New Evaluation Method for in Vitro/in Vivo Correlation of Enteric-Coated Multiple Unit Dosage Forms

Purpose. To establish the evaluating method for drug dissolution profiles in the gastrointestinal (GI) tract based on in vitro data for the enteric-coated multiple unit. Methods. Dissolution profile in the GI tract was calculated by the convolution procedure using an in vitro dissolution profile as a weighting function, and the gastric-emptying (GE) process as an input function (GE-convolution method). A computer program, GECONV, was developed for numerical execution of the convolution integral. Results. The in vivo dissolution profile of enteric-coated aspirin granules estimated by GE-convolution was in good agreement with the in vivo cumulative absorption profile calculated by the Wagner-Nelson method using the plasma concentration data after oral administration to healthy subjects. The in vitro/in vivo correlation improved markedly by taking the GE process into consideration. Conclusions. These findings indicated that this convolution method is useful for estimating the in vivo dissolution profile of drugs, when they are administered in an enteric-coated multiple unit type dosage form, because the gastric emptying process is a determinant process for the in vivo drug dissolution.     

Gastric emptying of non-disintegrating solid drug delivery systems in fasted state: relevance to drug dissolution

Importance of the field: Knowledge of gastric emptying (GE) of solid drug delivery systems (DDS) is meaningful for the development of new DDS as it enables the design of in vitro dissolution experiments with conditions close to those in vivo in order to predict drug plasma concentration profiles with high reliability.

Areas covered in this review: Gastric emptying of non-disintegrating pellets, tablets and mini-tablets in the fasted state is described on the basis of various studies performed in the last 30 years, which have evaluated the emptying process mostly by gamma scintigraphy. Different influences on GE and mathematical models describing GE kinetics of single and multiunit dosage forms are represented. A discussion on the implementation of these data in the development of drug dissolution testing procedures is given.

What the reader will gain: Readers will gain an insight into the kinetics and mechanisms of GE processes. Some suggestions on the use of the obtained knowledge in biopharmaceutical testing of DDS are also given.

Take home message: Gastric emptying of non-disintegrating solid DDS is a very important process, which might influence drug dissolution, bioavailability and the plasma concentration profile. It is reasonable to consider this process in biopharmaceutical testing of these DDS.     

Study on dissolution and absorption of four dosage forms of isosorbide mononitrate: Level A in vitro–in vivo correlation

The objective of the present study was to develop a novel in vitro system to simulate the process of dissolution and permeation of oral solid dosage forms in vivo, and to establish a correlation between in vitro permeation and in vivo absorption that could predict the bioavailability (BA) and bioequivalence (BE) of congeneric products. The in vitro dissolution and absorption kinetics of four dosage forms of isosorbide mononitrate (ISMN) were evaluated by the USP basket/paddle system and drug dissolution/absorption simulating system (DDASS). The corresponding pharmacokinetic study was performed in beagle dogs. A comparative study was carried out between the classical and the novel method to estimate the effectiveness of the modified DDASS in simulating the course of dissolution and absorption in vivo. Indeed, the correlation coefficients of in vitro dissolution and in vivo absorption obtained from DDASS and dogs were higher. Moreover, a higher level A in vitro–in vivo correlation (IVIVC) between DDASS permeation and dog absorption was established, with correlation coefficients of 0.9968, 0.9872, 0.9921, and 0.9728. The DDASS method was more accurate at modeling the process of dissolution and absorption in vivo for both immediate-release (IR) and sustained-release (SR) dosage forms of ISMN.     

Effect of Destruction Force on Drug Release from Multiple Unit Controlled Release Dosage Forms in Humans

Purpose. This study examined the effects of mechanical destructive forces on drug release from controlled release (CR) multiple unit dosage forms in vitro and in vivo and their colonic release, using two CR granules of acetaminophen, AG and BG, which differed in hardness (AG was hard and BG was soft), but which did not depend on agitation speed or pH for their release. Methods. In vitro release rates were determined using several official methods and the rotating dialysis cell method. Granules were administered to healthy volunteers under fasting and fed conditions. Results. Both granules showed similar release rates under mild destructive conditions in official dissolution tests, but BG showed a faster release rate in the rotating dialysis cell method. In the fasting state, the drug absorption-time profiles of AG and BG were almost equal. In the fed state, the drug release rate of BG increases whereas that of AG is almost equal to the fasted state. The food effect on BG could be caused by an increase in the mechanical stress of the GI tract due to food intake judging from the findings in vitro and in dogs. The colonic release from multiple unit CR products was larger than that from single unit ones. Conclusions. In vivo release of drug from a multiple unit CR product that is structurally weak is affected by mechanical stresses, which differ among human subjects but are increased by food ingestion. Colonic release from multiple unit CR products is larger than that from single unit products.     

