High-performance liquid chromatographic method for simple and rapid determination of linezolid in human plasma

A simple high-performance liquid chromatographic (HPLC) method was developed and validated for rapid quantification of linezolid in human plasma. Protein precipitation using a mixture of 5% trichloroacetic acid and methanol (3:1, v/v) provided a straightforward method of sample preparation and the internal standard eperezolid was employed. A concentration range from 0.20 to 40.0 mg/L was utilized to construct calibration curves, and analysis of low- (0.40 mg/L), medium- (7.50 mg/L) and high-quality (25.0 mg/L) control samples revealed excellent reproducibility (相似文献   

Validation of a new HPLC‐UV method for determination of the antibiotic linezolid in human plasma and in bronchoalveolar lavage

A rapid and selective HPLC‐UV method was developed for the quantification of linezolid (LNZ) in human plasma and bronchoalveolar lavage (BAL) at the concentrations associated with therapy. Plasma samples were extracted by solid‐phase extraction followed by evaporation to dryness and reconstitution in mobile phase solution. The chromatographic separation was carried out on a C₁₈ column with an isocratic mobile phase consisting of dihydrogen phosphate buffer 50 mm (pH 3.5) and acetonitrile (60:40 v/v). The detection was performed using a photodiode array. Under these conditions, a single chromatographic run could be completed within 12 min. The method was validated by estimating the precision and the accuracy for inter‐ and intra‐day analysis in the concentration range of 25–25600 ng/mL. The method was linear over the investigated range with all the correlation coefficients R > 0.999. The intra‐ and inter‐day precision was within 8.90% and the accuracy ranged from ?4.76 to +5.20%. This rapid and sensitive method was fully validated and could be applied to pharmacokinetic study for the determination of LNZ levels in human plasma and BAL samples. Copyright © 2013 John Wiley & Sons, Ltd.     

Simultaneous determination of serum propafenone and its metabolites using high‐performance liquid chromatography

Propafenone, a class Ic antiarrhythmic agent, is metabolized to 5‐hydroxypropafeone (5‐OHP) and N‐depropylpropafenone (NDPP). Simultaneous determination of serum propafenone and its metabolites was performed using HPLC equipped with a conventional octadecylsilyl silica column and ultraviolet detector. The wavelength was set at 250 nm. Propafenone and its metabolites in the serum were extracted using diethyl ether. The mobile phase solution, comprising 1‐pentanesulfonic acid sodium salt (0.1 m ), acetonitrile and acetic acid (280:185:2.5, v/v/v), was pumped at a flow rate of 1 mL/min. The recoveries of propafenone, 5‐OHP and NDPP were greater than 85, 82 and 60%, respectively, with the coefficients of variation (CVs) less than 5.4, 1.9 and 2.9%, respectively. The calibration curves were linear for a concentration range of 12.5–1500 ng/mL for propafenone and 2–500 ng/mL for 5‐OHP and NDPP (r > 0.999). CVs in the intraday assays were 1.0–3.8% for propafenone, 0.6–2.0% for 5‐OHP and 0.6–1.7% for NDPP. CVs in interday assays were 1.3–7.7% for propafenone, 1.1–6.5% for 5‐OHP and 5.4–8.0% for NDPP. The present HPLC method can be used to assess the disposition of propafenone and its metabolites for pharmacokinetic studies and therapeutic drug monitoring of propafenone.     

Determination of metoprolol enantiomers in human plasma and saliva samples utilizing microextraction by packed sorbent and liquid chromatography–tandem mass spectrometry

