Gabapentin In Human Plasma Research Articles

Determination of Gabapentin and Rabeprazole in Human Plasma by Using High-Performance Liquid Chromato-graphy and its Application to Therapeutic Drug Monitoring

Background: Gabapentin is an anticonvulsant drug developed to treat epilepsy. In recent years, the use of this medicine has increased in a variety of indications. Rabeprazole, a proton pump inhibitor, is mainly given in combination with gabapentin. The study aims to simultaneously estimate gabapentin and Rabeprazole and to monitor the therapeutic activity of gabapentin in human plasma samples.
 Method: To determine the plasma concentration of gabapentin in participants, a bioanalytical method was developed and validated using high-performance liquid chromatography. Forty-two epileptic participants received doses of gabapentin ranging from 100 to 800 mg, and plasma concentrations were examined. The average mean serum concentration for males was 723.64 ng/ml; for females, it was 1770.07 ng/ml.
 Results: The concentration of male to female ratio for gabapentin was 71:29 with Rabeprazole as comedication, Total mean serum concentration of levetiracetam from males is 723.64ng/ml and females is 1770.07ng/ml. Welsch t­test was plotted with males and females ranging from 31 to 11 sizes as an unpaired t­test with p=0.0035 (p≤0.05). TDM was still shown to be effective in the majority of patients to support dosage increases and individualization of therapy.
 Conclusion: The method proposed for measuring gabapentin concentration was convenient, reproducible, and specific. Only detailed clinical justifications should be used to request TDM and the service should be tailored to the therapeutic indication.

Simple and rapid HPLC-UV methods for gabapentin quantification in human plasma and urine: applicability in pharmacokinetics and drug monitoring

Aim: We aimed to develop methods to determine gabapentin (GAB) in biological samples using high-performance liquid chromatography (HPLC) with application in pharmacokinetics and therapeutic drug monitoring. Methods: Simple, rapid and efficient HPLC-UV methods to quantify GAB in human plasma and urine were developed and validated for clinical analysis of GAB. The 1-fluoro-2,4-dinitrobenzene (FDNB) was used as derivatization agent. For plasma samples, protein precipitation using acetonitrile was performed, before the derivatization reaction. Urine samples were cleaned-up by liquid-liquid extraction with dichloromethane:n-butanol (1:1, v/v) after derivatized. Amlodipine besilate was used as internal standard (IS). Results: Gabapentin and IS were resolved on LiChrospher® C18 RP column and a mixture of 50 mM sodium phosphate buffer (pH 3.9):methanol (27:73, v/v) as mobile phase, at 1.2 mL/min. The methods used small sample volumes, 100 and 50 μL of plasma and urine, respectively. Linearity was obtained in the interval of 0.2-14 μg/mL in plasma and 2-120 μg/mL in urine. Both methods showed to be selective, without carry-over effect, precise, accurate and stable in different conditions. GAB plasma concentration in patients receiving 600 to 3600 mg/day of GAB ranged between 0.40 to 11.94 μg/mL at steady-state. Conclusions: The methods described in this study were simple, rapid and fulfill all validation requirements. They were easily and successfully applied for population pharmacokinetics and therapeutic drug monitoring of GAB in patients with chronic pain.

Determination of Gabapentin in Human Plasma and Urine by Capillary Electrophoresis with Laser-Induced Fluorescence Detection.

A simple and reliable method based on capillary electrophoresis with laser-induced fluorescence detection was developed for the analysis of the antiepileptic drug Gabapentin in human plasma and urine. 4-Chloro-7-nitrobenzofurazan was used for precolumn derivatization of the drug. With an uncoated fused silica capillary (40.0 cm effective length, 50.2 cm total length and 75 μm internal diameter), optimal separation was achieved with 30 mM sodium dodecyl sulfate, 40 mM sodium borate (pH 10.25) and acetonitrile 10% (v/v) as running buffer. The applied voltage was 20 kV and the samples were injected by pressure (3.45 kPa × 3 s). The method was fully validated with regard to linear range, sensitivity, precision, limit of detection and limit of quantification in human plasma and urine samples. Linear ranges were 0.1-15 μg mL(-1) for plasma and urine. The intra- and interday precisions were ≤9.02 and 13.90%, respectively. The recoveries were 96.0-109.3% for plasma and 94.3-98.0% for urine. The method was successfully applied for the determination of Gabapentin in human plasma and urine.

