Influence of insoluble excipients on film coating systems

Taste-masking methods in multiparticulate dosage forms with a focus on poorly soluble drugs

In the past, the administration of medicines for children mainly involved changes to adult dosage forms, such as crushing tablets or opening capsules. However, these methods often led to inconsistent dosing, resulting in under- or overdosing. To address this problem and promote adherence, numerous initiatives, and regulatory frameworks have been developed to develop more child-friendly dosage forms. In recent years, multiparticulate dosage forms such as mini-tablets, pellets, and granules have gained popularity. However, a major challenge that persists is effectively masking the bitter taste of drugs in such formulations. This review therefore provides a brief overview of the current state of the art in taste masking techniques, with a particular focus on taste masking by film coating. Methods for evaluating the effectiveness of taste masking are also discussed and commented on. Another important issue that arises frequently in this area is achieving sufficient dissolution of poorly water-soluble drugs. Since the simultaneous combination of sufficient dissolution and taste masking is particularly challenging, the second objective of this review is to provide a critical summary of studies dealing with multiparticulate formulations that are tackling both of these issues.

Investigation into the Influence of the Process Parameters on the Stability of a Poly(Vinyl)-Alcohol-Based Coating System

Most tablets put on the market are coated with polymers soluble in water. The Opadry II 85 series from Colorcon Inc., is a family of PVA-based products marketed since the 1990s. Despite numerous publications on the properties of PVA, to date, limited work has been undertaken to determine the physico-chemical parameters (i.e., UV light, high temperature, and relative humidity) that could affect the performance of PVA-based coatings. To this end, we performed artificial ageing processes on samples made of Opadry Orange II or of some selected components of this coating and analysed them by means of a multidisciplinary approach, using, for example, FTIR, NMR, rheology, and DMTA measurements. In this way, we analysed the influence of the critical components of the Opadry Orange II formula, such as titanium dioxide and aluminium hydroxide, on the coating characteristics under ageing conditions.

Influence of talc and hydrogenated castor oil on the dissolution behavior of metformin-loaded pellets with acrylic-based sustained release coating

Multi-unit pellet system (MUPS) is of great interest as it is amenable to customization. MUPS comprises multi-particulates, usually as pellets or spheroids, which can be coated with diffusion barrier coatings. One commonly used diffusion barrier coating is the methacrylic acid copolymer, which can be used as a taste masking, enteric or sustained release polymer. While the versatility of methacrylic acid copolymers makes them pliable for pellet coating, there are impediments associated with their use. Additives commonly required with this polymer, including plasticizer and anti-adherent, have been shown to weaken the film strength. The objective of this study was to investigate the impact of osmotic pressure within the core on the sustained release coat integrity and functionality. Hydrogenated castor oil (HCO) was chosen as the additive to be studied. Metformin-loaded pellets, prepared via extrusion-spheronization, were coated with ethyl acrylate and methyl methacrylate copolymer (Eudragit RS 30 D) with talc, talc-HCO, or HCO to different coat thicknesses. Drug release was investigated using the USP dissolution apparatus 2 and an ultraviolet imager. The swelling of the pellets when wetted was monitored by video imaging through a microscope. When coated to 7.5 % coat weight gain, coats with HCO slowed down drug release more than the other pellets. The pellets also swelled the most, which suggests that they were more resistant to the osmotic pressure exerted by metformin. For drugs which exert high osmotic pressure, HCO can serve as an efficient alternative to talc in the preparation of methacrylic acid copolymer coatings.

Polymeric Coatings and Antimicrobial Peptides as Efficient Systems for Treating Implantable Medical Devices Associated-Infections

Many infections are associated with the use of implantable medical devices. The excessive utilization of antibiotic treatment has resulted in the development of antimicrobial resistance. Consequently, scientists have recently focused on conceiving new ways for treating infections with a longer duration of action and minimum environmental toxicity. One approach in infection control is based on the development of antimicrobial coatings based on polymers and antimicrobial peptides, also termed as “natural antibiotics”.

What's next in the use of opacifiers for cosmetic coatings of solid dosage forms? Insights on current titanium dioxide alternatives

The consolidated use of coatings containing E171 (i.e. titanium dioxide, TiO2) as an opacifier has made the white color of the resulting dosage forms a quality standard in the pharmaceutical and dietary supplement fields. This color is also associated with the efficiency of the coating layer in protecting the substrate from the effects of UV rays. However, health risks related to diet exposure to TiO2 has recently been advanced and its addition in coating formulations has been seriously questioned. As a consequence, in principle safer TiO2-free formulations have been recently launched on the market, especially for coatings of dietary supplements. In this work, we evaluated the overall physico-technological characteristics and performance of immediate release tablets coated with a variety of commercial cosmetic formulations free of E171. Moreover, a quantitative method based on the CIELab color space was proposed for the first time for studying the covering/coloring performance of the coating formulations. Based on the results obtained, the possibility to achieve a satisfactory covering capability and a degree of white comparable to that of a standard TiO2-containing reference with all the commercially-available ready-to-use TiO2-free products considered, without affecting the dissolution performance, was demonstrated.

