青霉素配伍利多卡因后的药物动力学研究

本文报道青霉素配伍利多卡因后的药物动力学及生物利用度研究结果,证明利多卡因对青霉素的生物利用度无影响,且可促进青霉素的吸收,为良好的青霉素无痛溶媒,建议推广使用。     

对药代动力学实验的两点改进

通过具体的实验数据，讨论在药代动力学实验中如何加入曲线下面积（AUC）的计算，以帮助学生理解并掌握这一概念；在实验室设置不同剂量组，给药后比较剂量与浓度是否呈等比例关系，以此加深学生对于一级动力学消除及其临床意义的理解。     

薄层扫描法测定血浆中盐酸氟桂利嗪浓度及药物动力学

血浆中盐酸氟桂利嗪经硼酸缓冲液酸化后，正戊烷－异丙醇（９８：２）提取其原型，加酸使成盐溶于无机相中，再加碱后用二氯甲烷提取，样品点于硅胶ＧＦ２５４薄层板上，以环己烷－丙酮－氯仿（９：３：５）为展开剂。氟桂利嗪在２５４ｎｍ紫外灯下呈紫色斑点，Ｒｆ＝０．５４，于ＣＳ－９３０薄层扫描仪上测定，λｓ＝２１５ｎｍ、λｇ＝３１０ｎｍ，线性范围０．３￣８μｇ，平均回收率９０．０２％。用此法测定了氟桂利嗪血药浓度     

Oral administration of methylergometrine shows a late and unpredictable effect on the non-pregnant human menstruating uterus

Objective: To study the pharmacodynamic and pharmacokinetic properties of oral and intravenous methylergometrine upon uterine motility during menstruation. Study-design: Intra-uterine pressure was measured in six volunteers with a fluid-filled sponge-tipped catheter during menstruation. Methylergometrine was given orally (0.5 mg) or intravenously (0.2 mg) in a cross-over design. Results: After intravenous administration, a fast increase of the frequency of uterine contractions and basal tone occurred with a decrease of amplitude, lasting at least 30 min. Oral administration had a late and less marked effect on uterine motility. An intravenous dose administered 24 h after an oral dose had no effect on uterine motility. Pharmacokinetic data, such as the maximum plasma concentration (C_max), the time at which C_max is reached (t_max) and the half-life of absorption (t_1/2abs) also demonstrated large individual variations after oral administration. Conclusion: Oral administration of methylergometrine had an unpredictable and late effect on uterine motility on the menstruating uterus, probably due to an unpredictable bioavailability, in contrast with the fast and predictable effect after intravenous administration.     

高效液相色谱法测定右旋儿茶素血浆浓度及药代动力学参数

本文建立了体液中右旋儿茶素的RP-HPLC测定方法。采用C_(18)键合相硅胶为填料的固相提取柱进行样品预处理,右旋儿茶素的提取回收率为79.8%.应用二极管阵列检测器对色谱峰纯度进行鉴定。该法精密度好,方法回收率近100%,日内、日间的变异系数为2.4～5.6%,血浓69.6～1160 ng/ml范围内呈线性关系,r=0.9993。家兔静注右旋儿茶素18mg/kg,其药代动力学过程符合二室模型,分布相半衰期为0.129 h,消除相半衰期为1.19h。     

Quantitative and comparative study of haematoporphyrin-derived photosensitizers on a murine tumour model

Eight commercially available HPD-photosensitizers intended for photodynamic therapy were tested in a murine tumour model with regard to their therapeutic efficacy. The regrowth delay of the fibrosarcoma SSK-2 on the mouse C3H, Neuherberg-line, was determined 3, 24, 48 and 72 h after injection of the drugs (dose: 9 mg kg^–1 body weight). The corresponding pharmacodynamics, as measured by regrowth delay, were approximated by an exponential function and the characterizing coefficients derived. These coefficients served to quantify the photodynamic properties of the drugs.The pharmacodynamics of five substances were compared with those obtained fluorometrically. The latter showed shorter decay constants than the therapy-correlated substances which indicates different metabolic behaviour of the therapeutic and diagnostically useful fluorescent components of haematoporphyrin-derived photosensitizers.     

