缓释微球的释放度试验及体内外相关性研究进展

简述了生物可降解的聚乳酸及乳酸-羟基乙酸共聚物微球的体外释放度试验方法及体内外相关性等，指出通过体外释放条件的选择可以获得较好的体内外相关性，并对体外释放通常快于体内的原因进行了探讨。     

药物经鼻-脑转运的离体牛嗅黏膜模型及体内外相关性

分离牛嗅黏膜，以石杉碱甲和盐酸锥双净为模型药物，用Franz扩散池，建立评价药物经鼻．脑转运的体外模型。通过测定药物透牛嗅黏膜的累积扩散率，考察药物亲脂性、浓度、pH、剂型和促透剂对其透黏膜扩散的影响，并通过测定鼻腔给药后大鼠脑脊液的药物浓度评价本模型的体内外相关性。结果表明药物透牛嗅黏膜转运以被动扩散为主，亲脂性是影响扩散的关键因素。药物透牛嗅黏膜累积扩散率与大鼠脑脊液药时曲线下面积线性相关。本研究建立的离体牛嗅黏膜模型实验手段简便，适用于经鼻脑靶向给药系统的体外评价。     

In vitro activities of beta-lactam antibiotics alone and in combination with sulbactam against Gram-negative bacteria

The resistance rates of ampicillin/sulbactam 2:1 against imipenem-susceptible and -resistant Acinetobacter baumannii were 23.5 and 30%, respectively. Ceftazidime/sulbactam combination showed significant reduction of resistant rates against Enterobacter cloacae, A. baumannii, ESBL Klebsiella pneumoniae. MIC₉₀ of cefoperazone against E. cloacae, Serratia marcescens, A. baumannii and ESBL K. pneumoniae were >128 mg/l. Addition of sulbactam enhanced the antimicrobial activities significantly. When imipenem was combined with sulbactam, the resistant rates against imipenem-resistant A. baumanni were significantly reduced. Cefepime/sulbactam combination was active against imipenem-resistant A. baumanni. The resistance rates of aztreonam/sulbactam combination against E. cloacae, imipenem-sensitive and resistant A. baumannii, ESBL K. pneumoniae were lowered significantly. The cefotaxime/sulbactam combination showed a significant improvement of activities against E. cloacae, S. marcescens, A. baumannii and ESBL K. pneumoniae.     

伐昔洛韦缓释片体外释放速率与人体内吸收速率的相关性

目的:研究伐昔洛韦缓释片体外释放速率与人体内吸收速率的相关性。方法:以水为释放介质,测定伐昔洛韦缓释片的体外释放速率;采用Wagner-Nelson法计算单剂量口服缓释片后体内吸收分数,考察吸收相体内吸收与体外释放的相关性。结果:伐昔洛韦缓释片体内吸收分数(f_a)与体外释放速率(f_r)的关系为:f_a=2.11f_r -20.12,r=0.994 0(n=5)。结论:伐昔洛韦缓释片人体内外相关性良好(P<0.001)。     

国产布洛芬缓释片的体内外相关性

目的对国产布洛芬缓释片的体内外相关性进行研究。方法体外释放度采用中国药典1995年版二部的转篮法,体内血药浓度用HPLC法和3P97程序计算药动学参数。结果在7h时平均累积释放77.44%;10名男性健康志愿者口服单剂量600mg布洛芬缓释片的体内过程符合开放一室模型,AUC,C     

Optimized self-nanoemulsifying drug delivery system of atazanavir with enhanced oral bioavailability: in vitro/in vivo characterization

Background: Atazanavir (ATV) is a HIV protease inhibitor. Due to its intense lipophilicity, the oral delivery of ATV encounters several problems such as poor aqueous solubility, pH-dependent dissolution and rapid first-pass metabolism in liver by CYP3A5, which result in low and erratic bioavailability.

Objective: The current study aimed to develop self-nanoemulsifying drug delivery systems (SNEDDS) using long-chain triglycerides of ATV in an attempt to circumvent such obstacles.

Methods: Equilibrium solubility studies indicated the choice of Maisine 35-1 as lipid, and of Transcutol P and Span 20 as surfactants, for formulating the SNEDDS. Ternary phase diagrams were constructed to select the areas of nanoemulsions, and the amounts of lipid (X₁) and surfactant (X₂) as the critical factor variables. The SNEDDS were optimized (OPT) using 3² central composite design and the OPT formulation located using overlay plot. The pharmacokinetics and in situ single-pass intestinal perfusion studies of OPT formulation were investigated in Wistar rats.

