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Simultaneous determination of eight antiepileptic drugs and two metabolites in human plasma by liquid chromatography/tandem mass spectrometry

Yu Hengyi, Ren Xiuhua, Liu Lu, Xiang Dong, Li Xiping, Li Juan, Liu Dong, Gong Xuepeng

Acta Chromatographica

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2023

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Vol. 35, no. 2

161--169

EN

Epilepsy is one of the most prevalent neurological conditions and antiepileptic drugs are the mainstay of epilepsy treatment. High variation in pharmacokinetic profiles of several antiepileptic drugs highlights the importance of therapeutic drug monitoring to estimate pharmacokinetic properties and consequently individualize drug posology. In this work, a simple, rapid and robust liquid chromatography-tandem mass spectrometry method was developed for simultaneous quantification of carbamazepine and its metabolite carbamazepine-10,11-epoxide, gabapentin, levetiracetam, lamotrigine, oxcarbazepine and its metabolite mono-hydroxy-derivative metabolite, phenytoin, topiramate, and valproic acid in human plasma for therapeutic drug monitoring. d6-Levetiracetam, d4-gabapentin and d6-valproic acid were used as internal standards. After addition of internal standards along with two-step protein precipitation and dilution sample preparation, plasma samples were analyzed on a C18 column using a gradient elution in 5 min without interference. The calibration curves were linear over a 100-fold concentration range, with determination coefficients (r2) greater than 0.99 for all analytes. The limit of quantification was 0.5 μg mL⁻¹ (0.1 μg mL⁻¹ for oxcarbazepine, 2 μg mL⁻¹ for levetiracetam, and 10 μg mL⁻¹ for valproic acid) with precision and accuracy ranging from 3% to 9% and from 94% to 112%, respectively. Intra- and inter-day precision and accuracy values were within 15% at low, medium and high quality control levels. No significant matrix effect was observed in the normal, hemolyzed, lipemic, and hyperbilirubin blood samples. This method was successfully used in the identification and quantitation of antiepileptic drugs in patients undergoing mono- or polytherapy for epilepsy.

2

Rapid RP-HPLC method for simultaneous estimation of metformin, pioglitazone, and glimepiride in human plasma

Sebaiy Mahmoud M., El-Adl Sobhy M., Baraka Mohmed M., Hassan Amira A.

Acta Chromatographica

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2020

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Vol. 32, no. 1

16--21

EN

An isocratic reversed-phase high-performance liquid chromatography (RP-HPLC) method has been developed for rapid and simultaneous separation and estimation of 3 antidiabetic drugs, namely, metformin, pioglitazone, and glimepiride, in human plasma within 3 min. Separation was carried out on a MAGELLEN 5U C18 (5 μm, 150 mm × 4.60 mm) using a mobile phase of MeOH–0.025 M KH2PO4 adjusted to pH 3.20 using ortho-phosphoric acid (85:15, v/v) at ambient temperature. The flow rate was 1 mL/min, and the maximum absorption was measured at 235 nm. The retention time of metformin, pioglitazone, and glimepiride was noted to be 1.24, 2.32, and 2.77 min, respectively, indicating a very short analysis time compared to that of other reported methods. Also, limits of detection were reported to be 0.05, 0.26, and 0.10 μg/mL for metformin, pioglitazone, and glimepiride, respectively, showing a high degree of method sensitivity. The method was then validated according to the FDA guidelines for the determination of the three drugs clinically in human plasma, in particular, regarding pharmacokinetic and bioequivalence simulation studies.

3

An HPLC–PDA method for determination of alectinib concentrations in the plasma of an adolescent

Lee Samiuela, Nath Christa E., Balzer Ben W. R., Lewis Craig R., Trahair Toby N., Anazodo Antoinette C., Shaw Peter J.

