Measurement of Sterigmatocystin Concentrations in Urine for Monitoring the Contamination of Cattle Feed

This study aimed (1) at determining the levels of the fungal toxin sterigmatocystin (STC) in the feed and urine of cattle and (2) at evaluating the effects of supplementing the feed with a mycotoxin adsorbent (MA) on STC concentrations in urine. Two herds of female Japanese Black cattle were used in this study. The cattle in each herd were fed a standard ration containing rice straw from different sources and a standard concentrate; two groups of cattle from each herd (n = six per group) received the commercial MA, mixed with the concentrate or given as top-dressing, whereas a third group received no supplement and served as control. Urine and feed samples were collected at various time points throughout the experiment. STC concentrations were measured using liquid chromatography-tandem mass spectrometry (LC-TMS). STC concentrations in straw were higher in Herd 1 (range 0.15–0.24 mg/kg DM) than in Herd 2 (range <0.01–0.06 mg/kg DM). In Herd 1, STC concentrations in urine significantly declined 2 weeks after replacing the contaminated feed, whereas MA supplementation had no effect. In conclusion, mycotoxins in urine samples are useful biological markers for monitoring the systemic exposure of cattle to multiple mycotoxins, as well as evaluating the effectiveness of interventions.     

Simultaneous quantitation of four androgens and 17-hydroxyprogesterone in polycystic ovarian syndrome patients by LC-MS/MS

BackgroundDue to the low concentration of androgens in women and the limitation of immunoassays, it remains a challenge to accurately determine the levels of serum androgens in polycystic ovary syndrome (PCOS) patients for clinical laboratories. In this report, a liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) method was developed and validated for simultaneous quantitation of testosterone (T), androstenedione (A4), dehydroepiandrosterone sulfate (DHEAS), dihydrotestosterone (DHT), and 17‐hydroxyprogesterone (17‐OHP) that are associated with PCOS.MethodsThe serum samples were processed by protein precipitation and solid phase extraction before analysis with the in‐house developed LC‐MS/MS. The chromatographic separation was achieved with a C18 column, using a linear gradient elution with two mobile phases: 0.02% formic acid in water (phase A) and 0.1% formic acid in methanol (phase B). The separated analytes were detected by positive or negative electrospray ionization mode under multiple reaction monitoring (MRM).ResultsThe assay for all the five analytes was linear, stable, with imprecision less than 9% and recoveries within ±10%. The lower limits of quantification were 0.05, 0.05, 5, 0.025, and 0.025 ng/mL for T, A4, DHEAS, DHT, and 17‐OHP, respectively. In the receiver operating characteristic curve (ROC) analyses with the PCOS (n = 63) and healthy (n = 161) subjects, the AUC of the four‐androgen combined was greater than that of any single androgen tested in PCOS diagnosis.ConclusionsThe LC‐MS/MS method for the four androgens and 17‐OHP showed good performance for clinical implementation. More importantly, simultaneous quantitation of the four androgens provided better diagnostic power for PCOS.     

Nitrosamine Contamination in Pharmaceuticals: Threat,Impact, and Control

Nitrosamine-contaminated medicinal products have raised safety concerns towards the use of various drugs, not only valsartan and all tetrazole-containing angiotensin II receptor blockers, but also ranitidine, metformin, and other medicines, many of which have been recalled and prone to shortage. At any stages, from drug substance synthesis throughout each product's lifetime, these impurities may evolve if an amine reacts with a nitrosating agent coexisting under appropriate conditions. Consequently, drug regulatory authorities worldwide have established stringent guidelines on nitrosamine contamination for all drug products in the market. This review encompasses various critical elements contributing to successful control measures against current and upcoming nitrosamine issues, ranging from accumulated knowledge of their toxicity concerns and potential root causes, precise risk evaluation, as well as suitable analytical techniques with sufficient sensitivity for impurity determination. With all these tools equipped, the impact of nitrosamine contamination in pharmaceuticals should be mitigated. An evaluation aid to tackle challenges in risk identification, as well as suitable industry-friendly analytical techniques to determine nitrosamines and other mutagenic impurities, are among unmet needs that will significantly simplify the risk assessment process.     

