Simultaneous determination of diclofenac potassium and drotaverine hydrochloride in human plasma using reversed-phase high-performance liquid chromatography

A simple high-performance liquid chromatographic method with ultraviolet detection is proposed for the estimation of diclofenac potassium and drotaverine hydrochloride in human plasma. Liquid-liquid extraction was carried out with a mixture of dichloromethane-isopropyl alcohol (80:20, v/v). Chromatographic separation of the analytes and internal standard was achieved on an analytical 250 × 4.6 mm i.d. reversed-phase Thermo BDS Hypersil C8 (5 μm particle size) column using a mobile phase of acetonitrile-0.02M ammonium acetate buffer (53:47, v/v) at pH 3.5. The run time was less than 15 min. Column eluate was monitored at 230 nm. The linearity over the concentration ranges of 25-1500 ng/mL and 32-960 ng/mL was obtained for diclofenac potassium and drotaverine hydrochloride, respectively. The limit of quantification was 25 and 32 ng/mL for diclofenac potassium and drotaverine hydrochloride, respectively. Recoveries of diclofenac potassium and drotaverine hydrochloride from plasma were 97.45% and 98.27%, respectively.     

Determination of diclofenac in plasma by high-performance liquid chromatography with electrochemical detection

A reversed-phase high-performance liquid chromatographic method with electrochemical detection for the quantitative determination of diclofenac potassium in plasma was developed. Naproxen was used as the internal standard. The drug and internal standard were isolated from plasma by extraction with dichloromethane and 2 M hydrochloric acid. Chromatographic separation was performed on a C18 column with methanol-water (68:32, v/v) adjusted to pH 3.2 with phosphoric acid as mobile phase. The oxidation potential for detection was established by constructing a voltammogram for diclofenac. The quantification limit for diclofenac in plasma was 5 ng mL(-1). Linearity of the method was confirmed in the range 5-2000 ng mL(-1), correlation coefficient 0.9998. Within-day relative standard deviations (RSDs) ranged from 0.66 to 14.00% and between-day RSDs from 0.59 to 15.78%. The method was successfully applied for the determination of pharmacokinetic parameters after ingestion of a 50 mg dose of diclofenac. Studies were performed on 18 healthy volunteers of both sexes.     

Resolution, quantification and confirmation of betamethasone and dexamethasone in equine plasma by liquid chromatography/tandem mass spectrometry

This method describes the simultaneous separation, identification, quantification and confirmation of betamethasone (BTM) and dexamethasone (DXM) in equine plasma by liquid chromatography (LC) integrated with multidimensional tandem mass spectrometry. Analytes were directly extracted from equine plasma by methyl tert-butyl ether (MTBE). The residues were reconstituted with sample solvent. LC separation of the analytes was performed on a Hypercarb column using acetonitrile/water/formic acid (95:5:0.5, v/v/v) as the mobile phase. Sample screening, quantification and confirmation were performed in multiple reaction monitoring (MRM) mode. The method was linear over the concentration range of 0.1-75 ng/mL for both analytes. Limit of detection (LOD) was 50 pg/mL and that of quantification (LOQ) was 100 pg/mL for both analytes. The limit of confirmation (LOC) for the presence of BTM or DXM by MRM was 0.5 ng/mL. The intra-and inter-day precisions expressed as coefficient of variation (CV) for quantification of DXM and BTM from 0.1 to 50 ng/mL were less than 7% and the accuracy was in the range of 97-105%. This method is capable of distinguishing BTM from DXM when both analytes are simultaneously present in equine plasma. Measurement uncertainty for both analytes was estimated at less than 16%. The method is rapid, specific, selective, sensitive, simple and reliable. The importance of this method is its usefulness in directly identifying and differentiating BTM from DXM without derivatization.     

