Development of an LC‐MS/MS method for quantification of kadsurenone in rat plasma and its application to a pharmacokinetic study

A sensitive and rapid LC‐MS/MS method was developed and validated for the determination of kadsurenone in rat plasma using lysionotin as the internal standard (IS). The analytes were extracted from rat plasma with acetonitrile and separated on a SB‐C₁₈ column (50 × 2.1 mm, i.d.; 1.8 µm) at 30 °C. Elution was achieved with a mobile phase consisting of methanol–water–formic acid (65:35:0.1, v/v/v) at a flow rate of 0.30 mL/min. Detection and quantification for analytes were performed by mass spectrometry in the multiple reaction monitoring mode with positive electrospray ionization m/z at 357.1 → 178.1 for kadsurenone, and m/z 345.1 → 315.1 for IS. Calibration curves were linear over a concentration range of 4.88–1464 ng/mL with a lower limit of quantification of 4.88 ng/mL. The intra‐ and inter‐day accuracies and precisions were <8.9%. The LC‐MS/MS assay was successfully applied for oral pharmacokinetic evaluation of kadsurenone using the rat as an animal model. Copyright © 2013 John Wiley & Sons, Ltd.     

An LC‐MS/MS method for determination of curculigoside with anti‐osteoporotic activity in rat plasma and application to a pharmacokinetic study

A rapid, simple, selective and sensitive LC‐MS/MS method was developed for the determination of curculigoside in rat plasma. The analytical procedure involves extraction of curculigoside and syringin (internal standard, IS) from rat plasma with a one‐step extraction method by protein precipitation. The chromatographic resolution was performed on an Agilent XDB‐C₁₈ column (4.6 × 50 mm, 5 µm) using an isocratic mobile phase of methanol with 0.1% formic acid and H₂O with 0.1% formic acid (45:55, v/v) at a flow rate of 0.35 mL/min with a total run time of 2.0 min. The assay was achieved under the multiple‐reaction monitoring mode using positive electrospray ionization. Method validation was performed according to US Food and Drug Administration guidelines and the results met the acceptance criteria. The calibration curve was linear over 4.00–4000 ng/mL (R = 0.9984) for curculigoside with a lower limit of quantification of 4.00 ng/mL in rat plasma. The intra‐ and inter‐day precisions and accuracies were 3.5–4.6 and 0.7–9.1%, in rat plasma, respectively. The validated LC‐MS/MS method was successfully applied to a pharmacokinetic study of curculigoside in rats after a single intravenous and oral administration of 3.2 and 32 mg/kg. The absolute bioavailability of curculigoside after oral administration was 1.27%. Copyright © 2013 John Wiley & Sons, Ltd.     

Simultaneous quantification of curdione,furanodiene and germacrone in rabbit plasma using liquid chromatography–tandem mass spectrometry and its application to a pharmacokinetic study

A simple, rapid and sensitive method was developed for the simultaneous quantification of curdione, furanodiene and germacrone in rabbit plasma using a LC‐MS/MS analysis. The plasma sample preparation was a simple deproteinization by the addition of 3 vols of acetonitrile followed by centrifugation. The analytes and internal standard (IS) costunolide were separated on a Zorbax SB‐C₁₈ column (3.5 µm, 2.1 × 100 mm) with mobile phase of methanol–water (90:10, v/v) containing 0.1% formic acid at a flow rate of 0.3 mL/min with an operating temperature of 25°C. Detection was carried out by atmospheric pressure chemical ionization in positive ion selected reaction monitoring mode. Linear detection responses were obtained for the three test compounds ranging from 5 to 5000 ng/mL and the lower limits of quantitation were 5‐10ng/mL. The intra‐ and inter‐day precisions (relative standard deviations) were within 9.4% for all analytes, while the deviation of assay accuracies was within ±10.0%. The average recoveries of analytes were >80.0%. All analytes were proved to be stable during all sample storage, preparation and analytical procedures. The method was successfully applied to the pharmacokinetic study of the three compounds after vaginal drug delivery of Baofukang suppository to rabbit. Copyright © 2015 John Wiley & Sons, Ltd.     

