Modeling of the controlled release of betacarotene into anhydrous ethanol from microcapsules

Engineering pH-sensitive erodible chitosan hydrogel composite containing bacteriophage: An interplay between hydrogel and bacteriophage against Staphylococcus aureus

Encapsulation of phages represents a key approach for improving phage stability and controlling phage delivery dosage. The hydrogel made from positively charged quaternized chitosan (QCS) and multivalent crosslinker, aldehyde-modified poly(xylitol sebacate)-co-poly(ethylene glycol) (APP) was introduced for the first time for drug (phage 44AHJD) delivery. The freeze-thawing (FT) treatment enhanced the porous structure and the stress resistance of native hydrogel with increased compression stress (stiffness) from 10 to 20 kPa. The stiffness of the phage-loaded hydrogel (FTP) was suitable for the proper release of phage particles and polymer chains, both working synergistically against bacterial growth. The FTP followed the Korsmeyer-Peppas model's anomalous diffusion of phage particles at different temperatures (30-45 °C) and pH (6.6-8.5) conditions. FTP was sensitive to pH, which released more phage particles at pH-neutral conditions, while the release under acidic and alkaline conditions was more based on gel degradation. The high biocompatibility of FTP hydrogel at its working concentration of 30 mg mL-1 was demonstrated through a hemolysis ratio of <2 %. Sixty percent of the total encapsulated phages and 6 mg mL-1 of hydrogel debris were released after 10 h of hydrogel submerge treatment, which can fight the growing bacteria and the emergence of phage-resistant bacteria.

Influence of HA on Release Process of Anionic and Cationic API Incorporated into Hydrophilic Gel

The properties of sodium hyaluronate (HA), such as hygroscopicity, flexibility, the ability to form hydrogels, as well as biocompatibility and biodegradability, are beneficial for the applications in pharmaceutical technology, cosmetics industry, and aesthetic medicine. The aim of this study was to prepare HA-based hydrogels doped with active pharmaceutical ingredient (API): a cationic drug—lidocaine hydrochloride or anionic drug—sodium. The interaction between the carrier and the implemented active pharmaceutical substances was evaluated in prepared systems by applying viscometric measurements, performing release tests of the drug from the obtained formulations, and carrying out FTIR and DSC. The data from release studies were analyzed using the zero-, first-, and second-order kinetics and Higuchi, Korsmeyer-Peppas, and Hixon-Crowell models. The respective kinetic parameters: the release rate constants, the half-release time and, in the case of the Korsmeyer-Peppas equation, the n parameter were calculated. The variability between the obtained release profiles was studied by calculating the difference (f1) and the similarity factor (f2) as well as employing statistical methods. It was revealed that the incorporation of the drugs resulted in an increase in the viscosity of the hydrogels in comparison to the respective drug-free preparations. The dissolution study showed that not entire amount of the added drug was released from the formulation, suggesting an interaction between the carrier and the drug. The FTIR and DSC studies confirmed the bond formation between HA and both medicinal substances.

Polyglycerol Adipate-Grafted Polycaprolactone Nanoparticles as Carriers for the Antimicrobial Compound Usnic Acid

Nanoparticle (NP) drug delivery systems are known to potentially enhance the efficacy of therapeutic agents. As for antimicrobial drugs, therapeutic solutions against drug-resistant microbes are urgently needed due to the worldwide antimicrobial resistance issue. Usnic acid is a widely investigated antimicrobial agent suffering from poor water solubility. In this study, polymer nanoparticles based on polyglycerol adipate (PGA) grafted with polycaprolactone (PCL) were developed as carriers for usnic acid. We demonstrated the potential of the developed systems in ensuring prolonged bactericidal activity against a model bacterial species, Staphylococcus epidermidis. The macromolecular architecture changes produced by PCL grafted from PGA significantly influenced the drug release profile and mechanism. Specifically, by varying the length of PCL arms linked to the PGA backbone, it was possible to tune the drug release from a burst anomalous drug release (high PCL chain length) to a slow diffusion-controlled release (low PCL chain length). The developed nanosystems showed a prolonged antimicrobial activity (up to at least 7 days) which could be used in preventing/treating infections occurring at different body sites, including medical device-related infection and mucosal/skin surface, where Gram-positive bacteria are commonly involved.

