Systematic formulation development of once-a-day gastroretentive controlled release tablets of rivastigmine using optimized polymer blends

Rivastigmine is a drug extensively prescribed for the treatment of Alzheimer’s disease. On therapeutic fronts, severe gastrointestinal (GI) adverse effects owing to a rapid rise and fall in drug plasma levels, and the high frequency of its dosing, tend to limit its usage. The present investigation, therefore, aimed at developing a gastroretentive floating-bioadhesive CR formulation for delivering rivastigmine in a sustained manner at the desired site of absorption. Employing 7-factor Taguchi design, the influential factors were embarked upon as Carbopol 971P and Methocel K15M CR. Effervescent floating-bioadhesive hydrophilic matrices were systematically formulated using a face-centered cube design (FCCD) and evaluated for in vitro drug release, floatation and ex vivo bioadhesive strength. Optimal composition of polymer blends systematically chosen using brute-force methodology, overlay plots and desirability function exhibited excellent bioadhesive and floatational characteristics besides possessing adequate drug release control (T₆₀ > 5 h). Pharmacokinetic studies carried out in rabbits showed the absence of any sharp peaks or troughs in the plasma drug levels, and various levels of in vitro/in vivo correlation (IVIVC) were successfully established. In vivo gamma scintigraphic studies in human volunteers ratified the gastroretentive characteristics of the optimized formulation with retention time of 6 h or more. Thus, besides unraveling the polymer synergism, the study helped in developing an optimal once-a-day gastroretentive drug delivery system exhibiting excellent swelling, floating, and bioadhesive characteristics.     

Novel sustained release, swellable and bioadhesive gastroretentive drug delivery system for ofloxacin

Oral sustained release gastroretentive dosage forms offer many advantages for drugs having absorption from upper gastrointestinal tract and improve the bioavailability of medications that are characterized by a narrow absorption window. A new gastroretentive sustained release delivery system was developed with floating, swellable and bioadhesive properties. All these properties were optimized and evaluated. Various release retarding polymers like psyllium husk, HPMC K100M and a swelling agent, crosspovidone in combinations were tried and optimized to get the release profile for 24 h. Formulations were evaluated for in vitro drug release profile, swelling characteristics and in vitro bioadhesion property. The in vitro drug release followed Higuchi kinetics and the drug release mechanism was found to be of anomalous or non-Fickian type. For the developed formulation, the value of n was found to be 0.5766 while for the marketed formulation the value was 0.5718 indicating the anomalous transport. The high water uptake leading to higher swelling of the tablet supported the anomalous release mechanism of ofloxacin. The similarity factor f2 was found to be 91.12 for the developed formulation indicating the release was similar to that of the marketed formulation (Zanocin OD). The swelling properties were increased with increasing crosspovidone concentration and contributed significantly in drug release from the tablet matrix. The bioadhesive property of the developed formulation was found to be significant (P < 0.005) in combination as compared to HPMC K100M and psyllium husk alone.     

QbD-enabled systematic development of gastroretentive multiple-unit microballoons of itopride hydrochloride

Abstract

The objectives of present studies were to develop the systematically optimized multiple-unit gastroretentive microballoons, i.e. hollow microspheres of itopride hydrochloride (ITH) employing quality by design (QbD)-based approach. Initially, the patient-centric QTPP and CQAs were earmarked, and preliminary studies were conducted to screen the suitable polymer, solvent, solvent ratio, pH and temperature conditions. Microspheres were prepared by non-aqueous solvent evaporation method employing Eudragit S-100. Risk assessment studies carried out by constructing Ishikawa cause-effect fish-bone diagram, and techniques like risk estimation matrix (REM) and failure mode effect analysis (FMEA) facilitated the selection of plausible factors affecting the drug product CQAs, i.e. percent yield, entrapment efficiency (EE) and percent buoyancy. A 3³ Box–Behnken design (BBD) was employed for optimizing CMAs and CPPs selected during factor screening studies employing Taguchi design, i.e. drug–polymer ratio (X₁), stirring temperature (X₂) and stirring speed (X₃). The hollow microspheres, as per BBD, were evaluated for EE, particle size and drug release characteristics. The optimum formulation was embarked upon using numerical desirability function yielding excellent floatation characteristics along with adequate drug release control. Drug-excipient compatibility studies employing FT-IR, DSC and powder XRD revealed absence of significant interaction among the formulation excipients. The SEM studies on the optimized formulation showed hollow and spherical nature of the prepared microspheres. In vivo X-ray imaging studies in rabbits confirmed the buoyant nature of the hollow microspheres for 8?h in the upper GI tract. In a nutshell, the current investigations report the successful development of gastroretentive floating microspheres for once-a-day administration of ITH.     

