Quality by Design Approach for Optimization of Microbial and pH-Triggered Colon-Targeted Tablet Formulation Using Carboxymethyl Tamarind Gum.

ABSTRACT The purpose of this study was to apply the quality by design (QbD) approach in the development of a microbial and pH-triggered colon-targeted budesonide tablet. A retrospective research strategy was used to select various polysaccharide-based natural gums such as tamarind gum, gellan gum, karaya gum, gum ghutti, and khaya gum, which were then evaluated for their effectiveness in microbial degradation and targeting the colon. Viscosity profiles were generated in the presence of a prebiotic culture medium prepared by using the Velgut capsule that mimicked the impact of 4% rat cecal content and helpful in screening of natural polymer. Based on the cumulative drug release data of preliminary batches, carboxymethyl (CM) tamarind gum was identified as a superior and an excellent polymer over the tamarind gum for formulation development. The presence of water as a bridging agent in wet granulation also played an important role in the retardation of drug release. Tablets were supercoated with the enteric polymer, Eudragit S100. The Box-Behnken design was utilized, where the selected independent variables were the proportion of CM tamarind gum, % water proportion, and % weight gain of Eudragit S 100 to optimize the formulation. The optimized design space was generated with the criteria that a drug release should be of less than 5% within the first 2 h, less than 10% within the first 5 h, and more than 70% within the first 8 h, to achieve colon targeting. The optimized batch F3 was found stable as per International Council for Harmonisation guidelines. The roentgenography study for optimized formulation demonstrated that it remained intact for 5 h and, at 7 h, was disseminated completely. CM tamarind gum is efficient for colon targeting, and its proportion in 100 mg along with an enteric coating of 6% led to the optimized formulation.

Phenylboronic Acid Modification Augments the Lysosome Escape and Antitumor Efficacy of a Cylindrical Polymer Brush-Based Prodrug.

Timely lysosome escape is of paramount importance for endocytosed nanomedicines to avoid premature degradation under the acidic and hydrolytic conditions in lysosomes. Herein, we report an exciting finding that phenylboronic acid (PBA) modification can greatly facilitate the lysosome escape of cylindrical polymer brushes (CPBs). On the basis of our experimental results, we speculate that the mechanism is associated with the specific interactions of the PBA groups with lysosomal membrane proteins and hot shock proteins. The featured advantage of the PBA modification over the known lysosome escape strategies is that it does not cause significant adverse effects on the properties of the CPBs; on the contrary, it enhances remarkably their tumor accumulation and penetration. Furthermore, doxorubicin was conjugated to the PBA-modified CPBs with a drug loading content larger than 20%. This CPBs-based prodrug could eradicate the tumors established in mice by multiple intravenous administrations. This work provides a novel strategy for facilitating the lysosome escape of nanomaterials and demonstrates that PBA modification is an effective way to improve the overall properties of nanomedicines including the tumor therapeutic efficacy.

Immune Effect Regulated by the Chain Length: Interaction between Immune Cell Surface Receptors and Synthetic Glycopolymers.

Glycopolymer-based drugs for immunotherapy have attracted increasing attention because the affinity between glycans and proteins plays an important role in immune responses. Previous studies indicate that the polymer chain length influences the affinity. In the studies on enhancing the immune response by glycans, it is found that both oligosaccharides and long-chain glycopolymers work well. However, there is a lack of systematic studies on the immune enhancement effect and the binding ability of oligomers and polymers to immune-related proteins. In this paper, to study the influence of the chain length, glycopolymers based on N-acetylglucosamine with different chain lengths were synthesized, and their interaction with immune-related proteins and their effect on dendritic cell maturation were evaluated. It was proved that compared with l-glycopolymers (degree of polymerization (DP) > 20), s-glycopolymers (DP < 20) showed better binding ability to the dendritic cell-specific ICAM-3-grabbing nonintegrin protein and the toll-like receptor 4 and myeloid differentiation factor 2 complex protein by quartz crystal microbalance and molecular docking simulation. When the total sugar unit amounts are equal, s-glycopolymers are proved to be superior in promoting dendritic cell maturation by detecting the expression level of CD80 and CD86 on the surface of dendritic cells. Through the combination of experimental characterization and theoretical simulation, a deep look into the interaction between immune-related proteins and glycopolymers with different chain lengths is helpful to improve the understanding of the immune-related interactions and provides a good theoretical basis for the design of new glycopolymer-based immune drugs.

