Gastro-intestinal transit of a multiple-unit formulation (metoprolol CR/ZOK) and a non-disintegrating tablet with the emphasis on colon

The main aim of the present study was to compare the transit through the entire gastro-intestinal channel of a membrane-coated, multiple-unit system containing metoprolol and a single-unit placebo tablet using gamma-scintigraphy. The two formulations were simultaneously administered, together with a breakfast (2800 kJ), to eight healthy male volunteers. The mean gastric emptying time for the pellets was 3.6 (range 1.5–5.0) h on average and the mean gastric emptying time for the tablet was 9.6 (range 3.3-(14–24)) h. This difference was statistically significant. The mean transit through the small intestine, 3.1 (range 1.5–5.7) h and 2.0 (range 1.0–3.3) h for the pellets and the tablet respectively, did not differ significantly between the formulations. The pellets had a longer residence time in the colon in all subjects compared with the tablet. The mean colon transit time was 28 (range 6.0–48) h on average for the pellets and 15 (range 3.8–26) h for the tablet. The tablet was expelled 26 (range 9.5–42) h after intake on average, whereas the pellets remained for a significantly longer time period (mean 35, range 10–55 h). The desired extended-release properties and metoprolol absorption was obtained throughout the entire gastrointestinal (GI) tract.     

Pulmonary Bioavailability of a Phosphorothioate Oligonucleotide (CGP 64128A): Comparison with Other Delivery Routes

Purpose. Phosphorothioate antisense oligodeoxynucleotides are promising therapeutic candidates. When given systemically in clinical trials they are administered via slow intravenous infusion to avoid their putative plasma concentration-dependent haemodynamic side-effects. In this study, we have evaluated alternative parenteral and non-parenteral administration routes which have the potential to enhance the therapeutic and commercial potential of these agents. Methods. The delivery of CGP 64128A by intravenous, subcutaneous, intra-peritoneal, oral and intra-tracheal (pulmonary) routes was investigated in rats using radiolabelled compound and supported by more specific capillary gel electrophoretic analyses. Results. Intravenously administered CGP 64128A exhibited the rapid blood clearance and distinctive tissue distribution which are typical for phosphorothioate oligodeoxynucleotides. Subcutaneous and intra-peritoneal administration resulted in significant bioavailabilities (30.9% and 28.1% over 360 min, respectively) and reduced peak plasma levels when compared with intravenous dosing. Administration via the gastrointestinal tract gave negligible bioavailability (<2%). Intra-tracheal administration resulted in significant but dose-dependent bioavailabilities of 3.2, 16.5 and 39.8% at 0.06, 0.6 and 6.0 mg/kg, respectively. Conclusions. Significant bioavailabilities of CGP 64128A were achieved following subcutaneous, intra-peritoneal and intra-tracheal administration. Pulmonary delivery represents a promising mode of non-parenteral dosing for antisense oligonucleotides. The dose-dependent increase in pulmonary bioavailability suggests that low doses may be retained in the lungs for local effects whereas higher doses may be suitable for the treatment of a broader spectrum of systemic diseases.     

Nonlinear Mixed Effects Modeling of Single Dose and Multiple Dose Data for an Immediate Release (IR) and a Controlled Release (CR) Dosage Form of Alprazolam

Purpose. NONMEM was applied to single dose and multiple dose bioavailability data for an immediate release (IR) and a controlled release (CR) dosage form of alprazolam to acquire additional information from the data which are not easily obtainable by traditional means. Methods. The objective function value (OBJ) and diagnostic plots were used as measures of goodness of fit of the model to the data. A change in the OBJ value of 7.9 was necessary to show statistical significance (p < 0.005) between two models when the two models differed by 1 parameter. Results. A two-compartment linear model with first-order absorption and elimination best describes the data. Including a lag time, two different rates of absorption (KA_IR and KA_CR), and bioavailability for the CR relative to the IR dosage form significantly improved the fit of the model to the data. Cigarette smoking was associated with a 100% increase in clearance of alprazolam as compared to non-smokers. The higher residual variability observed in this study, where interoccasion variability (IOV) was not initially modeled, could be explained to a large extent by the presence of significant interoccasion variability (IOV). Conclusions. Since alprazolam has been suggested to be mainly metabolized by the CYP3A4 isozyme in humans, it appears that tobacco could be an inducer of CYP3A4 and/or alprazolam may be metabolized by other isozyme(s) (specifically, CYP1A1/1A2) that are induced by cigarette smoke. The population pharmacokinetic model approach combined with exploratory graphical data analysis is capable of identifying important covariates from well-controlled 'data rich' Phase I studies early in drug development.     

