Single oral dose pharmacokinetics and comparative bioavailability of danazol in humans.

A comparative bioavailability study was conducted with two capsule formulations of danazol (200 mg) in 16 healthy adult male volunteers. Fasting subjects received single doses (400 mg) of each formulation on separate occasions 1 week apart. Blood samples were drawn at specified times up to 32 h after the dose and danazol concentrations in plasma were determined by a specific and sensitive HPLC method. The results for one subject were excluded as outlier values. The data from the other 15 subjects showed small differences, which did not achieve statistical significance between the formulations with respect to Cmax, Tpeak and AUC0-infinity. The mean elimination half-life for danazol was 9.44 +/- SD 2.74 h and the mean apparent total body clearance was 710 +/- SD 2161 h-1. These data differed from previously published results, probably as a result of the more sensitive and specific assay method used in the present work. It is likely that a high proportion of the oral dose of danazol is eliminated by presystemic metabolism.     

The pharmacokinetics and absolute bioavailability of selegiline in the dog

Selegiline is beneficial to Parkinsonian patients as an adjunct to levodopa therapy. Currently no pharmacokinetic data are available for selegiline in the literature, mainly due to lack of analytical methods that can measure concentrations below 10 ng mL^?1 in plasma. A sensitive fluorimetric assay based on inhibition of rat brain monoamine oxidase-B (MAO-B) in vitro has been developed to measure selegiline in plasma as low as 0.25 ng mL^?1. The pharmacokinetics of selegiline were investigated following intravenous and oral administration to four female mongrel dogs. Each dog received 1 mg kg^?1 selegiline in solution via gavage or by an intravenous route separated by one week. The mean terminal half-life, volume of distribution of the central compartment, and systemic clearance of selegiline were 60.24 ± 9.56 min, 6.56 ± 0.56 L kg^?1, and 159.91 ± 19.28 mL min^?1 kg^?1, respectively. After oral administration selegiline appeared to be absorbed rapidly with a t_max and C_max of 25 ± 5.8 min and 5.2 ± 1.36 ng mL^?1, respectively. The absolute bioavailability of selegiline in the dog was 8.51 ± 3.31%.     

穿琥宁药代动力学及绝对生物利用度的实验研究

目的研究穿琥宁经小肠给药后在小鼠体内的药代动力学及绝对生物利用度。方法取小鼠60只,随机分为静脉注射组和小肠给药组。小肠给药组小鼠麻醉后,直接在小肠灌注穿琥宁CMC-Na混悬液,静脉注射组为静脉注射穿琥宁溶液,给药后采用HPLC法测定血药浓度。结果经3p97药动学程序处理,穿琥宁经小肠给药的药—时数据符合二室药代动力学模型,其绝对生物利用度为15.88%。结论小鼠经小肠灌注穿琥宁有一定的生物利用度。     

盐酸西替利嗪巴布膏剂的药动学和生物利用度研究

目的研究盐酸西替利嗪巴布膏剂在大鼠体内的药代动力学特征,并与口服给药的药动学进行比较,考察生物利用度。方法选用SD大鼠,分为巴布膏剂组和口服给药组,采用高效液相色谱法测定血药浓度;并剥取剩余的西替利嗪巴布膏剂,测定剩余药量。结果西替利嗪巴布膏剂组的T_(max)为2.35 h,C_(max)为2.68μg/mL,AUC为21.01μg·h/mL,MRT为23.26 h;西替利嗪口服组的T_(max)为1.11 h,C_(max)为11.65μg/mL,AUC为35.62μg·h/mL,MRT为12.13 h。扣除巴布膏剂中的剩余药量,按照实际进入皮肤的剂量计算得西替利嗪巴布膏剂相当于片剂的生物利用度为30.81%;不扣除巴布膏剂中的剩余药量,西替利嗪巴布膏剂相当于片剂的生物利用度为14.75%。结论西替利嗪巴布膏剂的血药浓度平稳而持久,具有缓释的特征。     