Drug release from matrix tablets: physiological parameters and the effect of food

Introduction: As dissolution plays an important and vital role in the drug-delivery process of oral solid dosage forms, it is, therefore, essential to critically evaluate the parameters that can affect this process.

Areas covered: The consumption of food as well as the physiological environment and properties of the gastrointestinal tract, such as its volume and composition of fluid, the fluid hydrodynamics, properties of the intestinal membrane, drug dose and solubility, pK_a, diffusion coefficient, permeability and particle size, all affect drug dissolution and absorption rate. There are several dissolution approaches that have been developed to address the conditions as experienced in the in vivo environment, as the traditional dissolution being a quality control method is not biorelevant and as such do not always produce meaningful data. This review also describes the development of a systematic way that differentiates between robust and non-robust formulations by varying the effects of agitation and ionic strength through the use of the automated United States Pharmacopeia type III Bio-Dis apparatus.

Expert opinion: With the improved understanding of the physiological parameters that can affect the oral bioperformance of dosage forms, strides have, therefore, been made in making dissolution testing methods more biologically based with the view of obtaining more in vitro–in vivo correlations.     

Evaluation of a Three Compartment In Vitro Gastrointestinal Simulator Dissolution Apparatus to Predict In Vivo Dissolution

In vitro dissolution tests are performed for new formulations to evaluate in vivo performance, which is affected by the change of gastrointestinal (GI) physiology, in the GI tract. Thus, those environmental changes should be introduced to an in vitro dissolution test. Many studies have successfully shown the improvement of in vitro–in vivo correlations (IVIVC) by introducing those physiological changes into dissolution tests. The gastrointestinal simulator (GIS), a multicompartment in vitro dissolution apparatus, was developed to evaluate in vivo drug dissolution. A gastric-emptying rate along with transit rate are key factors to evaluate in vivo drug dissolution and, hence, drug absorption. Dissolution tests with the GIS were performed with Biopharmaceutical Classification System class I drugs at five different gastric-emptying rates in the fasted state. Computational models were used to determine in vivo gastric-emptying time for propranolol and metoprolol based on the GIS dissolution results. Those were compared with published clinical data to determine the gastric half-emptying time. In conclusion, the GIS is a practical tool to assess dissolution properties and can improve IVIVC. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:3416–3422, 2014     

Oral Solid Controlled Release Dosage Forms: Role of GI-Mechanical Destructive Forces and Colonic Release in Drug Absorption Under Fasted and Fed Conditions in Humans

Purpose. This study was undertaken to examine the effects of mechanical destructive forces on drug release from controlled release (CR) dosage forms in vitro and in vivo and their colonic release, using two CR tablets of acetaminophen A and B, showing slower and faster erosion rates, respectively. Methods. In vitro release rates were determined by several official methods. Tablets were administered to healthy volunteers under fasting and fed conditions. Results. Both tablets showed similar release rates under mild destructive conditions (e.g., paddle method at 10 rpm) but CR-B showed faster release under highly destructive conditions (e.g., rotating basket method at 150 rpm), where the tablet was eroded. The in vivo release from CR-B was faster than from CR-A, possibly because of enhanced erosion. The variable in vivo release from CR-B indicated large inter-subject differences in destructive GI forces. The fastest in vivo release from CR-B among individuals was approximated by the in vitro dissolution determined by destructive methods such as the rotating basket at 150 rpm. The slowest in vivo release from tablets A and B was lower than the dissolution by the paddle method at 10 rpm. The release from both tablets was markedly reduced at 3–4 hrs after dosing irrespective of feeding conditions which can be attributed to release inhibition in the colon. Conclusions. Effects of GI destructive forces on the tablet erosion and the release inhibition in the colon must be considered in the development of CR dosage forms.     