A sensitive, accurate and reliable bioanalytical method for the enantioselective determination of metoprolol in plasma and saliva samples utilizing liquid chromatography–electrospray ionization tandem mass spectrometry was developed and validated. Human plasma and saliva samples were pretreated by microextraction by packed sorbent (MEPS) prior to analysis. A new MEPS syringe form with two inputs was used. Metoprolol enantiomers and internal standard pentycaine (IS) were eluted from MEPS sorbent using isopropanol after removal of matrix interferences using aliquots of 5% methanol in water. Complete separation of metoprolol enantiomers was achieved on a Cellulose‐SB column (150 × 4.6 mm, 5 μm) using isocratic elution with mobile phase 0.1% ammonium hydroxide in hexane–isopropanol (80:20, v/v) with a flow rate of 0.8 mL/min. A post‐column solvent‐assisted ionization was applied to enhance metoprolol ionization signal in positive mode monitoring (+ES) using 0.5% formic acid in isopropanol at a flow rate of 0.2 mL/min. The total chromatographic run time was 10 min for each injection. The detection of metoprolol in plasma and saliva samples was performed using triple quadrupole tandem mass spectrometer in +ES under the following mass transitions: m/z 268.08 → 72.09 for metoprolol and m/z 303.3 → 154.3 for IS. The linearity range was 2.5–500 ng/mL for both R‐ and S‐metoprolol in plasma and saliva. The limits of detection and quantitation for both enantiomers were 0.5 and 2.5 ng/mL respectively, in both matrices (plasma and saliva). The intra‐ and inter‐day precisions were presented in terms of RSD values for replicate analysis of quality control samples and were <5%; the accuracy of determinations varied from 96 to 99%. The method was able to determine the therapeutic levels of metoprolol enantiomers in both human plasma and saliva samples successfully, which can aid in therapeutic drug monitoring in clinical laboratories. Copyright © 2016 John Wiley & Sons, Ltd.     

Simple determination of plasma ibrutinib concentration using high‐performance liquid chromatography

Ibrutinib is an oral inhibitor of Bruton tyrosine kinase, which is one of the key drugs used for the treatment of chronic lymphocytic leukemia and mantle cell lymphoma. In this study, we aimed to develop a simple method for determining plasma ibrutinib concentration. The analysis required extraction of a 200 μL plasma sample and precipitation of proteins using solid‐phase extraction. Ibrutinib and nilotinib, which was used as an internal standard, were separated using high‐performance liquid chromatography (HPLC) using a mobile phase of acetonitrile–0.5% monopotassium phosphate (KH₂PO₄, pH 3.0; 52:48, v/v) on a Capcell Pack C₁₈ MG II (250 × 4.6 mm) monitored at 260 nm, at a flow rate of 1.0 mL/min. The calibration curve was linear at the plasma concentration range of 10–500 ng/mL with a coefficient of determination (r²) of 0.9999. The coefficients of intra‐day and inter‐day validation were 4.0–6.6 and 2.6–7.7%, respectively. The assay accuracy was ?4.4–8.6%, and the recovery was >84%. This HPLC method coupled with ultraviolet (UV) detection for determining ibrutinib plasma concentration has several advantages such as simplicity and applicability to routine therapeutic drug monitoring at hospital laboratories.     

Evaluation of solid‐phase extraction procedures for the quantitation of venlafaxine in human saliva by high‐performance liquid chromatography

In recent years, the use of human saliva for diagnostic purposes has evoked great interest. Thus, the aim of this study was to choose the optimal solid‐phase extraction cartridges and extraction solvents for the quantitation of venlafaxine in saliva. Blank saliva samples spiked with venlafaxine concentrations between 25 and 750 ng/mL were analyzed using five solid‐phase extraction columns (C18, C8, Strata‐X, Strata‐X‐C, and Strata‐X‐AW), washing solvents (deionized water, phosphate buffer at pH 5.5, and their mixtures with methanol), and elution solvents (methanol, acetonitrile, and their mixtures with 25% ammonia). A high‐performance liquid chromatography system was used to quantify venlafaxine in saliva. The results of this study revealed that nine of 25 procedures enabled quantitation of venlafaxine in the tested concentration range. The procedure that used a C18 cartridge, a mixture of methanol and deionized water as the washing solvent, and methanol as the elution solvent was the most effective and allowed quantitation of all venlafaxine concentrations with an acceptable recovery. In contrast, the Strata‐X‐C cartridge could not detect venlafaxine at the lowest concentration (25 ng/mL). The data acquired from the high‐performance liquid chromatography system were confirmed by a multivariate data analysis.     