Formulation optimization of hydrodynamically balanced oral controlled release bioadhesive tablets of tramadol hydrochloride

The directly compressible floating-bioadhesive tablets of tramadol were formulated using varying amounts Carbopol 971P (CP) and hydroxy-propylmethyl cellulose (HPMC), along with other requisite excipients. In vitro drug release profile, floatational characteristics and ex vivo bioadhesive strength using texture analyzer were determined, and systematically optimized using a 3² central composite design (CCD). The studies indicated successful formulation of gastroretentive compressed matrices with excellent controlled release, mucoadhesion and hydrodynamic balance. Comparison of the dissolution profiles of the optimized formulation, with optimal composition of CP:HPMC :: 80.0:125.0, with that of the marketed controlled release formulation other indicated analogy of drug release performance with each other. Validation of optimization study using eight confirmatory experimental runs indicated very high degree of prognostic ability of CCD with mean ± SEM of −0.06% ± 0.37. Further, the study successfully unravels the effect of the polymers on the selected response variables.     

Development of sustained release gastroretentive drug delivery system for ofloxacin: in vitro and in vivo evaluation

Sustained release (SR)-gastroretentive dosage forms (GRDF) enable prolonged and continuous input of the drug to the upper parts of the gastrointestinal (GI) tract and improve the bioavailability of medications that are characterized by a narrow absorption window. A new strategy is proposed for the development of gastroretentive dosage forms for ofloxacin preferably once daily. The design of the delivery system was based on the sustained release formulation, with floating and swelling features in order to prolong the gastric retention time of the drug delivery systems. Different polymers, such as psyllium husk, HPMC K100M, crospovidone and its combinations were tried in order to get the desired sustained release profile over a period of 24 h. Various formulations were evaluated for buoyancy lag time, duration of buoyancy, dimensional stability, drug content and in vitro drug release profile. It was found that dimensional stability of the formulation increases with the increasing psyllium husk concentration. It was also found that in vitro drug release rate increased with increasing amount of crospovidone due to the increased water uptake, and hence increased driving force for drug release. The optimized formulation was subjected to stability studies at different temperature and humidity conditions as per ICH guidelines. In vivo studies were carried out for the optimized formulation in 24 healthy human volunteers and the pharmacokinetic parameters of developed formulations were compared with the marketed once daily (Zanocin) formulation. Based on the in vivo performance in a parallel study design in healthy subjects, the developed formulation shows promise to be bioequivalent to the marketed product (Zanocin). The percent relative bioavailability of developed formulation was found to be 97.55%.     

盐酸索他洛尔生物粘附微球的制备及体外释药特性研究

目的：制备盐酸索他洛尔生物粘附微球,考察其体外释药特性并评价其粘附性能。方法：应用正交试验筛选盐酸索他洛尔生物粘附微球的最佳处方,采用高效液相色谱法测定盐酸索他洛尔生物粘附微球的含量与释放度,选用滞留率为指标考察微球的粘附特性。结果：盐酸索他洛尔生物粘附微球的最佳处方为盐酸索他洛尔投药量占处方组成的30％．分散相与连续相比为70％,司盘80用量为9．0g;体外释药试验结果表明盐酸索他洛尔生物粘附微球30min累积释药百分率达30％,4h释药达90％;离体法与在体法测得微球胃黏膜上的滞留率分别为（87．6±2．8）％与（60．2±9．8）％。结论：盐酸索他洛尔生物粘附微球处方设计合理,制备工艺简单,与盐酸索他洛尔普通片相比,盐酸索他洛尔生物粘附微球具有一定缓释特性,且其在离体与在体模型中粘附性能良好。     

