粉防己碱在小鼠药时曲线中的双峰现象

目的:观察粉防己碱以不同方式给药后在小鼠体内血药浓度的变化.方法:采取灌胃和外敷两种给药方式,高效液相色谱法测定不同时项点的血药浓度.结果:两种给药途径药时曲线均呈双峰.结论:粉防己碱的异常分布可能是造成双峰形成的原因.     

加替沙星在人体内的药动学和血药浓度测定

目的:用HPLC-紫外法测定人体内加替沙星的血药浓度和药动学.方法:用HPLC-紫外法测定加替沙星的血药浓度,10名男性受试者口服单剂量400 mg加替沙星片后,研究人体内药动学.结果:HPLC-紫外法测定检测波长293 nm,血浆标准曲线回归方程:Y=0.590C 0.061,r=0.9998.检测浓度范围:0.057～5.22 mg·L-1,相对回收率在97.12%～102.56%之间,日内、日间RSD均在15%以内.10名男性受试者口服单剂量400 mg加替沙星,药时曲线符合二房室模型,主要药动学参数Tmax为1.97 h,Cmax为3.01 mg·L-1,t1/2(β)为9.83 h,AUC为28.77 mg·h·L-1,与国外文献基本一致.结论:HPLC-紫外法测定加替沙星血药浓度,操作简便易行,重现性好,符合血药浓度监测及人体内药动学研究要求.     

Variability in cimetidine absorption and plasma double peaks following oral administration in the fasted state in humans: correlation with antral gastric motility.

The role of gastrointestinal motility and pH in determining cimetidine bioavailability as well as double peaks in plasma profiles following oral administration, in the quiescent or active phase of antral motility, to humans in the fasted state was examined. Plasma cimetidine-time curves did not show the presence of double peaks in any subject following intravenous administration. The incidence of double peaks was 73% following oral administration and was independent of antral migrating motility complex phase. Further, it was found that oral administration of cimetidine in the quiescent phase resulted in significantly higher bioavailability and in other pharmacokinetic parameters compared to that obtained following administration in the active phase. Excellent linearity in plots of motility peaks vs. plasma peaks with slopes close to unity were evident for both quiescent (r(2)=0.93) and active phase (r(2)=0.97) administration. A total of 14 peaks out of 22 (10 subjects, 64%) and 20 out of 27 peaks (11 subjects, 74%), were accounted for in quiescent and active phase oral administration, respectively. The proximal occurrence of plasma peaks to antral motility peaks typical of phase III contractions strongly implies that motility patterns may be responsible for secondary maxima following oral cimetidine administration in the fasted state.     

Pharmacokinetics of pemoline in plasma, saliva and urine following oral administration.

1 Pemoline concentrations were measured in plasma and saliva following a single oral dose (37.5 or 50.0 mg) to healthy volunteers. In addition urinary excretion rates and cumulative urinary excretion of the parent compound and its oxazolidinedione metabolite were determined. 2 The plasma curves exhibited a mean elimination half-live of 11.0 +/- 1.2 h (n=4). Peak levels were reached at 2.7 +/- 0.6 h (n=4). The saliva concentrations were about 50% lower than the corresponding plasma concentrations during the elimination phase. During the absorption phase irregularities in the saliva to plasma concentration ratios were observed. 3 In urine 47.0 +/- 8.4% of the dose (n=6) administered was excreted as unchanged drug and only 3.7 +/- 0.8% (n=3) as the oxazolidinedione metabolite. Urinary half-lives were slightly shorter than the corresponding plasma half-lives.     