Aggregation Behavior of Poly(Acrylic acid-co-Octadecyl Methacrylate) and Bovine Serum Albumin in Aqueous Solutions.

Polymer-protein complexing systems have been extensively studied because of their wide application in biomedicine and industry. Here, we studied the aggregation behavior of the hydrophobically associating water-soluble polymer poly(acrylic acid-co-octadecyl methacrylate) [P(AA-co-OMA)] prepared with nonionic surfactant as an emulsifier and bovine serum albumin (BSA) in aqueous solution. We identified the optimal composite conditions of P(AA-co-OMA) and BSA aqueous solution. We measured the zeta potential, dynamic light-scattering particle size, and surface tension of P(AA-co-OMA) and BSA mixed aqueous solution. The results showed that the aggregation behavior between the polymer and BSA relied mainly on the hydrophobic interactions between the molecules. In addition, the best compounding condition was 8 wt.% of P(AA-co-OMA) content. The structure of hydrophobically associating polymer P(AA-co-OMA) and its aggregation with BSA were characterized by Fourier-transform infrared spectroscopy. The infrared spectroscopy results identified the hydrogen bonding behavior of the amino and carboxyl groups between the polymer and BSA. This behavior was also confirmed using thermogravimetric analysis and differential scanning calorimetry. The thermal decomposition temperature and melting temperature of BSA changed before and after it was combined with the polymer. We measured the morphology of the polymer BSA aggregate with 8 % polymer content by transmission electron microscopy. The binding mechanism was investigated, as well.

Bacterial Redox Potential Powers Controlled Radical Polymerization.

Microbes employ a remarkably intricate electron transport system to extract energy from the environment. The respiratory cascade of bacteria culminates in the terminal transfer of electrons onto higher redox potential acceptors in the extracellular space. This general and inducible mechanism of electron efflux during normal bacterial proliferation leads to a characteristic fall in bulk redox potential (Eh), the degree of which is dependent on growth phase, the microbial taxa, and their physiology. Here, we show that the general reducing power of bacteria can be subverted to induce the abiotic production of a carbon-centered radical species for targeted bioorthogonal molecular synthesis. Using two species, Escherichia coli and Salmonella enterica serovar Typhimurium as model microbes, a common redox active aryldiazonium salt is employed to intervene in the terminal respiratory electron flow, affording radical production that is mediated by native redox-active molecular shuttles and active bacterial metabolism. The aryl radicals are harnessed to initiate and sustain a bioorthogonal controlled radical polymerization via reversible addition-fragmentation chain transfer (BacRAFT), yielding a synthetic extracellular matrix of "living" vinyl polymers with predetermined molecular weight and low dispersity. The ability to interface the ubiquitous reducing power of bacteria into synthetic materials design offers a new means for creating engineered living materials with promising adaptive and self-regenerative capabilities.

Eudragit L-100 Capsules Aromatize and Quaternerize Chitosan for Insulin Nanoparticle Oral Delivery During Toxic Oxidative Stress in Rat Liver and Kidney.