Determination of meropenem levels in human serum by high‐performance liquid chromatography with ultraviolet detection

Meropenem is a β ‐lactam broad‐spectrum antibiotic and belongs to the subgroup of carbapenems. It is primarily used in intensive care units for intravenous treatment of severe infections. To avoid bacterial resistance or toxic side effects, the determination of serum meropenem concentration is highly advisable. A simple and fast method for the quantitative determination of meropenem in human serum using high‐performance liquid chromatography with ultraviolet detection (HPLC/UV) was developed and validated. Meropenem was determined by an isocratic HPLC using a tris(hydroxymethyl)aminomethane buffer (pH 8.5; 15% methanol) as a mobile phase and UV detection at 300 nm, with a flow rate of 1.0 mL/min and an analysis time of 10 min. Chromatographic separation was performed on a Kinetex C₁₈ column (5 μm, 150 × 4.6 mm). In order to remove undesired serum components, solid‐phase extraction was used for sample preparation. Since meropenem is not stable in solution, sample and stock solution were stored at −80°C. After preparation, samples were stable at room temperature for at least 6 h. The calibration curve was linear from 3.5 to 200 mg/L with a correlation coefficient r ² of 0.999. The method is accurate with an intra‐ and inter‐assay precision <18.5%.     

Hollow fiber‐based liquid membrane microextraction combined with high‐performance liquid chromatography for extraction and determination of trimetazidine in human plasma

A hollow fiber‐based liquid phase microextraction strategy combined with high‐performance liquid chromatography was evaluated for the quantitative determination of trimetazidine in human plasma. Trimetazidine was extracted from a 2.1 mL basified plasma sample (donor phase) into the organic solvent (n‐octanol) impregnated in the pores of a hollow fiber and then extracted into an acidic solution (acceptor phase) inside the lumen of the hollow fiber. The result showed that transport of drugs from alkaline sample solution into 0.5 m HCl occurred efficiently when 25 μL of 250 mm sodium 1‐octanesulfonate was added into the donor phase. Several parameters influencing the efficiency of the method, such as the nature of organic solvent used to impregnate the membrane, compositions of donor phase and acceptor phase, type and concentration of carrier, extraction time, stirring rate and salt concentration, were investigated and optimized. Under the optimal conditions, the calibration curves were obtained in the range of 5–200 ng/mL with reasonable linearity (r > 0.9980). The method was successfully applied to determine the concentration of trimetazidine in human plasma. Copyright © 2012 John Wiley & Sons, Ltd.     

Simultaneous determination of four antiepileptic drugs in human plasma samples using an ultra‐high‐performance liquid chromatography tandem mass spectrometry method and its application in therapeutic drug monitoring

Therapeutic drug monitoring of antiepileptic drugs is widely practiced to achieve optimal efficacy and avoid adverse side effects. We describe an ultra‐high‐performance liquid chromatography tandem mass spectrometry (UHPLC/MS/MS) method developed for the monitoring of four frequently prescribed antiepileptic drugs – lamotrigine, levetiracetam, oxcarbazepine and topiramate. The main pharmacologically active metabolite of oxcarbazepine (mono‐hydroxy‐derivative metabolite, MHD) was also quantified. After addition of internal standards and a simple stage of protein precipitation, plasmatic samples were analyzed on a C₁₈ column. All antiepileptic drugs were separated and quantified in 6 min, without interference. A good linearity was observed all over the calibration range (r² > 0.99), up to 20 μg/mL (40 μg/mL for MHD). The limit of quantification was 0.20 μg/mL (0.40 μg/mL for MHD) with precision and accuracy ranging from 1.0 to 2.1% and from 96.7 to 110.8%, respectively. Intra‐ and inter‐day precision and accuracy values were within 15%. No significant matrix effect was observed for all analytes. Clinical application was successfully evaluated in 259 samples from patients treated for epilepsy or bipolar disorders. In conclusion, a rapid, specific and sensitive UHPLC/MS/MS method was developed and validated for simultaneous quantification of antiepileptic drugs, suitable for therapeutic drug monitoring in neurology and psychiatry.     

Determination of rifampicin in human plasma by high‐performance liquid chromatography coupled with ultraviolet detection after automatized solid–liquid extraction

A precise and accurate high‐performance liquid chromatography (HPLC) quantification method of rifampicin in human plasma was developed and validated using ultraviolet detection after an automatized solid‐phase extraction. The method was validated with respect to selectivity, extraction recovery, linearity, intra‐ and inter‐day precision, accuracy, lower limit of quantification and stability. Chromatographic separation was performed on a Chromolith RP₈ column using a mixture of 0.05 m acetate buffer pH 5.7–acetonitrile (35:65, v/v) as mobile phase. The compounds were detected at a wavelength of 335 nm with a lower limit of quantification of 0.05 mg/L in human plasma. Retention times for rifampicin and 6,7‐dimethyl‐2,3‐di(2‐pyridyl) quinoxaline used as internal standard were respectively 3.77 and 4.81 min. This robust and exact method was successfully applied in routine for therapeutic drug monitoring in patients treated with rifampicin.     