Development and validation of a liquid chromatographic/tandem mass spectrometric method for the determination of sertraline in human plasma

A sensitive and rapid liquid chromatographic/tandem mass spectrometric method was developed and validated for the determination of sertraline in human plasma. The analyte and internal standard (IS, diphenhydramine) were extracted with 3 mL of diethyl ether/dichloromethane (2:1, v/v) from 0.25 mL plasma, then separated on a Zorbax Eclipse XDB C18 column using methanol/water/formic acid (75:25:0.1, v/v/v) as the mobile phase. The triple quadrupole mass spectrometry was applied via an atmospheric pressure chemical ionization (APCI) source for detection. The fragmentation pattern of the protonated sertraline was elucidated with the aid of product mass spectra of isotopologous peaks. Quantification was performed using selected reaction monitoring of the transitions of m/z 306 --> 159 for sertraline and m/z 256 --> 167 for the IS. The method was linear over the concentration range of 0.10-100 ng/mL. The intra-day and inter-day precisions, expressed by relative standard deviation, were both less than 6.7%. Assay accuracies were within +/-6.9% as terms of relative error. The lower limit of quantification (LLOQ) was identifiable and reproducible at 0.10 ng/mL with a precision of 8.3% and an accuracy of 9.6%. The validated method has been successfully applied for the pharmacokinetic study and bioequivalence evaluation of sertraline in 18 healthy volunteers after a single oral administration of 50 mg sertraline hydrochloride tablets.     

Development and validation of stability-indicating HPLC method for the simultaneous determination of paracetamol, tizanidine, and diclofenac in pharmaceuticals and human serum

A method is described for the simultaneous determination of paracetamol, tizanidine, and diclofenac in mixtures. The method was based on HPLC separation of the three drugs followed by UV detection at 254 nm. The separation was carried out on a Hypersil ODS, C18 (250 x 4.6 mm id, 10 microm particle size) column using the mobile phase aqueous 0.2% ammonium carbonate-methanol (60 + 40, v/v) at a flow rate of 1 mL/min. The linear regression analysis data were used for the regression curve in the range of 170-10 000 ng/mL for paracetamol, 120-10 000 ng/mL for tizanidine, and 20-10 000 ng/mL for diclofenac. No chromatographic interference from tablet excipients was found. In order to check the selectivity of the proposed method, degradation studies were carried out using hydrolysis (acid, basic, and neutral), thermolysis, and oxidation. The developed method, after being validated in terms of precision, robustness, recovery, LOD, and LOQ, was successively applied to the analysis of pharmaceutical formulations and human serum.     

超高效液相色谱-串联四极杆飞行时间质谱和超高效液相色谱-串联三重四极杆质谱用于血浆中苦杏仁苷及其代谢产物野黑樱苷的定性和定量分析

建立了大鼠灌胃麻杏石甘汤后血浆中苦杏仁苷、野黑樱苷的定性及定量方法。样品经液液萃取净化处理,定性采用超高效液相色谱-串联四极杆飞行时间质谱仪（UPLC-QTOF-MS/MS）,经Shim-pack XR-ODS Ⅲ色谱柱（75 mm×2.0 mm,1.6 μm）分离,定量采用超高效液相色谱-串联三重四极杆质谱仪（UPLC-Q-TRAP-MS）,经Agilent C₁₈色谱柱（50 mm×2.1 mm,1.7 μm）分离,电喷雾负离子化（ESI）及MRM模式测定,流动相均为乙腈-0.1%（v/v）甲酸水溶液。结果显示苦杏仁苷、野黑樱苷在相应浓度范围内线性关系良好（相关系数分别为0.9990、0.9970）,精密度（RSD）小于9.20%,回收率为82.33%~95.25%,检出限（LOD）约为0.50 ng/mL。本方法快速简便,为血浆样品中苦杏仁苷、野黑樱苷的定性和定量分析提供良好参考。     

Determination of bupropion using liquid chromatography with fluorescence detection in pharmaceutical preparations, human plasma and human urine

A novel pre-column derivatization reversed-phase high-performance liquid chromatography with fluorescence detection is described for the determination of bupropion in pharmaceutical preparation, human plasma and human urine using mexiletine as internal standard. The proposed method is based on the reaction of 4-chloro-7-nitrobenzofurazan (NBD-Cl) with bupropion to produce a fluorescent derivative. The derivative formed is monitored on a C18 (150 mm × 4.6 mm i.d., 5 μm) column using a mobile phase consisting of methanol-water 75:25 (v/v), at a flow-rate of 1.2 mL/min and detected fluorimetrically at λ(ex) = 458 and λ(em) = 533 nm. The assay was linear over the concentration ranges of 5-500 and 10-500 ng/mL for plasma and urine, respectively. The limits of detection and quantification were calculated to be 0.24 and 0.72 ng/mL for plasma and urine, respectively (inter-day results). The recoveries obtained for plasma and urine were 97.12% ± 0.45 and 96.00% ± 0.45, respectively. The method presents good performance in terms of precision, accuracy, specificity, linearity, detection and quantification limits and robustness. The proposed method is applied to determine bupropion in commercially available tablets. The results were compared with an ultraviolet spectrophotometry method using t- and F-tests.     

