Blends Of Ethylcellulose Research Articles

Ethyl cellulose-block-poly(benzyl glutamate) block copolymer compatibilizers for ethyl cellulose/poly(ethylene terephthalate) blends

A block copolymer with the structure ethylcellulose-block-poly(benzy glutamate) was synthesized via ring-opening polymerization and used as a compatibilizer to produce blends of ethylcellulose and poly(ethylene terephthalate).

Induction of protein specific antibody by carbonated hydroxy apatite as a candidate for mucosal vaccine adjuvant.

Buccal mucosae are considered as a site for vaccine delivery since they are relatively abundant with antigen-presenting dendritic cells, mainly Langerhans cells. In this study, we formulated carbonated hydroxy apatite (CHA) with ovalbumin (OVA) (denoted as CHA-OVA), incorporated it into bilayer buccal membrane to form hydrogel films containing CHA-OVA complex for vaccination via buccal mucosae. Ethylcellulose blend with polyethylene glycol 400 were used as impermeable backing layer. Physical properties of all tested buccal membranes were found suitable for mucosal application. In vitro and ex vivo release study showed there was no burst release of OVA found from all tested formula. From the in vivo examination, rabbit buccal mucosae vaccinated by mucoadhesive membranes containing CHA-OVA complex demonstrated mucosal specific antibody induction, represented the potential of CHA as a candidate of needle-free vaccine adjuvant. Future research is awaiting to investigate proper CHA crystallinity in complex with protein against targeted diseases.

An Insight into the Impact of Thermal Process on Dissolution Profile and Physical Characteristics of Theophylline Tablets Made through 3D Printing Compared to Conventional Methods.

The dissolution profile is of great importance in drug delivery and is affected by the manufacturing method. Thus, it is important to study the influence of the thermal process on drug release in emerging technologies such as 3D printing-fused deposition modeling (FDM). For this purpose, the characteristics of 3D printed tablets were compared to those of tablets prepared by other thermal methods such as hot-melt extrusion (HME) and non-thermal methods such as physical mixture (PM). Theophylline was used as a drug model and blends of ethyl cellulose (EC) and hydroxypropyl cellulose (HPC) were used as a matrix former. The solid state of the drug in all formulations was investigated by differential scanning calorimetry, X-ray powder diffraction, and Fourier-transformed infrared spectroscopy. All studied tablets had the same weight and surface area/volume (SA/V). Dissolution data showed that, for some formulations, printed tablets interestingly had a faster release profile despite having the highest hardness values (>550 N) compared to HME and PM tablets. Porosity investigations showed that 100% infill printed tablets had the highest porosity (~20%) compared to HME (<10%) and PM tablets (≤11%). True density records were the lowest in printed tablets (~1.22 g/m3) compared to tablets made from both HME and PM methods (~1.26 g/m3), reflecting the possible increase in polymer specific volume while printing. This increase in the volume of polymer network may accelerate water and drug diffusion from/within the matrix. Thus, it is a misconception that the 3D printing process will always retard drug release based on increased tablet hardness. Hardness, porosity, density, solid-state of the drug, SA/V, weight, and formulation components are all factors contributing to the release profile where the total balance can either slow down or accelerate the release profile.

Partially miscible polymer blends of ethyl cellulose and hydroxyl terminated polybutadiene

The phase behavior of the recently developed blend of ethyl cellulose (EC) and hydroxyl terminated polybutadiene (HTPB) for oxygen scavenging applications was investigated using thermal and thermomechanical analysis as well as morphological and topographical images. The complexity in the phase structure of this system is most probably related to the presence of special hydrogen bonding interactions between the blend's components verified by FTIR-ATR measurements, which led us to expect some degree of miscibility in our blends. The presence of partial miscibility was predicted using the miscibility guideline by Coleman and Painter. Scanning electron microscopy (SEM) revealed well dispersed trapped microdomains in the matrix that may have been related to the HTPB rich phase. Moreover, atomic force microscopy (AFM) images showed different contrasts, which was translated to the presence of partial miscibility and conjugated phases in the system. In addition, DSC analysis was performed to verify this concept in conjunction with DMTA measurements. Although glass transition temperatures were not well pronounced by DSC measurements, DMTA curves obviously depicted turning glass transition temperatures from one at the lowest HTPB composition into two and three transitions at two higher HTPB compositions which confirmed the presence of partial miscibility in our blends. Oxygen absorption measurements demonstrated a proper oxygen scavenging efficiency for the blend in comparison with pure EC.