The oral bioavailability of nitrate from nitrate-rich vegetables in humans

High dietary nitrate intake may pose a risk to human health. Since up to 80-85% of dietary nitrate intake comes from vegetables, the aim of this study was to determine the absolute bioavailability of nitrate from three nitrate-rich vegetables. In an open, four-way cross-over, single dose study, 12 human subjects underwent the following treatments: (1) intravenous infusion of 500mg sodium nitrate, (2) oral administration of 300g cooked spinach, (3) oral administration of 300g raw lettuce, and (4) oral administration of 300g cooked beetroot. The wash-out period between treatments was at least 6 days. Plasma samples were analysed to assess the nitrate and nitrite concentrations, and pharmacokinetic parameters were calculated. The bioavailability of nitrate was 98+/-12% from cooked spinach, 114+/-14% from raw lettuce and 106+/-15% from cooked beetroot. There was no significant increase in plasma nitrite concentrations. This study shows that nitrate from vegetables, whether cooked or uncooked, is absorbed very effectively, resulting in an absolute nitrate bioavailability of around 100%. Thus, reducing the amount of nitrate in vegetables can be an effective measure to lower the systemic nitrate exposure of the general population. However, other aspects, such as the costs to produce vegetables with a low nitrate content and the possible beneficial effects of nitrate in vegetables, need to be considered when evaluating the usefulness of such a measure.     

扑热息痛滴剂、酏剂和片剂在正常人中的生物利用度比较

本文报道7名健康受试者分别口服1g单剂量扑热息痛滴剂(A)、酏剂(B)和片剂(C)后的生物利用度和药代动力学比较。血药浓度用紫外分光光度法测定。结果表明:A和B比C吸收迅速、达峰早,Cp和AUC较C犬(P均<0.05)。与C相比,A和B能维持在有效治疗血浓的时间更长。A和B更适合于儿科应用。     

青霉素V钾健康人体药物动力学及相对生物利用度

以美国进口的青霉素 V钾片为标准参比制剂 ,研究国产青霉素 V钾片和胶囊在健康人体药物动力学及相对生物利用度。按 3制剂、3周期的 3× 3拉丁方试验设计 ,9名健康男性受试者 ,分别口服进口及国产青霉素 V钾 15 0 0 mg,采用微生物法测定血药浓度 ,用 3P87软件经微机处理药 -时数据。结果证明 ,进口及国产青霉素 V钾的体内过程均符合二房室模型 ,与标准参比制剂相比 ,两种被试制剂的 AUC、Cmax、Tmax均无显著差异 ,相对生物利用度分别为 10 2 .5 1± 11.0 9% (84.6 1%～ 114.49% )与 92 .5 0± 8.47% (82 .88%～10 6 .6 3% )。结论 :国产青霉素 V钾片和胶囊均具有生物等效性。     

Single oral dose proportionality pharmacokinetics of almitrine bismesylate in humans

A single-blind study was conducted in 10 healthy male subjects. Each subject was tested with four single oral doses of capsules containing 25, 50, 100, 200mg almitrine bismesylate and one dose of placebo. Blood samples were drawn as a function of time and the concentration of almitrine in plasma was determined by gas chromatography utilizing nitrogen-phosphorus detection. Linear regression analysis of the data suggested that a deviation from linearity existed between the area under the plasma concentration time curves and the dose (R = 0.96). Linear analysis of the individual data indicates that a slight negative deviation from linearity is apparent for the 200 mg dose. The same trend was observed for the mean maximum almitrine plasma concentration, Cmax, which ranged from 38.9 +/- 11.8 to 286.2 +/- 99.1 ng ml-1 for the 25 and 200 mg dose, respectively. The time to peak was relatively constant regardless of the administered dose and ranged from 2.4 +/- 0.5 h to 2.8 +/- 0.8 h. Good agreement was obtained between the observed bioavailability parameters and those predicted from the nonlinear fit of the data. Further kinetic analysis of the data revealed mean total body clearance over fraction of dose absorbed ranging from 268.2 +/- 132.8 to 436.4 +/- 191.4 ml min-1 for doses 50 and 200mg, respectively.     