Fast,simple, and sensitive high‐performance liquid chromatography method for measuring vitamins A and E in human blood plasma

Vitamins A and E are fat‐soluble vitamins that play important roles in several physiological processes. Monitoring their concentrations is needed to detect deficiency and guide therapy. In this study, we developed a high‐performance liquid chromatography method to measure the major forms of vitamin A (retinol) and vitamin E (α‐tocopherol and γ‐tocopherol) in human blood plasma. Vitamins A and E were extracted with hexane and separated on a reversed‐phase column using methanol as the mobile phase. Retinol was detected by ultraviolet absorption, whereas tocopherols were detected by fluorescence emission. The chromatographic cycle time was 4.0 min per sample. The analytical measurement range was 0.03–5.14, 0.32–36.02, and 0.10–9.99 mg/L for retinol, α‐tocopherol, and γ‐tocopherol, respectively. Intr‐aassay and total coefficient of variation were <6.0% for all compounds. This method was traceable to standard reference materials offered by the National Institute of Standards and Technology. Reference intervals were established using plasma samples collected from 51 healthy adult donors and were found to be 0.30–1.20, 6.0–23.0, and 0.3–3.2 mg/L for retinol, α‐tocopherol, and γ‐tocopherol, respectively. In conclusion, we developed and validated a fast, simple, and sensitive high‐performance liquid chromatography method for measuring the major forms of vitamins A and E in human plasma.     

Fast and sensitive analysis of beta blockers by ultra‐high‐performance liquid chromatography coupled with ultra‐high‐resolution TOF mass spectrometry

This paper presents a method for the determination of acebutolol, betaxolol, bisoprolol, metoprolol, nebivolol and sotalol in human serum by liquid–liquid extraction and ultra‐high‐performance liquid chromatography coupled with ultra‐high‐resolution TOF mass spectrometry. After liquid–liquid extraction, beta blockers were separated on a reverse‐phase analytical column (Acclaim RS 120; 100 × 2.1 mm, 2.2 μm). The total run time was 6 min for each sample. Linearity, limit of detection, limit of quantification, matrix effects, specificity, precision, accuracy, recovery and sample stability were evaluated. The method was successfully applied to the therapeutic drug monitoring of 108 patients with hypertension. This method was also used for determination of beta blockers in 33 intoxicated patients.     

A high-throughput liquid chromatography-tandem mass spectrometry method for simultaneous determination of direct oral anticoagulants in human plasma

Direct oral anticoagulants are widely used in many indications to prevent thromboembolic events. Routine therapeutic monitoring is not required; however, there is increasing evidence suggesting the benefit of plasma level measurement in some situations. In addition, laboratory monitoring might help improve patient and drug non-compliance and thus individualize therapy. In the present study, we developed a sensitive and high throughput ultra-high-performance liquid chromatography-tandem mass spectrometry method for simultaneous quantification of apixaban, dabigatran, edoxaban, and rivaroxaban in human plasma. A one-step extraction procedure in 96-well formate for phospholipid and protein removal was used for sample pre-treatment, and analytes were separated using gradient elution over 4.2 min. Analytes were detected on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring mode. The method was validated according to the European Medicine Agency guideline for the selectivity, linearity, and lower limit of detection, precision and accuracy, matrix effects, extraction recovery, carryover, dilution integrity, and stability over a concentration range of 3.0–1000 ng/ml for all analytes. The validated method was applied to real clinical samples of patients treated with one of the drugs. Therefore, we can conclude that our method is suitable for therapeutic drug monitoring of direct oral anticoagulants.     