Determination of gabapentin in human plasma using simultaneous cloud point extraction and precolumn derivatization by HPLC

A simultaneous cloud point extraction and precolumn derivatization method was developed for the determination of gabapentin in human plasma samples. o-Phthaldialdehyde in the presence of 3-mercaptopropionic acid and Triton X-100 were used as derivatization reagents and extraction solvent, respectively. Some parameters with an effect on the extraction, such as the concentration of Triton X-100, incubation time, equilibration temperature, ionic strength, and centrifuging time, were studied and optimized. Under the optimum conditions, average recovery of gabapentin was in the range of 94.5–98.7 %. The calibration curve was linear in the range of 0.01–50 μg/cm3. The limits of detection and quantification were 0.003 and 0.01 μg/cm3, respectively. The relative standard deviations were in the range of 0.9–5.2 %. The obtained results show that simultaneous derivatization and cloud point extraction combined with high-performance liquid chromatography is a sensitive and simple method for the determination of gabapentin in plasma samples.

Gabapentin Determination in Human Plasma and Capsule by Coupling of Solid Phase Extraction, Derivatization Reaction, and UV-Vis Spectrophotometry.

Gabapentin is an anticonvulsant widely used in the treatment of epilepsy. No peculiar chromophore is available on the gabapentin moiety for direct analysis by absorption spectrophotometry. A sensitive spectrophotometric method for the determination of gabapentin in bulk, pharmaceutical formulations and human plasma has been developed. In this method, gabapentin directly derivatized with vanillin and analyzed without any extraction in bulk and pharmaceutical dosage form and in plasma samples, it was extracted with a reversed-phase solid-phase extraction (SPE) cartridge followed by derivatization with vanillin. Analysis was performed by a spectrophotometer system. The quantitation limit of gabapentin in human plasma was 0.8 mg/L. The method was linear over the concentration range of 10.0-90.0 mg/L and 0.8-10.0 mg/L for pharmaceutical dosage form and plasma, respectively. The method was precise (relative standard deviation, RSD <1.20%) and accurate (relative mean error <5.5%) for both pharmaceutical dosage form and plasma samples. Mean absolute recoveries were 94.5% for plasma.

Determination of gabapentin in human plasma by capillary electrophoresis-laser induced fluorescence detection with and without solid-phase extraction

We have developed two methods for the quantitation of gabapentin in human plasma. They are based on capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) with and without solid-phase extraction (SPE) and the derivatizing reagent 5-(4,6-dichlorotriazinyl)amino fluoresencin. The conditions for derivatization, separation and extraction were investigated in detail, and the optimal labeling conditions include a temperature of 40 °C, a reaction time of 30 min, and the use of a borate buffer of pH 9.0 as the reaction medium. A borate buffer of pH 9.2 served as a background electrolyte for CE separations. The CE-LIF and SPE-CE-LIF methods have linear ranges of 5–200 nmol L−1 and 0.2–10 nmol L−1, respectively, and the limits of detection are 0.5 and 0.02 nmol L−1, respectively. The SPE-CE-LIF method was successfully applied to the determination of gabapentin in blood plasma samples.