High-Performance Liquid Chromatographic Assay of a Central Nervous System (CNS)-Directed Estradiol Chemical Delivery System and Its Application After Intravenous Administration to Rats

A redox-based chemical delivery system for estradiol (E₂-CDS) has been shown capable of sustained and brain-selective delivery of estradiol (E₂). A re versed-phase high-performance liquid chromatographic (HPLC) method is presented for the analysis of E₂-CDS and its oxidized quaternary metabolite (E₂-Quat) in biological fluids or tissues. The assay utilizes a precolumn enrichment technique and detects plasma levels down to 10 ng/ml E₂-Quat and 20 ng/ml E₂-CDS. Sample preparation is rapid and simple. Samples are homogenized with acetonitrile, then centrifuged, and the supernatant is directly injected into the HPLC system. A water delivering pump injects the sample on a precolumn where the drug is concentrated. The mobile phase backflushes the retained compound onto the analytical column. At the same time, another sample can be injected onto a second precolumn. This alternating precolumn sample enrichment technique allows the injection of large volumes, up to 1800 µl. Plasma and tissue samples of rats collected after i.v. administration of a single 15-mg/kg E₂-CDS dose were analyzed for E₂-CDS and E₂-Quat by this procedure. The results show sustained brain levels of E₂-Quat and prolonged half-life in brain compared to six peripheral tissues measured. These data support the concept of brain-targeted delivery using redox carrier systems of this type.     

Preparation and Evaluation of Multiple Emulsions Water-in-oil-in-water (w/o/w) as Delivery System for Influenza Virus Antigens

In this study, investigations have been carried out to prepare adjuvant active delivery systems; multiple water-in-oil-in-water (w/o/w) emulsion formulations, containing influenza virus surface antigen Hemagglutinin (HA). A modified two-stage emulsification method has been used to prepare multiple emulsions. After improving multiple (w/o/w) emulsion formulations; F1: purified antigen solution (PAS)/soybean oil, HCO-40 and span 80/pluronic F-68, F2: PAS and HPβCD/soybean oil, HCO-40 and span 80/pluronic F-68, F3: PAS/squalane, HCO-40 and span 80/pluronic F-68, formulations were selected for the stability study that continued for a 3 month duration. To evaluate the stability of these formulations, microscopic observation, osmolarities of the internal and external aqueous phases, pH, globule size and viscosity were determined. SDS-PAGE (silver staining) was used to evaluate HA and the micro-bicinchoninic acid (mBCA) assay was used to determine the in vitro release of antigen from formulations. Immune responses of formulations were investigated in Wistar Albino rats and compared with the immune response raised against the conventional vaccine. These responses were detected with Hemagglutination Inhibition (HAI) assay.

The results of this study demonstrated that HA was well entrapped in the multiple (w/o/w) emulsion formulations. Molecular weight and antigenicity of the entrapped HA were not affected by the emulsification procedure. These results suggest that multiple emulsion formulations entrapping influenza antigen may have potential for immunization studies as one of the vaccine delivery system with adjuvant properties.     

Preparation and Characterization of a Composite PLGA and Poly(Acryloyl Hydroxyethyl Starch) Microsphere System for Protein Delivery

Purpose. To prepare and characterize a novel composite microsphere system based on poly(D,L-lactide-co-glycolide) (PLGA) and poly(acryloyl hydroxyethyl starch) (acHES) hydrogel for controlled protein delivery. Methods. Model proteins, bovine serum albumin, and horseradish peroxidase were encapsulated in the acHES hydrogel, and then the protein-containing acHES hydrogel particles were fabricated in the PLGA matrix by a solvent extraction or evaporation method. The protein-loaded PLGA-acHES composite microspheres were characterized for protein loading efficiency, particle size, and in vitro protein release. Protein stability was examined by size-exclusion chromatography, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and monitoring the enzymatic activity. Results. Scanning electron microscopy showed discrete PLGA microspheres containing many acHES particles. The composite microspheres were spherical and smooth in size range of 39-93 m. The drug loading efficiency ranged from 51 to 101%. The composite microspheres showed more favorable in vitro release than conventional PLGA microspheres. The composite microspheres showed 20% less initial with a gradual sustained release compared to high burst (60%) followed by a very slow release with the conventional PLGA microspheres. The composite microspheres also stabilized encapsulated proteins from the loss of activity during the microsphere preparation and release. Proteins extracted from the composite microspheres showed good stability without protein degradation products and structural integrity changes in the size-exclusion chromatography and SDS-PAGE analyses. Horseradish peroxidase extracted from microspheres retained more than 81% enzymatic activity. Conclusion. The PLGA-acHES composite microsphere system could be useful for the controlled delivery of protein drugs.     