Hot melt extruded polysaccharide blends for controlled drug delivery

Different types of hot melt extrudates were prepared based on a variety of blends of ethylcellulose with a 2nd polysaccharide, namely hydroxypropyl methylcellulose (HPMC), pectin, maize starch, inulin, maltodextrin, guar gum, and chitosan. In selected cases, the polymer:polymer blend ratio was varied from 80:20, 70:30, 60:40, 50:50, 40:60, 30:70 to 20:80. The addition of appropriate amounts of plasticizers allowed reducing the extrusion temperature to about 100 °C. The impacts of the screw speed, extrusion temperature, amount and type of plasticizer as well as of the amount and type of drug (10–60% theophylline or diprophylline) were studied. Drug release was measured in 0.1 M HCl for 2 h, followed by phosphate buffer pH 6.8 and (optionally) fecal samples to simulate the colon (under anaerobic conditions). DSC measurements and optical microscopy were used to characterize the physical state and morphology of the systems. Interestingly, hot melt extrudates based on ethylcellulose:guar gum blends could be easily prepared at a temperature of 100 °C and offered large spectra of drug release patterns for both: slightly water-soluble theophylline as well as freely water-soluble diprophylline. About constant drug release rates could be obtained during prolonged periods of time. Importantly, the resulting drug release rates from hot melt extrudates based on ethylcellulose:guar gum 80:20 blends were similar in the presence and absence of colonic bacteria, indicating that the ethylcellulose seems to protect the guar gum from degradation upon exposure to fecal samples. Furthermore, these systems were long term stable for at least 1 year under ambient conditions. Thus, they can offer an interesting potential as oral controlled drug delivery systems.

The Influence of the Composition of Ethyl Cellulose–Rubber Blends on the Formation of a Thermoplastic Composite

Experimental data on the comprehensive physicochemical study (by structural, thermomechanical, and thermodynamic methods) of ethyl cellulose (EC) and rubber of different chemical nature, as well as blends of EC and nitrile butadiene rubber (NBR) in the wide composition range are given. The concentration range of the studied blends, which is characterized by the formation of a homogeneous thermoelastoplastic composite with high adhesion parameters relative to that of materials of various chemical nature (rubber, lignocellulosic materials, etc.), is experimentally identified.

Microsegregating blends of ethyl cellulose and poly(vinyl pyrrolidone): a combined thermo-mechanical and positron annihilation spectroscopy study

Polymer blends are a versatile playground for studying phase separation and its effect on the development of morphology and mechanical properties of the resulting materials. Blends obtained from two immiscible polymers, ethyl cellulose (EC) and poly(vinyl pyrrolidone) (PVP), are especially relevant for their practical applications as coatings for pharmaceutical preparations and controlled drug release. Here, films of EC–PVP blends are studied by means of thermal analysis, dynamic-mechanical analysis as well as positron annihilation lifetime spectroscopy. The morphology of the microstructures generated by phase separation is investigated by means of scanning electron microscopy. The effect of both components’ ratio and of molecular mass of PVP on the final properties of the blends is determined in a systematical way. The results obtained are not only of theoretical interest but will prove useful for the optimization of industrial formulations based on these polymers.

Development and bioequivalence study of potassium chloride extended release tablets

The purposes of this study are to prepare the generic extended release tablet of potassium chloride (PC) 600 mg and to compare the absorption of potassium ion from the experimental tablets to that of Kaleorid® LP 600 mg (Leo Pharmaceutical Products, Denmark). Carnauba wax was used as retardant in the matrix core tablets. The core tablets were coated with blends of ethyl cellulose (EC) and hydroxypropyl methyl cellulose (HPMC) to modulate the drug release. Results of a selective two-level, three-factor experiment design revealed that a blend of 41.75% of EC and 58.25% of HPMC at 4.5% weight gained could produce the coated tablets having dissolution profiles similar to those of Kaleorid®. A two-treatment, two-period, two-sequence crossover bioequivalence study was carried out on 24 healthy volunteers to compare the absorption of potassium ion from experimental tablets to that from Kaleorid®. The potassium ion in the urine was measured by a selective electrode of the ADVIA 1650 system (Bayer) and used to calculate cumulative urinary excretion and urinary excretion rate. Results of 90 percent confidence interval analysis showed that the limits for natural log-transformed cumulative urinary potassium excretion (Ln Ae0-24) of test product were in the range of 3.73–3.79 mEq, corresponding to 99.08%–100.92% of Kaleorid®, respectively, and the limits for natural log-transformed maximal potassium excretion rate (Rmax) of test product were in the range of 1.72–1.82 mEq/h, corresponding to 97.34%–102.66% of reference product, respectively. Both of them fell within the bioequivalence interval (80%–125%) of reference product, proving that experimental product is bioequivalent to Kaleorid®.

