Release phenomena of insulin from an implantable device composed of a polyion complex of chitosan and sodium hyaluronate

Promising brain biodistribution of insulin via intranasal dry powder for nose-to-brain delivery

Nose-to-brain delivery (NTBD) offering potential benefits for treating Alzheimer's disease. In previous research, insulin dry powder (IDP) formulation for NTBD was developed, exhibiting favorable stability. This study aims to conduct in vitro and ex vivo assessment of release, permeation, mucoadhesion and histopathology, as well as an in vivo biodistribution study to produce IDP for NTBD and evaluate brain biodistribution. Spray-freeze-dried IDP formulations with varying weight ratios of trehalose-to-inulin were produced and analyzed. The release study was carried out in PBS with a pH of 5.8 stirred at 50 rpm and maintained at 37 °C ± 0.5 °C. Goat nasal mucosa was used for ex vivo permeation and mucoadhesion testing under similar conditions. An ex vivo histopathological examination and an in vivo study using enzyme-linked immunosorbent assay, were also performed. The IDP dissolution study demonstrated complete release of all IDPs within 120 min. The permeation study indicated that steady-state conditions were observed between 30 and 240 min. The mucoadhesion study unveiled that IDP F5 exhibited the fastest mucoadhesion time and the least force required within the fastest time of 43.60 ± 2.57 s. The histopathological study confirmed that none of the tested IDPs induced irritation in the nasal mucosa. Furthermore, the biodistribution study demonstrated the absence of detectable insulin in the plasma, while IDP F3 exhibited the highest deposited concentration of insulin within both the olfactory bulb and the whole brain. The extensive evaluation of the IDP formulations through in vitro, ex vivo, and in vivo studies implies their strength non-invasive NTBD. IDP F3, with a 1:1 wt ratio of trehalose to inulin, exhibited favorable brain biodistribution outcomes and was recommended for further investigation and development in the context of NTBD.

Relationships between response surfaces for tablet characteristics of placebo and API-containing tablets manufactured by direct compression method

In this study, we evaluated the correlation between the response surfaces for the tablet characteristics of placebo and active pharmaceutical ingredient (API)-containing tablets. The quantities of lactose, cornstarch, and microcrystalline cellulose were chosen as the formulation factors. Ten tablet formulations were prepared. The tensile strength (TS) and disintegration time (DT) of tablets were measured as tablet characteristics. The response surfaces for TS and DT were estimated using a nonlinear response surface method incorporating multivariate spline interpolation, and were then compared with those of placebo tablets. A correlation was clearly observed for TS and DT of all APIs, although the value of the response surfaces for TS and DT was highly dependent on the type of API used. Based on this knowledge, the response surfaces for TS and DT of API-containing tablets were predicted from only two and four formulations using regression expression and placebo tablet data, respectively. The results from the evaluation of prediction accuracy showed that this method accurately predicted TS and DT, suggesting that it could construct a reliable response surface for TS and DT with a small number of samples. This technique assists in the effective estimation of the relationships between design variables and pharmaceutical responses during pharmaceutical development.

Chitin and chitosan: biopolymers for wound management

Chitin and chitosan are biopolymers with excellent bioactive properties, such as biodegradability, non-toxicity, biocompatibility, haemostatic activity and antimicrobial activity. A wide variety of biomedical applications for chitin and chitin derivatives have been reported, including wound-healing applications. They are reported to promote rapid dermal regeneration and accelerate wound healing. A number of dressing materials based on chitin and chitosan have been developed for the treatment of wounds. Chitin and chitosan with beneficial intrinsic properties and high potential for wound healing are attractive biopolymers for wound management. This review presents an overview of properties, biomedical applications and the role of these biopolymers in wound care.

