Pharmacokinetics of methimazole in humans

Summary A newly developed method for extracting and measuring methimazole in biological fluids was used to study the pharmacokinetics of methimazole in two euthyroid and eight hyperthyroid subjects. The volume of distribution approximated total body water; the biological half-life was 2–3 h in euthyroid and about 6 h in hyperthyroid patients. Total clearance was lower in hyperthyroid patients than in euthyroid subjects, and it did not increase after thyroid function was normalized. Bioavailability in euthyroid subjects was greater than 1 but only 0.5 in hyperthyroid subjects. The reasons for these observed differences are not known.Abbreviations AUC area under the serum concentration — time curve - HCl hydrochloric acid - HPLC high pressure liquid chromatography - M molar - ml/min milliliter per minute - N normal - NaOH aqueous sodium hydroxide - ng/ml nanogram per milliliter Dedicated to Professor Hans J. Dengler on the occasion of his 60th birthday     

Plasma concentrations of intravenous β-methyl digoxin with and without oral charcoal

Summary Six healty male volunteers received 1.0 mg of -methyl digoxin intravenously two times at a 21 day interval. In a randomized sequence they received orally 2 g t.i.d. of activated charcoal during one of the periods. Glycoside plasma levels were determined over a 48 hour period using a⁸⁶Rb-erythrocyte-assay. During the period with charcoal, plasma levels were somewhat lower, the difference was statistically not significant. The clinical relevance of the observation remains uncertain.     

Kinetics of elimination of thiocyanate in 7 healthy subjects and in 8 subjects with renal failure

Summary The concentration of thiocyanate in the serum of eight test subjects with renal failure and seven healthy control subjects was measured, as it declined with time, after oral doses of thiocyanate or i.v. injections of nitroprusside had been administered. Additional measurements were taken, on the healthy subjects only, of the concentrations of thiocyanate in the urine, and also of the influence of an increased chloride intake on the rate of elimination of thiocyanate. For the healthy subjects an elimination half-life of between one and five days (mean c. 3 days) was found. Increasing the chloride elimination rate to approximately twice normal did not significantly speed up the rate of thiocyanate elimination. The amounts of thiocyanate which had been administered as doses reappeared almost exclusively in the urine. For the subjects with renal failure, the elimination half-life had a mean value of approximately nine days. The elimination constants were found to be proportional to the creatinine-clearance rates. Thek _e value at a creatinine-clearance of zero ml/min was approximately 15% of thek _e value at a creatinine-clearance rate of 120 ml/min. The distribution volumes for thiocyanate were greater for the patients with renal failure than for the healthy subjects. The conclusions for therapies using nitroprusside are discussed.     

盐酸格拉司琼透皮贴剂在Beagle犬中多剂量给药的药代动力学研究

目的建立盐酸格拉司琼透皮贴剂在Beagle犬中的血药浓度测定方法,通过Beagle犬多剂量给药,揭示盐酸格拉司琼透皮贴剂在Beagle犬体内的药代动力学变化规律,阐明其在Beagle犬体内的药代动力学特征,提供重要的动力学参数。方法 Beagle犬给予盐酸格拉司琼透皮贴剂6次,每次贴片持续72 h,每次撤药和下次给药间隔24 h。用建立的HPLC-MS/MS法测定血浆中的格拉司琼的浓度,根据所得的血浆药物浓度-时间曲线,计算药动学参数。结果第1次给药和第6次给药后的谷浓度Cmin分别0.0459 ng/m L和0.2593 ng/m L,峰浓度Cmax分别为0.4637 ng/m L和1.3428 ng/m L,AUC0~96分别为18.92 h·ng/m L和40.21 h·ng/m L,第1次给药和第6次给药后的Tmax分别为48.3 h和45.3 h,MRT0-96分别为48.9 h和45.84 h。结论多次给药后格拉司琼在体内存在一定的蓄积效应,并在多次给药后第16天到达稳态。     

吗啡镇痛个体差异的遗传药理学进展

吗啡是广泛使用的一种阿片类镇痛药,不同个体间对吗啡镇痛的敏感性有较大差异,长期使用吗啡会导致镇痛效果降低而产生耐受,耐受的易感性在个体间也有较大差异,这些都给吗啡在临床的优化应用带来很多困扰。遗传因素通过控制蛋白质编码从药代动力学和药效动力学两方面影响个体对吗啡镇痛的反应。P-糖蛋白编码基因ABCB1的多样性影响吗啡的转运和分布,编码UDP-葡糖醛酸转移酶的基因UGT2B7的多样性则控制吗啡代谢转化。吗啡的主要作用靶点μ阿片受体的编码基因OPRM1和儿茶酚-O-甲基转移酶的编码基因COMT的多样性引起的下游信号通路反应性差异影响吗啡镇痛药效学。未来对吗啡镇痛个体差异的遗传学研究需要使用遗传多样性更复杂的个体,采用更系统全面的分析方法从更广的范围筛选关键基因。阐明遗传多样性与个体间对吗啡镇痛反应差异的关系,将有助于理解吗啡镇痛的遗传药理学调控机制,为临床吗啡镇痛使用实现个人化、精确化甚至联合基因治疗改善吗啡镇痛提供依据。     

Cyclodextrins in Parenteral Formulations

Most drugs have very limited solubility in water and some can be extremely difficult to formulate as parenteral solutions where the dose should preferably be dissolved in couple of ml of aqueous media without use of organic solvents and surface active agents, or application of somewhat extreme techniques such as prodrug formation. Thus, pharmaceutical formulators are constantly looking for new, biologically acceptable, and low-cost armamentarium for parenteral formulation development. Cyclodextrins (CDs) are enabling pharmaceutical excipients that can temporarily camouflage undesirable physiochemical drug properties such as low aqueous solubility through formation of drug/CD inclusion complexes. CDs are cyclic oligosaccharides that have similar physiological and biological properties like linear saccharides of comparable molecular weight. Due to their very favorable toxicological and pharmacokinetic profiles their usage in parenteral drug formulations is frequently preferred over other solubilizing techniques. Here the physiochemical and biological properties of CDs are reviewed as well as their pharmacokinetics after intravenous administration. Their regulatory status is briefly reviewed and their tendency to self-assemble to form clusters or aggregates discussed. Finally, some examples are given of how CDs are applied in aqueous parenteral formulations, how their solubilizing effect has been enhanced and how their target concentration is determined.     