Rapid and validated fluorometric HPLC method for determination of gabapentin in human plasma and urine for clinical application

A rapid derivatization and validated HPLC method for gabapentin in human plasma and urine is needed for clinical use. The objective of this study was to establish a rapid and validated analytical method for the determination of gabapentin in human plasma and urine using isocratic fluorometric HPLC for clinical application. This analytical method is based on precolumn fluorescent derivatization using 4-fluoro-7-nitro-benzofurazan. The derivatization was coupled to fast HPLC separation using a 2·3 μm-particle size ODS column (100 × 4·6 mm i.d.). The derivatization of gabapentin was optimized and HPLC separation was achieved over an ODS column with a run time of 3·5 min. Calibration curves in human plasma and urine were linear over the concentration ranges of 0·05-10 and 10-1000 μg/mL, respectively. Intra- and inter-assay precision and accuracy values of plasma were within 8·0% and 101-109% and within 8·3% and 94-108%, respectively. Those of urine were within 8·5% and 97-106% and within 9·5% and 97-105%, respectively. This validated method was applied to a pharmacokinetic study in healthy subjects. Interindividual variations in plasma disposition and urinary excretion of gabapentin were observed. A rapid and validated isocratic fluorometric HPLC method for the determination of gabapentin in human plasma and urine for clinical application has been established. This method can be utilized to evaluate the pharmacokinetic disposition of gabapentin in humans.

Dried plasma spots as an alternative sample collection technique for the quantitative LC-MS/MS determination of gabapentin

Dried plasma spots were employed as an alternative sample collection technique for the quantitative determination of gabapentin in human plasma, using an automated liquid chromatography tandem mass spectrometry method. After the methanolic extraction of single plasma, 1/8-in. disks which contained only 1.98 microL plasma volume, were placed in 96-well format plates, then gabapentin and its internal standard, 4-aminocyclohexanecarboxylic acid, were derivatized with n-butanol/HCl (3 M) and detected as butyl esters. The assay exhibited excellent linearity over the concentration range of 40.0-10.0 x 10(3) ng/mL, which is suitable for the determination of gabapentin after per os administration of a single tablet. Variations in intra- and inter-assay accuracy and precision were within internationally accepted criteria. Homogeneity of plasma spots was proven, whilst butyl ester stability for both analytes was estimated and found very satisfactory. The quantitative analysis of Gabapentin with dried plasma spot specimens seems to be a prominent and advantageous technique, especially when applied to pharmacokinetic studies, where plasma sampling procedure becomes rapid and required plasma volumes negligible.

Validated LC-MS-MS Method for the Determination of Gabapentin in Human Plasma: Application to a Bioequivalence Study

A simple and rapid liquid chromatography-tandem mass spectrometric method is developed and validated for the determination of gabapentin in human plasma. Metformin is used as an internal standard. The method utilizes protein precipitation with acetonitrile followed by separation on a C(8) column using 10 mM ammonium formate buffer pH 3.0 and acetonitrile as mobile phase. Detection was performed on a quadrupole mass spectrometer using an electrospray ionization interface in selected reaction monitoring mode. The method proves to be specific, sensitive, accurate, precise, and linear over the concentration range of 50-5000 ng/mL with correlation coefficients greater than 0.99. The lower limit of quantification for gabapentin is 50 ng/mL using a 200-microL plasma sample. Intra- and inter-day precisions are less than 8.4% whereas accuracies are within 10.2%. The method is successfully applied to a bioequivalence study of gabapentin in 24 healthy volunteers.

Validated LC‐MS/MS method for quantification of gabapentin in human plasma: application to pharmacokinetic and bioequivalence studies in Korean volunteers

A sensitive validated liquid chromatography-tandem mass spectrometric method (LC-MS/MS) for gabapentin (GB) in human plasma has been developed and applied to pharmacokinetic (PK) and bioequivalence (BE) studies in human. In a randomized crossover design with a 1-week period, each subject received a 300 mg GB capsule. The procedure involves a simple protein precipitation with acetonitrile and separated by LC with a Gemini C(18) column using acetonitrile-10 mm ammonium acetate (20:80, v/v, pH 3.2) as mobile phase. The GB and internal standard [(S)-(+)-alpha-aminocyclohexanepropionic acid hydrate] were analyzed using an LC-API 2000 MS/MS in multiple reaction monitoring mode. The ionization was optimized using ESI(+) and selectivity was achieved using MS/MS analysis, m/z 172.0 --> 154.0 and m/z 172.0 --> 126.0 for GB and IS, respectively. The assay exhibited good linearity over a working range of 20-5000 ng/mL for GB in human plasma with a lower limit of quantitation of 20 ng/mL. No endogenous compounds were found to interfere with the analysis. The accuracy and precision were shown for concentrations over the standard ranges. This method was successfully applied for the PK and BE studies by analysis of blood samples taken up to 36 h after an oral dose of 300 mg of GB in 24 healthy volunteers.