缬沙坦胶囊处方工艺筛选及溶出度评价

目的 研制以诺华制药产品“代文”(规格：80 mg)为仿制目标的缬沙坦胶囊。方法 通过比较自制制剂和原研制剂的体外溶出数据,筛选处方和工艺。为了达到两者溶出曲线一致,分析不同厂家原料药对溶出的影响,并对处方内增溶剂用法和用量进行考察。结果 调整处方解决原料药难溶会降低溶出度的问题,采用f2因子法比较仿制胶囊和“代文”在多介质中的溶出曲线,体外两者溶出相似。结论 最终的处方和工艺具有可行性,仿制制剂和原研制剂体外溶出相似性可为体内两者质量一致提供一定依据。     

Predictive Ability of Level A in Vitro-in Vivo Correlation for RingCap Controlled-Release Acetaminophen Tablets

Purpose. The goal of this study was to establish and validate an in vitro-in vivo correlation (IVIVC) for two sustained-release formulations (i.e., a matrix tablet and a RingCap banded matrix tablet) containing 750 mg of acetaminophen. Methods. The in vitro dissolution and in vivo disposition of these formulations were examined by using a USP type III dissolution apparatus and a single-dose, three-way, crossover study that included an immediate-release acetaminophen dosage form, respectively. An IVIVC was established by using the mean fraction dissolved (FD) and mean fraction absorbed (FA) and used to simulate the plasma concentation-time profile of acetaminophen after administration of the matrix tablet (i.e., internal validation) and RingCap banded matrix tablet (i.e., external validation). Results. A statistically significant relationship (r ² = 0.997, P < 0.001) existed between the FD and FA for matrix tablets and was best described by the equation (FA) = 0.984 × (FD) + 0.0133. The percent predictions errors in CMAX and AUCL were <10% when predicting the plasma concentration-time profiles for the two formulations, validating the internal and external predictability of the IVIVC. Conclusions. The data (i) show that in vitro dissolution data are a good predictor of in vivo fraction absorbed for acetaminophen, (ii) support the general use of in vitro dissolution data for readily soluble and readily absorbed drugs, (iii) suggest that acetaminophen may serve as a model drug for evaluating novel sustained-release delivery systems, and (iv) provide a tangible example of the limitations of current methods for predicting and validating IVIVC.     

The dissolution of aspirin and aspirin tablets

An attempt has been made to standardize the “beaker” method of measuring in vitro dissolution rates of tablets against published data for aspirin. An unexpected problem arose when it was found that samples of commercial aspirin have different intrinsic dissolution rates. The form of aspirin used in tablet manufacture is likely therefore to be of significance from the viewpoint of in vivo dissolution and drug availability.     

硝苯地平控释片体内外相关性溶出方法研究

目的 开发相应的能区分和反映参比制剂与自研制剂之间释放差异的溶出方法，使自研制剂与参比制剂体外释放达到最大程度的匹配，从而为生物等效性试验提供体内外更具相关性的研究。方法 采用美国药典(USP)溶出2法(桨法)作为质量控制方法；另采用流池法作为溶出区分性方法，评估不同实验参数下的溶出结果。结果 优化并确立方法为开环系统，流速3.0 mL·min^-1，加1/2勺玻璃珠。该方法可以有效区分处方和生产工艺变化对产品溶出的影响。以此法为基础所得到的体外溶出速率和溶出度与体内药动学研究结果一致。结论 本研究所开发的流池法适合作为硝苯地平控释片的溶出区分性方法，并具备一定的体内体外相关性。     

A Novel Extravascular Input Function for the Assessment of Drug Absorption in Bioavailability Studies

Purpose. Flexible parametric models describing the input process after extravascular drug administration are needed for the assessment of absorption rate and the use of population methods in bioavailability and bioequivalence studies. Methods. The oral concentration-time curve modeled as the product of the input and disposition function in the Laplace domain was obtained by numerical inversion methods for parameter estimation. The utility of the inverse Gaussian input density was examined using bioavailability data of an extended-release dosage form. Measures of rate of absorption and the cumulative absorbed amount profile were defined in terms of the estimated model parameters. Results. Accurate estimation of absorption parameters was achieved by simultaneous fitting of the extravascular and intravascular data (describing the latter by a triexponential function). The new input function allowed a direct estimation of both extent of absorption and mean absorption time. Conclusions. The findings suggest that the inverse Gaussian density is a useful input function. Its flexibility may reduce the effect of model misspecification in parameter estimation. All parameters can be readily interpreted in terms of the absorption process.     