Design and evaluation of gastroretentive mucoadhesive cephalexin tablets

The aim of this investigation was to develop gastroretentive mucoadhesive tablets of cephalexin, which will retain in the stomach for 10?h. Cephalexin, a first-generation cephalosporin, becomes ionized in intestinal pH because pKa is 4.5 and thus reducing its bioavailability. The various batches were prepared by wet granulation method using variety of mucoadhesive polymers such as hydroxyl propyl methyl cellulose K4M, hydroxyl propyl cellulose, chitosan, carbopol 934P and sodium carboxymethylcellulose and subjected to various evaluation parameters such as mucoadhesive strength, in vitro drug release profile, swelling characteristics and physical properties. It was evident from the study that the formulation containing HPMC K4M and carbopol 934P in combination exhibited maximum mucoadhesive strength of 144.42?gms, in vitro residence time was 8.73?h and in vitro drug release was found to be 75.03% in 10?h with non-Fickian diffusion mechanism. So, the optimized formulation F₂ was further subjected to in vivo retention time in rabbit by X-ray technique, SEM and Accelerated stability studies. Regarding all the properties evaluated, the formulation containing HPMC K4M and carbopol 934P in combination was found to be the best to achieve the aim of this study.     

双嘧达莫阿司匹林胃内漂浮胶囊的制备及犬体内外相关性研究

制备了阿司匹林双嘧达莫胃内漂浮胶囊,采用均匀设计优化处方,用HPLC法测定释放度和犬体内血药浓度.结果表明:用优化处方制备的胶囊体外漂浮性能良好,体外释药曲线符合Higuchi方程.双嘧达莫、阿司匹林的体外释放和犬体内吸收相关系数分别为0.9861和0.9902.     

Preparation, in vitro and in vivo evaluation of algino-pectinate bioadhesive microspheres: An investigation of the effects of polymers using multiple comparison analysis

Ionotropic gelation was used to entrap aceclofenac into algino-pectinate bioadhesive microspheres as a potential drug carrier for the oral delivery of this anti-inflammatory drug. Microspheres were investigated in vitro for possible sustained drug release and their use in vivo as a gastroprotective system for aceclofenac. Polymer concentration and polymer/drug ratio were analyzed for their influence on microsphere properties. The microspheres exhibited good bioadhesive property and showed high drug entrapment efficiency. Drug release profiles exhibited faster release of aceclofenac from alginate microspheres whereas algino-pectinate microspheres showed prolonged release. Dunnet's multiple comparison analysis suggested a significant difference in percent inhibition of paw edema when the optimized formulation was compared to pure drug. It was concluded that the algino-pectinate bioadhesive formulations exhibit promising properties of a sustained release form for aceclofenac and that they provide distinct tissue protection in the stomach.     

氯氮平漂浮缓释胶囊体内外相关性评价

目的建立氯氮平漂浮缓释胶囊体内外相关性评价模型 ,评价体内外相关性。方法利用Wanger Nelson方法和卷积模型分别评价氯氮平漂浮缓释胶囊体内外相关性。通过反卷积方法由体外释放数据得到了氯氮平漂浮缓释胶囊的体内输入函数。利用基本卷积模型和扩展卷积模型预测了氯氮平漂浮缓释胶囊体内血药浓度峰值 (Cmax)和血药浓度 时间曲线下面积值 (AUC)。结果Wanger Nelson方法的相关系数为0 9798;反卷积方法得到的体内输入值与体外释药量相关性良好 ,相关系数为 0 996。扩展卷积模型预测的Cmax和AUC值与实验值误差 <6 % ;而基本卷积模型预测值误差 >2 8%。结论氯氮平漂浮缓释胶囊体内外相关性良好。应用扩展的卷积模型能很好的预测氯氮平体内血药浓度 ,预测的体内情况可用来指导处方筛选     

In vitro-in vivo correlation study on nimesulide loaded hydroxypropylmethylcellulose microparticles

