High-throughput simultaneous determination of the HIV protease inhibitors indinavir and L-756423 in human plasma using semi-automated 96-well solid phase extraction and LC-MS/MS

A method for the simultaneous determination of the HIV protease inhibitors indinavir and L-756423, in human plasma has been developed. Plasma samples (0.5 ml) were extracted using a 3M Empore 96-well plate in the mixed phase cation exchange (MPC) format. The extraction method was automated through the application of both the Packard 204DT and TOMTEC Quadra 96 work stations, and the resulting extracts were analyzed using a PE-Sciex API-3000 LC-MS/MS with a heated nebulizer interface (500 degrees C). The assay was linear in the concentration range 1-2500 ng/ml for indinavir and 5 2500 ng/ml for L-756423 when 0.5-ml aliquots of plasma were extracted. Recoveries of indinavir and L-756423 were greater than 76 and 80%, respectively, over the calibration curve range when using the described sample preparation method. Within-batch precision and accuracy for the quantitation of indinavir over the range 1-2500 ng/ml were 5.4% R.S.D. or less and within 4.0%, respectively. Within-batch precision and accuracy for the quantitation of L-756423 over the range 5-2500 ng/ml were 5.3% R.S.D. or less and within 3.4%, respectively. Interbatch variability for the analysis of indinavir QC samples at low (3 ng/ml), middle (250 ng/ml) and high (2250 ng/ml) were 3.2, 2.9, and 1.9%, respectively. Interbatch variability for the analysis of L-756423 QC samples at low (15 ng/ml), middle (250 ng/ml) and high (2250 ng/ml) concentration were 2.0, 2.5, and 3.3%, respectively. The validated assay was used in support of human clinical trials.     

A sensitive LC-MS/MS assay for the determination of dextromethorphan and metabolites in human urine--application for drug interaction studies assessing potential CYP3A and CYP2D6 inhibition

The commonly used antitussive dextromethorphan can be used to simultaneously assess potential cytochrome P450 3A (CYP3A) and CYP2D6 inhibition during drug development. The metabolism of dextromethorphan to dextrorphan and subsequently to 3-hydroxymorphinan are via the 2D6 pathway, while the metabolism of dextromethorphan to 3-methoxymorphinan is via the 3A pathway. A sensitive and specific LC-MS/MS assay has been developed to determine the human urine concentrations of dextromethorphan and three metabolites (dextrorphan, 3-methoxymorphinan and 3-hydroxymorphinan) in support of drug interaction studies. Urine samples (0.5 ml), after enzymatic hydrolysis of the conjugates and containing 3-ethylmorphine as an internal standard, were extracted with chloroform under basic conditions. Following concentration and reconstitution, the samples were analyzed by LC-MS/MS. The assay was linear over the range of 5.00-500 ng/ml for dextromethorphan and 3-methoxymorphinan; and 200-3000 ng/ml for dextrorphan and 3-hydroxymorphinan using a Perkin-Elmer Sciex triple quadrupole mass spectrometer (API 300). The intra- and inter-day relative standard deviation (RSD) across three validation runs over the entire concentration range for all analytes was less than 15%. Accuracy determined at three or four concentrations (9.00, 200, and 400 ng/ml for dextromethorphan and 3-methoxymorphinan; 250, 400, 1300 and 2500 ng/ml for dextrorphan and 3-hydroxymorphinan) ranged between 96.3 and 113.8%. The stability of analytes in urine was demonstrated for 9 months at -20 degrees C, 24 h under ambient conditions and for up to three freeze/thaw cycles. The method described herein is suitable for the rapid and efficient measurement of dextromethorphan and different metabolites to estimate potential CYP3A inhibition by drug candidates and for screening of extensive and poor metabolizers of CYP2D6 in the heterogeneous population. The method has subsequently been validated on a Sciex API 3000 with lower limit of quantitation; 1.00 ng/ml for dextromethorphan and 3-methoxymorphinan; 60.0 ng/ml for dextrorphan and 100 ng/ml for 3-hydroxymorphinan.     