盐酸依匹斯汀片在健康人体的药代动力学和相对生物利用度

目的研究国产和进口盐酸依匹斯汀片(抗组胺药)在健康人体的药代动力学和相对生物利用度,并进行生物等效性评价。方法20名男性健康志愿者随机交叉单剂量口服国产和进口盐酸依匹斯汀片40mg后,用反相高效液相色谱法测定血浆盐酸依匹斯汀浓度,用DAS软件计算其药代动力学参数。结果2种制剂在人体的药时曲线均符合二室开放模型,主要药代动力学参数:t1/2分别为(10.12±1.28)和(10.43±2.44)h;tmax分别为(2.18±0.47)和(2.03±0.41)h;Cmax分别为(65.90±16.45)和(68.17±13.25)μg·L-1;AUC0-36分别为(591.63±88.22)和(600.90±93.74)μg·L-1.h;AUC0-∞分别为(647.04±101.58)和(657.96±87.56)μg·L-1.h。与进口制剂比较,国产制剂的相对生物利用度F0-36为(99.40±12.77)%;F0-36为(98.85±13.72)%。结论国产和进口制剂具有生物等效性。     

Acebutolol metabolite plasma concentration during chronic oral therapy.

1 We have measured the plasma concentration of acebutolol and a major metabolite in patients on chronic oral therapy with this drug, using a new assay, specific for each species. Our study suggests: 2 The acetyl metabolite was present in concentrations greater than those of acebutolol at all times during the dosing interval in all seven subjects. 3 The ratio of the mean steady-state plasma concentrations of the acetyl metabolite to unchanged acebutolol was 2.7 +/- 1.0. 4 Previous studies using non-specific methods that measure plasma concentrations of the acetyl metabolite and acebutolol as a single species cannot be used to determine pharmacokinetic parameters or to provide reliable correlations of plasma drug concentration with effect. 5 Future studies determining plasma concentration of acebutolol should take this metabolite into account. 6 Further work will be necessary to determine the metabolite's contribution to acebutolol's effects in man.     

唾液和血浆中10-羟基卡马西平的药动学及其浓度的相关性研究

目的:考察唾液与血浆中10-羟基卡马西平的药动学及其浓度的相关性。方法:20名志愿者禁食1晚后,服用奥卡西平600mg,在96h内同步收集血液和静息唾液样本,用已建立的高效液相色谱方法对10-羟基卡马西平进行分析。结果:唾液和血浆中10-羟基卡马西平的AUC_(0～∞)分别为(162±s 86)和(186±27)mg·h·L~(-1)。c_(m(?))分别为(8．1±1．4)和(7．2±1．3)mg·L~(-1),t_(max)分别为(4．7±2．7)和(5．4±1．5)h,t_(1/2)为(11．1±2．5)和(10．2±1．7)h,MRT_(0～(相似文献   

LC/MS/MS quantitation assay for pharmacokinetics of naringenin and double peaks phenomenon in rats plasma

A highly sensitive and specific electrospray ionization (ESI) liquid chromatography-tandem mass spectrometry (LC/MS/MS) method for quantitation of naringenin (NAR) and an explanation for the double peaks phenomenon was developed and validated. NAR was extracted from rat plasma and tissues along with the internal standard (IS), hesperidin, with ethyl acetate. The analytes were analyzed in the multiple-reaction-monitoring (MRM) mode as the precursor/product ion pair of m/z 273.4/151.3 for NAR and m/z 611.5/303.3 for the IS. The assay was linear over the concentration range of 5-2500 ng/mL. The lower limit quantification was 5 ng/mL, available for plasma pharmacokinetics of NAR in rats. Accuracy in within- and between-run precisions showed good reproducibility. When NAR was administered orally, only little and predominantly its glucuronidation were into circulation in the plasma. There existed double peaks phenomenon in plasma concentration-time curve leading to the relatively slow elimination of NAR in plasma. The results showed that there was a linear relationship between the AUC of total NAR and dosages. And the double peaks are mainly due to enterohepatic circulation.     

Multiple plasma peaks of acetaminophen and ranitidine after simultaneous oral administration to rats

Acetaminophen (AAP) and ranitidine (RT) were coadministered orally to nine rats, and the possible contribution of the gastric emptying to the plasma concentration profiles of them was examined. The drugs showed multiple plasma peaks similar to the respective ones after separated administration of each durg. It implies that there is no significant interaction between AAP and RT in terms of the gastric emptying or drug absorption. There were no significant linear correlations of the peak patterns (peak height and peak time) between AAP andd RT. It is contrary to the expectation from the biphasic gastric emptying (BGE) theory previously suggested for AAP and RT. The BGE theory, therefore, seemed to have some draw-backs in explaining satisfactorily the multiple plasma peaks of AAP and RT. Two more doubts raised previously against the BGE theory were also discussed.     