Simultaneous determination of ZLR-8 and its active metabolite diclofenac in dog plasma by high-performance liquid chromatography

ZLR-8 is a nitric oxide releasing derivative of diclofenac for the treatment of inflammation. In this paper, a sensitive and reliable high-performance liquid chromatography method for simultaneous determination of ZLR-8 and its active metabolite diclofenac in the plasma of beagle dogs has been developed and validated. After the addition of ketoprofen as the internal standard (IS), plasma samples were extracted with n-hexane-isopropanol (95:5, v/v) mixture solution and separated by HPLC on a reversed-phase C(18) column with a mobile phase of gradient procedure. Analytes were determined by the UV detector which was set at 280 nm. The method was proved to be sensitive and specific by testing six different plasma batches. Calibration curves of ZLR-8 and diclofenac were linear over the range 0.05-4.0 microg/mL. The within- and between-batch precisions (RSD%) were lower than 10% and accuracy ranged from 85 to 115%. The lower limit of quantification was identifiable and reproducible at 0.05 microg/mL. The proposed method has been readily implemented in preclinical pharmacokinetics studies of ZLR-8 and its active metabolite diclofeance. Representative plasma concentration vs time profiles resulting from administration of ZLR-8 to beagle dogs are presented in this communication.     

HPLC determination of diltiazem in human plasma and its application to pharmacokinetics in humans

A simple and sensitive reversed-phase high performance liquid chromatographic method (HPLC) has been developed and validated for the routine analysis of diltiazem in human plasma and the study of the pharmacokinetics of the drug in the human body. Diltiazem and diazepa (internal standard) were extracted with a mixed organic solution of hexane, chloroform and isopropanol (60:40:5, v/v/v), and then HPLC separation of the drugs was performed on an Spherisorb C(18) column and detected by ultraviolet absorbance at 239 nm. The use of methanol-water solution (containing 2.8 mm triethylamine, 80:20, v/v) as the mobile phase at a fl ow-rate of 1.2 mL/min enables the baseline separation of the drugs free from interferences with isocratic elution. The method was linear in the clinical range 0-300 ng/mL and the lower limit of detection of diltiazem in plasma was 3 ng/mL. The range of percentage of relative standard deviation (%RSD) was from 3.5 to 6.8% for within-day analyses and from 6.2 to 8.4% for between-day analyses, respectively. The extraction recoveries of diltiazem from spiked human plasma (n = 5) at three concentrations were 91.4-104.0%. The method has been used to determine diltiazem in human plasma samples from eight volunteers who had taken diltiazem hydrochloride slow release tables and the data obtained was fitted with a program on computer to study the pharmacokinetics. The results showed that the peak level in plasma approximately averaged 118.5 +/- 14.3 ng/mL at 3.1 +/- 0.4 h, and the areas under the drug concentration curves (AUC) was 793.1 +/- 83.1 ng.h/mL.     

Determination of halofuginone in bovine plasma by competing-ion high performance liquid chromatography after solid phase extraction

A high performance liquid chromatography (HPLC) method for the determination of the anticoccidial and antitheilerial drug halofuginone in bovine plasma was developed. Samples were diluted with acetic acid (10%, v/v) and cleaned up on a Bond Elut C8 column. The analyte was eluted from the extraction column and chromatographed by reversed-phase HPLC using decylamine as a competing-ion reagent. Detection was by UV at 243 nm. Recovery from plasma was 75%, and within-day and between-day coefficients of variation were 5.23 and 6.35% respectively. The specificity and sensitivity of this method (limit of detection in plasma, 1 ng/mL) were sufficiently high to enable us to characterize the time course of the drug in plasma after oral administration of therapeutic doses to cattle.     

