was accurate, rapid and reproducible, and was successfully applied to a pharmacokinetic study of tapentadol and WWJ01.     

LC‐MS/MS method for the determination of agomelatine in human plasma and its application to a pharmacokinetic study

A sensitive and selective LC‐MS/MS method for the determination of agomelatine in human plasma was developed and validated. After simple liquid–liquid extraction, the analytes were separated on a Zorbax SB‐C₁₈ column (150 × 2.1 mm i.d., 5 µm) with an isocratic mobile phase consisting of 5 mm ammonium acetate solution (containing 0.1% formic acid) and methanol (30:70, v/v) at a flow‐rate of 0.3 mL/min. The MS acquisition was performed in multiple reaction monitoring mode with a positive electrospray ionization source. The mass transitions monitored were m/z 244.1 → 185.3 and m/z 285.2 → 193.2 for agomelatine and internal standard, respectively. The methods were validated for selectivity, carry‐over, matrix effects, calibration curves, accuracy and precision, extraction recoveries, dilution integrity and stability. The validated method was successfully applied to a pharmacokinetic study of agomelatine in Chinese volunteers following a single oral dose of 25 mg agomelatine tablet. Copyright © 2013 John Wiley & Sons, Ltd.     

A sensitive LC‐MS/MS method for the quantification of febuxostat in human plasma and its pharmacokinetic application

An improved, simple and highly sensitive LC‐MS/MS method has been developed and validated for quantification of febuxostat with 100 μL human plasma using febuxostat‐d₇ as an internal standard (IS) according to regulatory guidelines. The analyte and IS were extracted from human plasma via liquid–liquid extraction using diethyl ether. The chromatographic separation was achieved on a Zorbax C₁₈ column using a mixture of acetonitrile and 5 mm ammonium formate (60:40, v/v) as the mobile phase at a flow rate of 0.5 mL/min. The total run time was 5.0 min and the elution of febuxostat and IS occurred at 1.0 and 1.5 min, respectively. A linear response function was established for the range of concentrations 1–6000 ng/mL (r > 0.99). The precursor to product ion transitions monitored for febuxostat and IS were m/z 317.1 → 261.1 and 324.2 → 262.1, respectively. The intra‐ and inter‐day precisions (%RSD) were within 1.29–9.19 and 2.85–7.69%, respectively. The proposed method was successfully applied to pharmacokinetic studies in humans. Copyright © 2013 John Wiley & Sons, Ltd.     

Rapid quantification of levosulpiride in human plasma using RP‐HPLC‐MS/MS for pharmacokinetic and bioequivalence study

A rapid and validated method for analysis of levosulpiride in human plasma using liquid chromatography coupled to tandem mass spectrometry was developed. Levosulpiride and tiapride (IS, internal standard) were extracted from alkalized plasma samples with ethylacetate and separation by RP‐HPLC. Detection was performed by positive ion electrospray ionization in multiple‐reaction monitoring mode, monitoring the transitions m/z 342.1 → m/z 112.2 and m/z 329.1 → m/z 213.2, for quantification of levosulpiride and IS, respectively. The standard calibration curves showed good linearity within the range of 2–200 ng/mL (r² ≥ 0.9990). The lower limit of quantitation was 2 ng/mL. The retention times of levosulpiride (0.63 min) and IS (0.66 min) presented a significant time saving benefit of the proposed method. No significant metabolic compounds were found to interfere with the analysis. This method offered good precision and accuracy and was successfully applied for the pharmacokinetic and bioequivalence study of a 25 mg of levosulpiride tablet in 24 healthy Korean volunteers. Copyright © 2009 John Wiley & Sons, Ltd.     

Development of a fast LC‐MS/MS assay for the determination of deferiprone in human plasma and application to pharmacokinetics

A fast and accurate liquid chromatography/tandem mass spectrometric (LC‐MS/MS) assay was first developed and validated for the determination of deferiprone in human plasma. The analytes were extracted with acetonitrile from only 50 μL aliquots of human plasma to achieve the protein precipitation. After extraction, chromatographic separation of analytes in human plasma was performed using a Synergi Fusion‐RP 80A column at 30 °C. The mobile phase consisted of methanol and 0.2% formic acid containing 0.2 mM EDTA (60:40, v/v). The flow rate of the mobile phase was 0.8 mL/min. The total run time for each sample analysis was 4 min. Detection was performed using electrospray ionization in positive ion multiple reaction monitoring mode by monitoring the precursor‐to‐parent ion transitions m/z 140.1 → 53.1 for deferiprone and m/z 143.1 → 98.1 for internal standard. A linear range was established from 0.1 to 20 µg/mL. The limit of detection was determined as 0.05 µg/mL. The validated method was estimated for linearity, recovery, stability, precision and accuracy. Intraday and interday precisions were 4.3–5.5 and 4.6–7.3%, respectively. The recovery of deferiprone was in the range of 80.1–86.8%. The method was successfully applied to a pharmacokinetic study of deferiprone in six thalassemia patients. Copyright © 2012 John Wiley & Sons, Ltd.