高效液相色谱法测定生长抑素含量及有关物质

目的建立高效液相色谱测定生长抑素含量的方法。方法采用Ominispher C18柱(250 mm×4.6 mm,5μm),流动相A:0.1%TFA水溶液,流动相B:0.1%TFA乙腈溶液,采用梯度洗脱,检测波长:215 nm,流速1.0 mL.min-1。结果方法的线性范围为40~140μg.mL-1。r=0.999 9,平均回收率100.3%,最低检测限为1 ng。结论采用HPLC梯度洗脱法测定生长抑素的含量,分离度好,方法简便,适用于生长抑素的含量测定。     

HPLC法测定红曲霉发酵液中洛伐他汀含量

目的建立测定红曲霉发酵液中洛伐他汀含量的方法。方法采用HPLC法,以甲醇作溶剂、摇床振荡(150 r/min)3 h提取洛伐他汀,色谱条件:以甲醇-18 mmol/L磷酸溶液(体积比为80∶20)为流动相,流速为1.0 mL/min,检测波长为237 nm。结果洛伐他汀在5~50μg/mL质量浓度范围内与峰面积线性关系良好,加样平均回收率为100.75%,RSD为0.87%。结论本方法简便有效,重复性好,可作为红曲霉相关产品的质量控制方法。     

洛伐烟酸缓释片的制备及释放度研究

目的：制备3种规格（分别含烟酸500、7501、000 mg）的洛伐烟酸缓释片并对其释放度进行评价。方法：以紫外分光光度法测定片芯中烟酸的释放度,考察不同黏度的羟丙基甲基纤维素（HPMC）对片芯中烟酸释放度的影响;设计2因素3水平正交试验,对释放数据进行多元逐步回归和方差分析,计算不同规格的洛伐烟酸缓释片中HPMC的理论用量;并测定3种规格的洛伐烟酸缓释片的释放度,采用相似因子法对试制品与国外上市品释放度进行比较。结果：确定了以HPMCK15M CR为骨架材料,统计分析得到3种规格的洛伐烟酸缓释片中HPMC的理论用量与实际用量接近;其烟酸释放均符合零级释放模型;试制品与国外上市品累积释放度相似。结论：研制的缓释片缓释效果较好,工艺简单。     

Pharmacokinetics of lovastatin extended-release dosage form (Lovastatin XL) in healthy volunteers

The purpose of this study was to evaluate pharmacokinetics and dose proportionality of lovastatin extended-release dosage form (ER-lovastatin) in the dosage levels of 10, 20 and 40 mg in 9 healthy male subjects. Each subject was randomized to receive a single oral dose of ER-lovastatin either 10, 20 or 40 mg in a three-way crossover design with a washout period of 7 days between the treatments. Subjects were served dinner at approximately 5:30 PM followed by dosing at approximately 10:00 PM in each study period. Serial plasma samples were collected up to 48 h after dosing and assayed for lovastatin and its active metabolite lovastatin acid using an LC/MS/MS method. The plasma concentration-time profiles of lovastatin and its active metabolite lovastatin acid exhibited delayed- and extended-release characteristics at each dose. Mean (+/-) values for the C(max) of lovastatin were 1.04+/-0.43, 2.03+/-0.65 and 4.03+/-3.02 ng/ml for the 10, 20 and 40 mg dosage, respectively. The corresponding values for the AUC(0-48 h) of lovastatin were 14.6+/-7.8, 34.1 +/-13.7, and 53.9+/-35.6 ng h/ml. The same tendency was also found for C(max) and AUC(0-48 h) values of lovastatin acid. Results from this study demonstrated as the dose of ER-lovastatin increased from 10 to 40 mg, the C(max) and AUC(0-48 h) values of lovastatin as well as lovastatin acid appeared to increase linearly.     