Development of antibiotic-loaded silk fibroin/hyaluronic acid polyelectrolyte film coated CoCrMo alloy

Bacteria related infections are still a major problem for the implant materials. Such infections have occurred in nearly 3% of hip and knee replacements resulting in failure of device. There are two main approaches for inhibiting the bacterial adhesion to the surface. These involve bactericidal substances and anti-adhesive coatings. In this study, the efficiency of antibiotic-loaded silk fibroin/hyaluronic acid polyelectrolyte film coated CoCrMo alloy, prepared by means of complex coacervate and layer by layer techniques, was investigated. A medical grade CoCrMo was coated with variable number of silk fibroin/hyaluronic acid up to 14 layers at room temperature. The morphological evolution during and after formation of the crystal structure on the coating layer, the resulting surface roughness, and the corresponding alterations in the coating layer thicknesses were thoroughly studied using various analytical techniques, including attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). As a result, only 10 layers of silk fibroin/hyaluronic acid complex coacervate films were found to convey the general characteristics of the mixture of silk I and II, while layer by layer coated samples exhibited the mixture of silk I and II. Moreover, regardless of the preparation method applied, the surface roughness and the coating layer thicknesses were determined to increase with the increasing number of layers. The antibacterial test results suggested that the samples loaded with antibiotic successfully induced a bactericidal resistance against

Complex coacervation of hyaluronic acid and chitosan: effects of pH, ionic strength, charge density, chain length and the charge ratio

Hyaluronic acid (HA) and chitosan (CH) can form nanoparticles, hydrogels, microspheres, sponges, and films, all with a wide range of biomedical applications. This variety of phases reflects the multiple pathways available to HA/CH complexes. Here, we use turbidimetry, dynamic light scattering, light microscopy and zeta potential measurements to show that the state of the dense phase depends on the molar ratio of HA carboxyl to CH amines, and is strongly dependent on their respective degrees of ionization, α and β. Due to the strong charge complementarity between HA and CH, electrostatic self-assembly takes place at very acidic pH, but is almost unobservable at ionic strength (I) ≥ 1.5 M NaCl. All systems display discontinuity in the I-dependence of the turbidity, corresponding to a transition from coacervates to flocculates. An increase in either polymer chain length or charge density enhances phase separation. Remarkably, non-stoichiometric coacervate suspensions form at zeta potentials far away from zero. This result is attributed to the entropic effects of chain semi-flexibility as well as to the charge mismatch between the two biopolymers.

Chitosan modified cerasomes incorporating poly (vinyl pyrrolidone) for oral insulin delivery

The most significant finding of this study is that a hybrid liposomal cerasome with high stability and good biocompatibility was successfully developed for oral insulin delivery by incorporating poly (vinyl pyrrolidone) (PVP) into the cerasome followed by coating with chitosan (CS).

Investigating the Release of a Hydrophobic Peptide from Matrices of Biodegradable Polymers: An Integrated Method Approach

The objectives of this work were: (1) to select suitable compositions of tyrosine-derived polycarbonates for controlled delivery of voclosporin, a potent drug candidate to treat ocular diseases, (2) to establish a structure-function relationship between key molecular characteristics of biodegradable polymer matrices and drug release kinetics, and (3) to identify factors contributing in the rate of drug release. For the first time, the experimental study of polymeric drug release was accompanied by a hierarchical sequence of three computational methods. First, suitable polymer compositions used in subsequent neural network modeling were determined by means of response surface methodology (RSM). Second, accurate artificial neural network (ANN) models were built to predict drug release profiles for fifteen polymers located outside the initial design space. Finally, thermodynamic properties and hydrogen-bonding patterns of model drug-polymer complexes were studied using molecular dynamics (MD) technique to elucidate a role of specific interactions in drug release mechanism. This research presents further development of methodological approaches to meet challenges in the design of polymeric drug delivery systems.

On designing stable magnetic vectors as carriers for malaria DNA vaccine

Superparamagnetic iron oxide nanoparticles (SPIONs) can be used as therapeutic and diagnostic agents due to their unique magnetic characteristics, provided that they are stable in physiological conditions. Here, the assembly of different magnetic vector configurations comprising SPIONs, polyethylenimine (PEI), and hyaluronic acid (HA), acting as carriers for malaria DNA vaccine encoding Plasmodium yoelii merozoite surface protein MSP1-19 (VR1020-PyMSP1-19), and their stability in different cell media were investigated. The order of assembly affected vector size, surface charge, stability, and ability to bind and release DNA. Generally, all vectors showed relatively small size of less than 200 nm in water, whereas higher degree of aggregation was observed immediately after transferring to high-ionic strength media such as 150 mM NaCl buffer and RPMI 1640 culture media (Roswell Park Memorial Institute medium). However, the pre-addition of HA to DNA effectively reduced the extent of aggregation in serum-free RPMI 1640 with sizes of almost all complexes remaining below 90 nm, particularly at HA:PEI charge ratio of 100%. The presence of fetal bovine serum (FBS) in RPMI 1640 culture media further converted the surface charge of vectors from positive to negative, decreasing the size to smaller than 50 nm. Partial disassembly of some vectors was observed in water, in RPMI, and in RPMI supplemented with 10% FBS after incubation for 1h, but not in NaCl buffer, indicating that incubation of complexes in NaCl buffer prior to transfection may limit the intracellular release of plasmid DNA. DNase sensitivity assay showed that plasmid DNA vaccine encoding the PyMSP1-19 in all configurations preserved their structural integrity without damage, even after DNase I treatment for 30 min. This study demonstrated that structurally well-defined magnetic gene carriers could be designed to improve malaria DNA vaccine delivery systems, particularly for in vivo applications.