BACKGROUND: Insulin, like most peptides, is classified as a hydrophilic and macromolecular drug that is considered as a low permeable and unstable compound in the gastrointestinal (GI) tract. The acidic condition of the stomach can degrade insulin molecules. Moreover, the presence of proteolytic activities of some enzymes such as trypsin and chymotrypsin can hydrolyze amide-bonds between various amino-acids in the structures of peptides and proteins. However, due to its simplicity and high patient compliance, oral administration is the most preferred route of systemic drug delivery, and for the development of an oral delivery system, some obstacles in oral administration of peptides and proteins including low permeability and low stability of the proteins in GI should be overcome. OBJECTIVE: In this study, the effects of orally insulin nanoparticles (INPs) prepared from quaternerized N-aryl derivatives of chitosan on the biochemical factors of the liver in diabetic rats were studied. METHODS: INPs composed of methylated (amino benzyl) chitosan were prepared by the PEC method. Lyophilized INPs were filled in pre-clinical capsules, and the capsules were enteric-coated with Eudragit L100. Twenty Male Wistar rats were randomly divided into four groups: group1: normal control rats, group 2: diabetic rats, group 3: diabetic rats received capsules INPs(30 U/kg/day, orally), group 4: the diabetic rats received regular insulin (5 U/kg/day, subcutaneously). At the end of the treatment, serum, liver and kidney tissues were collected. Biochemical parameters in serum were measured using spectrophotometric methods. Also, oxidative stress was measured in plasma, liver and kidney. Histological studies were performed using H and E staining . RESULTS: Biochemical parameters, and liver and kidney injury markers in serum of the diabetic rats that received INPs improved significantly compared with the diabetic group. INPs reduced oxidative toxic stress biomarkers in serum, liver and kidney of the diabetic treated group. Furthermore, a histopathological change was developed in the treated groups. CONCLUSION: Capsulated INPs can prevent diabetic liver and oxidative kidney damages (similar regular insulin). Therefore oral administration of INPs appears to be safe. Lay Summary: Although oral route is the most preferred route of administration, but oral delivery of peptides and proteins is still a challenging issue. Diabetes Mellitus may lead to severe complications, which most of them are life-threatening. In this study, we are testing the toxicity of oral insulin nanoparticles in kidney and liver of rats. For this investigation, we will prepare insulin nanoparticles composed of a quaternized derivative of chitosan. The nanoparticles will be administered orally to rats and the level of oxidative stress in their liver and kidney will be determined. The data will be compared to the subcutaneous injection of insulin.

Fabrication of a porous polymer membrane enzyme reactor and its enzymatic kinetics study in an artificial kidney model.

A porous polymer membrane-based d-amino acid oxidase (DAAO) reactor was developed that mimicked enzymatic activity in a renal ischemia model. Using glycidyl methacrylate as a biocompatible reactive monomer, poly(styrene-glycidyl methacrylate) was synthesized via a reversible addition fragment chain transfer polymerization technique. The prepared porous polymer membrane was used as a support to effectively immobilize DAAO. Compared to DAAO modified on nonporous polymer membrane and free DAAO in solution, the constructed porous polymer membrane-based DAAO enzyme reactor displayed 3-fold and 19-fold increase in enzymolysis efficiency, respectively. In addition, a chiral ligand exchange capillary electrophoresis system for DAAO was used to study DAAO enzymatic kinetics with d,l-methionine as the substrate. The proposed porous polymer membrane-based enzyme reactor showed excellent performance both on reproducibility and stability. Moreover, the enzyme reactor was successfully applied to mimic DAAO activity in a renal ischemia model. These results demonstrated that the enzyme could be efficiently immobilized onto a porous polymer membrane as an enzyme reactor and has great potential in mimicking the enzymatic activity in kidney.

Cellular AND Gates: Synergistic Recognition to Boost Selective Uptake of Polymeric Nanoassemblies.

The development of nanoparticle-based biomedical applications has been hampered due to undesired off-target effects. Herein, we outline a cellular AND gate to enhance uptake selectivity, in which a nanoassembly-cell interaction is turned on, only in the concurrent presence of two different protein functions, an enzymatic reaction (alkaline phosphatase, ALP) and a ligand-protein (carbonic anhydrase IX, CA IX) binding event. Selective uptake of nanoassemblies was observed in cells that overexpress both of these proteins (unicellular AND gate). Interestingly, selective uptake can also be achieved in CA IX overexpressed cells, when cocultured with ALP overexpressed cells, where the nanoassembly presumably acts as a mediator for cell-cell communication (bicellular AND gate). This logic-gated cellular uptake could find use in applications such as tumor imaging or theranostics.

"Tuning aggregative versus non-aggregative lectin binding with glycosylated nanoparticles by the nature of the polymer ligand".