Biorelevant Dissolution Testing to Predict the Plasma Profile of Lipophilic Drugs After Oral Administration

Purpose. To quantitatively compare in vitro dissolution data in biorelevant and compendial media, to investigate whether in vitro differences are reflected in the simulated plasma profile and to specify under which circumstances prediction of the plasma profile of orally administered lipophilic drugs can be achieved. Methods. Previously published dissolution data from seven products of four lipophilic drugs were compared using the first order model, the RRSBW distribution, and a model based on the Noyes-Whitney theory. Simulated plasma profiles were then obtained using a model-dependent approach. Simulated and observed plasma profiles were compared with the difference factor, f ₁. Results. No model consistently provided the best fit to the in vitrodata, which varied significantly with medium composition. Prediction of the plasma profile was possible (9.6 f ₁ 34.2) in seven out of eleven cases. Conclusions. Although prediction of the plasma profile of lipophilic drugs solely on the basis of in vitro data remains an ambitious target, this study shows that the plasma profile of a lipophilic drug can be predicted with appropriate in vitro dissolution data, provided that the absolute bioavailability of the drug is known and the drug has dissolution limited absorption.     

In Vitro-In Vivo Relationship of Oral Extended-Release Dosage Forms

Purpose. A method to establish the in vitro-in vivo relationship of oral extended-release products is proposed. Methods. The approach utilizes incremental amounts of drug released and absorbed within defined time intervals, to construct a ² distributed variable for testing in vitro-in vivo similarity. Results. A case study is used to demonstrate that the similarities between incremental values of in vivo absorbed and in vitro dissolved fractions are distinguishable for different dissolution profiles despite naturally significant linear correlations between cumulative in vivo absorbed and in vitro dissolved fractions (with different dissolution tests) of an oral extended-release product. Conclusions. The method enables investigators to compare different in vitro dissolution profiles of an oral extended-release product to find an optimized dissolution profile to be the surrogate of the in vivo release process of the product.     

索拉非尼固体分散体的制备及性质研究

目的制备索拉非尼(sorafenib,SFN)/介孔硅的固体分散体,并进行体内外性质研究。方法利用溶剂挥发法制备固体分散体,以溶出度为指标筛选药物和介孔硅比例;采用差示扫描量热法(DSC)和粉末X射线衍射(XRD)技术,考察药物存在状态及物理稳定性;通过电镜观察样品形貌;以大鼠为实验动物,以自制SFN粉末为对照,对固体分散体进行体内药动学研究。结果原料药为结晶态,溶出度<10%;随着介孔硅的比例增大,固体分散体的溶出度增加,当SFN与介孔硅的比例为1∶5时,SFN以非晶态存在,溶出度>90%,在6个月的加速实验中,药物存在状态和溶出度未见明显改变。固体分散体组的cmax是SFN粉末组的1.8倍,相对生物利用度为175%。结论 SFN/介孔硅固体分散体物理稳定性良好,能提高SFN的溶出度,改善其口服吸收效果。     

The Effect of In Vivo Dissolution,Gastric Emptying Rate,and Intestinal Transit Time on the Peak Concentration and Area-Under-the-Curve of Drugs with Different Gastrointestinal Permeabilities

Purpose. To theoretically investigate the impact of gastric emptying half-time, intestinal transit time and the time for 85% in vivo dissolution on the peak concentration and area-under-the curve of model drugs. Methods. Simulations were performed using mathematical models of gastrointestinal physiology and pharmacokinetics of model drugs with different gastrointestinal permeability. They were used to investigate the effect of different permutations of gastric emptying times, intestinal transit times, dissolution rates and effective permeabilities on the maximum plasma drug concentration and the area-under-the-curve of immediate release tablets relative to an oral solution (i.e., Cmax_tablet/ Cmax_solution and AUC_tablet/AUC_solution). Results. The higher the permeability of the drug, the more sensitive the Cmax ratio is to dissolution rate and gastric emptying rate. As the intestinal transit time becomes more rapid, the sensitivity to T85% dissolution time and gastric emptying half-time increases. There is less dependence for the AUC ratio on the gastric emptying time and dissolution rate. Conclusions. Under the assumptions of the models, the criterion of 85% dissolution in 15 minutes (T85%) for classifying a rapidly dissolving drug product is relatively conservative since the Cmax ratio exceeded 0.8 for a T85% dissolution time of one hour and a gastric emptying half-time faster than 0.2 hour over a wide range of permeabilities.     