Dual roles of hyaluronic acids in multilayer films capturing nanocarriers for drug-eluting coatings

We developed hyaluronic acid (HA)-based multilayer films capturing polymeric nanocarriers (NCs) for drug delivery. The electrostatic interactions between positively charged linear polyethylene imines (LPEI) and negatively charged HAs are the main driving forces to form multilayers based on the layer-by-layer (LbL) deposition. NCs were easily incorporated within the multilayer film due to intra- and/or inter-hydrogen bonding among HA chains. The amount of NCs captured by the HA chains was varied by the ratio between HAs and NCs as well as the length (i.e., molecular weight) and absolute number density of HAs in solution. Biocompatibility of the NC-capturing HA multilayer films was tested with the human dermal fibroblast (HDF) culture. In addition, the controlled release of paclitaxel (PTX) from the HA multilayer films successfully led to the apoptosis of human aortic smooth muscle cells (hSMC) in vitro, implying that the NC-capturing HA multilayer films would be quite useful as drug-eluting stent systems to prevent the restenosis after surgery.

Novel mucoadhesive nasal inserts based on chitosan/hyaluronate polyelectrolyte complexes for peptide and protein delivery

Objectives

The purpose of this study was the preparation and characterisation of mucoadhesive nasal inserts based on chitosan/hyaluronate polyelectrolyte complexes prepared at various pHs and at different molar ratios.

Methods

A suspension of chitosan/hyaluronate complexes with or without the model drugs (vancomycin or insulin) was lyophilised into small inserts. Complexation yield, FT-IR spectra and thermogravimetric analysis were used to study the degree of interactive strength between polyions. In-vitro swelling, mucoadhesion and release tests were performed in order to investigate delivery of vancomycin and insulin in the nasal cavity.

Key findings

The results indicated that the selection of complex preparative conditions allows modulation of insert swelling and mucoadhesion ability. Nasal inserts containing vancomycin or insulin had showed completely different drug release behaviour.

Conclusions

Chitosan/hyaluronate polyelectrolyte complexes can be used for the formulation of mucoadhesive nasal inserts for the delivery of peptide and protein drugs.

Novel approaches to neural and evolutionary computing in pharmaceutical formulation: challenges and new possibilities

The development of commercial pharmaceutical formulations can involve extensive experimentation that generates a large amount of data. Understanding such data and discovering the key relationships within them can be a complex process, adding considerably to the time and expense taken to get a product to market. However, new computational techniques such as neural and evolutionary computing have the potential to accelerate the mining and modeling of data, and these methodologies are now being packaged in a way that makes them readily accessible to the product formulator. This article outlines the basis of these technologies and reviews their use in pharmaceutical formulation, showing that they have gained acceptance as practical research tools, especially when integrated with complementary optimization and visualization tools. Neural and evolutionary computing are gaining widespread acceptance in the field of pharmaceutical formulation, with results being comparable with, or better than, those from traditional statistical methods.

Polymer-based sustained-release dosage forms for protein drugs, challenges, and recent advances

While the concept of using polymer-based sustained-release delivery systems to maintain therapeutic concentration of protein drugs for extended periods of time has been well accepted for decades, there has not been a single product in this category successfully commercialized to date despite clinical and market demands. To achieve successful systems, technical difficulties ranging from protein denaturing during formulation process and the course of prolonged in vivo release, burst release, and incomplete release, to low encapsulation efficiency and formulation complexity have to be simultaneously resolved. Based on this updated understanding, formulation strategies attempting to address these aspects comprehensively were reported in recent years. This review article (with 134 citations) aims to summarize recent studies addressing the issues above, especially those targeting practical industrial solutions. Formulation strategies representative of three areas, microsphere technology using degradable hydrophobic polymers, microspheres made of water soluble polymers, and hydrophilic in vivo gelling systems will be selected and introduced. To better understand the observations and conclusions from different studies for different systems and proteins, physicochemical basis of the technical challenges and the pros and cons of the corresponding formulation methods will be discussed.