HPLC-UV determination of morphine in human plasma and its application to the clinical study

A sensitive and specific high-performance liquid chromatography method with ultraviolet detection (HPLC-UV) has been developed for the quantification of morphine sulfate [(5alpha,6alpha)-7,8-didehydro-4,5-epoxy-17-methylmorphinan-3,6-diol], (CAS: 52-26-6) in human plasma. The analyte was extracted from plasma samples with chloroform - isopropyl alcohol (90:10, v/v) and analyzed on a Bondapak C18 column. The calibration curves were linear within the range of 10-150 ng/mL. The lower limit of quantitation was 10 ng/mL with 0.5 mL plasma sample. The mean recovery of the drug from plasma samples was 83.39%. The results from analysis of quality-control samples at concentrations of 30, 75, and 150 ng/mL were indicative of good accuracy and precision. This method was successfully used to analyze morphine in plasma samples of patients after abdominal hysterectomy.     

Semiautomated preparation of 3,5,6-trichloro-2-pyridinol in human urine using a Zymate XP laboratory robot with quantitative determination by gas chromatography-negative-ion chemical ionization mass spectrometry

A rapid and sensitive semiautomated method was developed for quantitation of the chlorpyrifos metabolite 3,5,6-trichloro-2-pyridinol (TCP) in human urine. A Zymark Zymate XP laboratory robotics system was used to mix urine samples, transfer aliquots, add the stable-isotope-labeled TCP internal standard (13C2- or 13C2,15N-), and liberate conjugates of TCP from urine via acid hydrolysis. Samples were manually extracted into toluene, derivatized, and analyzed by gas chromatography-negative-ion chemical ionization mass spectrometry. Determination of the metabolic TCP was performed by selected ion monitoring of the dichloropyridinol fragment ions: m/z 161 for TCP and m/z 165 for 13C2-TCP or m/z 168 for 13C2,15N-TCP. Interday precision and accuracy were demonstrated over 3 years of analyses using the 13C2-TCP internal standard, with an average recovery from fortified urine samples of 93+/-12% (N = 54, concentration range 1-140 ng/mL). The method was found to be linear over the range of 0.5 to 200 ng/mL, and the limit of detection for TCP in urine was estimated to be 0.2 ng/mL with a limit of quantitation of 1 ng/mL. The effect of solids distribution on the concentration of TCP in the thawed urine samples was examined, and the results indicated that homogeneous distribution is critical for quantitation. The precision and accuracy of the automated method with respect to the transfer of homgeneous urine aliquots and delivery of internal standard yielded equivalent or improved results over the manual techniques. Overall, this method is more simple than existing methodologies, and it yields results with improved precision, accuracy, and sensitivity over previously developed methods.     

Confirmation of low concentrations of urinary benzodiazepines, including alprazolam and triazolam, by GC/MS: an extractive alkylation procedure.

Urine samples containing diazolo- and triazolobenzodiazepines and metabolites were hydrolyzed with beta-glucuronidase and extracted with methylene chloride. The extracts were treated with methyl iodide, methylene chloride, and tetrahexylammonium hydrogen sulfate in basic solution to form the methyl derivatives of the drugs and metabolites. GC/MS analysis resulted in the following test characteristics: day-to-day precision at 360 ng/mL (120 ng/mL for the triazolobenzodiazepine metabolites) was 2.4 to 5.5% CV; calibration curves were linear to 6000 ng/mL (1000 ng/mL for the triazolobenzodiazepine metabolites), and operational limits of quantitation were in the range 13-25 ng/mL.     

Analysis of ritonavir in plasma/serum and tissues by high-performance liquid chromatography

A method has been developed to quantify ritonavir concentrations in human plasma and in mouse serum, liver, and brain using high-performance liquid chromatography. Extraction recoveries for ritonavir and its internal standard averaged greater than 95%. Within-day variability, expressed as a coefficient of variation, averaged 6% over the concentration range 0.5 μg/mL to 15 μg/mL ritonavir, and between-day variability averaged 5.6% over 5 μg/mL to 15 μg/mL ritonavir. The method was applied to quantitation of ritonavir in mouse serum and tissue. Measured values deviated less than 5% from the actual values in mouse serum, liver, and brain samples containing 5 μg/mL ritonavir. The slopes of calibration curves for extracted calf serum, mouse serum, mouse liver and mouse brain standards were nearly identical to the calibration slope of standards which were not extracted. All curves were linear through zero, and r² was no less than 0.998 for any form of calibration. In addition, there was no chromatographic interference from commonly prescribed medications.     