Validated HPLC method for the determination of gabapentin in human plasma using pre-column derivatization with 1-fluoro-2,4-dinitrobenzene and its application to a pharmacokinetic study

A rapid, sensitive and accurate high-performance liquid chromatographic method with UV detection was developed and validated for the quantification of gabapentin in human plasma. Gabapentin was quantified using pre-column derivatization with 1-fluoro-2,4-dinitrobenzene following protein precipitation of plasma with acetonitrile. Amlodipine was used as internal standard. The chromatographic separation was carried out on a Nova-Pak C 18 column using a mixture of 50 mM NaH 2PO 4 (pH = 2.5)–acetonitrile (30:70, v/v) as mobile phase with UV detection at 360 nm. The flow rate was set at 1.5 ml/min. The method was linear over the range of 0.05–5 μg/ml of gabapentin in plasma ( r 2 > 0.999). The within-day and between-day precision values were in the range of 2–5%. The limit of quantification of the method was 0.05 μg/ml. The method was successfully used to study the pharmacokinetics of gabapentin in healthy volunteers.

Determination of gabapentin in human plasma and urine by high-performance liquid chromatography with UV–vis detection

A simple and reliable high-performance liquid chromatographic (HPLC) method with UV–vis detection has been developed and validated for the determination of gabapentin (GBP) in human plasma and urine. The clean up of the sample was carried out by solid-phase extraction with C18-cartridge. After the clean up procedure, the samples were pre-column derivatizated with 1,2-naphthoquinone-4-sulphonic acid sodium salt (NQS). A chromatographic separation was achieved on a C18 column with a mobile phase consisting of acetonitrile and 10 mM orthophosphoric acid (pH 2.5) with isocratic elution (35:65). Baclofen was used as an internal standard (I.S.). The method developed for GBP was linear over the concentration range of 0.05–5.0 μg/ml and 0.1–10.0 μg/ml for plasma and urine, respectively. The method is precise (relative standard deviation, R.S.D. <4.05%) and accurate (relative mean error, RME <0.15%); mean absolute recoveries were 72.21% for plasma and 72.73% for urine.

Determination of gabapentin in human plasma using hydrophilic interaction liquid chromatography with tandem mass spectrometry

A rapid, sensitive and selective method for the determination of gabapentin in human plasma was developed using hydrophilic interaction liquid chromatography/tandem mass spectrometry (HILIC/MS/MS). The devised method involved protein precipitation with acetonitrile followed by separation on an Atlantis HILIC silica column using an acetonitrile/ammonium formate mobile phase (100 mM, pH 3.0) (85:15, v/v). Analytes were detected using an electrospray ionization mass spectrometer in the multiple-reaction monitoring mode. The standard curve was linear (r = 1.000) over the concentration range of 50.0-10000 ng/mL. The lower limit of quantification for gabapentin was 50.0 ng/mL (ca. 20 pg gabapentin) using a 10-microL plasma sample. The coefficients of variation and relative errors for intra- and inter-assay at four QC levels (i.e., 50.0, 125, 750, and 7500 ng/mL) were 4.7 to 9.4% and -4.1 to 1.6%, respectively. Absolute and relative matrix effects for gabapentin and metformin were practically absent. Gabapentin and metformin recoveries were 98.5% and 99.0%, respectively. This method was successfully applied to a bioequivalence study of gabapentin in humans.