A GLC method for estimation of chlorophenoxyisobutyric acid in plasma. Pharmacokinetics of a single oral dose of clofibrate in man

Summary A GLC method has been developed to measure chlorophenoxyisobutyric acid in plasma after benzol extraction and transformation to its methyl ester, using methyl laurate as the internal standard. Plasma free fatty acids did not interfere with the analysis, but it could not be employed in the presence of salicylates. The method has been employed to study the pharmacokinetics of chlorophenoxyisobutyric acid in man after oral ingestion of a single dose of clofibrate.     

Pharmacokinetics of reboxetine in healthy volunteers. Single oral doses,linearity and plasma protein binding

The pharmacokinetics of reboxetine, a new antidepressant agent, were found to be close to linear in a crossover study comparing administration of single 2, 3, 4 and 5 mg capsule doses in 15 healthy male volunteers, and in the same study the capsules were bioequivalent to the proposed therapeutic tablet formulation (4mg). Kinetic analysis was based on HPLC assay of reboxetine in plasma and urine collected up to 72 h after each administration. Plasma levels indicated a rapid absorption (t_max?2h) and an elimination half-life of about 13 h. Clearance and volume of distribution were modest (ratios to bioavailability: CL/F?29 mL min^?1; V_z/F?32L); urinary excretion was ～9% of dose, corresponding to a renal clearance of only 3 mL min^?1 (a value consistent with the rate of glomerular filtration of unbound drug). In vitro, binding to plasma proteins, estimated from radioactivity levels following dialysis of ¹⁴C-labelled reboxetine, appeared to be dominated by α₁-acid glycoprotein without marked saturation up to plasma concentrations of over 500 ng mL^?1 (2.8–3.1% unbound with human plasma from three additional volunteers; 1.8–2.0% for 2gL^?1 orosomucoid α₁-acid glycoprotein, and 46.4–47.4% for 40 gL^?1 albumin), whilst the mean C_max in the current study was much lower (164 ng mL^?1 after a 5 mg dose).     

Pharmacokinetics of intravenous and oral prednisolone.

1 Doses of 16, 32, 48 and 64 mg prednisolone were administered intravenously to normal volunteers who also received 100 prednisolone orally. Plasma prednisolone concentrations were estimated by quantitative thin layer chromatography. 2 The bioavailability fraction was 1.063 +/- 0.154 (s.d.) indicating complete availability of prednisolone following oral administration. 3 The mean T 1/2 over all doses were 4.11 +/- 0.97 (s.d.) h and there was no evidence of a dose-related change in its value. 4 The mean systemic clearance over all doses was 0.104 +/- 0.034 (s.d) 1 h-1 kg-1. There was no evidence of a dose-related change in clearance or in the apparent volume of distribution (overall mean 0.588 +/- 0.152 1 kg-1). 5 The area under the plasma concentration-time curve was linearly related to dose. 6 Plasma concentration-time curves normalised for dose were superimposable. 7 It was concluded that over the dose range investigated, non-linear pharmacokinetic behaviour had not been demonstrated in this group of normal volunteers.     

Pharmacokinetics of dipipanone after a single oral dose.

A single oral dose of Diconal (dipipanone HCl 10 mg, cyclizine HCl 30 mg) was given to six volunteers. The mean peak plasma dipipanone concentration was 29 ng ml-1, the time to peak plasma concentration was 1-2 h, the mean elimination half-life was 3.5 h and the mean AUC was 156 ng ml-1 min. Less than 1% of the dose was excreted in urine unchanged over 24 h.     