A simple and sensitive LC/MS/MS assay for 7-ethyl-10-hydroxycamptothecin (SN-38) in mouse plasma and tissues: application to pharmacokinetic study of liposome entrapped SN-38 (LE-SN38)

An LC/MS/MS method to quantify SN-38 in mouse plasma and tissue homogenates containing liposome entrapped SN-38 (LE-SN38) was developed. Camptothecin (CPT) was used as the internal standard (IS). Sample preparation consisted of simple protein precipitation by acetonitrile containing 0.5% acetic acid. SN-38 and IS were separated by a C18 HPLC column and detected using a mass spectrometer operating in the multiple reaction monitoring (MRM) mode. The peak area of the m/z 393.3-->349.1 transition of SN-38 and that of the m/z 349.1-->305.2 transition of the IS were measured and a standard curve was generated from their ratios. The method had a LLOQ of 0.5 ng/mL in mouse plasma, which corresponds to 2.5 pg for the 5 microL injection volume. The linear range was 0.5-1000 ng/mL of SN-38 in plasma sample spiked with LE-SN38. The LLOQ in tissue homogenates (5%, w/v) quantitation was 1 ng/mL (20 ng/g tissue) of SN-38 in kidney, liver, lung, and spleen homogenates, and 2 ng/mL (40 ng/g tissue) in heart homogenate containing LE-SN38. The assay was linear up to 400 ng/mL of SN-38 in tissue homogenates, and may be extended to 120 microg/mL by proper dilution of samples over the upper limit of quantitation. Acceptable precision and accuracy were obtained for concentrations over the entire standard curve range, both between-run and within-run for plasma and tissue homogenates. The method was successfully used to quantify SN-38 in plasma and tissues samples for pharmacokinetic and tissue distribution studies of LE-SN38 in mice.     

LC-MS/MS同时测定人血浆中洛匹那韦和利托那韦浓度

目的建立一种快速、灵敏并同时测定人体血浆中洛匹那韦（LPV）和利托那韦（RTV）浓度的液相色谱.质谱联用检测方法。方法采用Agilent Eclipse Plus C18柱（4．6mm×l50mm,3.5μm）,流动相为乙腈－水（含0．005tool·L＾-1甲酸铵,0．1％甲酸）（90：10）;流速：0．5mL·min＾-1,柱温：40℃,以乙酸乙酯为提取剂。采用选择反应监测（SRM）LPV（m／z629．5→155．1）、RTV（m／z721．4→296．1）和内标茚地那韦（IDV）（m／z614．5→465．4）进行测定。结果LPVN（10000μg·L＾-1）、中（1000μg.L＾-1）、低（40lag·L＾-1）3个浓度的平均方法回收率RSD均〈15％;线性范围为：20～20000μg·L＾－1,回归方程为Y＝1．6699X-0．0013,r=O．9984（n=7）,定量下限为20μg·L＾-1。RTV高（2500μg·L＾-1）、中（250μg·L。）、低（10μg·L＾-1）3个浓度的平均方法回收率RSD均〈15％;线性范围为5～5000μg·L＾-1,回归方程为Y＝1．7237X-3．2748×10-4,r=0．9987（n=7）,分析方法的定量下限为5μg·L＾-1。结论该方法灵敏、准确、简单、快速,可用于LPV和RTV同时应用时两者的临床血药浓度监测和药动学研究。     

Quantitative analysis of selegiline and three metabolites (N-desmethylselegiline,methamphetamine, and amphetamine) in human plasma by high-performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry

This report describes a sensitive and specific high-performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry method for the detection of subnanogram concentrations of selegiline and its three principle metabolites, N-desmethylselegiline, methamphetamine, and amphetamine, in human plasma. The assay has a dynamic range of 0.1-20 ng/mL for selegiline and N-desmethylselegiline (norselegiline) and 0.2-20 ng/mL for methamphetamine and amphetamine. The inter- and intra-assay precision and accuracy varied by less than 11% for all analytes at 0.3, 2.5, and 15 ng/mL and less than 16% at the lower limit of quantitation (0.1 ng/mL for selegiline and norselegiline; and 0.2 ng/mL for methamphetamine and amphetamine). Selegiline and its metabolites showed no significant loss in quantitative accuracy after three freeze/thaw cycles or after up to 6 h at room temperature prior to extraction. Extracted plasma samples retained quantitative accuracy after storage for at least 7 days at -20 degrees C or up to 70 h at room temperature. Methanolic stock solutions were stable for at least 6 h when kept at room temperature or at least 90 days when kept at -20 degrees C.     