Cellulose-polysaccharide film-coating of cyclodextrin based pellets for controlled drug release

An oral controlled release system based on blends of ethylcellulose and pectin as film-coating material for pellets was developed. Triamcinolone acetonide (TA) as drug useful in intestinal inflammatory disorders was loaded into cyclodextrin-based pellets. The combination of pectin and ethylcellulose as coating materials was investigated in terms of mechanical analysis, viscosimetry, DSC and TGA, water vapor permeability and TA diffusivity using membranes prepared at different ratios. The coating process by fluid bed coating system was used to obtain different thicknesses of coating for pellets previously fabricated by extrusion-spheronization. To investigate the influence of coating on controlled release properties, the microstructure, specific surface area, porosity and TA release profile from pellets were also assayed.The versatility of the system has been proven by selecting different combinations of blends of polymers. Further, by the reduction in the proportion of pectin in the ethlycellulose:pectin membrane and increasing the thickness of coating, it was possible to achieve a prolonged release over pH 6. These results suggest that the delivery system based on pectin:ethylcellulose coating for pellets has an excellent colon release performance for TA providing protection for drugs that are unstable at acidic pH.

Tailoring the degradation rate and release kinetics from poly(galactitol sebacate) by blending with chitosan, alginate or ethyl cellulose

Despite significant advances in recent times, the investigation of discovering a perfect biomaterial is perennial. In this backdrop, blending of natural and synthetic polymers is gaining popularity since it is the easiest way to complement the drawbacks and attain a superlative material. Based on this, the objective of this study was to synthesize a novel polyester, poly(galactitol sebacate), and subsequently blend this polymer with one of the three natural polymers such as alginate, chitosan or ethyl cellulose. FT-IR showed the presence of both the polymers in the blends. 1H NMR confirmed the chemical structure of the synthesized poly (galactitol sebacate). Thermal characterization was performed by DSC revealing that the polymers were amorphous in nature and the glass transition temperatures increased with the increase in ratio of the natural polymers in the blends. SEM imaging showed that the blends were predominantly homogeneous. Contact angle measurements demonstrated that the blending imparted the hydrophilic nature into poly (galactitol sebacate) when blending with alginate or chitosan and hydrophobic when blending with ethyl cellulose. In vitro hydrolytic degradation studies and dye release studies indicated that the polymers became more hydrophilic in alginate and chitosan blends and thus accelerated the degradation and release process. The reverse trend was observed in the case of ethyl cellulose blends. Modeling elucidated that the degradation and dye release followed first order kinetics and Higuchi kinetics, respectively. In vitro cell studies confirmed the cytocompatible nature of the blends. It can be proposed that the chosen natural polymers for blending showed wide variations in hydrophilicity resulting in tailored degradation, release and cytocompatibility properties and thus are promising candidates for use in drug delivery and tissue engineering.

DEVELOPMENT AND EVALUATION OF TRANSDERMAL THERAPEUTIC SYSTEM OF AN ANTIHYPERTENSIVE DRUG

Trans dermal drug delivery offers potential alternative to conventional techniques employed for administration of systemic therapeu tics. The present study was aimed at the formulation of matrix type transdermal system of Diltiazem hydrochloride using blends of e thyl cellulose and polyvinyl pyrrolidone in different ratios and selecting the suitable formulation for the development of transdermal system. Transdermal patches of the drug empl oying different ratios of ethyl cellulose and polyvinylpyrrolidone were devel oped and evaluated for physicochemical properties and potential drug delivery using freshly excised abdominal skin of rat. The drug excipient interactions were carried out using Fourier transform infrared spectroscopy and di fferential scanning calorimetry . In vitro permeation study was conducted for 11 hours using Franz diffusion cell. Interaction studies showed absence of any significant interaction between the drug and polymer as evidenced by the absence of additional peaks in the FTIR spectra. The in vit ro permeation study revealed that formulation F4 showed sustained and maximum release over a period of 11 h . The results obtained from in vitro release studies were subjected to various kinetic models and the formulations were found to follow zero order re lease mechanism. Thus the blends of Ethyl cellulose and Polyvinyl Pyrrolidone can be incorporated in other transdermal delivery systems also to produce sustained release.