Simple and sensitive liquid chromatographic method with fluorimetric detection for the analysis of gabapentin in human plasma

A simple and sensitive liquid chromatographic method is described for the quantitative analysis of gabapentin in human plasma. Gabapentin (GBP) is an anticonvulsant and widely used in the treatment of epilepsy. No peculiar chromophore is available on gabapentin moiety for direct analysis by absorption spectrophotometry. In human plasma after deproteinisation with acetonitrile, gabapentin was derivatized with a fluorescent reagent, (2-naphthoxy)acetyl chloride (NAC) in borate buffer (pH 10.0). The resulting naphthoxy derivative of gabapentin was separated on a phenyl-hexyl column with a mobile phase consisting of a mixture of sodium acetate buffer (100 mM; pH 5.0)-methanol (32:68, v/v) used in isocratic mode. Using fluorimetric detection (excitation at 225 nm and emission at 360 nm), a low detection limit of about 0.04 μM (S/N = 3, 10 μl injected) was reached. The relative standard deviations (RSD) of the method for intra- and inter- day analyses ( n = 5) are between 2.7 and 4.0%, respectively. The method was successfully applied to the analysis of gabapentin in plasma from dosed patients for therapeutic drug monitoring.

Rapid quantification of gabapentin in human plasma by liquid chromatography/tandem mass spectrometry

A simple, sensitive and rapid liquid chromatography/tandem mass spectrometry (LC–MS/MS) method was developed and validated for the quantification of gabapentin, a new antiepileptic drug, in human plasma using its structural analogue, 1,1-cyclohexane diacetic acid monoamide (CAM) as internal standard. The method involved a simple protein precipitation by means of acetonitrile followed by a rapid isocratic elution with 10 mM ammonium formate buffer/acetonitrile (20/80, v/v, pH 3.0) on Waters Symmetry ® C 18 reversed phase chromatographic column and analyzed by mass spectrometry in the multiple reaction monitoring mode. The precursor to product ion transitions of m/ z 172 → 154 and m/ z 200 → 182 were used to measure the analyte and the IS, respectively. The assay exhibited a linear dynamic range of 40–10 000 ng/mL for gabapentin in human plasma. The limit of detection and lower limit of quantification in human plasma were 10 and 40 ng/mL, respectively. Acceptable precision and accuracy were obtained for concentrations over the standard curve ranges. A run time of 2 min for each sample made it possible to analyze a throughput of more than 400 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability or bioequivalence studies.

Rapid Tandem Mass Spectrometric Method for Determination of Gabapentin in Human Plasma

A rapid tandem mass spectrometric (MS-MS) method for the quantification of gabapentin (GBP) in human plasma using 4-phenyl-4-aminobutanoic acid as an internal standard (IS) has been developed and validated. The drug and the internal standard were analyzed, by flow injection analysis without chromatographic separation, using a mobile phase of acetonitrile-water-formic acid (50:50:0.025, v/v/v) at a flow rate of 0.1 mL min−1. The run-cycle time was 154 and m/z 180 > 117 for GBP and the IS, respectively. Ion suppression study indicated practically no suppressive effect of plasma constituents on the mass ions detection of GBP and IS, when measured in MRM scanning mode. Calibration curves were linear over the concentration range of 0.1–10 μg mL−1 (r > 0.999) with a limit of quantification of 0.1 μg mL−1 (RSD%; 7.6 and % DEVs; −3.0 to +17.0%). Validation data showed that the RSD% values were in the range of 1.85 to 13.06%, whereas, the % DEVs values ranged from −1.4 to +10.0% indicating good precision and accuracy. Analytical recoveries of GBP from spiked human plasma were in the range of 98.9 to 101.3%. On the other hand, recoveries of GBP from stored human plasma samples were in the range of 100.0 to 107.5% indicating that GBP was stable in plasma, with no appreciable degradation, when stored at −20 °C. The developed method was applied for GBP monitoring in plasma samples of patients treated with GBP.

