Evaluation of the mechanical properties and drug release of cross-linked Eudragit films containing metronidazole

Eudragit Films as Carriers of Lipoic Acid for Transcorneal Permeability

Diabetes mellitus (DM) is a highly prevalent disease affecting almost 10% of the world population; it is characterized by acute and chronic conditions. Diabetic patients have twenty-five times higher risk of going blind and developing cataracts early than the general population. Alpha-lipoic acid (LA) is a highly valuable natural antioxidant for the prevention and treatment of ophthalmic complications, such as diabetic keratopathy and retinopathy. However, its applicability is limited due to its low solubility in water; therefore, suitable systems are required for its formulation. In this work we developed an erodible insert based on Eudragit E100 (E PO) and Lipoic Acid (LA) for the delivery of this compound for the preventive treatment of ocular diseases especially in diabetic patients. Film evaluation was carried out by mechanical and thermal properties, mucoadhesivity, drug release, dynamic light scattering and corneal permeability as the concentration of LA increased. It was shown that upon LA release, it forms nanoparticles in combination with E PO that favor corneal permeation and LA retention in the cornea. These E PO-LA films also resulted non-irritable hence they are promising for their application in the treatment of ocular diseases.

Wound dressing adherence: a review

Wound dressing adherence is an important problem that is frequently encountered in wound care, and is associated with both clinical and economic burdens. However, only a few review articles have focused on this issue. The objective of this review was to present a comprehensive discussion of wound dressing adherence, including the mechanism of dressing adherence, adverse consequences (clinical burdens and economic burdens), factors affecting adherence (dressing-, patient- and wound-related factors, and factors related to the wound care procedure), tests to assess dressing adherence (in vitro assay, in vivo assay and clinical trials), and reduction of wound adherence (modification of dressing adherence and special care in particular patients). Accordingly, this review article emphasises an awareness of dressing adherence, and is intended to be an informative source for the development of new dressings and for wound management.

Effect of plasticizers on drug-in-adhesive patches containing 5-fluorouracil

Topical patches containing 5-fluorouracil (5-FU) are a feasible alternative to overcome the shortcomings of commercial cream for the treatment of non-melanoma skin cancer (NMSC). Plasticizers are a critical component of drug-in-adhesive (DIA) patches as they can significantly affect the mechanical, adhesive and drug release characteristics of the patches. Eudragit® E (EuE) is a methacrylate-based cationic copolymer capable of producing flexible and adhesive films for topical application. In this study, the effect of plasticizers on the mechanical, adhesive and 5-FU release characteristics of EuE-based patches was comprehensively evaluated. While the elongation at break (%) and adhesion of the films were significantly increased with increasing triacetin, dibutyl sebacate (DBS) and triethyl citrate (TEC) concentrations, the tensile strength showed an inverse relationship. EuE plasticized with 40% triacetin, 30% DBS or 40% w/w TEC produced elastic and adhesive films most suitable for topical application. In vitro release studies of the 5-FU-loaded patches demonstrated an initial burst release pattern during the first 10 min followed by a slow release over 120 min. In summary, this study provides important information on effect of plasticizers for preparation of EuE-based patches with desired mechanical, adhesive and release characteristics of 5-FU towards their potential application in the treatment of NMSC.

Nanocellulose/palygorskite biocomposite membranes for controlled release of metronidazole

The incorporation of drugs in nanocomposites can be considered a potential strategy for controlled drug release. In this study, a nanocomposite based on bacterial cellulose and the palygorskite clay (BC/PLG) was produced and loaded with metronidazole (MTZ). The samples were characterized using X-ray diffraction (XRD) Spectroscopy, thermal analysis (TG/DTG) and Scanning Electron Microscopy (SEM). The barrier properties were determined to water vapor permeability (WVP). Adsorption tests with PLG were performed using MTZ and drug release profile of the membranes was investigated. The results indicated that PLG increased the crystallinity of the nanocomposites, and greater thermal stability when PLG concentration was 15.0% (BC/PLG15) was observed. WVP of the samples also varied, according to the clay content. Adsorption equilibrium was achieved from 400 mg/L of the PLG and a plateau in the MTZ release rates from BC/PLG was observed after 30 min. Therefore, the results of this study show the potential of these nanocomposite membranes as a platform for controlled drug release.