This study involves mathematical simulation model such as in vitro-in vivo correlation (IVIVC) development for various extended release formulations of nimesulide loaded hydroxypropylmethylcellulose (HPMC) microparticles (M1, M2 and M3 containing 1, 2, and 3 g HPMC, respectively and 1 g drug in each) having variable release characteristics. In vitro dissolution data of these formulations were correlated to their relevant in vivo absorption profiles followed by predictability worth analysis of these Level A IVIVC. Nimaran was used as control formulation to validate developed formulations and their respective models. The regression coefficients of IVIVC plots for M1, M2, M3 and Nimaran were 0.834 9, 0.831 2, 0.927 2 and 0.898 1, respectively. The internal prediction error for all formulations was within limits, i.e., < 10%. A good IVIVC was found for controlled release nimesulide loaded HPMC floating M3 microparticles. In other words, this mathematical simulation model is best fit for biowaiver studies which involves study parameters as those adopted for M3 because the value of its IVIVC regression coefficient is the closest to 1 as compared to M1 and M2.     

Floating-bioadhesive gastroretentive Caesalpinia pulcherrima-based beads of amoxicillin trihydrate for Helicobacter pylori eradication

Abstract

Context: An oral dosage form containing floating bioadhesive gastroretentive microspheres forms a stomach-specific drug delivery system for the treatment of Helicobacter pylori.

Objectives: To prepare and evaluate controlled release floating bioadhesive gastroretentive chitosan-coated amoxicillin trihydrate-loaded Caesalpinia pulcherrima galactomannan (CPG)-alginate beads (CCA-CPG-A), for H. pylori eradication.

Materials and methods: CCA-CPG-A beads were prepared by ionotropic gelation, using 2³ factorial design with quantity of drug, combination of CPG with sodium alginate and concentration of calcium chloride as variables. Beads facilitated mucoadhesion to gastric mucosa with floating nature caused by chitosan coating for wide distribution throughout GIT. Developed beads were evaluated for characteristics like beads size-morphology, entrapment efficiency, DSC, XRD, FTIR, swelling ratio, in vitro mucoadhesion, in vitro drug release, in vitro floating and in vitro H. pylori growth inhibition studies. CCA-CPG-A beads were studied in Wistar rats for in vivo gastric mucoadhesion, in vivo H. pylori growth inhibition studies using PCR amplification of isolated DNA, rapid urease test.

Result: Developed beads possess drug release of 79–92%, entrapment efficiency of 65–89%, mucoadhesion of 61–89%. In vivo mucoadhesion study showed more than 85% mucoadhesion of beads even after 7th hour. In vitro–in vivo growth inhibition study showed complete eradication of H. pylori.

Discussion: CPG-alginate and chitosan in beads interacts with gastric mucosubstrate surface for prolonged gastric residence with floating bioadhesion mechanism for H. pylori eradication in rats.

Conclusion: Floating bioadhesive CCA-CPG-A beads offer a promising drug delivery system for H. pylori eradication at lower dose, reduced adverse effect and enhance bioavailability.     

注射用乳酸-羟基乙酸共聚物微球的体内外相关性研究进展

注射用乳酸-羟基乙酸共聚物(polylactide-polyglycolide, PLGA)微球作为一种储库型释药系统,自1989年第1个产品Lupron depot获准在美国上市起,已成功用于多种疾病的治疗,具备在体内几天到几个月长时间释药的能力,可显著改善用药安全性,提升患者顺应性。体内外相关性(in vitro-in vivo correlation, IVIVC)研究给微球制剂的发展带来更多可能。IVIVC可以通过微球的体外释放行为阐述体内释药的动态信息,在表征微球性能的同时减轻各阶段的工作量,对药物的研发、生产变更和监督管理等具有指导或支持作用。本文将注射用PLGA微球的释放机制、体内外释放测定涉及的常用方法和理论进行归纳总结,重点讨论了IVIVC尤其是A级IVIVC在微球制剂领域的建立及应用,为进一步的微球体内外相关性研究提供参考。     

Application of in vitro-in vivo correlations (IVIVC) in setting formulation release specifications