Acta Chromatographica

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2020

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Vol. 32, no. 3

166--169

EN

Alectinib is a central nervous system-active small molecule anaplastic lymphoma kinase (ALK) inhibitor that is effective in the treatment of patients with ALK positive tumors, including advanced non-small cell lung cancers and lymphomas. A simple, isocratic high-performance liquid chromatography–photo diode array detection (HPLC–PDA) assay for measurement of alectinib in human plasma is described. Alectinib is extracted from the plasma matrix by addition of methanol, followed by centrifugation and acidification with 0.1% formic acid. It elutes with a run time of 4.6 min using a 250 mm × 4.6 mm RP-C18 column with 0.1% aqueous formic acid and methanol (35:65, v/v) and a flow rate of 1 mL/min. Detection was at 339 nm. Linear calibration plots were achieved in the range of 0.1–20 μg/mL for alectinib (r2 = 0.9996). With limits of detection and quantification of 0.05 and 0.1 μg/mL, respectively, and excellent precision (%CV < 10%), accuracy (bias < ±12%), and recovery (>97%) within the 1–20 μg/mL concentration range, this assay was suitable for measuring pre-dose alectinib concentrations in an adolescent receiving 600-mg doses twice daily.

4

Simultaneous determination of levocetirizine dihydrochloride and montelukast sodium in human plasma by LC–MS/MS: development, validation, and application to a human pharmacokinetic study

Rashed Noha Salem, Nasr Zeinab Adel

Acta Chromatographica

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2019

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Vol. 31, no. 3

194--200

EN

Objectives: A simple, rapid, selective, and sensitive high-performance liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed for the simultaneous determination of levocetirizine dihydrochloride and montelukast sodium in human plasma using fexofenadine hydrochloride as an internal standard. Method: Liquid–liquid extraction of both drugs and internal standard from plasma into ethyl acetate was used for sample preparation and analysis. Separation of both drugs and internal standard was achieved on an Inertsil ODS-3 (4.6 mm × 50 cm, dp 5 μm, particle size) column using an isocratic mobile phase of acetonitrile and 10 mM ammonium formate adjusted to pH 8 with 50 μL ammonium hydroxide in composition of 73:27 (v/v) at a flow rate of 0.7 mL/min. The LC–MS/MS was operated under the multiple reaction monitoring mode (MRM) using an electrospray ionization technique. Mass parameters were optimized to monitor transitions at m/z [M + H]+ 389.0 → 200.8 for levocetirizine dihydrochloride, m/z [M + H]+ 586.2 → 422.2 for montelukast sodium, and m/z [M + H]+ 502.2 → 466.0 for fexofenadine hydrochloride. Results: The method was found to be linear in the range of 1–500 ng/mL for both drugs. The intra-day and inter-day precision were in the range of 0.96–1.92% and 1.03–1.55%, respectively. Matrix effect was acceptable with %RSD < 15. Conclusion: The proposed method was validated and successfully applied for a pharmacokinetic study of both drugs in human plasma after oral administration of their pharmaceutical preparation.

5

Development of UPLC–MS/MS method for quantitative analysis of curcumin in human plasma

Hayun H., Rahmawati R., Harahap Y., Sari S.

Acta Chromatographica

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2018

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Vol. 30, no. 4

207--211

EN

A specific, very rapid, and sensitive ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method for quantitative analysis of curcumin in human plasma has been developed and validated. Diazepam was used as internal standard (IS). The analytes were isolated using liquid–liquid extraction method with the mixture of ethyl acetate–methanol (95:5). The organic solvents were evaporated, reconstituted in mobile phase, and injected to UPLC completed with UPLC BEH C18 column 1.7 μm, 2.1 × 100 mm Acquity® Waters as stationary phase, mixture of 0.15% formic acid–acetonitril (50:50, v/v) as mobile phase, and flow rate of 0.5 mL/min and detected in positive ionization mode tandem mass spectrometer operated in multiple reaction monitoring (MRM). The MS/MS ion transitions monitored were m/z 369.05 → 176.95 and 284.95 → 193 for curcumin and IS, respectively. The retention times for curcumin and IS were 1.7 and 1.4 min, respectively, and the linearity range was 1–100 ng/mL with a coefficient correlation (r) of 0.999 and lower limit of quantitation (LLOQ) of 1 ng/mL. The relative standard deviation (RSD) values of the intra- and inter-assay precisions of the method were below 8.3% and 12.7%, respectively, while the accuracy ranged from 89.5 to 98.7% and the extraction recovery of curcumin and IS was up to 86.6%. The data presented show that the method provides specific, very rapid, sensitive, precise, and accurate measurements of curcumin concentrations in human plasma.