Chitosan-Based Particles as Controlled Drug Delivery Systems

Chitosan, a natural-based polymer obtained by alkaline deacetylation of chitin, is nontoxic, biocompatible, and biodegradable. These properties make chitosan a good candidate for conventional and novel drug delivery systems. This article reviews the approaches aimed to associate bioactive molecules to chitosan in the form of colloidal structures and analyzes the evidence of their efficacy in improving the transport of the associated molecule through mucosae and epithelia. Chitosan forms colloidal particles and entraps bioactive molecules through a number of mechanisms, including chemical crosslinking, ionic crosslinking, and ionic complexation. A possible alternative of chitosan by the chemical modification also has been useful for the association of bioactive molecules to polymer and controlling the drug release profile. Because of the high affinity of chitosan for cell membranes, it has been used as a coating agent for liposome formulations. This review also examines the advances in the application of chitosan and its derivatives to nonviral gene delivery and gives an overview of transfection studies that use chitosan as a transfection agent. From the studies reviewed, we concluded that chitosan and its derivatives are promising materials for controlled drug and nonviral gene delivery.

Evaluation of the Reliability of Nonlinear Optimal Solutions in Pharmaceuticals Using a Bootstrap Resampling Technique in Combination With Kohonen's Self‐Organizing Maps

The response surface method incorporating multivariate spline interpolation (RSM-S) is a powerful technique for the formulation optimization of pharmaceuticals. However, no satisfactory method has been developed to evaluate the reliability of the optimal solution. We integrated bootstrap (BS) resampling and Kohonen's self-organizing maps (SOM) into RSM-S using the formulation optimization of theophylline tablets as the model experiment. The hardness and the 63.2% drug-release times of the tablets were measured as response variables. Based on the data set obtained, the simultaneous optimal solution was estimated using RSM-S. Leave-one-out cross-validation showed the optimal solution to be reliable. Concurrently, a large number of BS samples were generated from the original data set using BS resampling, and simultaneous optimal solutions for each BS sample (BS optimal solutions) were estimated. The distribution of the BS optimal solutions was far from a normal distribution, suggesting a mixture of global and local optimal solutions. SOM clustering was used to identify the set of global optimal solutions. SOM clustering divided the BS optimal solutions into several clusters, and the reliability of the optimal solution was evaluated from the cluster that included the optimal solution. This study offers a promising method for evaluating the reliability of nonlinear optimal solutions. .

Importance of evaluating the consolidation of granules manufactured by high shear mixer

The effects of the process parameters of high shear wet granulation on the granule properties and dissolution properties of mefenamic acid from tablets have been studied, and the importance of evaluating the consolidation of granules has been considered. The process parameters selected for investigation were the amount of water added, the impeller rotation speed and the kneading time. Increases in the amount of water and the kneading time led to increases in the particle diameter of the granules and to decreases in the mean pore diameter. The mean pore diameter decreased with increases in the impeller rotation speed, while the particle diameters were independent of the impeller rotation speed. The process parameters affected the surface morphology and the internal morphology of the granules. The mean particle diameter and the mean pore diameter of the granules basically correlated with the dissolution properties of the tablets. The contribution of the mean pore diameter to this correlation was higher than that of mean particle diameter. Therefore, it was concluded that evaluation of the granule consolidated state, such as the mean pore diameter, was important in order to assure the dissolution properties of drug products.

Complex coacervation of silk fibroin and hyaluronic acid

This study aimed to investigate the pH-induced complexation of silk fibroin (SF) and hyaluronic acid (HA). SF-HA complex coacervation was investigated by monitoring turbidity of the SF-HA system under slow acidification. Gravimetric analysis was performed to determine the yield of complex coacervation and viscosity of the system was measured to study the formation of the complexes at different pH values. The influences of total biopolymer concentration and biopolymer weight ratio on complex coacervation were examined during the analyses. Formation of the complexes was evidenced by the minimum viscosity and the maximum turbidity observed in the system. SF-HA complexes were formed within the pH-window of 2.5-3.5 regardless of the total biopolymer concentration or biopolymer ratio. Complex coacervation of SF-HA showed a reversible behavior and coacervation could be handled even in excess amounts of the biopolymers, which pointed out a non-stoichiometric complexation.