雷贝拉唑对不同CYP2C19基因型健康志愿者体内氯吡格雷及其活性代谢物药动学的影响

目的:探讨雷贝拉唑对不同CYP2C19代谢型健康志愿者体内氯吡格雷及其活性代谢物药动学特征的影响。方法:选择健康志愿者为对象,根据其CYP2C19基因型按随机数字表法挑选快代谢型、中间代谢型和慢代谢型受试者各8例分组,采用单剂量、随机、开放、两周期的交叉试验设计,各组患者在试验周期内分别单次口服硫酸氢氯吡格雷片300 mg或硫酸氢氯吡格雷片300 mg+雷贝拉唑钠肠溶片20 mg,清洗期为7天。采用超高效液相色谱-串联质谱法检测受试者血浆中氯吡格雷及活性代谢产物H4(MP-H4)的质量浓度,通过DAS 2.0软件计算药动学参数并比较。结果:3种代谢型受试者年龄、身高、体质量、肝酶、血肌酐等一般临床资料比较,差异均无统计学意义(P>0.05)。与单用氯吡格雷者比较,联用雷贝拉唑的快代谢型组受试者体内氯吡格雷的达峰浓度(c_max)和药-时曲线下面积(AUC_0-t)分别上升了36%和27%,MP-H4的c_max和AUC0_0-t分别下降了34%和28%(P<0.01);中间代谢型受试者氯吡格雷的c_max和AUC0_0-t分别上升了19%和18%,MP-H4的c_max和AUC0_0-t分别下降了19%和16%(P<0.05或P<0.01);而慢代谢型受试者联用雷贝拉唑后体内氯吡格雷及MP-H4的c_max、AUC0_0-t以及各代谢型受试者体内氯吡格雷及MP-H4的tmax与单用氯吡格雷者比较,差异均无统计学意义(P>0.05)。结论:在CYP2C19快代谢型和中间代谢型受试者中,联用雷贝拉唑可明显增加氯吡格雷的暴露量并降低其活性代谢产物MP-H4的暴露量;而这种联用对CYP2C19慢代谢型受试者体内氯吡格雷及其活性代谢产物的影响并不显著。     

LC-MS/MS法测定布洛芬颗粒剂的人体生物等效性研究

目的研究布洛芬颗粒在健康人体内的药动学及其生物利用度,以评价其与布洛芬混悬液的生物等效性。方法 23例健康男性志愿受试者,采用随机、开放、单剂量、双周期自身交叉试验设计。分别口服布洛芬颗粒(受试制剂)与布洛芬混悬液(参比制剂)后,采用液相色谱-串联质谱(LC-MS/MS)法测定血浆中布洛芬的药物浓度。结果受试制剂与参比制剂的Cmax分别为(17.438 6±5.304 0)、(18.557 7±4.641 7)mg/L,AUC0-24分别为(59.000 3±13.935 3)、(58.506 4±16.720 2)mg/(h·L),AUC0-∞分别为(59.718 0±14.020 0)、(59.227 8±16.815 8)mg/(h·L),Tmax分别为(1.478 3±0.922 9)、(1.021 7±0.822 0)h。结论空腹口服布洛芬颗粒受试制剂与参比制剂具有生物等效性。     

Comparison of pharmacokinetics and drug release in tissues after transarterial chemoembolization with doxorubicin using diverse lipiodol emulsions and CalliSpheres Beads in rabbit livers

CalliSpheres^® Beads (CB) is the first drug-eluting bead (DEB) product in China. Our aim was to compare the effect on the pharmacokinetics of doxorubicin (DOX) and its local concentration between lipiodol emulsions and CB in the process of TACE in rabbit livers. Twenty-five rabbits were distributed into two groups; Group 1 received lipiodol emulsions with DOX, and Group 2 received CB loaded with DOX (CBDOX). DOX was measured in the peripheral blood at different times after treatment. Livers were sampled at 1 week and 1 month for Group 2 after embolization. DOX concentration and distribution were measured in the liver. The administration of DOX by TACE with CBDOX resulted in peripheral blood DOX concentrations of 39.85?±?13.86?ng/mL at 5?min, with a gradual decrease to 6.89?±?1.62?ng/mL at 24?h, after treatment. Plasma concentration of DOX after chemoembolization with lipiodol was 225.91?±?64.88?ng/mL at 5?min and decreased with time by 24?h to 5.06?±?0.48?ng/mL. In CBDOX group, the drug impregnated an area as far as 200?μm from the bead edge. The tissue concentration of doxorubicin (tissC_DOX) ranged from 40.27?μg/mL to 245.70?μg/mL at 1 week and from 5.64?μg/mL to 28.09?μg/mL at 1 month. Plasma concentrations of DOX resulting from CBDOX embolization were significantly lower than that for cTACE. CB could deliver relatively high concentrations of DOX to an area as far as 200?μm from the bead edge for at least 1 month.