Alterations in membrane-bound and cytoplasmic K-ras protein levels in mouse lung induced by treatment with lovastatin,cholestyramine, or niacin: effects are highly mouse strain dependent

Agents that either increase (cholestyramine, CS) or decrease (lovastatin, Lov) de novo peripheral cholesterol synthesis may increase (CS) or decrease (Lov) ras protein membrane localization by altering protein prenylation, and potentially have pro- or anti-carcinogenic effects. Male A/J, Swiss, and C57/BL6 mice were treated with 2 or 4% CS, 1% dietary niacin, or 25mg/kg of Lov three times per week (Lov-3X) or five times per week (Lov-5X). After 3 weeks, serum cholesterol and triglycerides were determined enzymatically. Membrane and cytoplasmic K-ras proteins in lung were determined by immunoprecipitation followed by western blotting with a K-ras specific antibody. Results confirmed the hypothesis only in isolated instances. A/J mice had a significant 30% increase in cytoplasmic K-ras and a 40% decrease in membrane K-ras from Lov treatment, as predicted. C57/BL6 mice had a significant 77% increase in membrane K-ras, as expected from CS feeding. At variance with the hypothesis, Swiss mice had increased levels (3-28%) of membrane K-ras with all treatments (including Lov), and C57/BL6 mice treated with Lov had a 58-78% increase in cytoplasmic K-ras without any reduction in the levels of membrane K-ras. Niacin, predicted to have no effect on ras membrane localization, decreased cytoplasmic K-ras in A/J mice, increased both membrane and cytoplasmic K-ras in Swiss mice, and had no effect in C57/BL6 mice. Results may have differed from those predicted because of strain-dependent differences in response to the cholesterol-lowering agents. A difference in response among the mouse strains suggests that individual genetic differences may alter the effect of hypocholesterolemic agents on K-ras membrane localization, and potentially the risk of ras-dependent cancer.     

Lovastatin is a Potent Inhibitor of Meningioma Cell Proliferation: Evidence for Inhibition of a Mitogen Associated Protein Kinase

Lovastatin inhibits 3-hydroxy 3-methylglutaryl coenzyme A (HMG-CoA) reductase the rate limiting enzyme for synthesis of mevalonic acid, a precursor for cholesterol, farnesyl and geranylgeranyl pyrophosphate isoprenoids. Recent studies suggest it also has growth inhibitory properties. Posttranslational farnesyl or geranylgeranylation of low molecular weight GTP-binding proteins such as RAS and RHO are thought to be an essential step in activation of phosphorylation cascades such as the RAS–RAF-1–MEK-1–MAPK/ERK pathway which stimulate cell proliferation. In this study, we evaluated lovastatin effects on meningioma cell proliferation and activation of the MEK-1–MAPK/ERK pathway.The effect of lovastatin on cell proliferation was assessed in eight human meningioma cell cultures stimulated by platelet derived growth factor (PDGF)-BB, cerebrospinal fluid (CSF), and fetal bovine serum (FBS). Concomitant lovastatin effects on phosphorylation/activation of mitogen-activated protein kinase/extracellular signal regulated kinase (MAPK/ERK) kinase (MEK-1) and MAPK/ERK were assessed by Western blot. Whether lovastatin acts via a mevalonate-dependent mechanism was also evaluated.Coadministration of lovastatin completely blocked PDGF-BB, CSF, and FBS stimulation of [³H]-thymidine incorporation and cell proliferation. Lovastatin inhibited PDGF-BB's stimulatory effect in a dose dependent manner. Concomitant with its growth inhibitory effects, lovastatin reduced phosphorylation/activation of MEK-1/2 in five meningiomas and MAPK/ERK in seven. Coadministration of mevalonate with lovastatin partially restored PDGF's mitogenic effect.Lovastatin is a potent inhibitor of meningioma cell proliferation which may act in part by reducing activation of MEK-1–MAPK/ERK pathway. Additional studies are warranted to assess whether lovastatin and similar HMG-CoA reductase inhibitors represent a new adjunctive chemotherapy for recurrent meningiomas.     

