Diffusion Coefficient Of Drug Research Articles

Investigating the effect of heat flux on tetracycline absorption by bio-MOF-11 nanostructure: A molecular dynamics approach

Tetracycline is a type of antibiotic that falls under the category of antibiotics. Studying the absorption process of Tetracycline by bio-MOF-11 carrier is important for enhancing drug delivery efficiency, optimizing dosage, and increasing bioavailability, ultimately improving treatment outcomes and potentially leading to the development of new therapies. The present study examined the effect of variable amplitude heat flux (HF) on the bio-MOF-11 carriers' ability to absorb tetracycline. Various parameters were assessed and documented using molecular dynamics simulation and LAMMPS software, including the mean square displacement, number of drug particles, diffusion coefficient, and interaction energy. The results show that by increasing heat flux to 0.04 W/m2, the interaction energy became more negative, decreasing from −1376.35 to −1549.35 kcal/mol. Both mean square displacement and diffusion coefficient increased from 72.906 Å2 and 75.69 28 nm2/ns to 79.745 Å2 and 83.28 nm2/ns, respectively. Also, the number of penetrated Tetracycline-Drug in bio-MOF-11 carriers increased to 606, but it decreased to 520 with a further increase in HF to 0.08 W/m2. The different ways that heat affected adsorption process within the MOF structure may be the cause of this change. The first improvement in penetration can be a sign of improved drug binding and mobility at a moderate HFA. In contrast, the subsequent decrease at higher HFA levels could suggest that excessive heat disrupts the adsorption mechanism, potentially affecting the stability and efficiency of drug delivery within the system.

Mechanistic Investigation of Enzyme Triggered Release from a Xyloglucan Matrix Tablet for Controlled Colonic Drug Delivery

The objective of this study was to investigate the mechanisms underlying drug release from a controlled colonic release (CCR) tablet formulation based on a xyloglucan polysaccharide matrix and identify the factors that control the rate of release for the purpose of fundamentally substantiating the concept and demonstrating its robustness for colonic drug delivery. Previous work demonstrated in vitro limited release of 5-aminosalicylic acid (5-ASA) and caffeine from these tablets in small intestinal environment and significant acceleration of release by xyloglucanase, an enzyme of the colonic microbiome. Targeted colonic drug delivery was verified in an animal study in vivo. In the present work, interaction of the xyloglucan matrix tablets with aqueous dissolution media containing xyloglucanase was found to lead to the spontaneous formation of a hydrated highly viscous gummy layer at the surface of the matrix which had a reduced drug content compared to the underlying regions and persisted with a nearly constant thickness that was inversely correlated to the enzyme concentration throughout the duration of the release process. Enzymatic hydrolysis of xyloglucan was determined to take place at the surface of the matrix leading to matrix erosion and a relation for the rate of enzymatic reaction as a function of bulk enzyme concentration and the concentration of dissolved xyloglucan in the gummy layer was derived. A mathematical model was developed encompassing aqueous medium ingress, matrix metamorphosis due to xyloglucan dissolution and matrix swelling, enzymatic hydrolysis of the polysaccharide and concomitant drug release due to matrix erosion and simultaneous drug diffusion. The model was fitted to data of reducing sugar equivalents in the medium reflecting matrix erosion and released drug amount. Enzymatic reaction parameters and reasonable values of medium ingress velocity, xyloglucan dissolution rate constant and drug diffusion coefficient were deduced that provided an adequate approximation of the data. Erosion was shown to be the overwhelmingly dominant drug release mechanism while the role of diffusion marginally increased at low enzyme concentration and high drug solubility. Changing enzyme concentration had a rather weak effect on matrix erosion and drug release rate as demonstrated by model simulations supported by experimental data, while xyloglucan dissolution was slow and had a stronger effect on the rate of the process. Therefore, reproducible colonic drug delivery not critically influenced by inter- and intra-individual variation of microbial enzyme activity may be projected.

Development, Evaluation, and Molecular Dynamics Study of Ampicillin-Loaded Chitosan-Hyaluronic Acid Films as a Drug Delivery System.