Simultaneous quantitative analysis of dextromethorphan,dextrorphan and chlorphenamine in human plasma by liquid chromatography–electrospray tandem mass spectrometry

A sensitive and accurate HPLC‐MS/MS method was developed for the simultaneous determination of dextromethorphan, dextrorphan and chlorphenamine in human plasma. Three analytes were extracted from plasma by liquid–liquid extraction using ethyl acetate and separated on a Kromasil 60‐5CN column (3 µm, 2.1 × 150 mm) with mobile phase of acetonitrile–water (containing 0.1% formic acid; 50:50, v/v) at a flow rate of 0.2 mL/min. Quantification was performed on a triple quadrupole tandem mass spectrometer in multiple reaction monitoring mode using positive electrospray ionization. The calibration curve was linear over the range of 0.01–5 ng/mL for dextromethorphan, 0.02–5 ng/mL for dextrorphan and 0.025–20 ng/mL for chlorphenamine. The lower limits of quantification for dextromethorphan, dextrorphan and chlorphenamine were 0.01, 0.02 and 0.025 ng/mL, respectively. The intra‐ and inter‐day precisions were within 11% and accuracies were in the range of 92.9–102.5%. All analytes were proved to be stable during sample storage, preparation and analytic procedures. This method was first applied to the pharmacokinetic study in healthy Chinese volunteers after a single oral dose of the formulation containing dextromethorphan hydrobromide (18 mg) and chlorpheniramine malaeate (8 mg). Copyright © 2013 John Wiley & Sons, Ltd.     

Simultaneous quantification of two steroidal glycosides after oral gavage of Marsdenia tenacissima extract in rats using a LC‐MS/MS method

A specific, sensitive and accurate analytical LC‐MS/MS assay was developed for the simultaneous determination of two steroidal glycosides, tenacissoside H and tenacissoside I, in rat plasma. An Agilent ZORBAX SB‐C₁₈ column was used with an isocratic mobile phase system composed of methanol–water–formic acid (70:30:0.1, v/v/v) at a flow rate of 0.3 mL/min. The analysis was performed on a positive ionization electrospray mass spectrometer via selected reaction monitoring mode scan. One‐step protein precipitation with acetonitrile was chosen to extract the analytes from plasma. The lower limits of quantification were 0.9 ng/mL for tenacissoside H and tenacissoside I. The intra‐ and inter‐day precisions were 2.03–11.56 and 3.76–11.62%, respectively, and the accuracies were <110.28% at all quality control levels. The validated method was applied to a pharmacokinetic study in rats after oral gavage of Marsdenia tenacissima extract. Copyright © 2014 John Wiley & Sons, Ltd.     

A novel LC-MS/MS method for simultaneous quantification of tenofovir and lamivudine in human plasma and its application to a pharmacokinetic study

A new, rapid, sensitive and specific LC‐MS/MS method has been developed and validated for the simultaneous quantification of tenofovir and lamivudine in human plasma using abacavir as an internal standard. An API‐4000 LC‐MS/MS with electrospray ionization was operated in multiple‐reaction monitoring mode for the analysis. The analytes were extracted from plasma by solid‐phase extraction technique using an Oasis HLB cartridge. The reconstituted samples were chromatographed on a Chromolith ROD speed C₁₈ column using a mixture of 0.1% formic acid in water and acetonitrile (90:10 v/v) at a flow‐rate of 1 mL/min. The method was validated as per the FDA guidelines. The calibration curves were found to be linear in the range of 5–600 ng/mL for tenofovir and 25– 4000 ng/mL for lamivudine. The intra‐ and inter‐day precision and accuracy results were well within the acceptable limits. A run time of 2.8 min consumed for each sample made it possible to analyze more samples per day. The proposed assay method was found to be applicable to a pharmacokinetic study in human male volunteers. Copyright © 2012 John Wiley & Sons, Ltd.     

Liquid chromatography-tandem mass spectrometry for quantification of lacosamide, an antiepileptic drug, in rat plasma and its application to pharmacokinetic study

A rapid, simple and sensitive liquid chromatography–tandem mass spectrometry (LC/MS/MS) was developed for the determination of an antiepileptic drug, lacosamide, in rat plasma. The method involves the addition of acetonitrile and internal standard solution to plasma samples, followed by centrifugation. An aliquot of the supernatant was diluted with water and directly injected into the LC/MS/MS system. The separations were performed on column packed with octadecylsilica (5 µm, 2.0 × 50 mm) with 0.1% formic acid and acetonitrile as mobile phase, and the detection was performed on tandem mass spectrometry by the multiple‐reaction monitoring via an electrospray ionization source. The standard curve was linear over the concentration range from 0.3 to 1000 ng/mL. The lower limit of quantification was 0.3 ng/mL using 50 μL of rat plasma sample. The intra‐ and inter‐assay precision and accuracy were found to be less than 11.7 and 8.8%, respectively. The developed analytical method was successfully applied to the pharmacokinetic study of lacosamide in rats. Copyright © 2011 John Wiley & Sons, Ltd.     