6

Validation and application of HPLC–ESI–MS/MS method for the determination of irsogladine

Hoang N. H., Huong N. L., Hong S.-Y., Park J.-W

Acta Chromatographica

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2017

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Vol. 29, no. 4

459--462

EN

A highly sensitive analytical tool for the fast quantification of irsogladine in human plasma was developed. Cleanup using a solid-phase extraction technique is a simple method for extracting both irsogladine and lamotrigine (internal standard) spiked into human plasma. The resolvable separation of both analytes through reversed-phase high-performance liquid chromatography (HPLC) was carried out within 5 min. The HPLC–electrospray ionization (ESI)–tandem mass spectrometry (MS/MS) method, which was operated in a selected reaction monitoring mode specific to the target analytes, was verified for use in the quantification of irsogladine. The inter- and intra-day precision (relative standard deviation, RSD) of irsogladine spiked into quality control samples were <7%, and their accuracies were between 96.6% and 102.1%. The calibration curve for irsogladine spiked into human plasma was linear over the range from 1.8 to 100 ng mL−1 with lower limit of quantification at 1.8 ng Ml-1. The established method was successfully applied for a bioequivalence study of irsogladine.

7

Development and validation of rapid LC-MS with electrospray ionization for the quantification of pramipexole in human plasma

Lavudu P., Rani A. P., Sekharan C. B.

International Letters of Chemistry, Physics and Astronomy

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2014

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Vol. 18

1--15

EN

A rapid, accurate and precise LC-MS method is described for the quantitative determination of pramipexole in human plasma matrix using ropinirole as internal standard. Pramipexole and ropinirole were extracted from plasma by liquid-liquid extraction technique. The method was validated over the concentration range of 100-2514 pg/mL. The method was found to have acceptable accuracy, precision, linearity and selectivity. The mean extraction recovery from spiked plasma samples was in the range of 79.415-87.00 %. The intra-day accuracy of the assay ranged from 98.924 to 112.236 % and intra-day precision ranged from 3.489 to 6.756 %. Inter-day accuracy and precision results for quality control samples ranged between 100.340 and 107.443% of nominal and precision is observed to be 3.970-5.714 %. The pramipexole was found to be stable after several stability studies. The proposed method yielded a quick, simple and reliable protocol for estimating pramipexole concentrations in human plasma.

8

RP-HPLC determination of cilostazol in human plasma: Application to pharmacokinetic study in male albino rabbit

Pareek D., Jain S., Basniwa P. K., Jain D.

Acta Chromatographica

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2014

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Vol. 26, no. 2

283--296

EN

A sensitive validated high-performance liquid-chromatographic method for analysis of cilostazol in human plasma (in vitro) has been developed, and it was applied to determine pharmacokinetics of cilostazol in male albino rabbit. Cilostazol was extracted from human plasma (in vitro) by acetonitrile, and efficient chromatographic elution was achieved on a C18 column (250 × 4.60 mm i.d., 0.5 μm particle size) with an isocratic mobile phase [acetonitrile-50 mM acetate buffer (pH 5.0, glacial acetic acid)-water (50:20:30)] at flow rate of 1.5 mL min−1. Quantification was carried out by photo-diode array (PDA) detection at 248 nm. The linearity of the method was excellent over the range 0.2–2 μg mL-1 with low limits of detection (0.005 μg mL-1) and quantification (0.05 μg mL-1). The extraction recovery of the drug from plasma was consistently good (73.45–78.64%), with low relative standard deviation (0.44–1.65%). Robustness studies confirmed that peak area was unaffected by small changes in temperature, mobile phase (composition and pH). The maximum concentration (Cmax) in rabbit (in vivo) was determined 1.620 μg mL-1 at tmax (0.51 h) with 0.63% RSD by validated bioanalytical method.

9

Development and validation of a rapid and sensitive LC-MS/MS method for the determination of aripiprazole in human plasma: Application to a bioequivalence study

Patel D. S., Sharma N., Patel M. C., Patel B. N., Shrivastav P. S., Sanyal M.