Periodontitis is an inflammatory periodontal disease defined by the progressive loss of tissues surrounding the tooth. Ampicillin is an antibiotic for managing and treating specific bacterial infections, including periodontitis. Periodontal pockets occur due to periodontal disease progression and act as a natural reservoir that is easily reachable for the insertion of a delivery system, and the amount of drug to be released has a major role in the efficiency of treatment of the disease. Polyelectrolyte complexes (PECs), particularly those based on chitosan and hyaluronic acid combinations, offer a promising avenue to overcome the challenges associated with drug delivery. These complexes are both biodegradable and biocompatible, making them an optimal choice for enabling targeted drug delivery. This study centers on developing and assessing the structure and dynamic attributes of a drug-PEC system encompassing ampicillin and chitosan-hyaluronic acid components, which represents a targeted drug delivery system to better alleviate the periodontitis. To achieve this goal, we conducted experiments including weight and drug content uniformity, swelling ındex, drug release %, FT-IR and SEM analyses, and atomistic molecular dynamics simulations on the drug PECs loaded with ampicillin with varying amounts of hyaluronic acid. All simulations and the experimental analysis suggested that increased HA amount resulted in an increase in drug release % and swelling index. The simulation outcomes provide insights into the nature of the drug and PEC interactions alongside transport properties such as drug diffusion coefficients. These coefficients offer valuable insights into the molecular behavior of ampicillin-PEC drug delivery systems, particularly in the context of their application in periodontitis treatment.

Unlocking new dimensions in long-acting injectables using lipid mesophase-based beads

In this study, we explored the use of lipid mesophases (LMPs) as a biocompatible and biodegradable material for sustained drug delivery. Our hypothesis centered on leveraging the high surface-to-volume ratio of LMP-based beads to enhance strength, stability, and surface interaction compared to the LMP bulk gel. To modulate drug release, we introduced antioxidant vitamin E into the beads, influencing mesophase topologies and controlling drug diffusion coefficients. Four drugs with distinct chemical properties and intended for three different pathologies and administration routes were successfully loaded into the beads with a drug entrapment efficiency exceeding 80 %. Notably, our findings revealed sustained drug release, irrespective of the drugs' chemical properties, culminating in the development of an injectable formulation. This formulation allows direct administration into the target site, minimizing systemic exposure, and thereby mitigating adverse effects. Our approach demonstrates the potential of LMP-based beads for tailored drug delivery systems with broad applications in diverse therapeutic scenarios.

Application of Hydrogenated Soya Lecithin in Solid Dispersion and Oily Gel, and the Study of Skin-Applied Formulations

I have been studying the improvement of drug solubility using solid dispersion and skin-applied formulations. When preparing solid dispersions using phosphatidylcoline (PC) as a carrier, drug with hydrogen-donating groups interacts with PC to produce amorphous solid dispersions with high drug content; this overcomes improves drug absorption. The drug was solubilized and supersaturated in the oil-based gel formed with hyadrogenated lecithin; this facilitates drug permeation through the skin. The promoting effect differs with the nature of the oil used because of the skin penetration of the oil itself and the accompanying increase in drug solubility and diffusion coefficient in the skin. At actual application volumes of 10 µL/cm2 or less, the skin penetration of poorly-absorbable drugs depends on the molecular weight and surface tension of the oil. The penetration of the oil vehicle into the upper stratum corneum influences the reach of the drug into the stratum corneum; a high drug concentration near the 7th layer of the stratum corneum promotes migration through the skin by increasing the linear concentration gradient in deeper layers. In addition, we performed a risk assessment, in collaboration with toxicologists, for dermal safety that included the toxicity potential of substances and the parts related to skin transfer.