An in vitro-in vivo correlation (IVIVC) was established for an osmotic controlled-release dosage form by deconvolution using data from an immediate-release treatment as the characteristic response. The established IVIVC was evaluated internally (predicting data used to develop the IVIVC) and externally (predicting data not originally included in developing the IVIVC), and the application of the IVIVC in product development was demonstrated. The estimated in vivo dissolution profile compared favorably with the in vitro drug release profile. Good agreement was demonstrated between the estimated and observed cumulative drug release across the entire time course (level A correlation) with low (<10%) predictive error for both C(max) and AUC(infinity). External validation using lots not initially included in the model development compared very well with the observed in vivo profile, with mean prediction errors less than 10% for both C(max) and AUC(infinity). The proposed method demonstrates a schema for developing IVIVCs using data from biostudies routinely conducted during formulation development. The method should facilitate product optimization and can support setting in vitro dissolution specification.     

Formulation and development of hydrodynamically balanced system for metformin: in vitro and in vivo evaluation.

The objective of the present study was to develop a hydrodynamically balanced system of metformin as a single unit floating capsule. Various grades of low-density polymers were used for the formulation of this system. They were prepared by physical blending of metformin and the polymers in varying ratios. The formulation was optimized on the basis of in vitro buoyancy and in vitro release in simulated fed state gastric fluid (citrate phosphate buffer pH 3.0). Effect of various release modifiers was studied to ensure the delivery of drug from the HBS capsules over a prolonged period. Capsules prepared with HPMC K4M and ethyl cellulose gave the best in vitro percentage release and were taken as the optimized formulation. By fitting the data into zero order, first order and Higuchi model it was concluded that the release followed zero order release, as the correlation coefficient (R(2) value) was higher for zero order release. It was concluded from R(2) values for Higuchi model that drug release followed fickian diffusion mechanism. In vivo studies were carried out in rabbits to assess the buoyancy, as well as the pharmacokinetic parameters of the formulation using gamma scintigraphy. The formulation remained buoyant during 5h of study in rabbits. The comparative pharmacokinetic study was performed by administration of the optimized HBS capsules and immediate release capsules, both with radiolabeled metformin, using gamma counter. There was an increase in AUC in optimized HBS capsules of metformin when compared with immediate release formulation.     

A semiparametric deconvolution model to establish in vivo-in vitro correlation applied to OROS oxybutynin

In vitro-in vivo correlation (IVIVC) models may be used to predict in vivo drug concentration-time profiles given in vitro release characteristics of a drug. This prediction is accomplished by incorporating in vitro release characteristics as an input function (A(vitro)) to a pharmacokinetics model. This simple approach often results in biased predictions of observed in vivo drug concentrations, and it can result in rejecting IVIVC. To solve this problem we propose a population IVIVC model that incorporates the in vitro information and allows one to quantify possibly changed in vivo release characteristic. The model assumes linear kinetics and describes the in vivo release as a sum of A(vitro) and a nonparametric function (A(d), a spline) representing the difference in release due to in vivo conditions. The function A(vitro) and its variability enter the model as a prior distribution. The function A(d) is estimated together with its intersubject variability. The number of parameters associated with A(d) defines the model: no parameters indicates perfect IVIVC, a large number of parameters indicates poor IVIVC. The number of parameters is determined using statistical model selection criteria. We demonstrate the approach to solve the IVIVC problem of an oral extended release oxybutynin form (OROS), administered in three pharmacokinetic studies. These studies present a particular challenging case; that is, the relative bioavailability for the OROS administration is >100% compared with that of the immediate-release form. The result of our modeling shows that the apparent lack of IVIVC can be overcome: in vivo concentration can be predicted (within or across data sets) based on in vitro release rate together with a simple form of systematic deviation from the in vitro release.     