Determination of gabapentin in human plasma by capillary electrophoresis with laser-induced fluorescence detection and acetonitrile stacking technique

A sensitive analytical method for gabapentin [1-(aminomethyl) cyclohexaneacetic acid] (GBP) in human plasma based on capillary electrophoretic separation and laser-induced fluorescence (LIF) detection has been developed. 6-Carboxyfluorescein succinimidyl ester (CFSE) was used for precolumn derivatization of the non-fluorescent drug in plasma. Optimal separation and detection were obtained with an electrophoretic buffer of 50 mM sodium borate (pH 9.5) and an air-cooled argon-ion laser (excitation at 488 nm, emission at 520 nm). A calibration curve ranging from 0.3 to 150 μM was shown to be linear. The concentration limit of detection (LOD) in plasma was 60 nM. We also demonstrate how the detection limit can be enhanced by using acetonitrile stacking technique. With stacking, the limit of detection for gabapentin in plasma was 4.8 nM. A calibration curve ranging from 0.03 to 15 μM was shown to be linear. Both the within-day and day-to-day reproducibility and accuracy were ≤10.8 and 6.0%, respectively.

Simultaneous isocratic HPLC determination of vigabatrin and gabapentin in human plasma by dansyl derivatization.

A rapid and low-cost assay for simultaneous vigabatrin (VGA) and gabapentin (GBP) determination is described that can be performed with simple HPLC instrumentation. The method involves derivatization of the primary amine group of VGA and GBP with dansyl chloride followed by isocratic separation (column: microBondapak C-18, 10 microm, 300 x 3.9 mm; mobile phase: 50 mmol/L NaH(2)PO(4) in 40% acetonitrile) at 50 degrees C and fluorometric detection (excitation and emission wavelength: 318 and 510 nm, respectively) of the fluorescent product, which is stable for at least 7 days. Correlation coefficients of the calibration curves are >0.999 with a lower limit of detection of 0.3 microg/mL. Between- and within-run coefficients of variation are below 4.5%, and assay time is 15 minutes. This method may be used for therapeutic drug monitoring in the case of GBP and to control patient compliance in the case of VGA.

High-performance liquid chromatographic method for the determination of gabapentin in human plasma

A sensitive high-performance liquid chromatography (HPLC) method using UV detection for the determination of gabapentin in human plasma has been developed. In this method, gabapentin was extracted from human plasma with a reversed-phase solid-phase extraction (SPE) cartridge followed by derivatization with phenylisothiocyanate. Analysis was achieved by using a HPLC system that was equipped with a UV detector. The quantitation limit of gabapentin in human plasma was 0.03 μg/ml. The method is sensitive with excellent selectivity and reproducibility and it has been applied to a bioequivalence clinical study with great success.

Gabapentin quantification in human plasma by high-performance liquid chromatography coupled to electrospray tandem mass spectrometry. Application to bioequivalence study.

A rapid, sensitive and specific analytical method was developed and validated to quantify gabapentin in human plasma using acetaminophen as an internal standard. The method employs a single plasma protein precipitation. The analytes are chromatographed on a C4 reversed-phase chromatographic column and analyzed by mass spectrometry in the multiple reaction monitoring (MRM) mode. The method has a chromatographic run time of 4 min and a linear calibration curve over the range 50-10 000 ng x ml(-1) (r > 0.999). The between-run precision, based on the relative standard deviation for replicate quality controls, was < or = 4.8 % (200 ng x ml(-1)), 6.0% (1000 ng x ml(-1)) and 4.4% (5000 ng x ml(-1)). The between-run accuracy was +/-2.6, 4.4 and 0.5% for the above-mentioned concentrations, respectively. This method was employed in a bioequivalence study of two gabentin capsule formulations (Progresse from Biosintética, Brazil, as a test formulation, and Neurotin from Parke-Davis, as a reference formulation) in 24 healthy volunteers of both sexes who received a single 300 mg dose of each formulation. The study was conducted using an open, randomized, two-period crossover design with a 7-day washout interval. The 90% confidence interval (CI) of the individual ratio geometric mean for Progresse/Neurotin was 87.9-115.6% for AUC(0-36 h) and 88.6-111.7% for Cmax. Since both 90% CI for AUC(0-36 h) and Cmax were included in the 80-125% interval proposed by the US Food and Drug Administration, Progresse was considered bioequivalent to Neurotin according to both the rate and extent of absorption.