Electrophoretic Deposition and Characterization of Chitosan/Eudragit E 100 Coatings on Titanium Substrate

Currently, a significant problem is the production of coatings for titanium implants, which will be characterized by mechanical properties comparable to those of a human bone, high corrosion resistance, and low degradation rate in the body fluids. This paper aims to describe the properties of novel chitosan/Eudragit E 100 (chit/EE100) coatings deposited on titanium grade 2 substrate by the electrophoretic technique (EPD). The deposition was carried out for different parameters like the content of EE100, time of deposition, and applied voltage. The microstructure, surface roughness, chemical and phase composition, wettability, mechanical and electrochemical properties, and degradation rate at different pH were examined in comparison to chitosan coating without the addition of Eudragit E 100. The applied deposition parameters significantly influenced the morphology of the coatings. The chit/EE100 coating with the highest homogeneity was obtained for Eudragit content of 0.25 g, at 10 V, and for 1 min. Young’s modulus of this sample (24.77 ± 5.50 GPa) was most comparable to that of human cortical bone. The introduction of Eudragit E 100 into chitosan coatings significantly reduced their degradation rate in artificial saliva at neutral pH while maintaining high sensitivity to pH changes. The chit/EE100 coatings showed a slightly lower corrosion resistance compared to the chitosan coating, however, significantly exceeding the substrate corrosion resistance. All prepared coatings were characterized by hydrophilicity.

Fabrication and evaluation of Eudragit® polymeric films for transdermal delivery of piroxicam

The aims of this work were to develop and characterize the prolonged release piroxicam transdermal patch as a prototype to substitute oral formulations, to reduce side effects and improve patient compliance. The patches were composed of film formers (Eudragit^®) as a matrix backbone, with PVC as a backing membrane and PEG200 used as a plasticizer. Results from X-ray diffraction patterns and Fourier transform-infrared spectroscopy indicated that loading piroxicam into films changed the drug crystallinity from needle to an amorphous or dissolved form. Piroxicam films were prepared using Eudragit^® RL100 and Eudragit^® RS100 as film formers at various ratios from 1:0 to 1:3. Films prepared solely by Eudragit^® RL100 showed the toughest and softest film, while other formulations containing Eudragit^® RS100 were hard and brittle. Drug release kinetic data from the films fitted with the Higuchi model, and the piroxicam release mechanism was diffusion controlled. Among all formulation tested, Eudragit^® RL100 films showed the highest drug release rate and the highest drug permeation flux across human epidermal membrane. Increasing drug loading led to an increase in drug release rate. Eudragit^® can be used as a film former for the fabrication of piroxicam films.

Electrospun polyurethane/Eudragit ® L100-55 composite mats for the pH dependent release of paclitaxel on duodenal stent cover application

A nanofiber composite mat of PU and Eudragit(®) L100-55 was created using electrospinning process. The pH dependent release of paclitaxel was successfully done with the use of PU/EL100-55 nanocomposite mats as the controlling platform. The morphology of the nanofiber composites was surveyed using FESEM and ratios of the polymers affects the diameter of the nanofiber. Characterization of the nanofiber composite mat was done using FTIR, DSC-TGA method. The release rate of paclitaxel was determined and analyzed by in vitro drug release method. In order to mimic the condition of a human duodenum, the fibers were submersed on PBS of different pH levels (4.0, 6.0,) respectively, and then analyzed using high performance liquid chromatography (HPLC). Composite mats submersed in PBS with pH 4.0 showed lesser release profile compared to mats submersed in PBS with pH of 6.0. The composite mat has adequate mechanical properties and in vitro cell biocompatibility indicating that the material can be used for drug eluting stent cover application.