Quantification of the plant-derived hallucinogen Salvinorin A in conventional and non-conventional biological fluids by gas chromatography/mass spectrometry after Salvia divinorum smoking

A gas chromatography method with mass spectrometric detection is described for the determination of Salvinorin A, the main active ingredient of the hallucinogenic mint Salvia divinorum. The method was validated in plasma, urine, saliva and sweat using 17-alpha-methyltestosterone as internal standard. The analytes were extracted from biological matrices with chloroform/isopropanol (9:1, v/v). Chromatography was performed on a 5% phenyl methyl silicone capillary column and analytes were determined in the selected ion monitoring mode. The method was validated over the concentration range 0.015-5 microg/mL plasma, urine and saliva and 0.01-5 microg/patch in the case of sweat. Mean recoveries ranged between 77.1 and 92.7% for Salvinorin A in different biological matrices, with precision and accuracy always better than 15%. The method was applied to the analysis of urine, saliva and sweat from two consumers after smoking 75 mg plant leaves to verify the presence of the active ingredient of S. divinorum in human biological fluids as a biomarker of plant consumption. Salvinorin A was detected in urine (2.4 and 10.9 ng/mL) and saliva (11.1 and 25.0 ng/mL), but not in sweat patches from consumers.     

Determination of atrasentan by high performance liquid chromatography with fluorescence detection in human plasma.

Atrasentan is an endothelin antagonist selective for the ET(A) receptor in development at Abbott Laboratories for the treatment of cardiovascular disease and cell proliferation disorders. A simple and sensitive chromatographic method for the determination of atrasentan in human plasma has been developed and validated. The analytical method involves acidification of the plasma samples with 0.3 N HCl prior to extraction with 1:1 (v:v) hexane/tert-butylmethylether. The organic extract was evaporated to dryness, reconstituted with 20:80 (v:v) acetonitrile/0.05 M K(2)HPO(4) and washed with 75:25 (v:v) hexane/tert-butylmethylether. The organic layer was discarded and the aqueous layer was injected into the HPLC. Atrasentan and internal standard (ABT-790) were separated from interference using a 250 x 4.6 mm, 5 microm, 120 A Phenomenex Spherisorb C(8) analytical column with a 50 x 4.6 mm, Alltech Absorbosphere 5 microm CN guard cartridge using a mobile phase consisting of 25:15:5:55 (v:v:v:v) acetonitrile/isopropanol/methanol/0.05 M K(2)HPO(4), pH 7.0, at a flow rate of 1.0 mL/min. Fluorescence detection was achieved using lambda(ex) 278 nm and lambda(em) 322 nm. For a 1.0 mL plasma sample volume, the limit of quantitation was approximately 200 pg/mL. The method was linear from 0.2 to 1300 ng/mL (r(2) = 0.9986). Inter- and intra-day assay RSD (n = 6) were less than 10%. Mean accuracy determinations showed the quality control samples to range between 94 and 99% of the theoretical concentration.     

Determination of metoprolol in human plasma and urine by high‐performance liquid chromatography with fluorescence detection

A simple, specific and sensitive HPLC method has been developed for the determination of metoprolol in human plasma and urine. Separation of metoprolol and atenolol (internal standard) was achieved on an Ace C₁₈ column (5 μm, 250 mm×4.6 mm id) using fluorescence detection with λ_ex=276 nm and λ_em=296 nm. The mobile phase consists of methanol–water (50:50, v/v) containing 0.1% TFA. The analysis was performed in less than 10 min with a flow rate of 1 mL/min. The assay was linear over the concentration range of 3 – 200 and 5 – 300 ng/mL for plasma and urine, respectively. The LOD were 1.0 and 1.5 ng/mL for plasma and urine, respectively. The LOQ were 3.0 and 5.0 ng/mL for plasma and urine, respectively. The extraction recoveries were found to be 95.6 ± 1.53 and 96.4 ± 1.75% for plasma and urine, respectively. Also, the method was successfully applied to three patients with hypertension who had been given an oral tablet of 100 mg metoprolol.     