Glycan-lectin interactions drive a diverse range of biological signaling and recognition processes. The display of glycans in multivalent format enables their intrinsically weak binding affinity to lectins to be overcome by the cluster glycoside effect, which results in a non-linear increase in binding affinity. As many lectins have multiple binding sites, upon interaction with glycosylated nanomaterials either aggregation or surface binding without aggregation can occur. Depending on the application area, either one of these responses are desirable (or undesirable) but methods to tune the aggregation state, independently from the overall extent/affinity of binding are currently missing. Herein, we use gold nanoparticles decorated with galactose-terminated polymer ligands, obtained by photo-initiated RAFT polymerization to ensure high end-group fidelity, to show the dramatic impact on agglutination behaviour due to the chemistry of the polymer linker. Poly(N-hydroxyethyl acrylamide) (PHEA)-coated gold nanoparticles, a polymer widely used as a non-ionic stabilizer, showed preference for aggregation with lectins compared to poly(N-(2-hydroxypropyl)methacrylamide) (PHPMA)-coated nanoparticles which retained colloidal stability, across a wide range of polymer lengths and particle core sizes. Using biolayer interferometry, it was observed that both coatings gave rise to similar binding affinity and hence provided conclusive evidence that aggregation rate alone cannot be used to measure affinity between nanoparticle systems with different stabilizing linkers. This is significant, as turbidimetry is widely used to demonstrate glycomaterial activity, although this work shows the most aggregating may not be the most avid, when comparing different polymer backbones/coating. Overall, our findings underline the potential of PHPMA as the coating of choice for applications where aggregation upon lectin binding would be problematic, such as in vivo imaging or drug delivery.

The influence of gradient and statistical arrangements of guanidinium or primary amine groups in poly(methacrylate) copolymers on their DNA binding affinity.

Herein, we report the first gradient guanidinium containing cationic copolymers and investigate their binding ability to plasmid DNA (pDNA). To understand the effect of different charge distributions and cationic charge sources (primary amines vs. guanidinium group) on (pDNA) binding affinity, we synthesized a library of well-defined statistical cationic copolymers comprising N-(2-hydroxy-propyl)methacrylamide (HPMA) and N-(3-aminopropyl)methacrylamide (APMA) or N-(3-guanidinopropyl)methacrylamide (GPMA) and compared them with gradient polymers containing the same monomers of similar composition. All copolymers were synthesized through aqueous reversible addition-fragmentation chain transfer (aRAFT) polymerization at various monomer ratios by aiming at similar molar masses with low dispersity indices. For the molar mass characterization, in addition to size exclusion chromatography with two different systems, hydrodynamic characterization utilizing analytical ultracentrifugation, viscometry, and accompanied density measurements was conducted. pDNA was used as a model drug to demonstrate the impact of copolymer architecture on binding efficiency. For both HPMA-APMA and HPMA-GPMA copolymers, the gradient distribution demonstrated superior binding and denser packing of pDNA than their statistical counterparts at 20% and lower cationic charge contents. With respect to charge origin, the guanidinium group represented a higher binding efficiency than primary amines with the same nitrogen to phosphate ratio (N/P ratio). Our study demonstrates the profound effect of gradient monomer arrangement on the ability of polyplex formation and reveals the potential for further investigation in gene delivery applications. Gradient guanidinium containing copolymers have great promise for gene delivery applications due to their high affinity toward pDNA even at very low degrees (<20%) of charged monomer content.

A neutral water-soluble mitochondria-targeting polymer.

We report the first neutral and water-soluble polymer capable of strong mitochondrial targeting in vitro and in vivo, zwitterionic poly[2-(N-oxide-N,N-diethylamino)ethyl methacrylate] (OPDEA). OPDEA is quickly internalized via macropinocytosis by various cancer cells and transferred into the mitochondria, which slightly lowers the mitochondrial membrane potential as determined by the JC-1 assay.

Physiological Stimuli Induce PAD4-Dependent, ROS-Independent NETosis, With Early and Late Events Controlled by Discrete Signaling Pathways.