Effects of polymeric surfactants with low HLB values on drug and excipient release from self-emulsifying drug delivery systems

In this study, we evaluated the effects of polymeric surfactants with low hydrophile–lipophile balance values (PSLH) lauryl PEG-8 dimethicone (LP8D) and Pluronic L121 (P121) on drug and excipient release from self-emulsifying drug delivery systems (SEDDS). Valsartan (logKOW 1.5) was used as a model drug, whereas oleic acid (logKOW 7.64) was loaded in SEDDS as a model excipient. Diffusion of valsartan from oil phase to aqueous phase was significantly reduced when adding 5 % LP8D or P121 into the oil phase consisting of isopropyl myristate:Capmul MCM 4:1 m/m. Drug diffusion reached plateau phases after 72 h compared to 3 h in case of the non-PSLH oil phase. Adding 10 % either LP8D or P121 further decreased drug diffusion to aqueous phase. P121 showed a more controlled drug diffusion profile than LP8D at the same loading level. PSLH were loaded in SEDDS preconcentrates at different concentrations in the ranges of 0–15 % LP8D and 0–10 % P121 m/m to yield emulsion with size ∼200 nm and polydispersity index <0.3 upon dilution. The burst release phases from PSLH loaded SEDDS were suppressed and better controlled with higher PSLH loading ratios. The presence of PSLH in the oil phase could increase intermolecular interactions such as hydrogen bonding and London dispersion forces between PSLH and drug or excipient molecules as shown by FTIR difference spectra. Furthermore, PSLH can accumulate at the oil-water interfacial barrier and increase the activation energy level for solute molecules diffusion, i.e. adding 10 % LP8D led to a 3-fold increase in activation energy for oleic acid. Therefore, incorporation of PSLH in SEDDS formulation could be a potential approach to reduce drug diffusion coefficients, enhance drug affinity to oil phase and control drug release rate.

Prabhakar fractional scrutinization of a colloidal mixture of aluminum oxide and copper nanoparticles flowing over a channel subject to slip effects

According to a remarkable result, the polarization diffusion coefficient of drugs, such as those that slow down and ease the body, may be determined based on the rise in magnetism that follows. This research examines how a magnetic field impacts the Casson-type flow of a viscous, incompressible hybrid nanofluid that naturally flows across two parallel plates. Copper (Cu) and aluminum-oxide (Al2O[Formula: see text] are the two nanoparticles and their physical properties are intended to be the foundation fluids, together with water and sodium alginate as based fluids. The revised fractional model is investigated using the Laplace transformation using the most current and updated definition of the fractional-order derivative with memory effect, i.e. Prabhakar fractional derivative. The impacts of various constraints on distinct nanoparticles are investigated and visually depicted. As a result, we have concluded that a drop in volumetric percentage reduces fluid velocity. The water-based hybrid nanofluid (HNF) has a more significant influence on the temperature and momentum profile than the sodium alginate-based HNF due to the physical appearances of the investigated nanoparticles. The Casson fluid parameter augmentation also regulates the velocity profile by decreasing the velocity field.

Diffusion Kinetics-Based Loading of Lipoic Acid into Cyclodextrin Metal–Organic Frameworks via a Solvent-Free Method and Mechanism of Stability Enhancement

It is difficult to accurately distinguish the amount of a drug inside versus outside of a carrier during drug loading, which limits the ability to determine the kinetic data (the drug diffusion coefficient, energy barrier, etc.). Here, we demonstrated the feasibility of determining the drug diffusion coefficient and content without distinguishing whether it is inside or outside of a carrier. Specifically, the sample of gamma-cyclodextrin metal–organic frameworks (CD-MOF) loaded with unstable and viscous alpha-lipoic acid (LA) was examined. Furthermore, the LA stability was enhanced by the CD-MOF via a straightforward and unambiguous solvent-free method, and the mechanism behind it was thoroughly explored based on the diffusion coefficient. For the first time, a combination of mathematical modeling and new experimental measurements was used to determine the diffusion coefficient of LA in CD-MOF crystals. Accordingly, the strong adhesion free energy (−8.64 ± 0.56 kcal·mol–1) between LA and the dicyclodextrin cavity in the CD-MOF was determined. Furthermore, the nature of the adhesion force was identified to be the chemisorption dominated by hydrogen binding employing a combination of molecular modeling (docking and density functional theory, DFT) and experimental methods (solid-state nuclear magnetic resonance, ssNMR). Finally, this study revealed that the stability enhancement of LA in the CD-MOF is due to the combined actions of the high binding free energy of LA with the dicyclodextrin cavity and its steric hindrance, together with the accelerating roles of the CD-MOF cage environment.