Acta Chromatographica

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2014

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Vol. 26, no. 2

203--227

EN

A rapid, selective, and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay has been proposed for the determination of aripiprazole in human plasma. The analyte and propranolol as internal standard (IS) were extracted from 200 μL of human plasma via liquid-liquid extraction using methyl tert-butyl ether under alkaline conditions. The best chromatographic separation was achieved on an Aquasil C18 (100 × 2.1 mm, 5 μm) column using methanol-deionized water containing 2 mM ammonium trifluoroacetate and 0.02% formic acid (65:35, v/v) as the mobile phase under isocratic conditions. Detection of analyte and IS was done by tandem mass spectrometry, operating in positive ion and multiple reaction monitoring (MRM) acquisition mode. The method was fully validated for its selectivity, interference check, sensitivity, carryover check, linearity, precision and accuracy, reinjection reproducibility, recovery, matrix effect, ion suppression/enhancement, stability, ruggedness, and dilution integrity. The assay was linear over the concentration range of 0.10–100 ng mL -1 for aripiprazole. The intra-batch and inter-batch precision (%CV) was ≤4.8%, while the mean extraction recovery was >96% for aripiprazole across quality control levels. The method was successfully applied to a bioequivalence study of 10 mg aripiprazole orally disintegrating tablet formulation in 27 healthy Indian subjects under fasting and fed condition. The reproducibility in the measurement of study data was demonstrated by reanalysis of 260 incurred samples.

10

Method development and validation of an HPLC assay for the detection of hopantenic acid in human plasma and its application to a pharmacokinetic study on volunteers

Pozharitskaya O. N, Kosman V. M, Karlina M. V, Shikov A. N, Makarov V. G, Djachuk G. I

Acta Chromatographica

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2011

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Vol. 23, no. 3

403--414

EN

A reliable and sensitive reversed-phase high performance liquid chromatography (RP-HPLC) with ultraviolet (UV) detection method was developed and validated for the quantification of hopantenic acid in human plasma. Hopantenic acid, with protocatechuic acid as the internal standard (IS), was extracted from plasma samples using a liquid-liquid extraction with methanol. A chromatographic separation was achieved on a Luna C18 column (4.6 mm × 150 mm, 5-μm particle size) and precolumn of the same sorbent (2.0 mm). An isocratic elution, at a flow rate of 1.0 mL min -1, was used with a mobile phase consisting of acetonitrile, water, and 0.03% trifluoroacetic acid. The UV detector was set to 205 nm. The elution times for hopantenic acid and IS were ∼4.3 and 5.4 min, respectively. The calibration curve of hopantenic acid was linear (r > 0.9994) over the range of 0.5–100 μg mL−1 in human plasma. The limit of detection and limit of quantification for hopantenic acid were 0.034 and 0.103 μg mL -1, respectively. The present method was successfully applied for the estimation of pharmacokinetic parameters of hopantenic acid following single oral administration of tablets containing 250 mg hopantenic acid to healthy volunteers. For hopantenic acid, the data showed a mean maximum plasma concentration (Cmax) of 2.32 μg mL, -1 with a time to reach peak plasma concentration (tmax) of 1.56 h.

11

Determination of free 3-nitrotyrosine in human plasma using HPLC method with fluorescence detection

Guo S., Shao L., Pei J., Rong L., Wang X., Chi D.

Chemia Analityczna

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2009

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Vol. 54, No. 4

691-703

EN

High performance liquid chromatography assay for determination of free 3-nitrotyrosine in human plasma was developed. After precipitation of plasma proteins and solid phase extraction of 500 μL-in-volume plasma sample, derivatization reaction between 3-nitrotyrosine and 4-fiuoro-7-nitrobenzofurazon was carried out under alkaline conditions (pH 9.5). A 20μL aliquot of the reaction mixture was injected directly into a HPLC appa ratus using acetonitrile-phosphate buffer (0.02 mol L-1, plus 500 μ L-1TFA, pH 3.0) (36:64, v/v) mobile phase at a flow rate of 1.0 mL min-1. Separation was performed on C18 column at 35°C. Analytical signals were obtained using a fluorescence detector at excitation and emission wavelengths of 470 nm and 530 nm, respectively. Calibration plot was linear over the analyte concentration range in plasma 0.5-50.0 nmol L-1. Limit of detection was 0.15 nmol L-1. Intra- and inter-day variation coefficients were lower than 6.4% and 7.2%, respectively. The proposed method was sensitive, accurate, and reproducible; it allowed for determination of 3-nitrotyrosine in human plasma at a nanomolar level. It was successfully applied to the determination of 3-nitrotyrosine in plasma of healthy volunteers and patients with chronic hepatitis B.