An automated method for the determination of diclofenac sodium in human plasma

An automated method utilizing laboratory robotics has been developed for quantifying diclofenac sodium concentrations in human plasma. The robotic system aliquots the biological sample, adds the internal standard (CGP 4287), extracts the compounds from the acidified biological matrix (pH less than 2) into an organic phase (hexane-isopropyl alcohol), and concentrates the extracts for reversed-phase, high-performance liquid chromatographic (HPLC) analysis. The laboratory robot is directly interfaced to the HPLC system, and the data are automatically collected and results calculated. Separation is achieved on a 3-microns ODS (6.2-mm x 8.0-cm) column with ultraviolet (UV) detection of the drug and internal standard at 280 nm. Recovery and reproducibility assessments indicate good accuracy (overall mean relative recovery of 99.8%) and precision (coefficient of variation from 0.5 to 11.1%) over the diclofenac sodium concentration range of 5.0-1000 ng/mL, with a quantification limit of 5.0 ng/mL. The method has been successfully applied to a pharmacokinetic study in which normal volunteers received 150 mg of a prototype controlled-release formulation of diclofenac sodium.     

Determination of triptolide and triptonide in human plasma by high-performance liquid chromatography

An isocratic high-performance liquid chromatographic method for determination of triptolide and triptonide in human plasma is described. Plasma samples were extracted with OasisHLB solid-phase extraction (SPE) cartridges. After pretreatment, they were separated on a SymmetryShieldRP(18) column with a mobile phase of acetonitrile-water (40:60,v/v) at 40 degrees C. The effluent was monitored at UV 217 nm. Linearity (0.010-1.0 mg/L) was good, and the lower limit of detection was 3 ng/mL for triptolide and 4.5 ng/mL for triptonide (S/N = 3). The relative standard deviations of intra- and inter-day assay were less than 15% and the recoveries were better than 80%. The developed method was applied to the determination of triptolide and triptonide concentration in a patient's plasma after taking the medicament containing Tripterygium wilfordii Hook. F.     

A validated high-performance liquid chromatographic method for the determination of moclobemide and its two metabolites in human plasma and application to pharmacokinetic studies

A rapid and sensitive reversed-phase high-performance liquid chromatographic method (RP-HPLC) with ultraviolet detection has been developed for the determination of moclobemide and its metabolites, p-chloro-N-(-2-morpholinoethyl)benzamide N'-oxide (Ro 12-5637) and p-chloro-N-[2-(3-oxomorpholino)ethyl]-benzamide (Ro 12-8095), in human plasma. The assay was performed after single liquid-liquid extraction with dichloromethane at alkaline pH using phenacetin as the internal standard. Chromatographic separation was performed on a C(18) column using a mixture of acetonitrile and water (25:75, v/v), adjusted to pH 2.7 with ortho-phosphoric acid, as mobile phase. Spectrophotometric detection was performed at 239 nm. The method has been validated for accuracy, precision, selectivity, linearity, recovery and stability. The quantification limit for moclobemide and Ro 12-8095 was 10 ng/mL, and for Ro 12-5637 was 30 ng/mL. Linearity of the method was confirmed for the range 20-2500 ng/mL for moclobemide (r = 0.9998), 20-1750 ng/mL for Ro 12-8095 (r = 0.9996) and 30-350 ng/mL for Ro 12-5637 (r = 0.9991). Moreover, within-day and between-day precisions and accuracies of the method were established. The described method was successfully applied in pharmacokinetic studies of parent drug and its two metabolites after a single oral administration of 150 mg of moclobemide to 20 healthy volunteers.     

Establishment of a HPLC method for preclinical pharmacokinetic study of the novel anti-Parkinson's disease candidate drug FLZ in rats

An HPLC method was established and validated for the determination of compound FLZ, a synthetic novel anti-Parkinson's disease candidate drug, in rat plasma. FLZ and the internal standard bicyclol were extracted from plasma by solid-phase extraction method and analyzed on a Restek C18 column (4.6 x 250 mm, 5 microm) with a mobile phase consisting of methanol and water (60:40, v/v) at a flow rate of 1.0 mL/min. The detection wavelength was set at 320 nm. The calibration curve was linear within the concentration range from 25 to 500 ng/mL (r2 > 0.999), the limit of quantitation was 25 ng/mL and the average recovery was 92.0% with the RSD less than 5.9%. The relative standard deviation for intra- and inter-day precision was less than 3.8 and 6.9%, respectively. The established HPLC method was validated to be a simple, rapid and reliable procedure and applied to study the preclinical pharmacokinetics of FLZ in rat plasma, and it was the first time that the pharmacokinetics of FLZ had been investigated.     