Plasticizer effects on physical-mechanical properties of solvent cast Soluplus® films

Soluplus® is a novel amphiphilic polymer that has been shown to enhance the solubility and drug dissolution rate of poorly soluble drugs. However, there still is a lack of information regarding the physical mechanical properties of Soluplus® with addition of the plasticizers. This study characterized the mechanical properties of Soluplus® with four different plasticizers. The plasticizers selected were polyethylene glycol 6, triethyl citrate, propylene glycol, and glycerin; they were studied at three different levels (15%, 20%, and 25% w/w). The effects of these plasticizers on the glass transition temperature, tensile strength, percent elongation, and Young's modulus of free films made from Soluplus® were measured and the toughness and ratio of tensile strength to Young's modulus were calculated. These results showed these four plasticizers are capable to plasticizing Soluplus® as indicated by the glass transition temperature lowering, tensile strength, and Young's modulus while increasing the percent elongation and film toughness. Among the plasticizers tested, polyethylene glycol 6 showed greatest changed in the mechanical properties studied.

Plasticization and antiplasticization of an acrylic pressure sensitive adhesive by ibuprofen and their effect on the adhesion properties

In transdermal patches, an unpredictable alteration of the mechanical behavior of the pressure sensitive adhesive (PSA) can occur if a drug is added. In the present study, the suitability of Dynamic Mechanical Analysis (DMA)/Dynamic Mechanical Thermal Analysis (DMTA) as methodologies to detect the change in adhesion properties caused by the addition of an API was examined. With DMA/DMTA, time- and temperature-dependent viscoelastic properties were determined. Tack and shear adhesion of blends of the acrylic adhesive DuroTak® 87-4287 and ibuprofen at increasing concentrations were investigated. Interestingly, the probe tack test showed highest values at 1% ibuprofen concentration in the PSA and decreasing values with increasing ibuprofen concentrations. The shear adhesion of the PSA was decreased at all investigated ibuprofen concentrations. With DMA/DMTA, it could be demonstrated that antiplasticization and plasticization are responsible for the change in tack. The main reason for the decrease in shear adhesion is a shift of the Tg to lower temperatures, while antiplasticization only has a marginal effect. The term "antiplasticizing space" was introduced because antiplasticization depends on time, temperature, stress, strain, and API concentration. In general, this antiplasticizing space can have an impact on processing, stability, and in vivo behavior of API/polymer blends in drug formulations.

The effect of plasticizers on the erosion and mechanical properties of polymeric films

Cellulose acetate phthalate and Pluronic F-127 combined together (70:30 wt:wt) create a rigid, surface-eroding association polymer. To impart flexibility into the polymer system and allow for a drug delivery film that can contour to varying wound shapes, plasticizers were added. Triethyl citrate or tributyl citrate was combined with cellulose acetate phthalate and Pluronic F-127 at 0, 10, or 20 wt%. Mechanical analysis was performed on the films as they were prepared and following a 2-h incubation in phosphate-buffered saline. Tensile tests showed that higher plasticizer content increased the % elongation but decreased the elastic modulus and ultimate tensile strength. The effect triethyl citrate had on the % elongation was twice as much than that of tributyl citrate. After incubation, % elongation, elastic modulus, and ultimate tensile strength all increased because plasticizer leached out of the films. Microcomputed tomography and scanning electron microscopy were performed on the samples both before and after incubation to determine how erosion and leaching of plasticizer affected the interior and exterior structure of the films. Porosity increased as plasticizer content increased; however, plasticizer content did not have a significant effect on the rate of erosion. The mechanical properties of cellulose acetate phthalate-Pluronic films can be adjusted by the type and amount of plasticizer added to the system and therefore can be tailored for different drug delivery applications.