Conceptual biotransformation of 4-oxo-all-trans-retinoic acid, 4-oxo-13-cis-retinoic acid and all-trans-retinoyl-beta-glucuronide in rat whole embryo culture.

In cultured rat conceptuses, intraamniotic microinjections of 2500 ng/mL of 4-oxo-13-cis-retinoic acid, 600 ng/mL 4-oxo-all-trans-retinoic acid or 4000 ng/mL all-trans-retinoyl-beta-glucuronide, produce qualitatively and quantitatively similar patterns of dysmorphogenesis as those reported after the intraamniotic microinjection of 250 ng/mL all-trans-retinoic acid [Lee et al., Teratology 44: 313-323, 1991; Creech Kraft et al., Teratology 45: 259-270, 1992]. In the present study, we utilized HPLC techniques to analyze retinoid levels in cultured rat conceptuses, 1.5 hr after intraamniotic microinjections of 4-oxo-13-cis-retinoic acid (2500 ng/mL), 4-oxo-all-trans-retinoic acid (600 ng/mL) or all-trans-retinoyl-beta-glucuronide (4000 ng/mL). Our findings show that, after the microinjections of 4-oxo-all-trans-retinoic acid or 4-oxo-13-cis-retinoic acid (at these selected concentrations), 4-oxo-all-trans-retinoic acid was predominant in the embryos proper at concentrations of about 200 nM. This was roughly equivalent to the levels of all-trans-retinoic acid assayed after microinjections of all-trans-retinoyl-beta-glucuronide (4000 ng/mL). We conclude from these studies that both 4-oxo-all-trans-retinoic acid and all-trans-retinoic acid behave as ultimate or proximate dysmorphogens.     

HPLC 法测定盐酸氨溴索注射液中有关物质

目的采用HPLC法测定盐酸氨溴索注射液中的有关物质。方法采用Agela Venusil MPC18柱(250mm×4.6mm,5μm),以磷酸氢二铵缓冲液(pH4.0)-甲醇(40:60)为流动相,体积流量为1.0mL/min,检测波长为250nm,柱温:30℃。结果盐酸氨溴索和反式-4-[6,8-二溴-1,4-二氢喹唑啉-3(2H)]环己醇的最小检出限分别为15、30ng;杂质的线性范围为0.72～1.68μg/mL(r=0.9996),加样平均回收率为101.32%,RSD为0.92%(n=9)。结论该方法测定盐酸氨溴索注射液中的有关物质方法简便、准确、专属性强。     

The effect of the use of mouthwash on ethylglucuronide concentrations in urine

Two studies were performed to evaluate the effect of alcohol containing mouthwash on the appearance of ethyl glucuronide (EtG) in urine. In the first study, 9 volunteers were given a 4-oz bottle of mouthwash, which contained 12% ethanol. They gargled with all 4 oz. of the mouthwash at intervals over a 15-min period. All urine samples were collected over the next 24 h. Of 39 provided urine samples, there were 20 > 50 ng/mL, 12 > 100 ng/mL, 5 > 200 ng/mL, 3 > 250 ng/mL, and 1 > 300 ng/mL. The peak concentrations were all within 12 h after the exposure. In the second study, 11 participants gargled 3 times daily for 5 days. The first morning void was collected. Sixteen of the 55 submitted samples contained EtG concentrations of greater than 50 ng/mL. All of them were less than 120 ng/mL. These studies show that incidental exposure to mouthwash containing 12% ethanol, when gargling according to the manufacturer's instructions, can result in urinary EtG values greater than 50 ng/mL. All specimens were negative for ethanol. The limits of detection and quantitation for the EtG testing were 50 ng/mL.     