A simple and simultaneous determination of acyclovir and ganciclovir in human plasma by high-performance liquid chromatography

A simple high-performance liquid chromatographic method was developed for the simultaneous determination of the therapeutic levels of acyclovir and ganciclovir in human plasma. After precipitation of plasma proteins with 6% perchloric acid, acyclovir and ganciclovir were simultaneously determined by reversed-phase chromatography with spectophotometric detection at 254 nm. The peak heights for acyclovir and ganciclovir were linearly related to their concentrations ranging from 0.063 to 2.080 micro g/mL. The recovery was 100.48-102.84% for acyclovir and 99.26-103.07% for ganciclovir. The intra- and inter-day relative standard deviation values were in the range 0.186-8.703% for acyclovir and 0.137-6.424% for ganciclovir. The detection limits for both compounds were 0.01 micro g/mL determined as the signal-to-noise ratio of 3. The present method is applicable to therapeutic monitoring during antiviral medication.     

A simple and rapid high‐performance liquid chromatography method for determination of alendronate sodium in beagle dog plasma with application to preclinical pharmacokinetic study

A simple and rapid high performance liquid chromatographic (HPLC) method for quantifying alendronate in beagle dog plasma was developed, validated and applied to a pharmacokinetic study. The sample preparation involved coprecipitation with CaCl₂ and derivatization with o‐phthalaldehyde. Chromatographic separation was achieved on a Diamonsil? C₁₈ (250 × 4.6 mm, 5 µm) using acetonitrile–0.4% EDTA‐Na₂ (16:84, v/v) containing 0.034% of NaOH as mobile phase. The fluorimetric detector was operated at 339 nm (excitation) and 447 nm (emission). The linearity over the concentration range of 5.00–600 ng/mL for alendronate was obtained and the lower limit of quantification was 5.00 ng/mL. For each level of quality control samples, inter‐day and intra‐day precisions were less than 8.52 and 7.42% and accuracies were less than 9.07%. The assay was applied to the analysis of samples from a pharmacokinetic study. Following the oral administration of 70 mg alendronate sodium to beagle dogs, the maximum plasma concentration (C_max) and elimination half‐life were 152 ± 27.3 and 1.75 ± 0.267 h, respectively. The method was demonstrated to be highly feasible and reproducible for pharmacokinetic studies. Copyright © 2009 John Wiley & Sons, Ltd.     

Quantitative determination of regorafenib and its two major metabolites in human plasma with high‐performance liquid chromatography and ultraviolet detection

A simple, highly sensitive and specific high‐performance liquid chromatography (HPLC) method was developed for the simultaneous quantitation of regorafenib, N‐oxidemetabolite (M‐2) and the desmethyl N‐oxide metabolite (M‐5) in human plasma. Regorafenib, M‐2, M‐5 and the internal standard sorafenib were separated using a mobile phase of 0.5% KH₂PO₄ (pH 3.5)–acetonitrile (30:70, v/v), on a Capcell PAK MG II column at a flow rate of 0.5 mL/min and measurement at UV 260 nm. The lower limits of quantification for regorafenib, M‐2 and M‐5 were 10 ng/mL for each analyte. A procedure using solid‐phase extraction required only a small amount of plasma (100 μL) for one analysis while providing high extraction recovery (>81% for all compounds) and good selectivity. Coefficients of variation for intra‐ and inter‐day assays were <12.2% for regorafenib, <12.3% for M‐2 and <15.1% for M‐5. Accuracies for intra‐ and inter‐day assays were <9.4% for regorafenib, <8.0% for M‐2 and <12.8% for M‐5 over a linear range from 10 to 10,000 ng/mL. This HPLC assay is suitable for clinical pharmacokinetic studies of regorafenib. The present HPLC method is currently in use for our observational studies of patients under treatment. Copyright © 2016 John Wiley & Sons, Ltd.     

Novel on‐line column extraction apparatus coupled with binary peak focusing for high‐performance liquid chromatography determination of rifampicin in human plasma: A strategy for therapeutic drug monitoring

In order to develop a method that is completely suitable for the routine therapeutic drug monitoring, a sensitive and fully automated on‐line column extraction apparatus in combination with high‐performance liquid chromatography allowing binary peak focusing was developed and validated for the determination of rifampicin in human plasma. Rifapentine was used as an internal standard. The analytical cycle started with the injection of 100 μL of the sample pretreated by protein precipitation in a Venusil SCX extraction column. After the elution, the analytes were transferred and concentrated in an Xtimate C₁₈ trap column. Finally, the trapped analytes were separated by an Xtimate C₁₈ analytical column and were analyzed by an ultraviolet detector at 336 nm. With this new strategy, continuous on‐line analysis of the compounds was successfully performed. The method showed excellent performance for the analysis of rifampicin in plasma samples, including calibration curve linearity (All r were larger than 0.9996), sensitivity (lowest limit of quantification was 0.12 μg/mL), method accuracy (within 6.6% in terms of relative error), and precision (relative standard deviations of intra‐ and interday precision were less than 7.8%). These results demonstrated that the simple, reliable, and automatic method based on on‐line column extraction and binary peak focusing is a promising approach for therapeutic drug monitoring in complex biomatrix samples.     