Preparation and characterization of konjac glucomannan and ethyl cellulose blend films

Konjac glucomannan (KGM)/ethyl cellulose (EC) blend films were prepared at different blend ratios (KGM/EC = 10/0, 9/1, 8/2, 7/3, 6/4, and 0/10, w/w) in the presence of dibutyl sebacate at 25% (w/w) of total solids content.Hydrogen bond interactions between KGM and EC occurred. An ethyl cellulose phase consisting of oval-shaped particles was uniformly embedded in the KGM continuous phase. The maximum values of tensile strength and elongation at break of blend films were respectively 48 MPa and 12.7% when the ratio of KGM and EC was 7/3 (w/w). Compared to KGM film, the moisture resistance, thermal stability, tensile strength, and elongation at break of blend films were increased. In addition, water vapor transmission was decreased, but the oxygen permeability was increased by blending. Applications of the blend film of KGM and EC for food packaging are suggested.

Ethanol-resistant polymeric film coatings for controlled drug delivery

The sensitivity of controlled release dosage forms to the presence of ethanol in the gastro intestinal tract is critical, if the incorporated drug is potent and exhibits severe side effects. This is for instance the case for most opioid drugs. The co-ingestion of alcoholic beverages can lead to dose dumping and potentially fatal consequences. For these reasons the marketing of hydromorphone HCl extended release capsules (Palladone) was suspended. The aim of this study was to develop a novel type of controlled release film coatings, which are ethanol-resistant: Even the presence of high ethanol concentrations in the surrounding bulk fluid (e.g., up to 40%) should not affect the resulting drug release kinetics. Interestingly, blends of ethylcellulose and medium or high viscosity guar gums provide such ethanol resistance. Theophylline release from pellets coated with the aqueous ethylcellulose dispersion Aquacoat® ECD 30 containing 10 or 15% medium and high viscosity guar gum was virtually unaffected by the addition of 40% ethanol to the release medium. Furthermore, drug release was shown to be long term stable from this type of dosage forms under ambient and stress conditions (without packaging material), upon appropriate curing.

Properties of solutions and films of blends of ethyl cellulose with polyvinylpyrrolidone and Poviargol

Viscosity properties of dilute and concentrated ethanol solutions of blends of ethyl cellulose with polyvinylpyrrolidone and Poviargol bactericidal formulation (silver metal nanoparticles stabilized with polyvinylpyrrolidone) were studied. The physicomechanical and thermomechanical properties of films prepared from solutions of the polymer blends were determined. Experiments on solvent vapor sorption showed that ethyl cellulose is incompatible with polyvinylpyrrolidone and Poviargol in the solid state in the entire composition range examined.

Optical properties of cellulose derivatives blend film carrying a chalcogenide material

Polymeric films composed of mixture of ethyl cellulose (EC) and hydroxypropyl cellulose (HPC) are prepared from casting combined solvent (methylene chloride and methanol in 1:1 ratio) containing 8% weight/volume of both polymers (EC to HPC in 1:3 weight ratio). The structural and optical studies of the films are carried out by X-ray diffraction and UV–vis spectrophotometer. The films are polycrystalline structure with an average grain size from 23.15 to 10.79nm. The possible optical transition in these films is found to be allowed direct transition. The optical band gap energy (Eg) is estimated to be 5.02eV for HPC–EC plain film and then decreases with increasing the filler content reaching to 4.24eV for the film filled with maximum Se80Te14Sn6 content of 1w%. This suggests that Se80Te14Sn6, as filler, is a good choice to control the optical properties of HPC–EC blend film.

Preparation and Characterization of Polymer Blends of Ethyl Cellulose and its Composites

The polymer blend of Ethyl Cellulose (EC) with Poly (vinyl) pyrrolidone (PVP) of various weight percentages at different thickness are used for measurement of dielectric permittivity, electrical conductivity and optical properties. The activation energies of the EC and its blend with PVP are obtained through measurement of dc conductivity. The samples are characterized by using X-ray diffractometer (XRD). The blends of EC with PVP in the ratio of 50:50 weight percent using FTIR over the range of wavenumber 4000-500 cm-1. Key words: Polymer Blend, XRD, SEM, FTIR, dielectric permittivity, activation energy.

Miscibility and interfacial property studies of the blends of ethyl cellulose with copolyamide6/66/1010

Interfacial properties governing reverse osmosis separations were studied by using liquid chromatography data with respect to ethyl cellulose/copolyamide6/66/1010 (EC/PA-130) blends. The miscibility of ethyl cellulose/copolyamide6/66/1010 (EC/PA-130) blends was investigated by using differential scanning calorimetry (DSC) and Fourier transform infrared, while the interfacial properties of the blends, including the interfacial adsorption, hydrophobicity, polar and non-polar parameters and β-parameters, were studied by using liquid chromatography. The results show that EC and PA-130 are miscible at compositions of (80/20), (70/30) and (50/50). The hydrophobicity of EC/PA-130 increases with the of PA-130 content. The EC/PA-130(70/30) is superior to the other blends for separating non-dissociable polar organic solute and is more suitable for use as desalting membrane material. It seems that liquid chromatography is an effective tool for studying the interfacial properties of polymer blend materials and selecting high performance of membrane materials.