Neutrophils are known to extrude decondensed chromatin, thus forming NETs (neutrophil extracellular traps). These structures immobilize pathogens, thereby preventing their spreading, and are also adorned with antimicrobial molecules. NETs can also influence pathogenesis in chronic inflammation, autoimmunity, and cancer. Despite the importance of NETs, the molecular mechanisms underlying their formation, as well as the upstream signaling pathways involved, are only partially understood. Likewise, current methodological approaches to quantify NETs suffer from significant drawbacks, not the least being the inclusion of a significant non-specific signal. In this study, we used novel, fluorescent polymers that only bind extruded chromatin, allowing a specific and standardized quantification of NETosis. This allowed us to reliably rank the relative potency of various physiologic NET inducers. In neutrophils activated with such stimuli, inhibition of the Syk or PI3K pathways blocked NETosis by acting upon late events in NET formation. Inhibition of the TAK1, p38 MAPK, or MEK pathways also hindered NETosis, but by acting on early events. By contrast, inhibiting PKC, Src family kinases, or JNK failed to prevent NETosis; cycloheximide or actinomycin D were also ineffective. Expectedly, NET formation was deeply compromised following inhibition of the NADPH oxidase in PMA-activated neutrophils, but was found to be ROS-independent in response to physiological agonists. Conversely, we show for the first time in human neutrophils that selective inhibition of PAD4 potently prevents NETosis by all stimuli tested. Our data substantially extends current knowledge of the signaling pathways controlling NETosis, and reveals how they affect early or late stages of the phenomenon. In view of the involvement of NETs in several pathologies, our findings also identify molecular targets that could be exploited for therapeutic intervention.

Histidine-rich glycoprotein-induced vascular normalization improves EPR-mediated drug targeting to and into tumors.

Tumors are characterized by leaky blood vessels, and by an abnormal and heterogeneous vascular network. These pathophysiological characteristics contribute to the enhanced permeability and retention (EPR) effect, which is one of the key rationales for developing tumor-targeted drug delivery systems. Vessel abnormality and heterogeneity, however, which typically result from excessive pro-angiogenic signaling, can also hinder efficient drug delivery to and into tumors. Using histidine-rich glycoprotein (HRG) knockout and wild type mice, and HRG-overexpressing and normal t241 fibrosarcoma cells, we evaluated the effect of genetically induced and macrophage-mediated vascular normalization on the tumor accumulation and penetration of 10-20 nm-sized polymeric drug carriers based on poly(N-(2-hydroxypropyl)methacrylamide). Multimodal and multiscale optical imaging was employed to show that normalizing the tumor vasculature improves the accumulation of fluorophore-labeled polymers in tumors, and promotes their penetration out of tumor blood vessels deep into the interstitium.

Mucoadhesive Properties of Eudragit®RS100, Eudragit®S100, and Poly(ε-caprolactone) Nanocapsules: Influence of the Vehicle and the Mucosal Surface.

The use of polymers as mucoadhesive materials has been explored in several drug delivery systems. It is well known that the resulting mucoadhesiveness not only depends on the polymers by themselves, but also on the way they are delivered and on the application target. However, little attention has been given to the combined effect of such characteristics. Therefore, the objective of this study is to analyze the mucoadhesion resulting from combined effects of nanocapsules produced with polymers of different ionic properties, Eudragit®RS100, Eudragit®S100, or poly(ε-caprolactone), when they are incorporated into different vehicles (suspension, hydrogel, and powder) and applied on different mucosal surfaces (mucin, porcine vaginal, and buccal mucosa). Mucoadhesion was measured by a tensile stress tester. Our findings show that polymeric self-assembling as nanocapsules improved the mucoadhesion of the polymers. Eudragit®RS100 nanocapsules have the best performance, independently of the vehicle and surface used. Regarding the vehicle, hydrogels showed higher adhesion when compared to suspensions and powders. When considering different types of surfaces, mucin presented a similar pattern like the animal mucosa, but it overestimated the mucoadhesiveness of all formulations. In conclusion, this study demonstrated that the best strategy to achieve high mucoadhesive formulations is by incorporating Eudragit®RS100 nanocapsules in hydrogels. Moreover, mucin is a suitable substrate to compare and screen different formulations but not as a conclusive estimation of the mucoadhesion values that can be achieved. These results are summarized in a decision tree that can help to understand different strategies of combination of these factors and the expected outcomes.

Interactions of dimethylaminoethyl methacrylate copolymer with non-acidic drugs demonstrated high solubilization in vitro and pronounced sustained release in vivo.