Quantification of lurasidone, an atypical antipsychotic drug, in rat plasma with high-performance liquid chromatography with tandem mass spectrometry

A liquid chromatography–tandem mass spectrometric (LC/MS/MS) method was developed for the determination of an atypical antipsychotic drug, lurasidone, in rat plasma. The method involves the addition of acetonitrile and ziprasidone (internal standard) solution to plasma samples, followed by centrifugation. An aliquot of the supernatant was diluted with water and directly injected into the LC/MS/MS system. The separations were performed on a column packed with octadecylsilica (5 μm, 2.0 × 50 mm) with 0.1% formic acid and 0.1% formic acid in acetonitrile as mobile phase and the detection was performed using tandem mass spectrometry by multiple‐reaction monitoring via an electrospray ionization source. The standard curve was linear (r = 0.9982) over the concentration range 0.002–1 μg/mL. The intra‐ and inter‐assay precisions were 1.7 and 8.6%, respectively. The accuracy range was from 90.3 to 101.8%. The lower limit of quantification was 2.0 ng/mL using 50 μL of rat plasma sample. The developed analytical method was successfully applied to the pharmacokinetic study of lurasidone in rats. Copyright © 2011 John Wiley & Sons, Ltd.     

Determination of a novel paclitaxel derivative (NPD‐103) in human plasma by ultra‐performance liquid chromatography–tandem mass spectrometry

A sensitive and specific ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC‐MS‐MS) method for quantification of a newly developed anticancer agent NPD‐103 has been established. An aliquot of human plasma sample (200 µL) was spiked with ¹³C‐labeled paclitaxel (internal standard) and extracted with 1.3 mL of tert‐butyl methyl ether. NPD‐103 was quantitated on a C₁₈ column with methanol–0.1% formic acid (75:25, v/v) as mobile phase using UPLC‐MS‐MS operating in positive electrospray ionization mode with a total run time of 3.0 min. For NPD‐103 at the concentrations of 1.0, 5.0 and 10.0 µg/mL in human plasma, the absolute extraction recoveries were 95.58, 102.43 and 97.77%, respectively. The linear quantification range of the method was 0.1–20.0 µg/mL in human plasma with linear correlation coefficients greater than 0.999. The intra‐ and inter‐day accuracy for NPD‐103 at 1.0, 5.0 and 10.0 µg/mL levels in human plasma fell into the ranges of 95.29–100.00% and 91.04–94.21%, and the intra‐ and inter‐day precisions were in the ranges of 8.96–11.79% and 7.25–10.63%, respectively. This assay is applied to determination of half‐life of NPD‐103 in human plasma. Copyright © 2008 John Wiley & Sons, Ltd.     

Highly sensitive determination of Schisandrin and Schisandrin B in plasma of rats after administration of Wurenchun (Fructus Schisandrae Chinensis Extracts) preparations by LC‐ESI‐MS/MS

A sensitive and specific method based on liquid chromatography‐tandem mass spectrometry using electrospray ionization (LC‐ESI‐MS/MS) has been developed for the determination of Schisandrin and Schisandrin B in rat plasma. A 100 μL plasma sample was extracted by methyl tert‐butyl ether after spiking the samples with nimodipine (internal standard) and performed on an XTerra®MS‐C₁₈ column (150 mm × 2.1 mm, 3.5 μm) with the mobile phase of acetonitrile–water–formic acid (80:20:0.2, v/v) at a flow rate of 0.2 mL/min in a run time of 8.5 min. The lower limit of quantification of the method was 40 ng/mL for Schisandrin and 20 ng/mL for Schisandrin B. The method showed reproducibility with intra‐day and inter‐day precision of less than 13.8% RSD, as well as accuracy, with inter‐ and intra‐assay accuracies between 93.5 and 107.2%. Finally, the LC‐ESI‐MS/MS method was successfully applied to study the pharmacokinetics of Schisandrin and Schisandrin B in rats after administration of Wurenchun commercial formulations to rats. Copyright © 2009 John Wiley & Sons, Ltd.     