Hyaluronan: pharmaceutical characterization and drug delivery

Hyaluronic acid (HA), is a polyanionic polysaccharide that consists of N-acetyl-D-glucosamine and beta-glucoronic acid. It is most frequently referred to as hyaluronan because it exists in vivo as a polyanion and not in the protonated acid form. HA is distributed widely in vertebrates and presents as a component of the cell coat of many strains of bacteria. Initially the main functions of HA were believed to be mechanical as it has a protective, structure stabilizing and shock-absorbing role in the body. However, more recently the role of HA in the mediation of physiological functions via interaction with binding proteins and cell surface receptors including morphogenesis, regeneration, wound healing, and tumor invasion, as well as in the dynamic regulation of such interactions on cell signaling and behavior has been documented. The unique viscoelastic nature of hyaluronan along with its biocompatibility and nonimmunogenicity has led to its use in a number of cosmetic, medical, and pharmaceutical applications. More recently, HA has been investigated as a drug delivery agent for ophthalmic, nasal, pulmonary, parenteral, and dermal routes. The purpose of our review is to describe the physical, chemical, and biological properties of native HA together with how it can be produced and assayed along with a detailed analysis of its medical and pharmaceutical applications.

Formulation optimization of photocrosslinked polyacrylic acid modified with 2-hydroxyethyl methacrylate hydrogel as an adhesive for a dermatological patch

A photopolymerization technique was applied in the preparation of a hydrogel composed of polyacrylic acid (PAA) in which 2-hydroxyethyl methacrylate (HEMA) was modified. The formulation of photocrosslinked PAA modified with HEMA hydrogel as an adhesive for a dermatological patch was optimized based on the simultaneous optimization technique. Photocrosslinked PAA modified with HEMA hydrogels that retained a large amount of water, above 85%, were successfully prepared. Based on the analysis of ANOVA, the gel strength and adhesiveness increased with an increase in the degree of modification with HEMA and the concentration of PAA modified with HEMA in the aqueous solution. For the optimization study, the modification with HEMA and the concentration of initiator were selected as causal factors. Gel yield, probe tack, degree of swelling and turbidity were selected as response variables. A set of causal factors and response variables was used as a tutorial date for the prediction of optimal formulation with a quadratic regression model, an artificial neural network (ANN) and a multivariate spline interpolation (MSI). Response surfaces generated with MSI well represented the nonlinear relationship between the factors and the responses, and all the observed values of the response variables coincided with the predictions. A high functional photocrosslinked PAA modified with HEMA hydrogel as an adhesive for a dermatological patch was successfully created using the simultaneous optimization technique incorporating MSI.

Formulation optimization of water-in-oil-water multiple emulsion for intestinal insulin delivery

Formulation optimization of the water-in-oil-in-water multiple emulsion incorporating insulin was performed based on statistical methods such as the orthogonal experimental design and the response surface evaluation. As model formulations, 16 types of emulsions were prepared according to the orthogonal experimental design. To optimize the formulation, the influence of causal factors such as amounts of gelatin, insulin, oleic acid (OA) and the volume ratio of the outer aqueous phase to total and agitation time of the second emulsification process on individual characteristics of the emulsion, such as inner droplet size, viscosity, stability and pharmacological effect, was evaluated first. Based on the analysis of ANOVA, it was concluded that the droplet size of the emulsion was influenced by the volume ratio of the outer aqueous phase significantly. The viscosity of the emulsion was affected by these causal factors and their interactions; however, the most predominant contribution of all causal factors was the volume ratio of the outer aqueous phase. Similarly, one of the most important characteristics in the design of the formulation, stability, was affected by the causal factors. With regard to the hypoglycemic effect, the most influential factor was the content of OA in the emulsion. By means of a novel optimization technique involving a multivariate spline interpolation (MSI), formulation optimization was performed with respect to pharmacological effect and stability, and the optimum formulation with a desirable pharmacological effect and high stability was successfully estimated.