The prediction of compatibility/incompatibility in blends of ethyl cellulose with hydroxypropyl methylcellulose or hydroxypropyl cellulose using 2-dimensional solubility parameter maps.

Typical two dimensional solubility parameter maps for ethyl cellulose, hydroxypropyl methylcellulose and hydroxypropyl cellulose have been constructed using literature data. The maps of the polymers showed some degree of overlap indicating some mutual compatibility. Compatibility between ethyl cellulose and hydroxypropyl cellulose was greater than between ethyl cellulose and hydroxypropyl methylcellulose. The maps may also be used to predict the effect of added plasticizers.

Optimised process and formulation conditions for extended release dry polymer powder-coated pellets

The objective of this study was to improve the film formation and permeability characteristics of extended release ethylcellulose coatings prepared by dry polymer powder coating for the release of drugs of varying solubility. Ethylcellulose (7 and 10 cp viscosity grades) and Eudragit(R) RS were used for dry powder coating of pellets in a fluidised bed ball coater. Pre-plasticised ethylcellulose powder was prepared by spray-drying aqueous ethylcellulose dispersions (Surelease(R) and Aquacoat(R)) or by hot melt extrusion/cryogenic grinding of plasticised ethylcellulose. Chlorpheniramine maleate and theophylline were used as model drugs of different solubilities. The film formation process, polymeric films and coated pellets were characterised by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM) and dissolution testing. Film formation and extended drug release was achieved with ethylcellulose, a polymer with a high glass transition temperature (T(g)) without the use of water, which is usually required in dry powder coating. DMA-measurements revealed that plasticised ethylcellulose had a modulus of elasticity (E') similar to the low T(g) Eudragit(R) RS. With increasing plasticiser concentration, the T(g) of ethylcellulose was reduced and the mechanical properties improved, thus facilitating coalescence of the polymer particles. SEM-pictures revealed the formation of a dense, homogeneous film. The lower viscosity grade ethylcellulose (7 cp) resulted in better film formation than the higher viscosity grade (10 cp) and required less stringent curing conditions. Successful extended release ethylcellulose coatings were also obtained by coating with pre-plasticised spray-dried ethylcellulose powders as an alternative to the separate application of pure ethylcellulose powder and plasticiser. The permeability of the extended release coating could be controlled by using powder blends of ethylcellulose with the hydrophilic polymer HPMC. In conclusion, dry polymer powder coating is an interesting technique to achieve extended release of drugs with varying solubility as an alternative to classical coatings obtained from organic polymer solution or aqueous polymer dispersions.

Enzymatically activated coated multiparticulates containing theophylline for colon targeting

Different types of polymer blends were studied with respect to their potential to provide colon specific drug delivery. The water uptake and dry mass loss kinetics of thin films in media simulating the contents of the upper GIT were used as surrogate parameters for drug permeability of the polymeric networks. Nutriose 100 % fibers, Lycoat NG 73, FOS, wheat dextrin and inulin were studied as “targeting compounds”, which are to be preferentially degraded by bacterial enzymes in the colon of inflammatory bowel disease patients. Ethylcellulose was used as water-insoluble polymer to avoid premature film dissolution/significant swelling in the upper GIT. The “targeting compound”:ethylcellulose blend ratio was varied from 1:2 to 1:5 and the films were exposed to 0.1 M HCl and phosphate buffer pH 6.8, optionally containing pepsin or pancreatin. Furthermore, the mechanical properties of the polymeric networks were measured using a texture analyzer and the puncture test in the dry state as well as upon exposure to media simulating the contents of the upper GIT. Importantly, crack formation in vivo due to the motility of the stomach and small intestine or hydrostatic pressure built up upon water penetration into the delivery systems is unlikely in all cases. Once the polymeric films came into contact with fecal samples from Crohn’s disease and ulcerative colitis patients, the “targeting compound” was (at least partially) degraded by bacterial enzymes, resulting in significant water uptake, dry mass loss and increased permeability for the drug. Theophylline release from pellets coated with 20 % Nutriose 100 % fibers: ethylcellulose 1:5 was effectively limited in media simulating the contents of the upper GIT, but set on as soon as the multiparticulates came into contact with fecal samples.