A double absorption-phase model adequately describes mycophenolic acid plasma profiles in de novo renal transplant recipients given oral mycophenolate mofetil

BACKGROUND: Mycophenolic acid (MPA) shows complex plasma concentration-time profiles, particularly in the immediate (first month) post-transplantation phase for which no relevant pharmacokinetic model has been proposed thus far. OBJECTIVE: The aim of this study was to develop a model to accurately describe the time profile of plasma MPA concentrations after oral administration of mycophenolate mofetil in adult kidney transplant patients, in any post-transplantation period. METHOD: Full interdose pharmacokinetic profiles were collected in 45 adult renal transplant patients who were orally administered mycophenolate mofetil and ciclosporin; 25 patients were de novo transplant patients for whom individual pharmacokinetics were assessed at three post-transplantation periods (days 3, 7 and 30) and 20 patients were stable transplant patients (>3 months post-transplantation). MPA was determined in plasma by liquid chromatography-mass spectrometry. Models combining a single- or double-input (described as single or double gamma distributions) with one- or two-compartments were developed using in-house software and fitted to the individual profiles by nonlinear regression. RESULTS: Visual inspection of the pharmacokinetic profiles showed highly variable absorption profiles and secondary peaks of various intensity. The pharmacokinetic models including a double gamma distribution best fitted these various profiles in the immediate post-transplantation period (mean bias and precision of -0.92% and 20.19%; -1.5% and 18.02%, on day 7 and day 30, respectively), while in the stable post-grafting phase (beyond 3 months), the single- and double-absorption models performed similarly (mean bias and precision of -3.37% and 17.64%; -3.12% and 18.44%, on day 7 and day 30, respectively). CONCLUSION: The proposed pharmacokinetic models adequately describe the concentration-time profiles of MPA in renal transplant patients and could be helpful in the development of tools for MPA monitoring.     

Pharmacokinetics of pyrazinamide in plasma and CSF of rabbits following intravenous and oral administration

The pharmacokinetics of pyrazinamide (PZA) in cerebrospinal fluid (CSF) and plasma of 10 rabbits were studied after separate intravenous (i.v.) and oral (p.o.) administration, in a cross-over study. Concentrations of PZA in biological fluids were determined by high performance liquid chromatography (HPLC). After p.o. dose PZA was absorbed rapidly and peak plasma concentration was attained at 0.5 h post administration. After i.v. dose, the plasma PZA concentrations declined rapidly within 10 min and subsequently more slowly following a bi-exponential manner. No difference was observed in the area under plasma concentration-time curves indicating oral absorption was complete and no apparent first-pass metabolism occurred. The (mean +/- S.D.) elimination t1/2 after i.v. (1.04 +/- 0.18 h) was significantly shorter (P less than 0.0005) than that after oral (1.95 +/- 0.63 h) dose and the apparent volume of distribution was also significantly smaller (P less than 0.005) after i.v. (3.211 +/- 0.412 l) than after oral (5.936 +/- 1.607 l) administration. The elimination t1/2 of PZA in CSF was nearly identical to that in plasma after either i.v. (1.07 +/- 0.20 h) or p.o. (1.84 +/- 0.56 h) administration. There is no apparent barrier in rabbits for the penetration of PZA into CSF from the general circulation.     

组胺H1受体拮抗剂盐酸依匹斯汀片人体药动学与生物等效性研究

目的研究盐酸依匹斯汀片的药动学与生物利用度,并进行生物等效性评价.方法20名健康男性志愿者单剂量口服盐酸依匹斯汀试验或参比制剂各 40 mg;采用反相高效液相色谱法测定其血药浓度.结果人体药动学研究表明,口服盐酸依匹斯汀片的药-时曲线符合二室开放模型.受试制剂与参比制剂的主要药动学参数tmax分别为(2.2±0.5)和(2.0±0.4)h;Cmax分别为(66±16)和(68±13)μg/L;t1/2分别为(10.1±1.3)和(10.4±2.4)h;AUC0-36分别为(592±88)和(601±94)μg·h·L-1;相对生物利用度为(99±13)%.结论盐酸依匹斯汀片两种制剂具有生物等效性.     

大鼠一次性灌服酸枣仁汤剂提取物后芒果苷的药代动力学研究

沈阳药科大学 药学院, 辽宁 沈阳 110016