Quantitation of benzodiazepines in urine, serum, plasma, and meconium by LC-MS-MS

A single method for confirmation and quantitation of a panel of commonly prescribed benzodiazepines and metabolites, alpha-hydroxyalprazolam, alpha-hydroxyethylflurazepam, alpha-hydroxytriazolam, alprazolam, desalkylflurazepam, diazepam, lorazepam, midazolam, nordiazepam, oxazepam, temazepam, clonazepam, and 7-aminoclonazepam, was developed for three specimen types, urine, serum/plasma, and meconium. Quantitation was by liquid chromatography tandem-mass spectrometry (LC-MS-MS) using a Waters Alliance-Quattro Micro system. The instrument was operated in multiple reaction monitoring mode with an electrospray ionization source in positive ionization mode. The method was evaluated for recovery, imprecision, linearity, analytical measurement range, specificity, and carryover. Average recovery and imprecision (within-run, between-run, and total % CV) were within +/- 15% of the target concentrations for urine (10 to 5000 ng/mL) and serum/plasma (10 to 2500 ng/mL) and within +/- 20% for meconium (10 to 5000 ng/g). In all, 205 patient specimens were analyzed, and the results compared to a previous in-house gas chromatography-MS method or LC-MS-MS results from an outside laboratory. Oxazepam glucuronide was evaluated as a hydrolysis control for the urine and meconium specimens.     

液相色谱-质谱-质谱联用法快速测定人血浆中法莫替丁含量

目的建立测定人血浆中法莫替丁含量的液相色谱 质谱 质谱联用法。方法取 0 2mL血浆样品经液 液萃取后 ,以乙腈 水 甲酸 (3 0∶70∶1 ,V∶V∶V)为流动相 ,采用ZorbaxSBC8柱分离 ,通过电喷雾离子化四极杆串联质谱 ,以选择反应监测 (SRM)方式进行检测。用于定量分析的离子反应分别为m/z 3 3 8→m/z1 88(法莫替丁 )和m/z2 40→m/z1 47(内标 ,沙丁胺醇 )。结果法莫替丁线性范围是 2 5～ 5 0 0 0ng/mL ,最低定量限为 2 5ng/mL。日内、日间精密度 (RSD)小于 8% ,准确度(RE)在± 2 %范围内。每个样品测试时间仅为 4min,应用此法每天可以测试 1 0 0多个样品。结论该法灵敏度高 ,样品处理简单 ,分析测试速度快 ,适用于临床药物动力学研究。     

Simultaneous determination of ketamine, tramadol, methadone, and their metabolites in urine by gas chromatography-mass spectrometry

An automated solid-phase extraction procedure combined with gas chromatography-mass spectrometry methodology, without derivatization, has been developed for the identification and quantitation of ketamine, norketamine, tramadol, methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine, and 2-ethyl-5-methyl-3,3-diphenylpyrroline in urine. The analytical approach is simple and rapid, yet reliable. Good linearity (r(2) > 0.995 over the concentration range of 30 to 600 ng/mL), sensitivity (limits of quantitation 15-30 ng/mL), accuracy (81.0-109.9%), precision (RSD < 13.8%), and recovery (> 79.6% in average) were achieved for all analytes. Ninety-one urine specimens from suspected drug users and 21 clinical urine specimens from methadone substitution therapy patients were analyzed to validate the method compatibility and stability. Results have demonstrated that this GC-MS method is a good confirmation and quantitation test scheme for the six target compounds in urine.     

固相萃取-反相高效液相色谱法测定全血中环孢素浓度

目的建立测定全血中环孢素浓度的固相萃取-反相高效液相色谱（RP-HPLC）法。方法采用Supelclean Envi-18固相萃取小柱提取全血中环孢素,RP-HPLC法测定药物浓度。以Shim-Pack C18柱（250mm×4.6mm,5μm）为分析柱,Shim-Pack C18柱（10mm×4.6mm,5μm）为预柱,流动相为乙腈-水（76∶24）,流速1.0mL/min,检测波长210nm,柱温68℃。结果环孢素质量浓度的线性范围为50～1000ng/mL,回归方程A=370.4C＋4771.5（r=0.9999,n=3）,平均回收率为96.17%,日内、日间精密度的RSD分别小于1.79%和6.12%（n=5）。结论固相萃取-反相高效液相色谱法灵敏、准确、重现性好,适用于环孢素的临床血药浓度监测。     