Results: OPT formulation indicated marked improvement in drug release profile vis-à-vis pure drug. Cloud point determination and accelerated stability studies ascertained the stability of OPT formulation. Augmentation in the values of K_a (1.96-fold) and AUC (2.57-fold) indicated significant enhancement in the rate and extent of bioavailability by the OPT formulation compared to pure drug. Successful establishment of in vitro/in vivo correlation Level A substantiated the judicious choice of the in vitro dissolution milieu for simulating the in vivo conditions.

Conclusion: The studies, therefore, indicate the successful formulation development of SNEDDS with distinctly improved bioavailability of ATV.     

卡马西平片体外溶出度与体内吸收相关性

目的：考察卡马西平（ＣＢＺ）片溶出度与体内吸收的相关性。方法：应用ＺＲＳ－４溶出度仪测定卡马西平片的溶出度。４名男性健康志愿性ｐｏ单剂量２００ｍｇＣＢＺ用ＴＤｘ分析仪测定血药浓度，并按照Ｗａｇｎｅｒ－Ｎｅｌｓｏｎ公式计算药物吸收分数。结果：体外溶出度与体内药物吸收分数的相关系数ｒ＝０．９２６１，体外溶出度与体内药物吸收分数的相关系数ｒ＝０．９９７７。结论：ＣＢＺ片体外溶出度与体内吸收有较好的相关性     

In Vivo Pharmacokinetics of Felodipine Predicted from in Vitro Studies in Rat,Dog and Man

Abstract: The elimination of felodipine in liver microsomes from dog and man were characterized by K_m and V_max. The results were compared with previous data reported for rat. In all species studied, felodipine was primarily metabolized to its corresponding pyridine analogue. The elimination rate order was rat> dog> man. The same species difference was observed in vivo for the oral plasma clearance which was; rat 26 1/hr/kg, dog 7.5 1/hr/kg and man 4.3 1/hr/kg. The intrinsic hepatic clearance of felodipine was predicted in vitro from V_max over K_m. The in vitro values were not significantly different from those observed in vivo. Felodipine is a high-clearance drug and the in vivo extraction ratios were about the same in all species: rat 0.80, dog 0.83 and man 0.84. The extraction ratios predicted from the in vitro studies, rat 0.91, dog 0.70 and man 0.80, agreed well with those observed in vivo.     

Atazanavir-loaded Eudragit RL 100 nanoparticles to improve oral bioavailability: optimization and in vitro/in vivo appraisal

Abstract

Atazanavir (ATV) is a HIV protease inhibitor. Due to its intense lipophilicity, the oral delivery of ATV encounters several problems such as poor aqueous solubility, pH-dependent dissolution, rapid first-pass metabolism in liver by CYP3A5, which result in low bioavailability. To overcome afore mentioned limitations, ATV-loaded Eudragit RL100 nanoparticles (ATV NPs) were prepared to enhance oral bioavailability. ATV NPs were prepared by nanoprecipitation method. The ATV NPs were systematically optimized (OPT) using 3² central composite design (CCD) and the OPT formulation located using overlay plot. The pharmacokinetic study of OPT formulation was investigated in male Wistar rats, and in-vitro/in-vivo correlation level was established. Intestinal permeability of OPT formulation was determined using in situ single pass perfusion (SPIP) technique. Transmission electron microscopy studies on OPT formulation demonstrated uniform shape and size of particles. Augmentation in the values of K_a (2.35-fold) and AUC_0-24 (2.91-fold) indicated significant enhancement in the rate and extent of bioavailability by the OPT formulation compared to pure drug. Successful establishment of in vitro/in vivo correlation (IVIVC) Level A substantiated the judicious choice of the in vitro dissolution milieu for simulating the in vivo conditions. In situ SPIP studies ascribed the significant enhancement in absorptivity and permeability parameters of OPT formulation transport through the Peyer's patches. The studies, therefore, indicate the successful formulation development of NPs with distinctly improved bioavailability potential and can be used as drug carrier for sustained or prolonged drug release.     