Simultaneous Determination of Silybin A and Silybin B in Rat Plasma and Pharmacokinetic Study

Objective To investigate the bioavailability and pharmacokinetics of silybin A and silybin B in rats,respectively. Methods Following iv and ig administration of silybin to 20 Wistar rats,the plasma samples were collected at different time points up to 12 h.Sample pretreatment was involved in one-step protein precipitation with acetonitrile. Silybin A and silybin B were simultaneously determined by LC-MS/MS.Results After ig dosing silybin 28,56,and 112 mg/kg to rats,the t1/2βvalues were 5.48,5.08,and 5.73 h for silybin A,and 4.56,4.12,and 5.53 h for silybin B; The Cmax were 674.3,1349.4,and 2042.5 ng/mL for silybin A,and 671.0,1365.4,and 2066.2 ng/mL for silybin B; The Tmax were 0.20,0.23,and 0.20 h for silybin A,and 0.20,0.23,and 0.20 h for silybin B;The AUC were 454.4, 845.9,and 1219.5 h·ng/mL for silybin A,and 432.0,817.1,and 1153.6 h·ng/mL for silybin B.The absolute bioavailabilities of silybin A and silybin B were 2.86%and 1.93%,respectively.Conclusion Silybin A and silybin B have very low bioavailability after ig administration,and there is no significant difference in the pharmacokinetic parameters between silybin A and silybin B,which indicates that the two diastereoisomers have similar pharmacokinetic behavior in rats.     

Type 2C protein phosphatases directly regulate abscisic acid-activated protein kinases in Arabidopsis

Abscisic acid (ABA) signaling is important for stress responses and developmental processes in plants. A subgroup of protein phosphatase 2C (group A PP2C) or SNF1-related protein kinase 2 (subclass III SnRK2) have been known as major negative or positive regulators of ABA signaling, respectively. Here, we demonstrate the physical and functional linkage between these two major signaling factors. Group A PP2Cs interacted physically with SnRK2s in various combinations, and efficiently inactivated ABA-activated SnRK2s via dephosphorylation of multiple Ser/Thr residues in the activation loop. This step was suppressed by the RCAR/PYR ABA receptors in response to ABA. However the abi1–1 mutated PP2C did not respond to the receptors and constitutively inactivated SnRK2. Our results demonstrate that group A PP2Cs act as ‘gatekeepers’ of subclass III SnRK2s, unraveling an important regulatory mechanism of ABA signaling.     

Disposition of desloratadine in healthy volunteers

The absorption, metabolism and excretion of desloratadine (DL, Clarinex®) were characterized in six healthy male volunteers. Subjects received a single oral 10-mg dose of [¹⁴C]DL (～104?µCi). Blood, urine and feces were collected over 240?h. DL was well absorbed; drug-derived radioactivity was excreted in both urine (41%) and feces (47%). With the exception of a single subject, DL was extensively metabolized; the major biotransformation pathway consisted of hydroxylation at the 3 position of the pyridine ring and subsequent glucuronidation (3-OH-DL-glucuronide or M13). In five of the six subjects, DL was slowly eliminated (mean t_½?=?19.5?h) and persisted in the plasma for 48–120?h post-dose. This is in contrast to a t_½ of ～110?h and quantifiable plasma DL concentrations for the entire 240-h sampling period in one subject, who was identified phenotypically as a poor metabolizer of DL. This subject also exhibited correspondingly lower amounts of M13 in urine and 3-OH-DL (M40) in feces. Disposition of DL in this subject was characterized by slow absorption, slow metabolism and prolonged elimination. Further clinical studies confirmed the lack of safety issues associated with polymorphism of DL metabolism (Prenner et al. 2006, Expert Opinion on Drug Safety, 5: 211–223).     