PL

Opracowano metodę analityczną opartą na wysokosprawnej chromatografii do oznaczania wolnej 3-nitrotyrozyny w osoczu ludzkim. Po wytrąceniu białek i ekstrakcji (stała faza) z próbki plazmy o objętości 500 μ L modyfikowano chemicznie 3-nitrotyrozynę w reakcji z 4-fluoro-7-nitrobenzofurazonem przy pH 9,5.2 L końcowego roztworu wstrzykiwano do kolumny z ruchomą fazą o składzie acetonitryl-bufor fosforanowy o pH 3,0 (36:64 v/v) i szybkości przepływu l ,0 mL min-1. Do rozdzielania używano kolumny C18 w temperaturze 35°C. Fluorescencyjny detektor pracował przy długościach fali 471 (wzbudzenie) i 530 nm (emisja). Krzywa kalibrowania była liniowa w zakresie stężeń 0,5-50,0 nmol LL-1. Granica wykrywalności wyniosła 0,15 nmol L-1. Współczynniki zmienności w ciągu dnia i miedzy-dniowe były odpowiednio niższe niż 6,4 i 7,2%. Opracowana metoda jest czuła, dokładna i odtwarzalna; pozwoliła na oznaczenie 3-nitrotyrozyny w osoczu na poziomie nanomolo-wym. Badano poziom tego związku u zdrowych ochotników i pacjentów z chronicznym zapaleniem wątroby.

12

Capillary electrophoresis-electrochemiluminescence method for simultaneous detection of azithromycin, roxithromycin and erythromycin ethylsuccinate

Wang Z., Yang Z., Ye J., Tan G., Xu H., Liu Y.

Chemia Analityczna

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2009

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Vol. 54, No. 5

883-894

EN

In this paper, a capillary electrophoresis-electrochemiluminescence method for simulta- ' neous detection of three macrolide antibiotics: azithromycin (ATM), roxithromycin (RTM) and erythromycin ethylsuccinate (ETMES) has been presented. The method is based upon the enhancement effect of these compounds on electrochemiluminescence of tris(2,2- , bipyridyl) ruthenium(II) (Ru(bpy)32+). Under the optimized conditions, complete separation of ATM, RTM and ETMES was achieved within 6 min using 20 mmol L -1phosphate buffer of pH 7.3 as a background electrolyte and applying a separation voltage of 20 kV. Detection limits were 0.1 μmol L-1 for ATM, 0.2 μmol L-1 for RTM, and 0.4 umol L-1 for ETMES (S/N = 3). Relative standard deviations for all analytes were below 5%. The proposed method has been successfully applied to the determination of the content of the studied compounds in spiked human plasma and urine samples.

PL

Opracowano metodę elektroforezy kapilarnej z użyciem elektrochemiluminescencji do ., równoczesnego oznaczania trzech antybiotyków makrolidowych: azytromycyny (ATM), roksytromycyny (RTM) oraz etylobursztynianu erytromycyny (ETMES). Metoda wykorzystuje wzmocnienie przez badane antybiotyki elektrochemiluminescencji tris(2.2-bipi-rydylo)rutenu (Ru(bpy)+2. W optymalnych warunkach w czasie 6 min uzyskano całkowite rozdzielenie ATM, RTM i ETMES stosując 20 mmol L-1 bufor fosforanowy o pH 7,3 jako elektrolit podstawowy, przy napięciu 20 kV. Granica wykrywalności ATP, RTP i ETMES ' wynosiła odpowiednio: 0,1; 0,2 i 0,4 μ mol L-1(S/N = 3). Względne odchylenie standardowe wszystkich elektrolitów było pniżej 5%. Proponowana metoda została z powodzeniem zastosowana do oznaczania zawrtości badanych związków w próbkach krwi i moczu.