Single-dose pharmacokinetics and bioavailability of famotidine in man. Results of multicenter collaborative studies

Pharmacokinetics and bioavailability of famotidine, a new H2-receptor antagonist, were investigated in healthy subjects in five clinical studies. Linear pharmacokinetics were observed following either intravenous or oral administration. Plasma clearance averaged 463 ml min-1. Renal clearance averaged 310 ml min-1, which exceeded the glomerular filtration rate. Renal excretion was the major route of elimination. Urinary recovery of unchanged drug following intravenous administration was about 67 per cent. Famotidine plasma half-life was approximately 2.6 h. Oral absorption was incomplete. The bioavailability averaged 43 per cent of the dose.     

微生物法测定环丙沙星片在人体中的药物动力学和生物利用度

8名健康受试验者交叉口服单剂量德国产及国产环丙沙星片(750mg)后,用微生物法测定血药浓度,按单室模型处理分析得各药物动力学参数。结果表明二者基本相似其相对生物利用度为97±20%。     

Butriptyline: Human pharmacokinetics and comparative bioavailability of conventional and sustained release formulations

The pharmacokinetics and relative bioavailability of butriptyline from conventional and a sustained release (SR) formulation have been studied in a panel of 14 volunteers. A single oral dose of 75 mg butriptyline hydrochloride was administered and a 2 × 2 latin square design was followed. Pharmacokinetic modelling has shown that the plasma butriptyline concentration/time profile is adequately described by a two-compartment open model; good agreement was obtained for the model-fitted and measured parameters. The SR formulation was shown to possess sustained release characteristics as evidenced by the increase in T_max for 2.6 to 7.5 h, the decrease in C_max from 46.5 to 20.3 ng ml^?1, and a three-fold increase in ‘half-value duration’ (HVD). The changes have been achieved without any significant decrease in the relative bioavailability of the SR formulation. The half-life of butriptyline in plasma was about 20 h and was not formulation dependant.     

氧氟沙星缓释片单次、多次给药人体药代动力学和生物等效性研究

目的：研究氧氟沙星缓释片单次、多次给药的人体药代动力学特征,并与氧氟沙星片比较其缓释特征与生物等效性。方法：单次给药20例健康成年男性受试者随机分组,自身双周期交叉对照,单次口服药物400mg;多次给药18例健康成年男性受试者随机分组,自身双周期交叉对照,多次口服药物（参比制剂400mg／2次／d×5d,受试制剂400mg／次／d×5d）。通过反相HPLC法测定血浆氧氟沙星浓度,采用非房室模型计算药代动力学参数,并进行统计分析。结果：单次给药参比制剂与受试制剂的Cmax分别为（5382±1558）、（3419±1034）μg／L;Tmax分别为（1．7±0．6）、（4．2±1．8）h;t1／2分别为（8．2±1．0）、（7．6±1．8）h;MRT分别为（8．6±0．9）、（10．3±1．4）h;AUC分别为（33764±5297）、（31280±4412）／zg·L-1·h;AUC分另别为（34643±5356）、（32642±4257）Frel为（97．9±12．4）％。方差分析显示,MRT各参数受试制剂与参比制剂差异具有统计学意义;各参数受试制剂与参比制剂差异无统计学意义。等效性检验显示,受试制剂与参比制剂90％可信限。为89．0％～97．0％;AUC为91．4％～97．8％。多次给药参比制剂与受试制剂的Cmax分别为（3732±1502）、（3564±982）μg／L;Cmax分别为（750±193）、（438±89）分别为（1．5i0．5）、（3．7±1．7）h;AUCss分别为（32689±4786）、（33591±7929）分别为（1362±199）、（1405±337）μg／L;DF分别为（216．1±76．5）、（221．5i33．9）％;F刊为（102．9±22．5）％。方差分析显示,AUCss、DF受试制剂与参比制剂差异均无统计学意义。等效性检验显示,909／6可信限Cmax为80．8％～114．6％;AUCss为89．3％～111．9％;为89．5％～112．4％;DF为93。7％～122．4％。结论：受试制剂氧氟沙星缓释片相对于参比制剂氧氟沙星片,单次给药具有缓释动力学特征及吸收程度生物等效,多次给药达稳态时具有生物等效性。     