A rapid and sensitive LC‐MS/MS method for quantification of 3,29‐dibenzoyl rarounitriol in rat plasma: application to a pharmacokinetic study

A rapid, sensitive and high‐throughput liquid chromatography–tandem mass spectrometry was established and validated to assay the concentrations of 3,29‐dibenzoyl rarounitriol in rat plasma. Plasma samples were processed by liquid–liquid extraction with ethyl acetate and separated on a Hypersil Gold C₁₈ column (50 × 4.6 mm, 3 µm) at an isocratic flow rate of 0.5 mL/min using methanol–10 mm ammonium acetate–formic acid (90:10:0.1, v/v/v) as mobile phase. The total run time was 5 min for each sample. MS/MS detection was accomplished in selected reaction monitoring mode with positive electrospray ionization. The calibration curve was linear over the concentration range of 0.125–50 ng/mL with lower limit of quantification of 0.125 ng/mL. The intra‐ and inter‐day precisions were <10.1% in terms of coefficient of variation, and the accuracy was within ±11.7% in terms of relative error. The developed method was successfully applied to a pharmacokinetic study of 3,29‐dibenzoyl rarounitriol following intragastric administration of 3.65 mg/kg to Wistar rats. Copyright © 2015 John Wiley & Sons, Ltd.     

Validated LC‐ESI‐MS/MS method for simultaneous quantitation of felodipine and metoprolol in rat plasma: application to a pharmacokinetic study in rats

A highly sensitive and specific LC‐ESI‐MS/MS method has been developed and validated for simultaneous quantification of felodipine (FDP) and metoprolol (MPL) in rat plasma (50 μL) using phenacetin as an internal standard (IS) as per the FDA guidelines. Liquid–liquid extraction method was used to extract the analytes and IS from rat plasma. The chromatographic resolution of FDP, MPL and IS was achieved with a mobile phase consisting of 0.2% formic acid in water–acetonitrile (25:75, v/v) with a time program flow gradient on a C₁₈ column. The total chromatographic run time was 4.0 min and the elution of FDP, MPL and IS occurred at 1.05, 2.59 and 1.65 min, respectively. A linear response function was established for the range of concentrations 0.59–1148 and 0.53–991 ng/mL for FDP and MPL, respectively, in rat plasma. The intra‐ and inter‐day accuracy and precision values for FDP and MPL met the acceptance as per FDA guidelines. FDP and MPL were stable in battery of stability studies viz., bench‐top, auto‐sampler and freeze–thaw cycles. The validated assay was applied to a pharmacokinetic study in rats. Copyright © 2013 John Wiley & Sons, Ltd.     

Simultaneous determination of idelalisib and its metabolite GS‐563117 in dog plasma by LC–MS/MS: Application to a pharmacokinetic study

The purpose of this study was to develop and validate an LC–MS/MS method for simultaneous determination of idelalisib and GS‐563117 in dog plasma. The analytes were extracted using ethyl acetate and then separated on a Waters Acquity UPLC BEH C₁₈ column (50 × 2.1 mm, i. d., 1.7 μm) using 0.1% formic acid in water and acetonitrile as mobile phase at a flow rate of 0.3 mL/min in gradient elution mode. The analytes were quantified using selected reaction monitoring with precursor‐to‐product transitions at m/z 416.2 → 176.1, m/z 432.2 → 192.1 and m/z 421.2 → 176.1 for idelalisib, GS‐563117 and [²H₅]‐idelalisib (internal standard). The assay showed good linearity (r > 0.9992) over the tested concentration range of 0.1–600 ng/mL for idelalisib and 0.1–300 ng/mL for GS‐563117. The intra‐ and inter‐day RSD values for idelalisib and GS‐563117 were <8.84 and 12.41%, respectively. The intra‐ and inter‐day RE values were within the range of ?7.21–8.52%, and ?6.44–14.23%, respectively. The extraction recovery was found to be >84.59% and no matrix effects were observed. The validated LC–MS/MS method has been successfully applied for the simultaneous determination of idelalisib and GS‐563117 in a pharmacokinetic study in dogs. Our results suggested that idelalisib was rapidly metabolized into its metabolite GS‐563117 in dog and the in vivo exposure of GS‐563117 was 17.59% of that of idelalisib.     