13

Microemulsion liquid chromatographic screening of Simvastatin and its active metabolite in human plasma

Malenovic A., Jancic-Stojanovic B., Medenica M., Ivanovic D.

Acta Chromatographica

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2008

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Vol. 20, no. 4

595-607

EN

This paper reports development and validation of a new microemulsion liquid chromatographic (MELC) method for rapid screening of simvastatin and simvastatin acid in human plasma. Plasma samples were injected directly into the HPLC system after appropriate sample dilution with mobile phase. Separations were performed on a 4.6 mm × 150 mm, 5-µm particle, C 18 column, with UV detection at 238 nm. The mobile phase was 0.5% ( w/u ) diisopropyl ether, 1.0% ( w/u ) sodium dodecylsulphate (SDS), 4.0% ( w/v ) n -butanol, and 94.5% ( w/w ) aqueous 25 mM disodium hydrogen phosphate, pH 7.0, at a flow rate of 1 mL min -1 . The method was evaluated according to criteria stated in FDA bioanalytical method validation guidance. The unique approach applied in this paper enables direct analysis of simvastatin and simvastatin acid, so the method can be used to obtain reliable results in a rapid and simple way.

14

Analysis of lovastatin in human plasma by liquid chromatography coupled with tandem mass spectrometry

Yu X. R., Song M., Hang T. J., Wen A. D.

Acta Chromatographica

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2008

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Vol. 20, no. 3

399-410

EN

A sensitive and selective liquid chromatographic tandem mass spectrometric (LC-MS-MS) method for analysis of lovastatin in human plasma has been developed and validated. Ethyl acetate extraction was used for plasma sample preparation and simvastatin was used as internal standard. Chromatographic separation was achieved on a C 18 column by isocratic elution with 83:17:0.1 ( v/v ) methanol-2 µM aqueous sodium acetate-formic acid as mobile phase, delivered at 1.0 mL min -1. MS-MS detection was performed using positive electrospray ionization and multiple-reaction monitoring with argon for collision-induced dissociation. Calibration plots were generated over the concentration range 0.05 to 20 ng mL -1 (r > 0.999) with a lower limit of quantification (LLOQ) of 0.05 ng mL -1. Intra and inter-day precision and accuracy were determined at four different concentrations, 0.05, 0.5, 2.0, and 10.0 ng mL -1, and precision ranged from 0.4 to 11.4% with the deviation always less than 15% ( n = 5). Extraction recoveries were from 86.8 to 94.1% for lovastatin and approximately 88.0% for simvastatin. The validated method was successfully applied to a bioequivalence study of two lovastatin tablets in 20 healthy volunteers.

15

Validation of the assay of metoprolol in human plasma using liquid-liquid extraction and high performance liquid chromatography with fluorescence detection

Farca A., Tache F., Medvedovici A., David V.

Chemia Analityczna

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2003

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Vol. 48, No. 4

677-688

EN

Metoprolol was successfully assayed in human plasma samples. The sample preparation procedure was based upon liquid-liquid extraction, using propranolol as internal standard (I.S.). The HPLC procedure developed using a Merck Chromolith column was based on the ion pairing separation mechanism. Fluorescence detection (ex. 230 nm; em. 305 nm) provided an excellent detectability (the determined quantitation limit, LOQ was 7.5 ng ml/1). Both sample preparation and chromatographic procedure were validated and used in a single-dose comparative bioequivalence study carried out on thirteen healthy volunteers. The same column was used for the entire determination and no major alteration of the separation behaviour was observed.

PL

Oznaczano metoprolol w próbkach ludzkiej plazmy. W procedurze przygotowania próbek zastosowano ekstrakcję cieczową z propranololem jako wewnętrznym standardem. Rozdzielanie HPLC prowadzono na kolumnie Merck Chromolith wykorzystując mechanizm parowania jonowego oraz detekcję fluoroscencyjną . Uzyskano bardzo dobrą wykrywalność (LOQ - 7.5 ng L'1). Przeprowadzono walidację procedury przygotowania próbek oraz ich chromatograficznego oznaczania. Metodę zastosowano do badań porównawczych między trzynastoma zdrowymi wolontariuszami, którzy zażywali po jednej dawce lekarstwa. Tę samąkolunmę zastosowano do wszystkich oznaczeń i nie obserwowano żadnych istotnych zmian.