国产头孢克洛分散片药动学及生物利用度的研究

采用高效液相色谱法对９例健康志愿者交叉服用国产头孢克洛分散片及进口头孢克洛胶囊５００ｍｇ后，测定４ｈ内不同时间的血药浓度，以对国产和进口头孢克洛制剂进行药动学及生物利用度的研究。结果表明，国产分散片与进口胶囊的药－时曲线符合开放式一室模型，分散片的相对生物利用度为１０８．４％，分散片与胶囊的峰浓度分别为１３．４±３．３４７与１０．９９±２．８３５μｇ／ｍｌ；达峰时间分别为０．５５６８±０．１４５４与０．７３１５±０．１９１９ｈ；ＡＵＣ分别为１７．７０±２．８６０与１６．５２±３．７２６ｈμｇ／ｍｌ，上述各项药动学参数经配对ｔ检验表明ＡＵＣ与峰浓度均无统计学差异（Ｐ＞０．０５），但达峰时间有统计学差异（Ｐ＜０．０５）。同时经ＮＤＳＴ程序进行配对交叉设计的生物等效性检验，国产分散片与进口胶囊具有相同的生物药效性。     

The relationship between buspirone bioavailability and dose in healthy subjects

Dose dependency of the pharmacokinetics of buspirone, a new anxiolytic agent, was tested in 24 healthy volunteers. Each subject received 10, 20, and 40 mg doses according to a randomized, three-way crossover design with a 7-day interval between treatments. Buspirone AUC values at 10, 20, and 40 mg doses were in the ratio of 1:1.7:3.5 while Cmax values had a ratio of 1:1.9:3.7. The dose normalized (10 mg basis) AUC and Cmax values, Tmax values, and half-lives were not significantly different (p greater than 0.05) among the doses. Buspirone half-life did not change as a function of dose (mg kg-1). It was concluded that buspirone exhibits linear pharmacokinetics following doses in the therapeutic range.     

Pharmacokinetics and bioavailability of the anti-emetic agent bromopride

The pharmacokinetics of bromopride, an anti-emetic agent chemically related to metoclopramide, has been investigated in normal human subjects. After intravenous bolus doses of 10 mg, a one-compartment open model appeared adequate to describe the plasma drug concentration data. The systemic clearance of bromopride was 899 ml min-1 +/- 22 per cent CV, the volume of distribution was 2151 +/- 16 per cent CV, and the elimination half-life was 2.9 h +/- 21 per cent CV. Over a wide drug concentration range of up to 650 ng ml-1, bromopride was only 40 per cent bound to plasma proteins. The systemic availability of orally and intramuscularly administered solution doses of 20 mg of bromopride was 54 per cent and 78 per cent, respectively. Formulation of bromopride as the solid material in capsules delayed absorption but did not affect the extent of drug bioavailability. The pharmacokinetics of bromopride appeared similar to that of metoclopramide. No evidence for non-linear kinetics was found when bromopride was administered orally in the dose range 10-30 mg: after single oral doses of 10, 20, and 30 mg, peak mean plasma drug concentrations were 20 ng ml-1 +/- 32 per cent CV, 38 ng ml-1 +/- 16 per cent CV, and 64 ng ml-1 +/- 23 per cent CV, respectively.     