Determination of levetiracetam in human plasma by online heart‐cutting liquid chromatography: Application to therapeutic drug monitoring

Levetiracetam is an antiepileptic drug for the treatment of psychiatric patients. In this study, a selective, straightforward, and rapid online heart‐cutting liquid chromatography method was developed for the therapeutic drug monitoring of levetiracetam. This method allows for the determination of levetiracetam in human plasma without complex sample preparation. The mobile phases consisted of 30 mM aq. orthophosphoric acid solution/methanol (70:30) at a flow rate of 1 mL/min for the first system and 10 mM aq. orthophosphoric acid solution/methanol (55:45) at a flow rate of 1 mL/min for the second system. The first separation was carried out on a GL Sciences Intersil ODS‐3 column (4.6 mm × 150 mm, 3 µm) and the second separation was carried out on a Restek Ultra PFPP column (4.6 mm × 150 mm, 5 µm). The detection was carried out at 205 nm for both systems. The method was validated for selectivity and linearity, which were in the 6–60 µg/mL range. Intra‐ and interassay accuracies were <112.6%, and the intra‐ and interassay precisions were <6.4% for all quality control samples. The lower limit of quantitation was 6 µg/mL. The developed method was successfully applied for therapeutic drug monitoring of plasma samples from patients.     

High‐performance liquid chromatography with solid‐phase extraction for the quantitative determination of nilotinib in human plasma

A simple, rapid and sensitive high‐performance liquid chromatography (HPLC)‐based method with ultraviolet detection was developed for the quantitation of nilotinib, a tyrosine kinase inhibitor, in human plasma. Nilotinib and the internal standard dasatinib were separated using a mobile phase of 0.5% KH₂PO₄ (pH2.5)–acetonitrile–methanol (55:25:20, v/v/v) on a Capcell Pak MG II column (250 × 4.6 mm) at a flow rate of 0.5 mL/min and optical measurement at 250 nm. Analysis required only 100 μL of plasma and involved a rapid and simple solid‐phase extraction with an Oasis HLB cartridge, which gave recoveries from 72 to 78% for nilotinib and from 74 to 76% for dasatinib. The lower limit of quantification for nilotinib was 10 ng/mL. The linear range of this assay was between 10 and 5000 ng/mL (r² > 0.9992 for the regression line). Intra‐ and inter‐day coefficients of variation were less than 10.0% and accuracies were within 10.4% over the linear range. Our results indicate that this method is applicable to the monitoring of plasma levels of nilotinib in a clinical setting. Copyright © 2009 John Wiley & Sons, Ltd.     

A novel and nonderivatization method for the determination of valproic acid in human serum by two-dimensional liquid chromatography

A novel and robust two-dimensional liquid chromatography with ultraviolet detection method (2D-LC–UV) was developed and validated for high-throughput determination of the concentrations of valproic acid (VPA) in human plasma. This 2D-LC system was composed of a first-dimensional LC column, a second-dimensional LC column and an intermediate transfer column. The sample was directly injected into the 2D-LC system after an easy protein precipitation treatment. After online preconcentration and primary separation by the first-dimensional column, the target was captured by an intermediate column and then transferred to second-dimensional column for analysis. The system transferred the target through “central cutting” mode whereby the drug peak was not subject to interference from the matrix. The analysis cycle time was completed within 7.0 min. Compared with other methods that have been developed, the analysis time was reduced and the operation was much easier without any derivatization. The calibration curve was linear over the 5.90–188.94 μg/ml range for the VPA concentrations. The intra-day and inter-day precisions were <5.6%. The recoveries were in the range from 95.2 to 98.0%. This method appears to be sensitive, precise, rapid and low-cost for the quantification of VPA in serum sample.