16

Application of HPLC for the determination of racemic fluoxetine and norfluoxetine in human plasma

Misztal G., Skibiński R., Olajossy M., Paw B., Przyborowski L., Hopkała H.

Chemia Analityczna

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2002

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Vol. 47, No. 2

229-240

EN

A selective, simple and accurate HPLC method for the determination of fluoxetine and nor-fluoxetine in blood plasma of patients is presented. The samples were chromatographed on a Nova-Pak Cs column after purification using a LiChrolut RP-I8 column. The mobile phase was methanol-acetonitrile-phosphate buffer of pH 2.65 (0.0657 mol L(-1)-triethyla-mine (10.9 + 32.7 + 56 + 0.4, v/v). Fluvoxamine was applied as an internal standard. The U V detection was carried out at 228 nm. The method was tested for linearity (over the range 20-600 ng mL'1) both for fluoxetine and norfluoxetine. The mean recoveries were 91.13% for fluoxetine and 95.69% for norfluoxetine. The described method has been successfully applied for the determination of these substances in plasma of patients, who received 20 mg fluoxetine daily.

PL

Przedstawiono selektywną, prostą i dokladnąmetodę HPLC oznaczania fluoksetyny i norfluo-ksetyny w osoczu krwi pacjentów. Próbki były oznaczane na kolumnie chromatograficznej Nova-Pak C8 po wyizolowaniu substancji do fazy stałej na kolumnach LiChrolut RP-18. Fazą ruchomą była mieszanina metanol-acetonitryl-bufbr fosforanowy o pH 2.65 (0.0657 mol L(-1)-trietyloamina(10.9 + 32.7 + 56 + 0.4, v/v). Jako standard wewnętrzny zastosowano fiuwoksaminę oraz detekcję w UV przy 228 nm. Liniowość opracowanej metody oceniono w granicach stężeń analizowanych substancj i od 20-600 ng mL(-1). Średni odzysk dla trzech różnych stężeń fluoksetyny w osoczu wynosi 91.13%, zaś dla norfluoksetyny 95.69%. Opracowana metoda może być zastosowana do oznaczenia tych substancj i u chorych, pobierających terapeutyczne dawki fluoksetyny 20 mg dziennie.

17

A simple and fast method for the determination of ranitidine in human plasma by HPLC-DAD

David V., Ionescu M., Tache F., Medvedovici A.

Chemia Analityczna

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2001

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Vol. 46, No. 6

865-871

EN

A simple and fast method for the determination of ranitidine in plasma samples is described. This method is based on plasma deproteinization in the presence of trichloroacetic acid, and determination by HPLC-DAD, on a XDB C(18) column, at 320 nm. Elution was isocratic, using a mobile phase containing 60% phosphate buffer 20 mmol 1(-1) (pH 7.3) and 40% methanol, with a flow rate of 1 ml min(-1), at 40°C. Applied to a bioequivalence study, this method reaches a limit of determination of 15 ng ml (-1) ranitidine in plasma samples, for an injection volume of 50 ul.

PL

Opisano prostą i szybką metodę oznaczania ranitydyny w osoczu krwi. Próbki osocza od-białczano kwasem trichlorooctowym i oznaczano metodą HPLC-DAD przy długości fali 320 nm z zastosowaniem kolumny XDBC]g. Stosowano elucję izokratyczną fazą ruchomą zawierającą 60% buforu fosforanowego (20 mmol 1(-1), pH 7.3) i 40% metanolu o szybkości przepływu 1 ml min(-1) w temperaturze 40°C. Granica oznaczalności metody w próbkach osocza krwi wynosi 15 ug ml(-1) ranitydyny (na kolumnę wprowadzano próbki o objętości 50ul. Metoda może być zastosowana do badań farmakokinetycznych.