Forecasting the In Vivo Performance of Four Low Solubility Drugs from Their In Vitro Dissolution Data

Purpose. To assess the usefulness of biorelevant dissolution tests in predicting food and formulation effects on the absorption of four poorly soluble, lipophilic drugs. Methods. Dissolution was studied with USP Apparatus II in water, milk, SIF_sp, FaSSIF, and FeSSIF. The in vitro dissolution data were compared on a rank order basis with existing in vivo data for the tested products under fasted and fed state conditions. Results. All drugs/formulations showed more complete dissolution in bile salt/lecithin containing media and in milk than in water and SIF_sp (USP 23). Comparisons of the in vitro dissolution data in biorelevant media with in vivo data showed that in all cases it was possible to forecast food effects and differences in absorption between products of the same drug with the physiologically relevant media (FaSSIF, FeSSIF and milk). Differences between products (both in vitro or in vivo) were less pronounced than differences due to media composition (in vitro) or dosing conditions (in vivo). Conclusions. Although biorelevant dissolution tests still have issues which will require further refinement, they offer a promisingin vitro tool for forecasting the in vivo performance of poorly soluble drugs.     

Human Drug Absorption Kinetics and Comparison to Caco-2 Monolayer Permeabilities

Purpose. This study aims to assess the drug absorption kinetics of three drugs and compare their resulting first-order intestinal permeation rate constants to their Caco-2 monolayer permeabilities. Methods. In vitro dissolution — in vivo absorption analysis was conducted on four formulations of each ranitidine HC1, metoprolol tartrate, and piroxicam to yield apparent and "true human clinical permeation rate constants. Drug permeability coefficients through Caco-2 monolayers were also determined. Results. In vitro dissolution — in vivo absorption analysis revealed different relative and absolute contributions of dissolution and intestinal permeation to overall drug absorption kinetics for various drug formulations and yielded estimates of each drug's true and apparent human intestinal permeation rate constant [k _p = 0.225 hr^–1, 0.609 hr^–l, and 9.00 hr^–1 for ranitidine, metoprolol, and piroxicam, respectively]. A rank order relationship was observed for both the apparent and true permeation rate constant with Caco-2 monolayer permeability. The decrease in the true permeation rate constant relative to the apparent permeation rate constant was most significant (almost three-fold) for the least permeable compound, ranitidine. Conclusions. There were marked differences in the permeation kinetics of ranitidine, metoprolol, and piroxicam. The possibility of an association between absorption kinetics from dosage forms in humans and Caco-2 monolayer permeability may allow for a direct kinetic interpretation of human oral absorption from Caco-2 monolayer permeability values.     

光纤传感过程分析不同剂型头孢氨苄的溶出度

目的:建立紫外光纤监测头孢氨苄五种固体剂型的溶出度的方法,比较同一药物不同剂型溶出行为差异。方法:采用《中国药典》2010年版中头孢氨苄片溶出度测定方法,结合六通道光纤传感原位过程分析仪原位、在线监测头孢氨苄5种不同固体制剂溶出度。结果:不同剂型头孢氨苄溶出曲线能够反映释药特性,5种剂型释药行为各具特点。结论:光纤药物溶出仪具有实时、在线、过程监测的特点,所得溶出曲线可直观反映不同剂型药物释药特点,为全面评价药物内在质量和临床用药提供参考。     

溶出度试验预测固体制剂餐后生物利用度的研究进展

目的 综述近年来国内外溶出度试验方法的研究进展,为餐后生物利用度的预测提供理论依据。方法 综述药物的食物效应、溶出介质、溶出方法等对溶出度试验体内外相关性的影响。结果 药物性质、食物效应、溶出介质、溶出装置均影响溶出度方法的体内外相关性,均影响口服药物的餐后生物利用度。结论 在一致性评价任务重,国内餐后生物利用度研究经验少的前提下,开发能够预测餐后体内药动学的体外溶出方法,可以一定程度上减少研发风险和成本。