应用HPLC-MS法检测洛伐他汀血药浓度及其生物利用度

目的建立人血浆中洛伐他汀的HPLC-ESI -MS测定法,以测定志愿者口服洛伐他汀胶囊(20 mg/粒)后的血药浓度,并对受试制剂和参比制剂的生物等效性进行评价。方法 20名健康志愿者交叉口服供试胶囊和参比胶囊,剂量均为40mg。采用HPLC-ESI-MS法测定人血浆中洛伐他汀浓度。采用BAPP2·0软件计算主要药动学参数及相对生物利用度。结果在0·5 ~30 ng·mL-1范围内,洛伐他汀和内标辛伐他汀的峰面积比值与浓度线性关系良好,最低定量限为0·5 ng·mL-1。受试制剂及参比制剂的t1/2分别为(6·02 ±1·67) h和(5·63 ±1·00) h ,Tmax分别为(2·8 ±0·5)和(2·7 ±0·4) h ,Cmax分别为(14·58 ±4·55)和(14·38 ±4·51) ng·mL-1。以AUC0 -24计算的受试制剂的相对生物利用度为(95·9 ±14·4) %。结论本实验建立的人血浆中洛伐他汀HPLC -MS分析方法简便,且灵敏、准确。统计学结果表明两种洛伐他汀制剂生物等效。     

洛伐他汀烟酸缓释片在比格犬体内的药代动力学

目的研究洛伐他汀烟酸缓释片在Beagle犬体内的药动学变化。方法6只Beagle犬采用两周期随机交叉实验设计,口服500mg洛伐他汀烟酸缓释片或烟酸片,采用反相高效液相色谱法(RP-HPLC)内标定量法测定烟酸血药浓度及药代动力学参数。结果Beagle犬口服给予洛伐他汀烟酸缓释片和烟酸片后,两者在犬体内的代谢均表现为一室模型,主要药动学参数:T12(Ke)64.99min vs.106.09min,T(peak)75.67min vs.112.20min,C(max)52.95μg.ml-1vs.28.50μg.ml-1,AUC 10831.10 vs.9086.42μg.ml-1。结论RP-HPLC内标定量测定烟酸,该方法操作简便、准确灵敏、重现性好,可用于烟酸在体内的药动学研究。单剂量口服洛伐他汀烟酸缓释片后测得的T12(Ke)、T(peak)和C(max)与烟酸组相比,差异性显著;AUC基本一致。缓释片的T12(Ke)、T(peak)明显长于烟酸片,Cmax低于烟酸片,这表明我们制备的复方洛伐他汀烟酸缓释片在Beagle犬体内具有缓释作用,相对生物利用度基本一致。     

Lovastatin stimulates up-regulation of alpha7 nicotinic receptors in cultured neurons without cholesterol dependency, a mechanism involving production of the alpha-form of secreted amyloid precursor protein

The cholesterol-lowering drug lovastatin enhances the secretion of the alpha-secretase cleavage product of amyloid precursor protein (APP). To investigate whether this effect is mediated via activation of alpha7 nicotinic acetylcholine receptors (nAChRs), we treated SH-SY5Y cells and PC12 cells with lovastatin and measured the levels of alpha7 nAChRs, the alpha-form of secreted APP (alphaAPPs), and lovastatin-related lipids, including cholesterol and ubiquinone. The results showed that low concentrations of lovastatin significantly induced up-regulation of alpha7 nAChRs. No effects of lovastatin were observed on alpha3-containing nAChRs, muscarinic receptors, or N-methyl-D-aspartate receptors. alphaAPPs levels increased in the culture medium of cells treated with lovastatin, whereas no change in whole APP was observed. The increase in alphaAPPs was inhibited by prior exposure of these cells to alpha-bungarotoxin, an antagonist of alpha7 nAChRs. The concentrations of lovastatin used in the study did not change the cholesterol content, but high doses can decrease the levels of ubiquinone and cell viability. These results indicate that lovastatin may play a neuronal role that is cholesterol independent. We also show that the up-regulation of alpha7 nAChRs stimulated by lovastatin is involved in a mechanism that enhances production of alphaAPPs during APP processing.