Analysis of retinol, α‐tocopherol, 25‐hydroxyvitamin D2 and 25‐hydroxyvitamin D3 in plasma of patients with cardiovascular disease by HPLC–MS/MS method

Fat‐soluble vitamins play a pivotal role in the progression of atherosclerosis and the development of cardiovascular disease. Therefore, plasma monitoring of their concentrations may be useful in the diagnosis of these disorders as well as in the process of treatment. The study aimed to develop and validate an HPLC–MS/MS method for determination of retinol, α‐tocopherol, 25‐hydroxyvitamin D2 and 25‐hydroxyvitamin D3 in plasma of patients with cardiovascular disease. The analytes were separated on an HPLC Kinetex F5 column via gradient elution with water and methanol, both containing 0.1% (v/v) formic acid. Detection of the analytes was performed on a triple‐quadrupole MS with multiple reaction monitoring via electrospray ionization. The analytes were isolated from plasma samples with liquid–liquid extraction using hexane. Linearity of the analyte calibration curves was confirmed in the ranges 0.02–2 μg/mL for retinol, 0.5–20 μg/mL for α‐tocopherol, 5–100 ng/mL for 25‐hydroxyvitamin D2 and 2–100 ng/mL for 25‐hydroxyvitamin D3. Intra‐ and inter‐assay precision and accuracy of the method were satisfactory. Short‐ and long‐term stabilities of the analytes were determined. The HPLC‐MS/MS method was applied for the determination of the above fat‐soluble vitamin concentrations in patient plasma as potential markers of the cardiovascular disease progression.     

Determination of corilagin in rat plasma using a liquid chromatography–electrospray ionization tandem mass spectrometric method

A sensitive and simple liquid chromatography–tandem mass spectrometric (HPLC‐MS/MS) method for the determination of corilagin in rat plasma has been developed. Samples were prepared with protein precipitation method and analyzed with a triple quadrupole tandem mass spectrometer. We employed negative electrospray ionization as the ionization source and the analytes were detected in multiple reaction monitoring mode. Separation was achieved on a C₈ column eluted with mobile phase consisting of methanol–0.1% formic acid in a gradient mode at the flow rate of 0.3 mL/min. The total run time was 7.0 min.This method was proved to have good linearity in the concentration range of 2.5–1000.0 ng/mL. The lower limit of quantification of corilagin was 2.5 ng/mL. The intra‐ and inter‐day relative standard deviationa across three validation runs for four concentration levels were both <9.8%. The relative error was within ±6.0%. This assay offers advantages in terms of expediency and suitability for the analysis of corilagin in rat plasma. The practical utility of this new HPLC‐MS/MS method was confirmed in pilot plasma concentration studies in rats following oral administration. Copyright © 2015 John Wiley & Sons, Ltd.     

Validation of an LC–MS/MS method for simultaneous detection of four HDAC inhibitors – belinostat,panobinostat, rocilinostat and vorinostat in mouse plasma and its application to a mouse pharmacokinetic study

A sensitive and rapid LC–MS/MS method was developed and validated for the simultaneous quantitation of four HDAC inhibitors, namely belinostat (BST), panobinostat (PST), rocilinostat (RST) and vorinostat (VST), in mouse plasma as per regulatory guidelines. The analytes and internal standard were extracted from 50 μL mouse plasma by protein precipitation, followed by chromatographic separation using an Atlantis C₁₈ column with an isocratic mobile phase comprising 0.1% formic acid–acetonitrile (25:75, v /v) at a flow rate of 0.5 mL/min within 2.5 min. Detection and quantitation were done by multiple reaction monitoring on a triple quadrupole mass spectrometer following the transitions: m/z 319 → 93, 350 → 158, 434 → 274 and 265 → 232 for BST, PST, RST and VST, respectively, in the positive ionization mode. The calibration curves were linear from 2.92 to 2921 ng/mL for BST and PST and from 1.01 to 1008 ng/mL for RST and VST with r ² ≥ 0.99 for all of the analytes. The intra‐ and inter‐batch accuracy and precision (CV) across quality controls varied from 85.5 to 112% and from 2.30 to 12.5, respectively, for all of the analytes. Analytes were found to be stable under different stability conditions. The method was applied to an i.v. pharmacokinetic study in mice.     

Simultaneous quantification of methylene blue and its major metabolite,azure B,in plasma by LC‐MS/MS and its application for a pharmacokinetic study

A simple and sensitive liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) method was developed for the quantification of methylene blue (MB) and its major metabolite, azure B (AZB), in rat plasma. A simple protein precipitation using acetonitrile was followed by injection of the supernatant on to a Zorbax HILIC Plus column (3.5 µm, 2.1 × 100 mm) with isocratic mobile phase consisting of 5 mM ammonium acetate in 10:90 (v/v) water:methanol at a flow rate of 0.3 mL/min and detection in positive ionization mode. The standard curve was linear over the concentration range from 1 to 1000 ng/mL for MB and AZB with coefficient of determination above 0.9930. The lower limit of quantification was 1 ng/mL using 20 μL of rat plasma sample. The intra‐ and inter‐assay precision and accuracy were <12%. The developed analytical method was successfully applied to the pharmacokinetic study of MB and AZB in rats. Copyright © 2013 John Wiley & Sons, Ltd.     