Pharmacokinetics of thiopental after single and multiple intravenous doses in critical care patients

Thiopental was administered to neurosurgical patients for cerebral protection and its pharmacokinetic parameters were determined after a single bolus of 540, 1000 or 1500 mg (3 subjects) or after multiple doses of 250 mg (5 subjects) and 500 mg (2 subjects) every two hours for up to 7 days. The data were analysed by a two- or three- compartment model and linear kinetics. After a single IV bolus, the mean initial volume of distribution (V1) was 0.4811·kg^–1, and the steady-state volume of distribution (V_ss) was 2.16 1·kg^–1. The distribution (t_1/2) and elimination (t_1/2) half-lives were 0.590 and 5.89 h, respectively, and the mean residence time (MRT) was 7.44 h. The clearance was 5.41 ml·min^–1·kg^–1. With repeated injections, the pharmacokinetic parameters for each patient were estimated taking into account all administered doses and blood samples, which were taken whenever possible daily at steady state and after the last dose. The variability observed in the pharmacokinetic parameters of thiopental reflected by the coefficient of variation (CV%) was wide but was of similar magnitude within patients (CV_intra) as it was between patients (CV_inter). The steady-state trough plasma concentration (C_min obs) ranged from 4.8 to 30 mg·1^–1 (mean 16.0 mg·1^–1 and median 14.3 mg·1^–1). Peak concentrations (C_max obs) ranged from 8.35 to 45 mg·1^–1 (25.4 mg·1^–1, and median 23.3 mg·1^–1). The values of V1 and V_ss were similar to those obtained after a single dose. For V1, the mean was 0.333 1·kg^–1. The mean V_ss was 2.68 1·kg^–1, with a CV_intra of 12.6 to 56% and a CV_inter of 13.2%. A shorter distribution half-life t_1/2 was noted on multiple dosing; the mean value was 0.122 h. The elimination half-life t_1/2 and the mean residence time became longer due to a decrease in clearance. For t_1/2 the mean value was 16.3 h. The mean MRT was 21.9 h, CV_intra 9.19 to 48.5%, and the CV_inter 35.3%. The mean clearance was 2.16 ml·min^–1·kg^–1, CV_intra 7.28 to 25.5%, and the CV_inter 20.4%. This value is 50% lower than after a single dose.Identification of the kinetic parameters of thiopental allows simulation of the effects of doses on subsequent plasma levels and will permit a priori prediction of day to day adjustment of drug dosage.     

普拉西坦在动物体内的药物代谢动力学

为研究普拉西坦在犬和大鼠体内药代动力学规律,给犬灌服普拉西坦后,抽取不同时间的血液,分离血浆,用ＨＰＬＣ测定血浆中药物浓度,采用３ｐ８７ 程序计算药代参数;应用ＨＰＬＣ测定大鼠灌服普拉西坦后各组织和胆汁、尿、粪中药物浓度。结果显示：血药浓度－时间曲线符合一室开放模型,其体内的Ｔ１／２为２．３～３．９ 小时;大鼠灌服普拉西坦后３ 小时各组织中有较高的浓度,以肾脏为最高,肝脏次之,依序为肠、肺、肌、心、生殖腺、脾、脂肪;脑组织也能测到一定的量。２４小时从胆汁排泄原形药物占给药量的０．７％ ,７２小时从尿和粪中排出原形药物量分别占给药量的２８．２６％ 和６．３５％ 。用平衡透析法测定普拉西坦的血浆蛋白结合率约为２０．１％ ～２２．２％ 。以上结果表明,普拉西坦吸收快,分布广,消除也快。     

Pharmacokinetic aspects of rectal formulations of Temazepam

An in vitro/in vivo study was carried out with different rectal formulations of temazepam. Pharmacokinetic data were determined in a cross-over study in 10 volunteers after rectal administration of 10 mg temazepam as a polyethylene glycol based suppository (selected from in vitro data), a liquid-filled capsule and a micro-enema respectively, using oral administration of a liquid-filled capsule as a reference. Serum levels of temazepam indicate an instantaneous and complete release from the micro-enema (F_rel=0.94±0.21, C_max 205±36.9 g/l, t_max 0.49±0.31 hour) and a slower but complete release of temazepam from the suppository (F_rel=1.01±0.25, C_max 202±41.3 g/l, t_max 1.48±0.41 hour). A high interindividual variation in absorption profiles was observed after rectal administration of the liquid-filled capsule (F_rel 0.72±0.36, C_max 182±122 g/l, t_max 4.08±4.28 hour), which makes it less suitable for rectal use. The micro-enema and suppository appear to be useful as rectal formulations for temazepam.