Model-based optimization of drug release rate from a size distributed population of biodegradable polymer carriers

In the present study, a comprehensive polymer degradation-drug diffusion model is developed to describe the polymer degradation kinetics and quantify the release rate of an active pharmaceutical ingredient (API) from a size-distributed population of drug-loaded poly(lactic-co-glycolic) acid (PLGA) carriers in terms of material and morphological properties of the drug carriers. To take into account the spatial–temporal variation of the drug and water diffusion coefficients, three new correlations are developed in terms of spatial–temporal variation of the molecular weight of the degrading polymer chains. The first one relates the diffusion coefficients with the time-spatial variation of the molecular weight of PLGA and initial drug loading and, the second one with the initial particle size, and the third one with evolution of the particle porosity due to polymer degradation. The derived model, comprising a system of partial differential and algebraic equations, is numerically solved using the method of lines and validated against published experimental data on the drug release rate from a size distributed population of piroxicam-PLGA microspheres. Finally, a multi-parametric optimization problem is formulated to calculate the optimal particle size and drug loading distributions of drug-loaded PLGA carriers to realize a desired zero-order drug release rate of a therapeutic drug over a specified administration period of several weeks. It is envisaged that the proposed model-based optimization approach will aid the optimal design of new controlled drug delivery systems and, consequently, the therapeutic outcome of an administered drug.

Interaction of gentamicin and gentamicin-AOT with poly-(lactide-co-glycolate) in a drug delivery system - density functional theory calculations and molecular dynamics simulation

Gentamicin is used to treat brucellosis, an infectious disease caused by the Brucella species but the drug faces several issues such as low efficacy, instability, low solubility, and toxicity. It also has a very short half-life, therefore, requiring frequent dosing. Consequently, several other antibiotics are also being used for the treatment of brucellosis as a single dose as well as in combination with other antibiotics but none of these therapies are satisfactory. Nanoparticles in particular polymer-based ones utilizing polymers that are biodegradable and biocompatible for instance PLGA are a method of choice to overcome such drug delivery issues and enable potential targeted delivery. The current study focuses on the evaluation of the structural and dynamical properties of a drug-polymer system consisting of gentamicin drug and PLGA polymer nanoparticles in the water representing a targeted drug delivery system for the treatment of brucellosis. For this purpose, all-atom molecular dynamics simulations were carried out on the drug-polymer systems in the absence and presence of the surfactant bis(2-Ethylhexyl) sulfosuccinate (AOT) to determine the structural and dynamical properties as well as the effect of the surfactant on these properties. We also investigated systems in which the polymer constituents were in the form of monomeric units toward decoupling the primary interactions of the monomer units and polymer effects. The simulation results explain the nature of the interactions between the drug and the polymer as well as transport properties in terms of drug diffusion coefficients, which characterize the molecular behavior of gentamicin-polymer nanoparticles for use in brucellosis.

Pharmacokinetic Study of Triptolide Nanocarrier in Transdermal Drug Delivery System-Combination of Experiment and Mathematical Modeling.