卷积法在体内外相关性研究中的应用

本文介绍了体内外相关性和卷积法/反卷积法的概念及原理, 阐述了采用卷积法使用Excel根据制剂的药代动力学数据计算其在体内释放行为的策略及方法, 并用于体内外相关性研究。该法用数学软件对药代动力学数据进行拟合以弥补缺失的数据点, 在假设输入函数基本符合威布尔规律的前提下, 在Excel中根据卷积法原理以试错法的方式确定拟合度最佳的输入函数(威布尔函数)参数, 最后以拟合度最佳的输入函数作为制剂的体内释放行为与体外释放数据进行相关性研究。在实例中不仅详细说明了该法的应用, 并且通过与隔室模型法和反卷积法的比较证明此方法简单有效, 可以作为体内外相关性研究的有力工具。     

In vitro/in vivo correlation of prolonged release dosage forms containing diltiazem HCl

Six preparations were considered: three multiple unit dosage forms (micropellets in capsules) (D, E and G) and one matrix tablet (B) were experimental prolonged release formulations, two non-disintegrating tablets (A and C) were commercial products. The in vitro dissolution behaviour of the differing formulations was investigated using the USP XXII paddle apparatus. The in vivo study was effected on a panel of 12 healthy volunteers. The two commercial tablets (A and C) showed mean dissolution time (MDT) of 1.34 and 1.44 h and t_d of 91 and 92 min, respectively; for prolonged release formulations (B, E, D, and G) MDT ranged between 2.28 and 4.23 h and t_d between 149 and 291 min. The mean residence time (MRT) was 8.68 and 6.47 h for tablets A and C, respectively; it ranged between 9.62 and 10.24 h for the multiple unit formulations E, D, and G and was 11.27 h for matrix B. Formulation B also showed the higher apparent elimination half-life t_1/2 (7.12 h), while apparent t_1/2 for all the other formulations were very similar, ranging between 5.04 and 5.28 h. High variability between the various formulations was found for C_max and AUC values, and no relationships could be established with the type of formulation. An in vitro/in vivo correlation was found for all the formulations examined on the basis of analogous parameters (MDT and MRT); (r = 0.83, p <0.05). In a few cases the Wagner-Nelson deconvolution method was applied to individual plasma level versus time curves and the corresponding absorption curves were obtained. In these cases the in vitro/in vivo correlation was tested on the basis of the comparison of the in vivo absorption curves with the in vitro dissolution profiles. This was accomplished using the ‘Levy's plot’ (per cent released versus per cent absorbed) approach and provided further support for the correlation found.     

In vitro and in vivo glucuronidation of midazolam in humans

AIMS

Midazolam (MDZ) is a benzodiazepine used as a CYP3A4 probe in clinical and in vitro studies. A glucuronide metabolite of MDZ has been identified in vitro in human liver microsome (HLM) incubations. The primary aim of this study was to understand the in vivo relevance of this pathway.

METHODS

An authentic standard of N-glucuronide was generated from microsomal incubations and isolated using solid-phase extraction. The structure was confirmed using proton nuclear magnetic resonance (NMR) and ¹H-¹³C long range correlation experiments. The metabolite was quantified in vivo in human urine samples. Enzyme kinetic behaviour of the pathway was investigated in HLM and recombinant UGT (rUGT) enzymes. Additionally, preliminary experiments were performed with 1′-OH midazolam (1′-OH MDZ) and 4-OH-midazolam (4-OH MDZ) to investigate N-glucuronidation.

RESULTS

NMR data confirmed conjugation of midazolam N-glucuronide (MDZG) standard to be on the α-nitrogen of the imidazole ring. In vivo, MDZG in the urine accounted for 1–2% of the administered dose. In vitro incubations confirmed UGT1A4 as the enzyme of interest. The pathway exhibited atypical kinetics and a substrate inhibitory cooperative binding model was applied to determine K_m (46 µM, 64 µM), V_max (445 pmol min⁻¹ mg⁻¹, 427 pmol min⁻¹ mg⁻¹) and K_i (58 µM, 79 µM) in HLM and rUGT1A4, respectively. From incubations with HLM and rUGT enzymes, N-glucuronidation of 1′-OH MDZ and 4-OH MDZ is also inferred.

CONCLUSIONS

A more complete picture of MDZ metabolism and the enzymes involved has been elucidated. Direct N-glucuronidation of MDZ occurs in vivo. Pharmacokinetic modelling using Simcyp™ illustrates an increased role for UGT1A4 under CYP3A inhibited conditions.     