Determination of faropenem in human plasma and urine by liquid chromatography-tandem mass spectrometry

A simple, rapid and sensitive liquid chromatography/electrospray tandem mass spectrometry (LC-MS/MS) quantitative detection method, using cefalexin as internal standard, was developed for the analysis of faropenem in human plasma and urine. After precipitation of the plasma proteins with acetonitrile, the analytes were separated on a C18 reversed-phase column with 0.1% formic acid-methanol (45:55, v/v) and detected by electrospray ionization mass spectrometry in positive multiple reaction monitoring mode. Calibration curves with good linearities (r=0.9991 for plasma sample and r=0.9993 for urine sample) were obtained in the range 5-4000 ng/mL for faropenem. The limit of detection was 5 ng/mL. Recoveries were around 90% for the extraction from human plasma, and good precision and accuracy were achieved. This method is feasible for the evaluation of pharmacokinetic profiles of faropenem in humans, and to our knowledge, it is the first time the pharmacokinetic of faropenem has been elucidated in vivo using LC-MS/MS.     

Determination of darusentan enantiomers in rat plasma by enantioselective liquid chromatography with tandem mass spectrometry using cellulose-based chiral stationary phase

A sensitive, specific and rapid liquid chromatography-mass spectrometry (LC-MS/MS) method has been developed and validated for enantioselective determination of darusentan enantiomers, orally active potent endothelin-A receptor antagonist, in rat plasma. The plasma samples were pretreated by protein precipitation with methanol and baseline chromatographic separation was performed on a Chiralcel OD-RH column with a mobile phase consisting of acetonitrile/water/formic acid (50:50:0.1, v/v/v) at a flow rate of 0.5 mL/min. The detection was accomplished by multiple-reaction monitoring (MRM) scanning via electrospray ionization (ESI) source operating in the negative ionization mode. The calibration curve was linear over the investigated concentration from 0.500 to 2500 ng/mL (r≥0.995) for each enantiomer using 50 μL of rat plasma. The lower limit of quantitation (LLOQ) for each enantiomer was 0.500 ng/mL. The intra- and inter-day precisions were not more than 10.2% and the accuracy was within the range from -5.4 to 6.3% for darusentan enantiomers. No chiral inversion was observed during the plasma preparation, storage and analysis. The method proved adequate for enantioselective pharmacokinetic studies of darusentan enantiomers after oral administration of three different doses of racemic darusentan.     

Simultaneous determination of aceclofenac and three of its metabolites in human plasma by high-performance liquid chromatography

Aceclofenac [[2-(2',6'-dichlorophenyl)amino]phenylacetoxyacetic acid] is a phenylacetic acid derivative with potent analgesic and anti-inflammatory properties and an improved gastro-intestinal tolerance. In the present study, a liquid-liquid extraction-based reversed-phase HPLC method with UV detection was validated and applied for the analysis of aceclofenac and three of its metabolites (4'-hydroxy-aceclofenac, diclofenac, 4'-hydroxy-diclofenac) in human plasma. The analytes were separated using an acetonitrile-phosphate buffer gradient at a flow rate of 1 mL/min, and UV detection at 282 nm. The retention times for aceclofenac, diclofenac, 4'-hydroxy-aceclofenac, 4'-hydroxy-diclofenac and ketoprofen (internal standard) were 69.1, 60.9, 46.9, 28.4 and 21.2 min, respectively. The validated quantitation range of the method was 10-10000 ng/mL for aceclofenac, 4'-hydroxy-aceclofenac and diclofenac, and 25-10000 ng/mL for 4'-hydroxy-diclofenac. The developed procedure was applied to assess the pharmacokinetics of aceclofenac and its metabolites following administration of a single 100 mg oral dose of aceclofenac to three healthy male volunteers.