Compared with traditional oral and injection administration, the transdermal administration of traditional Chinese medicine has distinctive characteristics and advantages, which can avoid the "first pass effect" of the liver and the destruction of the gastrointestinal tract, maintain a stable blood concentration, and prolong drug action time. However, the basic theory and technology research in transdermal drug delivery are relatively limited at present, especially regarding research on new carriers of transdermal drug delivery and pharmacokinetic studies of the skin, which has become a bottleneck of transdermal drug delivery development. Triptolide is one of the main active components of Tripterygium wilfordii, which displays activities against mouse models of polycystic kidney disease and pancreatic cancer but its physical properties and severe toxicity limit its therapeutic potential. Due to the previously mentioned advantages of transdermal administration, in this study, we performed a detail analysis of the pharmacokinetics of a new transdermal triptolide delivery system. Triptolide nanoemulsion gels were prepared and served as new delivery systems, and the ex vivo characteristics were described. The metabolic characteristics of the different triptolide transdermal drug delivery formulations were investigated via skin-blood synchronous microdialysis combined with LC/MS. A multiscale modeling framework, molecular dynamics and finite element modeling were adopted to simulate the transport process of triptolide in the skin and to explore the pharmacokinetics and mathematical patterns. This study shows that the three-layer model can be used for transdermal drug delivery system drug diffusion research. Therefore, it is profitable for transdermal drug delivery system design and the optimization of the dosage form. Based on the drug concentration of the in vivo microdialysis measurement technology, the diffusion coefficient of drugs in the skin can be more accurately measured, and the numerical results can be verified. Therefore, the microdialysis technique combined with mathematical modeling provides a very good platform for the further study of transdermal delivery systems. This research will provide a new technology and method for the study of the pharmacokinetics of traditional Chinese medicine transdermal drug delivery. It has important theoretical and practical significance in clarifying the metabolic transformation of percutaneous drug absorption and screening for appropriate drugs and dosage forms of transdermal drug delivery.

Metformin delivery via iontophoresis based on κ-carrageenan cryogels

Transdermal drug delivery system (TDDS) is the system for transmitting a drug through the skin into the blood circulation. In this work, κ-Carrageenan (κC) was used as the drug matrix material. The porous κC matrices were fabricated by dissolving the κC in deionized water to obtain hydrogels and then using the freeze-dryer to obtain cryogels. The porous (κC) matrices showed interconnected pore sizes varying between 6.05 to 25.8 nm. In the drug release experiments, the drug diffusion coefficient increased and the drug release duration was reduced with decreasing κC concentration due to the larger κC pore sizes. The diffusion coefficient increased with a shorter release time under the applied electric strength of +1.0 V due to the electro-repulsive force between the Metformin and the anode. For the drug release-permeation of the κC 0.8 % v/v cryogel through the pig skin under applied positive electrical potentials, the amounts of drug release-permeation and diffusion coefficients were enhanced with shorter durations relative to without electrical potential. The κC 0.8 % v/v matrix at the applied electric strength of +6.0 V has been shown here to be potential to be used as the Metformin transdermal controlled delivery patch for abdominal obesity and diabetes.

Coarse-Grained Simulations of Release of Drugs Housed in Flexible Nanogels: New Insights into Kinetic Parameters.

The diffusion-controlled release of drugs housed in flexible nanogels has been simulated with the help of a coarse-grained model that explicitly considers polymer chains. In these in silico experiments, the effect of its flexibility is assessed by comparing it with data obtained for a rigid nanogel with the same volume fraction and topology. Our results show that the initial distribution of the drug can exert a great influence on the release kinetics. This work also reveals that certain surface phenomena driven by steric interactions can lead to apparently counterintuitive behaviors. Such phenomena are not usually included in many theoretical treatments used for the analysis of experimental release kinetics. Therefore, one should be very careful in drawing conclusions from these formalisms. In fact, our results suggest that the interpretation of drug release curves in terms of kinetic exponents (obtained from the Ritger-Peppas Equation) is a tricky question. However, such curves can provide a first estimate of the drug diffusion coefficient.

Phase-Field Model for Drug Release of Water-Swellable Filaments for Fused Filament Fabrication.

This paper treats the drug release process as a phase-field problem and a phase-field model capable of simulating the dynamics of multiple moving fronts, transient drug fluxes, and fractional drug release from swellable polymeric systems is proposed and validated experimentally. The model can not only capture accurately the positions and movements of the distinct fronts without tracking the locations of fronts explicitly but also predict well the release profile to the completion of the release process. The parametric study has shown that parameters including water diffusion coefficient, drug saturation solubility, drug diffusion coefficient, initial drug loading ratio, and initial porosity are critical in regulating the drug release kinetics. It has been also demonstrated that the model can be applied to the study of swellable filaments and has wide applicability for different materials. Due to explicit boundary position tracking being eliminated, the model paves the way for practical use and can be extended for dealing with geometrically complex drug delivery systems. It is a useful tool to guide the design of new controlled delivery systems fabricated by fused filament fabrication.