Quantitative determination of buprenorphine,naloxone and their metabolites in rat plasma using hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry

A rapid and sensitive LC–MS/MS method was developed and validated for the simultaneous determination of buprenorphine and its three metabolites (buprenorphine glucuronide, norbuprenorphine and norbuprenorphine glucuronide) as well as naloxone and its metabolite naloxone glucuronide in the rat plasma. A hydrophilic interaction chromatography column and a mobile phase containing acetonitrile and ammonium formate buffer (pH 3.5) were used for the chromatographic separation. Mass spectrometric detection was achieved by an electrospray ionization source in the positive mode coupled to a triple quadrupole mass analyzer. The calibration curves for the six analytes displayed good linearity over the concentration range 1.0 or 5.0–1000 ng/mL. The intra and inter‐day precision (CV) ranged from 2.68 to 16.4% and from 9.02 to 14.5%, respectively. The intra‐ and inter‐day accuracy (bias) ranged from −14.2 to 15.2% and from −9.00 to 4.80%, respectively. The extraction recoveries for all the analytes ranged from 55 to 86.9%. The LC–MS/MS method was successfully applied to a pharmacokinetic study of buprenorphine–naloxone combination in rats.     

UPLC‐MS/MS assay for the simultaneous quantification of carvedilol and its active metabolite 4′‐hydroxyphenyl carvedilol in human plasma to support a bioequivalence study in healthy volunteers

An ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC‐MS/MS) method has been developed for the simultaneous determination of carvedilol and its pharmacologically active metabolite 4′‐hydroxyphenyl carvedilol in human plasma using their deuterated internal standards (IS). Samples were prepared by solid‐phase extraction using 100 μL human plasma. Chromatographic separation of analytes was achieved on UPLC C18 (50 × 2.1 mm, 1.7 µm) column using acetonitrile‐4.0 mm ammonium formate, pH 3.0 adjusted with 0.1% formic acid (78:22, v/v) as the mobile phase. The multiple reaction monitoring transitions for both the analytes and IS were monitored in the positive electrospray ionization mode. The method was validated over a concentration range of 0.05–50 ng/mL for carvedilol and 0.01‐10 ng/mL for 4′‐hydroxyphenyl carvedilol. Intra‐ and inter‐batch precision (% CV) and accuracy for the analytes varied from 0.74 to 3.88 and 96.4 to 103.3% respectively. Matrix effect was assessed by post‐column analyte infusion and by calculation of precision values (coefficient of variation) in the measurement of the slope of calibration curves from eight plasma batches. The assay recovery was within 94–99% for both the analytes and IS. The method was successfully applied to support a bioequivalence study of 12.5 mg carvedilol tablets in 34 healthy subjects. Copyright © 2013 John Wiley & Sons, Ltd.     

LC–MS/MS method for the simultaneous determination of tenofovir,emtricitabine, elvitegravir and rilpivirine in dried blood spots

A simple, short, and rugged LC–MS/MS method for the simultaneous determination of tenofovir, emtricitabine, elvitegravir and rilpivirine was developed and validated. Dried blood spots were prepared with 25 μL of spiked whole blood. A 3 mm punch was extracted with methanol containing labeled internal standards. Ten microliters was injected into the LC–MS/MS using isocratic mobile phase composed of 0.1% formic acid in water and 0.1% formic acid in acetonitrile (45: 55 v/v) at a flow rate of 0.25 mL/min. The method was validated in the range of 10–2000 ng/mL for all four analytes. The intra‐assay accuracy (RE) of the method was −4.73–4.78, 1.35–2.89, −8.89 to −0.49 and − 1.40–1.81 for tenofovir, emtricitabine, elvitegravir and rilpivirine, respectively. The inter‐assay accuracy was within ±15% of nominal and precision (CV) was <15%. The hematocrit effect on quantification was nonsignificant at the tested hematocrit levels (35–70%). The dried blood spot method showed good agreement with the plasma method, and hence can be used as an alternative to plasma method.