盐酸头孢替安酯的聚合物检查方法的建立与验证

目的建立高效分子排阻色谱（HPSEC）发测定盐酸头孢替安酯聚合物。方法采用凝胶色谱柱（偈KG2500PWxl,7.8mm×30cm）;流动相为PH7.0的0．001mol／L磷酸盐缓冲液[0.001mol／L的磷酸氢二钠溶液-0．001mol／L的磷酸二氢钠溶液（61：39）]一乙睛（80：20）;流速0．5mL／min;检测波长为：254nm;进样量为20uL;自身外标法定量。结果头孢替安的线性范围为1.03—20．60μg/mL定量限为0．66×10^-5mg／mL;重复性（nsu）为0．44％;对照品溶液室温放置8h内稳定,满足检测要求。样品测定的线性范围为1．03—20．60μg／mL;重复性（RSD）为1．48％;样品溶液室温放置8h内不稳定,需要临用现配。结论该方法能够较好的分离盐酸头孢替安酯及其聚合物,可用于盐酸头孢替安酯中聚合物的检验。     

High-performance liquid chromatographic analysis of pterostilbene in biological fluids using fluorescence detection

A method of analysis of pterostilbene [trans-3,5-dimethoxy-4'-hydroxystilbene] is necessary to study the kinetics of in vitro and in vivo metabolism and determine its concentration in foodstuffs. A novel and simple high-performance liquid chromatographic method was developed for determination of pterostilbene in rat serum. Serum proteins (0.1 mL) are precipitated with cold acetonitrile after addition of the internal standard, pinosylvin. Separation was achieved on a Phenomenex C18 column (250 mm x 4.60 mm) with fluorescence excitation at 330 nm and emission at 374 nm. The calibration curves were linear ranging from 0.5 to 100 microg/mL. The mean extraction efficiency was >99%. Precision of the assay was <15% (CV), and was within 14% at the limit of quantitation (0.5 microg/mL). Bias of the assay was lower than 14%, and was within 9% at the limit of quantitation. The assay was applied successfully to the study of pterostilbene pharmacokinetics in rats.     

Simultaneous quantitation of buspirone and its major metabolite 1-(2-pyrimidinyl)piperazine in human plasma by high-performance liquid chromatography with coulometric detection

Buspirone is a member of the azapirone group of anxiolytic drugs and has one major metabolite, 1-(2-pyrimidinyl)piperazine (1-PP). The analyte, its metabolite and the internal standard were extracted from plasma utilizing solid-phase extraction columns. Chromatography was performed using isocratic reversed-phase high-performance liquid chromatography with coulometric end-point detection. The calibration graph was linear over the range 0–50 ng ml⁻¹ of plasma. The lower limits of quantitation for buspirone and 1-PP were 0.5 and 2 ng ml⁻¹, respectively, when 1 ml of plasma was extracted. The intra-assay relative standard deviations (RSD) over the range of the calibration graph varied from 4 to 12.5% for buspirone and 1-PP. The inter-assay RSD was 6.9% for 1-PP and 9.6% for buspirone. The recovery averaged 96% for buspirone and 66% for 1-PP. Plasma profiles of buspirone and 1-PP following oral dosing are presented.     

高效液相色谱法测定四乙酰葛根素的含量及有关物质

目的建立测定四乙酰葛根素的含量及有关物质的高效液相色谱法。方法采用AgilentXDB—C18色谱柱（250mm×4．6mm,5μm）,流动相为乙腈一水（45：55）,流速为1．2mL／min,检测波长为250nm,柱温为30℃。结果四乙酰葛根素的质量浓度在0．1038～0．9342μg范围内与峰面积线性关系良好,Y=12871x-24．554,r=0．9999（n=7）,检测限为6．65ng／mL（S／N=3）;平均加样回收率为99．94％,RSD=1．32％（n=9）,有关物质含量为1．02％-1．28％。结论该方法简便、准确,可用于四乙酰葛根素的含量测定。