Drug-inorganic-polymer nanohybrid for transdermal delivery

For transdermal drug delivery, we prepared a drug-inorganic nanohybrid (FB-LDH) by intercalating a transdermal model drug, flurbiprofen (FB), into the layered double hydroxides (LDHs) via coprecipitation reaction. The X-ray diffraction patterns and FT-IR spectra of the FB-LDH indicated that the FB molecules were successfully intercalated via electrostatic interaction within the LDH lattices. The in vitro drug release revealed that the Eudragit(®) S-100 in release media could facilitate the drug out-diffusion by effectively replacing the intercalated drug and also enlarging the lattice spacing of the FB-LDH. In this work, a hydrophobic gel suspension of the FB-LDH was suggested as a transdermal controlled delivery formulation, where the suspensions were mixed with varying amounts of Eudragit(®) S-100 aqueous solution. The Frantz diffusion cell experiments using mouse full-skins showed that a lag time and steady-state flux of the drug could be controlled from 12.8h and 3.28μgcm(-2)h(-1) to less than 1h and 14.57μgcm(-2)h(-1), respectively, by increasing the mass fraction of Eudragit(®) S-100 solution in gel suspensions from 0% to 20% (w/w), respectively. Therefore, we conclude gel formulation of the FB-LDH have a potential for transdermal controlled drug delivery.

Polymeric Eutectic System

The liquid eutectic system comprising 1:1 menthol:camphor was selected to use as solvent due to it was lowest viscosity. Both menthol and camphor used in this eutectic system have been reported for their many pharmaceutical used. Various polymers were tested for their solubility in this eutectic system. Eudragit® EPO showed the highest solubility. Eudragit® EPO was the one of biocompatible polymer which could dissolve in this eutectic system up to 40% w/w with no chemical interaction of each compound. Viscosity of this system showed the exponential curve as a function of polymer concentration but all concentration showed the newtonian rheology. The pH and surface tension were slightly affected by type and amount of polymers. The obtained polymeric eutectic mixture should control the drug release for pharmaceutical applications.

Novel application of Eudragit RL and cholesteryl oleyl carbonate to thermo-sensitive drug delivery system

The Eudragit RL 100 and propylene glycol (PG) membranes with and without cholesteryl oleyl carbonate (COC) were prepared by the solvent casting method to pioneer a novel application of a thermo-sensitive drug delivery system. After that, the properties of these membranes were investigated by thermal, scanning, and porosity studies. Drug permeation studies through all membranes were carried out using salbuthamol sulphate (SBS) at constant temperatures (25°C and 37°C), respectively. The permeability of SBS through the membranes with COC has been shown to be a discontinuous function of temperature, that is, their permeability increased steeply above the phase transition temperature (37°C) of the COC. The thermo-sensitive permeation mechanism for the membranes might be based on the structure change of the membranes caused by the phase transition, so that the membranes could absorb more water. Considering the high biological safety of Eudragit RL 100 and PG membranes with and without COC might be used to develop a novel thermo-sensitive drug delivery system.

Adhesive properties: a critical issue in transdermal patch development

INTRODUCTION

Transdermal patches and medicated plasters (patch) represent well-established prolonged release dosage forms. Even if satisfactory adhesion to the skin is strictly linked to the efficacy and safety of the therapeutic treatment, nowadays numerous reports of in vivo 'adhesion lacking' are still addressed to regulatory agencies. The adhesive properties of a patch should be characterized considering i) the ability to form a bond with the surface of another material on brief contact and under light pressure (tack); ii) the resistance of the adhesive to flow (shear adhesion); and iii) the force required to peel away a patch from a surface (peel adhesion).

AREAS COVERED

In this manuscript, the most widely used methods to measure adhesive properties during development studies are described, along with the quality control of patches. The influence of formulative variables on patch adhesive properties, and their possible relationship with the in vivo adhesion performances, is also discussed.

EXPERT OPINION

The Pharmacopoeias should consider the opportunity of introducing compendial testing to assay the quality of adhesive patch properties, and regulatory agencies should issue proper guidelines to evaluate these features during development.