Pulsatile Controlled Release and Stability Evaluation of Polymeric Particles Containing Piper nigrum Essential Oil and Preservatives

Considerable efforts have been spent on environmentally friendly particles for the encapsulation of essential oils. Polymeric particles were developed to encapsulate the essential oil from Piper nigrum based on gelatin and poly-ε-caprolactone (PCL) carriers. Gas Chromatography ((Flame Ionization Detection (GC/FID) and Mass Spectrometry (GC/MS)), Atomic Force Microscopy (AFM), Nanoparticle Tracking Analysis (NTA), Confocal Laser Scanning Microscopy (CLSM), Attenuated Total Reflectance-Fourier-transform Infrared Spectroscopy (ATR-FTIR), and Ultraviolet-Visible (UV-VIS) spectroscopy were used for the full colloidal system characterization. The essential oil was mainly composed of β-caryophyllene (~35%). The stability of the encapsulated systems was evaluated by Encapsulation Efficiency (EE%), electrical conductivity, turbidity, pH, and organoleptic properties (color and odor) after adding different preservatives. The mixture of phenoxyethanol/isotialzoni-3-one (PNE system) resulted in enhanced stability of approximately 120 and 210 days under constant handling and shelf-life tests, respectively. The developed polymeric system presented a similar controlled release in acidic, neutral, or basic pH, and the release curves suggested a pulsatile release mechanism due to a complexation of essential oil in the PCL matrix. Our results showed that the developed system has potential as an alternative stable product and as a controlling agent, due to the pronounced bioactivity of the encapsulated essential oil.

Fate of β-Carotene within Loaded Delivery Systems in Food: State of Knowledge

Nanotechnology has opened new opportunities for delivering bioactive agents. Their physiochemical characteristics, i.e., small size, high surface area, unique composition, biocompatibility and biodegradability, make these nanomaterials an attractive tool for β-carotene delivery. Delivering β-carotene through nanoparticles does not only improve its bioavailability/bioaccumulation in target tissues, but also lessens its sensitivity against environmental factors during processing. Regardless of these benefits, nanocarriers have some limitations, such as variations in sensory quality, modification of the food matrix, increasing costs, as well as limited consumer acceptance and regulatory challenges. This research area has rapidly evolved, with a plethora of innovative nanoengineered materials now being in use, including micelles, nano/microemulsions, liposomes, niosomes, solidlipid nanoparticles, nanostructured lipids and nanostructured carriers. These nanodelivery systems make conventional delivery systems appear archaic and promise better solubilization, protection during processing, improved shelf-life, higher bioavailability as well as controlled and targeted release. This review provides information on the state of knowledge on β-carotene nanodelivery systems adopted for developing functional foods, depicting their classifications, compositions, preparation methods, challenges, release and absorption of β-carotene in the gastrointestinal tract (GIT) and possible risks and future prospects.

Physicochemical, pharmacokinetic, and pharmacodynamic characterization of isradipine tablets for controlled release

Isradipine is a dihydropyridine calcium channel blocker (CCB) commonly used as vasodilator with antihypertensive properties. A remote-controlled release formulation for isradipine would substantially improve the clinical outcomes of the patients requiring chronic long-term treatment. In this work, sustained release (SR) tablets of isradipine, composed of hydroxypropylmethyl cellulose (HPMC), have been produced by wet granulation and their in vitro and in vivo characterization was compared to a conventional tablet dosage form of immediate release (IR) as preliminary assessment. Tablets composed of 15.0% (wt/wt) HPMC exhibited a SR profile over a period of 24 hours. The release of isradipine followed a Fickian diffusion pattern obeying to the first order kinetics and the extent of absorption was even higher in comparison to the developed conventional tablets, which showed immediate drug release. In vivo studies were carried out in rabbits, showing that the extent of isradipine absorption from the developed tablets was higher in comparison to IR tablets due to the modified release profile obtained for the former (p < 0.05). Our results suggest that SR tablets of isradipine are an efficient solid dosage form to overcome the limitations encountered in conventional IR tablets.