pH响应纳米载药系统DOX@MIL-101(Fe)-NH2/HA的制备及靶向抗肿瘤作用研究

目的 制备透明质酸(hyaluronan acid,HA)修饰的纳米金属有机框架MIL-101(Fe)-NH₂载药系统,并进行体外抗肿瘤活性评价。方法 采用溶剂热法制备MIL-101(Fe)-NH₂,通过物理吸附法制备HA修饰载阿霉素的DOX@MIL-101(Fe)- NH₂/HA(DMNH)。并利用扫描电子显微镜、X射线衍射仪、氮气吸附-脱附法等对所合成材料及载药系统进行表征。采用透析法考察了载药系统的体外释药行为,并利用激光共聚焦显微镜观察HepG2细胞对其摄取情况。结果 MIL-101(Fe)-NH₂形貌为规则的正八面体,比表面积和粒径分别为1 061.45 m²·g^-1和200 nm。载药后DMNH的尺寸均一,比表面积为205.84 m²·g^-1,粒径为300 nm。MIL-101(Fe)-NH₂的最佳载药率为65.3%,根据药物释放曲线,从装有阿霉素的MIL-101(Fe)-NH₂载药体系(DMN)、DMNH中释放阿霉素显示出时间和pH依赖性。细胞摄取试验结果显示DMNH较其他组别可以运输更多的阿霉素进入HepG2细胞。细胞毒性的结果证实在相同的药物浓度下,DMNH表现出更高的肿瘤细胞杀伤效率。结论 本研究制备的DMNH载药系统结构稳定、载药量和释药效率高,同时具有优异的肿瘤细胞靶向性及pH响应释放特性,在抗肿瘤药物靶向传输方面具有应用前景。     

Application of Artificial Neural Networks in the Design and Optimization of a Nanoparticulate Fingolimod Delivery System Based on Biodegradable Poly(3-Hydroxybutyrate-Co-3-Hydroxyvalerate)

Formulation of a nanoparticulate Fingolimod delivery system based on biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) was optimized according to artificial neural networks (ANNs). Concentration of poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PVA and amount of Fingolimod is considered as the input value, and the particle size, polydispersity index, loading capacity, and entrapment efficacy as output data in experimental design study. In vitro release study was carried out for best formulation according to statistical analysis. ANNs are employed to generate the best model to determine the relationships between various values. In order to specify the model with the best accuracy and proficiency for the in vitro release, a multilayer percepteron with different training algorithm has been examined. Three training model formulations including Levenberg-Marquardt (LM), gradient descent, and Bayesian regularization were employed for training the ANN models. It is demonstrated that the predictive ability of each training algorithm is in the order of LM > gradient descent > Bayesian regularization. Also, optimum formulation was achieved by LM training function with 15 hidden layers and 20 neurons. The transfer function of the hidden layer for this formulation and the output layer were tansig and purlin, respectively. Also, the optimization process was developed by minimizing the error among the predicted and observed values of training algorithm (about 0.0341).     

In Vivo and In Vitro Diclofenac Sodium Evaluation After Rectal Application of Soft Gelatine Capsules Enabling Application Induced Transformation (AIT) into a Semisolid System of Liquid Crystals (SSLC) for Controlled Release

Purpose. Reverse micellar solutions of diclofenac sodium were encapsulated in soft gelatine capsules. On contact with aqueous media they exhibited an application induced transformation (AIT) into a semisolid system of liquid crystals (SSLC) which slows down drug release. The aim of the present paper was to study in vitro and in vivo drug release from these systems after rectal application. Methods. In vitro drug release was determined in a self-constructed dissolution apparatus to simulate rectal application. For in vivo bioavailability studies rabbits were used as animal models. In vitro release and in vivobioavailability of the capsules was compared to Voltaren^® suppositories. Results. The release profiles of the in vitro experiments show zero-order kinetics. The in vivo bioavailability studies show bioequivalence in terms of AUC for both formulations (capsules and Voltaren^® suppositories). The mean residence time (parameter of sustained release) of the capsules is three time longer in comparison to Voltaren^® suppositories. Conclusions. Rectal administration of capsules provides an appropiate route for controlled release via AIT-SSLC which could be clearly verified in rabbits.     

Biochemical Characterization of a Glucocorticoid-Induced Membrane Protein (RM3/1) in Human Monocytes and Its Application as Model System for Ranking Glucocorticoid Potency

Purpose. Upon glucocorticoid stimulation, human mononuclear leucocytes express an antigen, RM3/1, which characterizes a subpopulation of human monocytes and macrophages evolving in late phase of inflammation. We investigated biochemical properties of the RM3/1 antigen and correlations between antigen expression and glucocorticoid potency. Methods. Biochemical properties were analyzed after solubilization by immunoaffmity methods and SDS-PAGE. Results. Induction of the RM3/1 antigen is a glucocorticoid receptor mediated process, in contrast, inflammatory mediators such as LPS or TPA were not able to upregulate RM3/1 expression. After SDS-PAGE, the antigen appeared as a 130 kDa (nonreduced)/150 kDa (reduced) glycoprotein with a 25 kDa N-linked glycoportion. The interdependence between antigen density and glucocorticoid efficacy was assessed by calculation of relative antigen expression induced by dexamethasone, fluticasone propionate, budesonide, triamcinolone acetonide, flunisolide, beclomethasone, prednisolone and triamcinolone. Relative antigen expression was significantly correlated with the relative receptor affinity of the glucocorticoid. Conclusions. We described biochemical properties of the glucocorticoid-induced protein RM3/1. Though the precise role of the RM3/1 antigen in the antiinflammatory process is not fully understood yet, an useful application of the induced expression could already be demonstrated for pre-clinical screening of glucocorticoid potency.