In vitro — In vivo correlation of dissolution,a time scaling problem? Transformation of in vitro results to the in vivo situation,using theophylline as a practical example

Summary Two principal approaches to demonstrating the continuous in vivo relevance of an in vitro dissolution test are outlined. The first uses the convolution technique to predict the concentration-time course in vivo; the second uses deconvolution as a mathematical tool to estimate the in vivo dissolution profile. The weighting function must be known to utilise either technique. Defined by the aim of the analysis the dose-normalized response to the oral solution is regarded as the weighting function (Impulse Response). In both cases the essential step is continuous comparison of the predicted time dependent data with actual readings of the same class. To permit the prediction of concentration-time data from in vitro dissolution data the basic equations for the transformation of the time base from in vitro to in vivo conditions are developed. The transformation is essential, since one cannot assume that the time scales for the in vitro and the in vivo experiment are definitely the same. The estimated in vivo dissolution profile using the deconvolution technique gives a hypothetical image of the true in vivo dissolution curve. Comparison with in vitro dissolution test results, using one of the equivalence testing procedures, reveals how closely and for how long the in vitro dissolution test simulates the in vivo dissolution process. For the formulation of theophylline studied, equivalence of the in vitro and the estimated in vivo dissolution profiles was not confirmed for the entire period of observation, but it was demonstrated for approximately the first 5 h. The later inequivalence is not due to possible non-linear or time-dependent kinetics of theophylline. There is a discussion of whether a change in pH, agitation of the formulation, diffusion conditions or the absorption rate constant along the gastrointestinal tract might explain the biphasic linear correlation of the in vitro and in vivo data observed.     

Bioanalytical approaches,bioavailability assessment,and bioequivalence study for waiver drugs: In vivo and in vitro perspective

Evidence of differences in bioavailability from different oral formulations of the same therapeutic agents had become obvious by the early 1960s. The consequent 40 years have produced the body of scientific belief, debate, and policy on the subject of bioequivalence. The motivating force behind many of these events has been the continued interest of the food and drug administration (FDA) to improve the manner in which these studies are conducted, the quality of the data generated from such studies, and the methods by which they are evaluated. Bioanalytical data used to support regulatory submission needs to be accurate and reproducible. In order to have confidence in the reliability of the data, it is important that the analytical method used to generate it is well characterized and fully validated. However, bioavailability assessment (BA) and bioequivalence (BE) studies are necessary in filing of the data towards the drug approval. This review article describes the methods for assessing bioavailability and bioequivalence; and bioanalytical approaches of pharmaceuticals in vivo and in vitro and also a waiver of BA/BE studies based on the biopharmaceutical classification (BCS) system.     

盐酸噻吩诺啡缓释微球的体外释放度及其体内外相关性研究

目的 建立体内外相关性良好的盐酸噻吩诺啡缓释微球的体外释放度测定方法.方法 采用直接释药法和透析释药法测定盐酸嚷吩诺啡缓释微球的体外释放度;采用高效液相色谱法测定盐酸噻吩诺啡缓释微球在大鼠注射部位的残留量,计算微球在体内的释药速度.通过相关性评价确定最佳的体外释放度测定方法.结果 透析释药法和直接释药法均可获得良好的体内外相关性.结论 直接释药法和透析释药法均可用于测定盐酸噻吩诺啡微球的体外释放度.     

Continuous vs. intermittent cefotaxime administration in patients with chronic obstructive pulmonary disease and respiratory tract infections: pharmacokinetics/pharmacodynamics, bacterial susceptibility and clinical efficacy