Comparative bioavailability and pharmacokinetics of hydrochlorothiazide from oral tablet dosage forms,determined by plasma level and urinary excretion methods

The bioavailability and pharmacokinetics of two hydrochlorothiazide products were compared following single 50 mg oral doses to 20 healthy male volunteers. Plasma and urine were assayed for hydrochlorothiazide by a specific and sensitive HPLC method. Plasma profiles of hydrochlorothiazide were adequately described by a triexponential function. The bioavailability of hydrochlorothiazide from the two brands did not differ significantly as judged by the values of C_max, t_max, AUC^0→x, mean residence time, variance of residence time, and urinary excretion of unchanged drug. Close similarity was observed between urinary excretion rates and concentrations of drug in plasma.     

Relative bioavailability of carbocysteine from three dosage forms, investigated in healthy volunteers

The aim of the present study was to evaluate the bioavailability of a new tablet formulation of carbocysteine relative against two other oral carbocysteine containing dosage forms, viz. a syrup and capsules. Plasma levels and urine concentrations of carbocysteine were monitored, following oral administration of all three dosage forms to healthy human volunteers, by direct derivatization of carbocysteine using dabsylchloride and subsequent high performance liquid chromatography. There was no difference in bioavailability of carbocysteine from these dosage forms as expressed by the respective areas under the plasma concentration-time curves and total amounts of unchanged carbocysteine excreted in urine.     

Pharmacokinetics and oral bioavailability of carbimide in man

A pharmacokinetic study of carbimide, an inhibitor of aldehyde dehydrogenase, used as an adjuvant in the aversive therapy of chronic alcoholism, has been carried out in male human volunteers for intravenous and oral administration. Carbimide plasma concentrations were determined by a sensitive and specific high performance liquid chromatographic method. The intravenous doses administered were 0.1, 0.3, 0.6, and 1 mg kg-1 and linear pharmacokinetics were observed for this dose range. Elimination half-life and total plasma clearance values ranged from 42 to 52 min and from 14.4 to 20.5 ml kg-1 min-1, respectively. After oral administration of 1 and 1.5 mg kg-1 of carbimide, elimination half-life values were 75 and 61 min, respectively, being higher than the corresponding value obtained after 0.3 mg kg-1 doses, i.e. 39 min. In all cases, rapid absorption was indicated by tmax values ranging from 10.5 to 15.5 min. Absorption was not complete, the oral bioavailability being 53 per cent and 70 per cent for the 0.3 and 1 mg kg-1 carbimide dose, respectively. The data indicate that there is a first-pass effect for carbimide.     

Pharmacokinetics and bioavailability of ergoloid mesylates

The pharmacokinetics and bioavailability of ergoloid mesylates following single administrations of various dose levels (3-9 mg), dosage forms (oral swallow and sublingual tablets, solution) and under different dosing conditions (fasted, with meal) were studied in young healthy volunteers. Male and female subjects showed a similar rate and extent of bioavailable ergoloid after drug treatment. The absorption of ergoloid using either the tablet dosage forms or the drug administered as a solution was rapid, with peak levels of about 60-80 pg ml-1 mg-1 dose achieved after 0.6 to 1.3 h. The elimination half-life for ergoloid in plasma was 2-5 h. Administration of drug with food had no effect on the extent of absorption (AUC) but lowered the absorption rate. This resulted in a reduction of (by 25 per cent) and delay in (by 1 h) achieving peak levels (Cmax). Increasing the ergoloid dose caused a proportional increase in the AUC, but a smaller than proportional increase for Cmax. The tablet formulations provided similar AUCs as the solution; the objective of the sublingual tablet formulation to provide improved bioavailability over the swallow tablet via circumvention of first-pass metabolism was therefore not realized. Transient decreases in blood pressure after ergoloid treatment paralleled the plasma level profiles. Higher ergoloid levels were paired with the larger pressure decreases.