Recent work demonstrated remarkable solubilization effects of methacrylate-copolymer Eudragit EPO (EPO) not only with acidic drugs but interestingly also with poorly soluble basic compounds. The current work studied EPO-mediated solubilization effects first in vitro using felodipine (FLP) and tamoxifen (TMX) as model compounds. EPO-containing solutions were subsequently compared in a rat pharmacokinetic study against reference solutions and suspensions. Surprisingly, solution formulations with EPO did not result in an increased relative oral bioavailability. Exposure was reduced for both drugs and plasma-profiles of the EPO solutions showed a delayed and lower maximum plasma concentration compared to the reference formulations. This sustained in vivo release was likely due to combined effects of strong drug-polymer interactions and pH-dependent precipitation of the polymer in the rat intestine. Remarkable was that in vitro drug-polymer coprecipitates did not reveal crystalline drug by polarized light microscopy. Thus, such a formulation approach provides a rather simple opportunity to modify drug release in vivo. However, this may be rather an approach for preclinical formulations, if high peak-to-trough ratios of plasma levels are problematic regarding adverse effects related to Cmax or if plasma concentrations drop too fast below required pharmacological concentrations.

Antifungal activity of osthol in vitro and enhancement in vivo through Eudragit S100 nanocarriers.

In vitro interaction of osthol (Ost) and fluconazole (FLC) was investigated against 11 fluconazole-resistant clinical isolates of Candida albicans. Synergistic activities were determined using the checkerboard microdilution assay. The results of agar diffusion test confirmed the synergistic interaction. We used an enteric material Eudragit S100 for preparation of Ost nanoparticle (Ost-NP) to improve the oral bioavailability, biological activity of Ost. The physicochemical characteristics of Ost-S100-NP revealed Ost-S100-NP with mean particle size of 55.4±0.4 nm, encapsulation efficiency of 98.95±0.06%, drug loading efficiency of 23.89±0.25%, yield of 98.5±0.1% and a polydispersity index (PDI) of 0.165. As the Ost concentration-time curve showed, Ost-S100-NP can increase the plasma concentration and relative bioavailability of Ost compared with Ost-suspension by oral administration. In vivo, Ost-S100-NP enhanced the therapeutic efficacy of Ost against FLC-resistant C. albicans in immunosuppressed candidiasis mice model. The available information strongly suggests that Ost-S100-NP may be used as a promising compound against drug-resistant fungi.

Investigation of Dissolution Behavior HPMC/Eudragit®/Magnesium Aluminometasilicate Oral Matrices Based on NMR Solid-State Spectroscopy and Dynamic Characteristics of Gel Layer.

Burst drug release is often considered a negative phenomenon resulting in unexpected toxicity or tissue irritation. Optimal release of a highly soluble active pharmaceutical ingredient (API) from hypromellose (HPMC) matrices is technologically impossible; therefore, a combination of polymers is required for burst effect reduction. Promising variant could be seen in combination of HPMC and insoluble Eudragits® as water dispersions. These can be applied only on API/insoluble filler mixture as over-wetting prevention. The main hurdle is a limited water absorption capacity (WAC) of filler. Therefore, the object of this study was to investigate the dissolution behavior of levetiracetam from HPMC/Eudragit®NE matrices using magnesium aluminometasilicate (Neusilin® US2) as filler with excellent WAC. Part of this study was also to assess influence of thermal treatment on quality parameters of matrices. The use of Neusilin® allowed the application of Eudragit® dispersion to API/Neusilin® mixture in one step during high-shear wet granulation. HPMC was added extragranularly. Obtained matrices were investigated for qualitative characteristics, NMR solid-state spectroscopy (ssNMR), gel layer dynamic parameters, SEM, and principal component analysis (PCA). Decrease in burst effect (max. of 33.6%) and dissolution rate, increase in fitting to zero-order kinetics, and paradoxical reduction in gel layer thickness were observed with rising Eudragit® NE concentration. The explanation was done by ssNMR, which clearly showed a significant reduction of the API particle size (150-500 nm) in granules as effect of surfactant present in dispersion in dependence on Eudragit®NE amount. This change in API particle size resulted in a significantly larger interface between these two entities. Based on ANOVA and PCA, thermal treatment was not revealed as a useful procedure for this system.