甘草酸二铵胶囊人体相对生物利用度研究

目的建立甘草酸二铵的活性代谢产物甘草次酸血药浓度的液 质联用色谱测定法(LC MS),并对甘草酸二铵胶囊在健康受试者体内的生物等效性进行研究。方法采用两制剂双周期随机交叉试验设计,20例男性健康受试者先后分别单剂量口服甘草酸二铵受试制剂或参比制剂150 mg,采用液 质联用色谱法,以熊果酸为内标,测定血浆中其活性代谢产物甘草次酸的浓度。采用 DAS 2.0 药动学软件进行数据处理。结果试验制剂与参比制剂的AUC0 t分别为（1 648.49±230.55）和（1 609.27 ± 265.59） ng&#8226;mL 1&#8226;h;Cmax分别为（95.97±14.99）和（93.05±17.91） ng&#8226;mL 1;tmax分别为(12.00±1.30)和(11.80±1.44) h。结论两种制剂人体内血药浓度变化符合二室模型,两药的平均生物利用度为（103.5±12.7）%（AUC0 t）,具有生物等效性。     

Beagle犬血浆中辛伐他汀的LC-MS测定

建立了LC-MS法测定Beagle犬血浆中的辛伐他汀。采用C_(18)柱,流动相为乙腈-0.1%甲酸溶液(60:40),以洛伐他汀为内标,采用电喷雾离子化法(ESI)采集正离子,单离子方式检测m/z 419(辛伐他汀)和m/z 405(洛伐他汀)。辛伐他汀在0.5～160ng/ml浓度范围内线性良好,检测限为0.25ng/ml。血浆样品的日内、日间RSD均小于7.7%,方法回收率为92.2%～99.2%,提取回收率为92.8%～100.9%。     

LC-MS/MS法快速测定人血浆中美沙酮的浓度

目的:建立快速测定人血浆中美沙酮浓度的方法。方法:采用高效液相色谱串联质谱电喷雾检测(LC-MS/MS)法。色谱柱为AgilentTCC18,流动相为甲醇-5mmol·L-1甲酸铵(90∶10),流速为1mL·min-1,柱温为25℃,提取剂为醋酸乙酯∶二氯甲烷(4∶1)。样品经电喷雾离子源正离子化后,通过三重四级杆串联质谱仪,采用选择反应监测(SRM)对美沙酮(m/z310.0→264.9)和内标地西泮(m/z285.1→154.0)进行测定。结果:美沙酮血药浓度在2.5～500μg·L-1范围内线性关系良好(r=0.9990),分析方法的最低定量限为2.5μg·L-1;其高、中、低(300、100、5μg·L-1)3种浓度的平均方法回收率分别为100.23%、101.20%和101.39%,日内(n=5)、日间(n=3)RSD均<10%。结论:本方法简单、快速、灵敏、准确、重现性好,可用于美沙酮的临床血药浓度监测和药动学研究。     

LC-MS／MS法测定人血浆中米格列醇

目的:建立测定人血浆中米格列醇的 LC-MS/MS 法。方法:以盐酸格拉司琼为内标,以 Kromasil CN 柱(2.1 mm×150mm,3.0μm)为分析柱;采用0.05%三氟乙酸乙腈溶液-0.05%三氟乙酸水溶液(80:20)为流动相;流速0.2 mL·min~(-1);柱温45℃。质谱条件为电喷雾电离源(ESI~ ),以选择反应离子监测(SRM)方式进行检测,用于定量分析的反应离子分别为 m/z208.1→146.1(米格列醇),m/z 313.1→138.0(盐酸格拉司琼)。结果:米格列醇在0.01～4.0μg·mL~(-1)浓度范围内线性良好;最低检测限为2.0 ng·mL~(-1)(S/N=4);日内、日间精密度(RSD)均小于7%;低、中、高3个浓度的方法回收率均大于90%。结论:本法专属性强,灵敏度高,样品处理简单,可用于米格列醇临床药物动力学研究。