AIM: To compare the pharmacokinetics/pharmacodynamics, antibiotic resistance and clinical efficacy of continuous (CA) vs. intermittent administration (IA) of cefotaxime in patients with obstructive pulmonary disease and respiratory infections. METHODS: A randomized controlled prospective nonblinded study was performed in 93 consecutive hospitalized patients requiring antibiotics for acute exacerbations of chronic obstructive pulmonary disease. Forty-seven patients received 2 g of cefotaxime intravenously over 24 h plus a loading dose of 1 g, and 46 patients were given the drug intermittently (1 g three times daily). RESULTS: Similar pathogens were identified in both groups, being mostly Haemophilus influenzae (51%), Streptococcus pneumoniae (21%) and Moraxella catharralis (18%). Mean minimal inhibitory concentration (MIC) values were also similar before and after treatment in both groups. Clinical cure was achieved in 37/40 (93%) (CA) vs. 40/43 (93%) (IA) of patients (P = 0.93). In microbiologically evaluable patients, criteria such as 70% of treatment time with antibiotic concentrations > or = MIC (CA 100%vs. IA 60% of patients) and/or > or = 5 x MIC (CA 100%vs. IA 55% of patients) were significantly better following continuous administration (P < 0.01). Samples with suboptimal antibiotic concentrations were found in 0% of CA vs. 65% of IA patients (P < 0.01). CONCLUSIONS: Although clinical cure rates were comparable, continuous cefotaxime administration led to significantly greater proportions of concentrations > MIC and > 5 x MIC compared with intermittent dosing. Continuous administration of cefotaxime at a lower dose [2 g (CA) vs. 3 g (CI)] is equally effective pharmacodynamically and microbiologically, may be more cost-effective and offers at least the same clinical efficacy. Based on these observations, we recommend continuous administration of cefotaxime as the preferred mode of administration.     

格列美脲片溶出度测定及对其体内外相关性考察

目的 建立格列美脲片体内外相关的溶出度测定方法.方法 采用桨法及流通池法,进行体外溶出试验,计算平均累积溶出度,并与体内吸收分数线性拟合;用相似因子(f2)评价7个厂家格列美脲片溶出度曲线的相似性.结果 传统溶出方法测定格列美脲片在pH6.8条件下区分度较强,但体内外相关性较差;建立的流通池测定体外累积溶出量与体内吸收...     

美洛昔康片溶出度考察及其体内外相关性

目的:考察2种市售美洛昔康片的体外溶出度,评价其质量及其体内外相关性.方法:采用转篮法测定溶出度,计算累积溶出百分率并与体内吸收百分率进行相关性评价;用Weibull分布模型对溶出曲线进行拟合,提取溶出参数并进行统计分析.结果:2种美洛昔康片的溶出参数之间差异有非常显著意义(P＜0.01).t检验表明同一厂家3批产品的参数之间差异有时也有显著性(P＜0.05).2种片剂的体外溶出与体内吸收之间均具有显著相关性.结论:2个厂家产品的溶出度之间存在差异并且体内外具有相关性,提示在临床用药时应加以注意.     

盐酸氨溴索缓释片体内外相关性研究

目的考察盐酸氨溴索缓释片体外释放度与体内吸收的相关性。方法应用释放度测定法研究盐酸氨溴索缓释片体外释药行为 ,采用HPLC法测定盐酸氨溴索缓释制剂在家犬体内的血药浓度 ,按照Wagner Nelson公式计算药物的吸收分数。 结果 3种自制盐酸氨溴索缓释片与参比制剂生物等效 ,以药物累积吸收百分数 f(t)与相应时刻的体外累积释放百分数F(t)建立的一元线性回归方程 ,参比制剂与 3种自制制剂的体内外相关系数分别为 0 969、0 979、0 970和 0 983。结论盐酸氨溴索缓释片的体外释放度与体内吸收具有显著的相关性。     

In vitro cytotoxicity and bioavailability of solid lipid nanoparticles containing tamoxifen citrate

Abstract

The objective of this study was to evaluate the influence of solid lipid nanoparticles (SLN) loaded with the poorly water-soluble drug tamoxifen citrate (TC) on the in vitro antitumor activity and bioavailability of the drug. TC-loaded SLN were prepared by solvent injection method using glycerol monostearate (GMS) or stearic acid (SA) as lipid matrix. Poloxamer 188 or tween 80 were used as stabilizers. TC-loaded SLN (F3 and F4) prepared using GMS and stabilized by poloxamer 188 showed highest entrapment efficiency % (86.07?±?1.74 and 90.40?±?1.22%) and reasonable mean particle sizes (130.40?±?9.45 and 243.80?±?12.33?nm), respectively. The in vitro release of TC from F3 and F4 exhibited an initial burst effect followed by a sustained drug release. In vitro cytotoxicity of F3 against human breast cancer cell line MCF-7 showed comparable antitumor activity to free drug. Moreover, the results of bioavailability evaluation of TC-loaded SLN in rats compared to free TC indicated that 160.61% increase in the oral bioavailability of TC. The obtained results suggest that incorporation of the poorly water-soluble drug TC in SLN preserves the in vitro antitumor activity and significantly enhance oral bioavailability of TC in rats.