High efficiency dry coating of non-subcoated pellets for sustained drug release formulations using amino methacrylate copolymers.

Dry coating utilizing a fluidized bed was evaluated in order to produce films with sustained drug release using amino methacrylate copolymers as film former. In contrast to other dry coating procedures using amino methacrylate copolymers, the described method enables an appropriate polymer adhesion by the selection of a plasticizer additive mixture in combination with the use of a three-way nozzle for simultaneous application. Well spreading fatty acid esters were found to increase the coating efficiency from 73% to approximately 86%, when they were used in conjunction with the plasticizer. Pellets were used as drug cores without previous treatment. After a curing step at 55 °C, the pellets exhibited a prolongation of the drug release over a period of about 6 h. Mainly the three parameters, coating level, composition of the polymers in the coating mixture, and the type of plasticizer, were found to exert distinct influence on the dissolution profile. Despite the differences in the coating procedure, the dissolution profiles of the coated pellets as well as the influencing parameters were similar to those known from conventional coating techniques.

Sustained-release solid dispersion of pelubiprofen using the blended mixture of aminoclay and pH independent polymers: preparation and in vitro/in vivo characterization.

The present study aimed to develop the sustained-release oral dosage form of pelubiprofen (PEL) by using the blended mixture of 3-aminopropyl functionalized-magnesium phyllosilicate (aminoclay) and pH-independent polymers. The sustained-release solid dispersion (SRSD) was prepared by the solvent evaporation method and the optimal composition of SRSD was determined as the weight ratio of drug: Eudragit® RL PO: Eudragit® RS PO of 1:1:2 in the presence of 1% of aminoclay (SRSD(F6)). The dissolution profiles of SRSD(F6) were examined at different pHs and in the simulated intestinal fluids. The drug release from SRSD(F6) was limited at pH 1.2 and gradually increased at pH 6.8, resulting in the best fit to Higuchi equation. The sustained drug release from SRSD(F6) was also maintained in simulated intestinal fluid at fasted-state (FaSSIF) and fed-state (FeSSIF). The structural characteristics of SRSD(F6) were examined by using powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR), indicating the change of drug crystallinity to an amorphous form. After oral administration in rats, SRSD(F6) exhibited the prolonged drug exposure in plasma. For both PEL and PEL-transOH (active metabolite), once a day dosing of SRSD(F6) achieved oral exposure (AUC) comparable to those from the multiple dosing (3 times a day) of untreated drug. In addition, the in vivo absorption of SRSD(F6) was well-correlated with the in vitro dissolution data, establishing a good level A in vitro/in vivo correlation. These results suggest that SRSD(F6) should be promising for the sustained-release of PEL, thereby reducing the dosing frequency.

Influence of lipid composition of model membranes on methacrylate antimicrobial polymer-membrane interactions.

Using atomistic molecular dynamics simulations, the role of lipid composition in the interactions of multiple methacrylate antimicrobial polymer agents with model membranes, and the consequent response of the membranes is studied. In our earlier study, methacrylate polymers were observed to induce phase demixing and associated thickness mismatch in a POPE-POPG model microbial membrane. In this work, we probe (1) the role of varying the degree of saturation in lipid acyl chains in the membrane interactions of methacrylate polymers, and (2) whether electrostatics (addition of anionic lipids) can influence the interactions of the polymers with model mammalian membranes. Lipid composition is observed to significantly modify membrane-polymer interactions, leading to differences in both the mode of partitioning and the conformations adopted by the polymers, in addition to impacting membrane properties differently. The results strongly suggest that the oft-cited electrostatic interactions between the antimicrobial agents and the microbial membranes do not fully account for the recognition and subsequent partitioning of the antimicrobial agents. The ability of the methacrylate polymers to sense interfacial lipid packing defects, determined by the PE/PC head groups of lipids, is also found to be influential in their membrane partitioning. Deliberate inclusion of charged anionic lipids into a model mammalian membrane, leading to additional favorable electrostatics, does not reproduce a similar polymer partitioning mechanism to that in its microbial counterpart. The differences observed in the interactions of methacrylate polymers with the various model membranes can be instrumental in extending our understanding of underlying modes of membrane disruption by general antimicrobial agents as well.