Characterization of Drug Release from Mesoporous SiO2-Based Membranes with Variable Pore Structure and Geometry.

Transdermal drug delivery systems (TDDSs) play important roles in therapy due to distinct advantages over other forms and types of drug application. While common TDDS patches mainly consist of polymeric matrices so far, inorganic carriers show numerous advantages such as high mechanical stability, possible re-use and re-loading of drugs, and a broad chemical compatibility with therapeutically relevant compounds and chemical enhancers. Mesoporous glasses can be prepared in different monolithic shapes, and offer a particularly wide range of possible pore volumes, pore diameters, and specific surface areas. Further, they show high loading capacities and favorable physical, technical, and biological properties. Here, we explored for the first time monolithic SiO2-based carriers as sustained release systems of therapeutic drugs. In an ideally stirred vessel as model system, we systematically analyzed the influence of pore diameter, pore volume, and the dimensions of glass monoliths on the loading and sustained release of different drugs, including anastrozole, xylazine, imiquimod, levetiracetam, and flunixin. Through multilinear regression, we calculated the influence of different parameters on drug loading and diffusion coefficients. The systematic variation of the mesoporous glass properties revealed pore volumes and drug loading concentrations, but not pore diameter or pore surface area as important parameters of drug loading and release kinetics. Other relevant effectors include the occurrence of lateral diffusion within the carrier and drug-specific properties such as adsorption. The structure–property relationships derived from our data will allow further fine-tuning of the systems according to their desired properties as TDDS, thus guiding towards optimal systems for their use in transdermal drug applications.

Understanding Formulation and Temperature Effects on Dermal Transport Kinetics by IVPT and Multiphysics Simulation

It is often unclear how complex topical product formulation factors influence the transport kinetics through skin tissue layers, because of multiple confounding attributes. Environmental factors such as temperature effect are also poorly understood. In vitro permeation testing (IVPT) is frequently used to evaluate drug absorption across skin, but the flux results from these studies are from a combination of mechanistic processes. Two different commercially available formulations of oxybenzone-containing sunscreen cream and continuous spray were evaluated by IVPT in human skin. Temperature influence between typical skin surface temperature (32°C) and an elevated 37°C was also assessed. Furthermore, a multiphysics-based simulation model was developed and utilized to compute the flux of modeled formulations. Drug transport kinetics differed significantly between the two drug products. Flux was greatly influenced by the environmental temperature. The multiphysical simulation results could reproduce the experimental observations. The computation further indicated that the drug diffusion coefficient plays a dominant role in drug transport kinetics, influenced by the water content which is also affected by temperature. The in vitro testing and bottom-up simulation shed insight into the mechanism of dermal absorption kinetics from dissimilar topical products.

Microemulsions formed by PPG-5-CETETH-20 at low concentrations for transdermal delivery of nifedipine: Structural and in vitro study

Nifedipine is a potent anti-hypertensive, which is poorly orally bioavailable on account of first-pass metabolism, short half-life, and low water solubility. This study aimed to develop a microemulsified system with low surfactant concentration and to evaluate the influence of microemulsion (ME) phase behavior on skin permeation of nifedipine, as drug model. Thereafter, MEs were obtained using PPG-5-CETETH-20, oleic acid, and phosphate buffer at pH 5.0. The selected MEs were isotropic, with droplet diameters less than 10 nm, polydispersity index < 0.25, and pH between 5.0 and 5.2. MEs presented low viscosity and Newtonian behavior. SAXS results confirmed bicontinuous and oil-in-water (o/w) MEs formation. The presence of the drug promoted only very slight modifications in the ME structure. The MEs presented ability to deliver nifedipine via the transdermal route when in comparison with the control. Nevertheless, the skin permeated and retained amounts from the o/w and bicontinuous formulations did not differ significantly. The ATR-FTIR demonstrated that both formulations promoted fluidization and disorganization of lipids and increased the drug diffusion and partition coefficients in the skin. In conclusion, PPG-5-CETETH-20 MEs obtained proved to be effective skin permeation enhancers, acting by rising the coefficients of partition and diffusion of the nifedipine in the skin.