头孢氨苄胃漂浮缓释片的制备与质量评价

目的制备头孢氨苄胃漂浮缓释片,并考察其漂浮延迟时间及体外药物释放度。方法采用粉末直接压片工艺制备头孢氨苄胃漂浮缓释片,采用单因素实验方法筛选得到影响头孢氨苄胃漂浮缓释片体外漂浮延迟时间、漂浮时间和释放度的关键性辅料用量范围,最终以羟丙甲纤维素(HPMC K15M)用量、碳酸氢钠用量以及压片主压力作为考察因素,以头孢氨苄胃漂浮缓释片的漂浮延迟时间和1,4和8 h时间点的药物释放度作为评价指标,通过Box-Behnken实验设计优化得到头孢氨苄胃漂浮缓释片处方设计空间,并在设计空间任取一点连续制备3批头孢氨苄胃漂浮缓释片,评价其漂浮延迟时间及体外释放度。结果优化得到头孢氨苄胃漂浮缓释片的处方设计空间,每片HPMC K15M用量为260 mg,碳酸氢钠用量为60 mg,压片主压力为8 kN,制备的头孢氨苄胃漂浮缓释片漂浮延迟时间仅为12.1±0.5 min,在12 h内药物释放平缓,无药物突释。结论通过Box-Behnken实验设计优化得到的头孢氨苄胃漂浮缓释片处方,漂浮延迟时间较短,12 h维持漂浮状态,药物释放平稳。     

绿原酸生物黏附微球的制备及其体外释放特性的研究

目的制备绿原酸生物黏附微球,并考察其体外释放规律和黏附性。方法采用液中干燥法制备绿原酸生物黏附微球,结合微球的释放行为,单因素筛选最佳处方和工艺;用HPLC法考察其体外释放性质,采用滞留率作为考察其黏附性的指标。结果绿原酸生物黏附微球在最佳处方条件下的平均载药量为17.25%,平均包封率为57.25%;微球在体外12 h可释放92.07%,体外释药符合Weibull模型:ln[ln[1/(1-Q)]]=0.6376lnt-0.4373(r=0.9819);体外黏膜平均滞留率为78.54%,体内黏膜平均滞留率为30.23%。结论所用制备工艺稳定可行,所制微球具有明显的缓释效果。     

An investigation into the usefulness of generalized regression neural network analysis in the development of level A in vitro-in vivo correlation.

Quantitative correlations between in vivo and in vitro data (IVIVC) reduce the number of human in vivo studies, thus decreasing the overall time and expenses necessary for the development of optimal drug product formulation. Although linear regression analysis represents the simplest relationship, it is recognized that IVIVC should not be limited to linear relationship. With regards to the implementation of non-linear IVIVC models and the ability of artificial neural network (ANN) computing to cope with non-linear relationships, the usefulness of ANN analysis in the development of IVIVC merits further evaluation. The present paper is an attempt to develop an IVIVC for model sustained release paracetamol matrix tablet formulations employing various correlation approaches based on linear and non-linear modeling of in vitro and in vivo data. Currently accepted compendial methodology was compared with the alternative approaches, involving general mixed effects model and generalized regression neural network (GRNN) analysis, in order to evaluate their usefulness for predicting the in vivo behavior of drug products. Although based on analogous approaches, data generated by GRNN were closer to those observed in vivo, leading to the higher level of IVIVC than obtained by convolution. It can be assumed that GRNN analysis was able to generalize complex relations between the output and input parameters and could account for the differences in drug release kinetics observed under various conditions in vitro, thus offering potential as a reliable and robust estimate of drug products in vivo behavior.     

Preparation and evaluation of glyceryl monooleate-coated hollow-bioadhesive microspheres for gastroretentive drug delivery

The purpose of this study was to produce hollow and bioadhesive microspheres to lengthen drug retention time in the stomach. In these microspheres, ethylcellulose was used as the matrix, Eudragit EPO was employed to modulate the release rate, and glyceryl monooleate (GMO) was the bioadhesive polymer in situ. The morphological characteristics of the microspheres were defined using scanning electron microscopy. The in vitro release test showed that the release rate of drug from the microspheres was pH-dependent, and was not influenced by the GMO coating film. The prepared microspheres demonstrated strong mucoadhesive properties with good buoyancy both in vitro and in vivo. Pharmacokinetic analysis indicated that the elimination half-life time of the hollow-bioadhesive microspheres was prolonged, and that the elimination rate was decreased. In conclusion, the hollow-bioadhesive synergic drug delivery system may be advantageous in the treatment of stomach diseases.