Studies of Emission Processes of Polymer Additives into Water Using Quartz Crystal Microbalance-A Case Study on Organophosphate Esters

Plastic materials contain various additives, which can be released during the entire lifespan of plastics and pose a threat to the environment and human health. Despite our knowledge on leakage of additives from products, accurate and rapid approaches to study emission kinetics are largely lacking, in particular, methodologies that can provide in-depth understanding of polymer/additive interactions. Here, we report on a novel approach using quartz crystal microbalance (QCM) to measure emissions of additives to water from polymer films spin-coated on quartz crystals. The methodology, being accurate and reproducible with a standard error of ±2.4%, was applied to a range of organophosphate esters (OPEs) and polymers with varying physicochemical properties. The release of most OPEs reached an apparent steady-state within 10 h. The release curves for the studied OPEs could be fitted using a Weibull model, which shows that the release is a two-phase process with an initial fast phase driven by partitioning of OPEs readily available at or close to the polymer film surface, and a slower phase dominated by diffusion in the polymer. The kinetics of the first emission phase was mainly correlated with the hydrophobicity of the OPEs, whereas the diffusion phase was weakly correlated with molecular size. The developed QCM-based method for assessing and studying release of organic chemicals from a polymeric matrix is well suited for rapid screening of additives in efforts to identify more sustainable replacement polymer additives with lower emission potential.

Drug delivery from microcapsules: How can we estimate the release time?

Predicting the release performance of a drug delivery device is an important challenge in pharmaceutics and biomedical science. In this paper, we consider a multi-layer diffusion model of drug release from a composite spherical microcapsule into an external surrounding medium. Based on this model, we present two approaches for estimating the release time, i.e. the time required for the drug-filled capsule to be depleted. Both approaches make use of temporal moments of the drug concentration at the centre of the capsule, which provide useful insight into the timescale of the process and can be computed exactly without explicit calculation of the full transient solution of the multi-layer diffusion model. The first approach, which uses the zeroth and first temporal moments only, provides a crude approximation of the release time taking the form of a simple algebraic expression involving the various parameters in the model (e.g. layer diffusivities, mass transfer coefficients, partition coefficients) while the second approach yields an asymptotic estimate of the release time that depends on consecutive higher moments. Through several test cases, we show that both approaches provide a computationally-cheap and useful tool to quantify the release time of composite microcapsule configurations.

Mechanically Robust Gastroretentive Drug-Delivery Systems Capable of Controlling Dissolution Behaviors of Coground β-Lapachone

In this study, we aimed to design a highly swellable and mechanically robust matrix tablet (SMT) as a gastroretentive drug-delivery system (GRDDS) capable of improving the dissolution behavior of β-lapachone with low aqueous solubility. For the preparation of SMTs, the cogrinding technique and freeze–thaw method were used to disperse β-lapachone in SMTs in an amorphous state and to enhance the swelling and mechanical properties of SMTs, respectively. As a result, the crystallinity of coground β-lapachone incorporated in the SMTs was found to be considerably decreased; thereby, the dissolution rates of the drug in a simulated gastric fluid could be substantially increased. The SMTs of β-lapachone also demonstrated significantly enhanced swelling and mechanical properties compared to those of a marketed product. The reason for this might be because the physically crosslinked polymeric networks with a porous structure that were formed in SMTs through the freeze–thaw method. In addition, β-lapachone was gradually released from the SMTs in 6 h. Therefore, SMTs of β-lapachone developed in this study could be used as GRDDS with appropriate swelling and mechanical properties for improving the dissolution behavior of hydrophobic drugs such as β-lapachone.

Mechanistic modelling of drug release from multi-layer capsules

We propose a novel in silico model for computing drug release from multi-layer capsules. The diffusion problem in such heterogeneous layer-by-layer composite medium is described by a system of coupled partial differential equations, which we solve analytically using separation of variables. In addition to the conventional partitioning and mass transfer interlayer conditions, we consider a surface finite mass transfer resistance, which corresponds to the case of a coated capsule. The drug concentration in the core and through all the layers, as well as in the external release medium, is given in terms of a Fourier series that we compute numerically to describe and characterize the drug release mechanism.