Release of 5-FU loaded pectin/Fe3O4 from porous PBSA matrix under magnetic and electric fields

In this work, the porous poly(butylene succinate co adipate) (PBSA) was used as the drug matrix for transdermal drug delivery system (TDDS). The porous PBSA matrices were fabricated via solvent casting and particulate leaching method using Tween20 as a pore generator, and the matrices were capable of absorbing the drug solution within 3 s prior to the release. The Fe3O4 magnetic nanoparticles were successfully synthesized via co-precipitation method and successfully coated with pectin through the electrostatic attraction. The 5-fluorouracil, the model drug, was successfully loaded onto the pectin coated Fe3O4 magnetic nanoparticles through the hydrogen bonding. Under magnetic fields, the drug diffusion coefficient increased by the factors of 2 and 5 by the 157 and 247 mT permanent magnets, respectively, whereas the drug release duration was reduced. This was due to the magnetic attraction between the magnetic particles and the magnets. Under the combined electric voltage of 3 V and the magnetic flux of 157 mT, the drug diffusion coefficient increased and the release duration was reduced further, due to the combined driving forces between the magnetic attraction, the electrostatic repulsion of the negative charged pectin layer, and the electro-osmosis. The present work demonstrates the potentials and benefits of the porous matrices along with the combined magnetic and electric fields in the transdermal drug delivery.

Reactive Magnetron Plasma Modification of Electrospun PLLA Scaffolds with Incorporated Chloramphenicol for Controlled Drug Release.

Surface modification with the plasma of the direct current reactive magnetron sputtering has demonstrated its efficacy as a tool for enhancing the biocompatibility of polymeric electrospun scaffolds. Improvement of the surface wettability of materials with water, as well as the formation of active chemical bonds in the near-surface layers, are the main reasons for the described effect. These surface effects are also known to increase the release rate of drugs incorporated in fibers. Herein, we investigated the effect of plasma modification on the chloramphenicol release from electrospun poly (lactic acid) fibrous scaffolds. Scaffolds with high—50 wt./wt.%—drug content were obtained. It was shown that plasma modification leads to an increase in the drug release rate and drug diffusion coefficient, while not deteriorating surface morphology and mechanical properties of scaffolds. The materials’ antibacterial activity was observed to increase in the first day of the experiment, while remaining on the same level as the unmodified group during the next six days. The proposed technique for modifying the surface of scaffolds will be useful for obtaining drug delivery systems with controlled accelerated release, which can expand the possibilities of local applications of antibiotics and other drugs.

Drug diffusion and release from a bioerodible spherical capsule

Controlled release of a drug contained in a spherical polymer capsule is of significant interest in many fields of medicine. There is growing interest in tailoring the erosion properties of the drug to help control and optimize the drug release process. Theoretical understanding of the nature of drug release from a bioerodible capsule is, therefore, important for designing effective drug delivery systems. While drug release from a fixed-radius capsule is relatively easier to model, the shrinking nature of a bioerodible capsule due to surface erosion presents several difficulties in theoretical modeling. This work presents a closed-form solution for the drug concentration distribution and drug delivery characteristics from a spherical capsule undergoing linear surface erosion. This problem is solved by a transformation that converts the moving boundary problem into a fixed boundary problem. For uniform initial drug distribution, the solution is shown to depend on a single non-dimensional parameter. The theoretical model is used to develop an understanding of the impact of varying the drug diffusion coefficient and rate of erosion on drug delivery characteristics. It is found that, in general, the nature of drug release in a bioerodible sphere is determined by a delicate balance between two simultaneously occurring processes – erosion and diffusion. This work improves the theoretical understanding of diffusion in drug delivery systems by accounting for the practical erosion phenomena, and may contribute towards the design and optimization of drug delivery systems.