Understanding the release performance of pellets with hydrophobic inclusions in sustained-release coating

The aim of this study was to evaluate how the addition of hydrophobic inclusions to sustained-release pellet film coat can affect drug release. Sustained-release formulations, in particular multiparticulate systems are gaining popularity because they are able to reduce the dosing frequency of drugs that require multiple dosing. In addition, the risk of dose dumping is low and local gastrointestinal irritation is minimised. Metformin-loaded pellets, prepared via extrusion-spheronisation, were coated with ethyl cellulose (EC)-based film coat, with and without hydrophobic inclusions to a series of coat thickness. Stearic acid 50 (SA) and hydrogenated castor oil (HCO) were the hydrophobic inclusions used. Drug release was investigated using the USP dissolution apparatus 2 and an ultraviolet imager. Release kinetics were analysed using the zero-order model. The physical properties of the pellets were characterised before and after dissolution. The addition of hydrophobic inclusions to EC-based film coat slowed down drug release, with SA slowing down drug release more than HCO. The influence of hydrophobic inclusions on drug release was clearly observable when the pellets were coated to 10% weight gain. It was postulated that the hydrophobic inclusions acted as physical barriers to increase the tortuosity of the diffusional path through the pellet film coat. The use of hydrophobic inclusions to control the rate of drug dissolution was shown to be promising. This could translate into potential cost and time savings with less materials and time used.

Development of metoprolol tartrate-loaded sustained-release pellets: effect of talc on the mechanism of drug release

Talc is one of the most commonly used antiadherents in the coating film. However, the mechanism of influence of talc on drug release has yet to be fully understood. In this study, metoprolol tartrate (MT)-loaded Eudragit NE 30 D-coated sustained-release (SR) pellets were prepared using talc as an antiadherent in the layering and coating processes. Talc significantly reduced the stickiness of the layered or coated substrates, thus enhancing the process smoothness. Moreover, the incorporation of talc into the coating film significantly affected drug release. The water vapor permeability and drug permeability of free films increased as the concentration of talc increased. Importantly, talc had a dynamic effect on the drug release. The drug release rate of the pellets in the initial stage (within 2 h) increased with increasing talc concentrations, which exceeded the critical pigment volume concentration resulted in leaks formation in the coated film. However, subsequent swelling of the membrane and expansion of the copolymer network eliminated the influence of talc and the drug release was then controlled by the polymeric membrane. These results suggest that talc contributed to the reduction of the sticking of layered or coated substrates, and facilitated the manufacturing process and drug release properties.

Pore blocking: An innovative formulation strategy for the design of alcohol resistant multi-particulate dosage forms

In this work calcium stearate (CaSt) multi-particulates loaded with codeine phosphate (COP) were developed in an attempt to provide extended release (ER) combined with alcohol dose dumping (ADD) resistance. The pellets were prepared via wet/extrusion spheronization and ER characteristics were obtained after fluid bed drying at 30°C. Pore blockers (i.e., xanthan, guar gum and TiO2) were integrated to control the uptake of ethanolic media, the CaSt swelling and consequently, the COP release. While all three pore blockers are insoluble in ethanol, xanthan dissolves, guar gum swells and TiO2 does not interact with water. The incorporation of 10 and 15% TiO2 still provided ER characteristics and yielded ADD resistance in up to 40v% ethanol. The in-vitro data were subjected to PK simulations, which revealed similar codeine plasma levels when the medication is used concomitantly with alcoholic beverages. Taken together the in-vitro and in-silico results demonstrate that the incorporation of appropriate pore blockers presents a promising strategy to provide ADD resistance of multi-particulate systems.

Antimicrobial films containing microparticles for the enhancement of long-term sustained release

Coated packagings with thin films containing antimicrobial agents are an alternative technology to ensure the protection of products against microbial contaminations. Indeed, they allow lowering the antimicrobial concentration in the bulk of the product while meeting the safety requirements and the growing consumer demand for low preservative concentrations. Microencapsulation is a suitable way for controlling active agent release and providing a long-term activity. This work aims at combining both technical solutions with coatings containing antimicrobial microparticles for the achievement of long-term sustained release. Polyethylene surfaces were functionalized with microparticles of poly(methyl methacrylate) (PMMA) loaded with phenylethyl alcohol (PEA) as antimicrobial agent by the dip coating process using a polyurethane binder. The release of PEA into water from coated polyethylene surfaces and from PMMA microparticles was investigated to assess the sustained release and its mechanisms. Films with various thicknesses of 400-1000 µm containing antimicrobial microparticles demonstrated unusual long-term release longer than 3 months. The diffusion of the antimicrobial agent through PMMA was the rate limiting step of the sustained release. PEA release increased as the contact area of the protruding microparticles with the external medium increased and the thickness of the film decreased. Such antimicrobial agents encapsulated inside thin coatings are promising with regards to antimicrobial preservation of products along their full shelf-life.

Model drug as pore former for controlled release of water-soluble metoprolol succinate from ethylcellulose-coated pellets without lag phase: opportunities and challenges

The objective of the present study was to evaluate the feasibility of using model drug metoprolol succinate (MS) as a pore former to modify the initial lag phase (i.e., a slow or non-release phase in the first 1-2 h) associated with the drug release from coated pellets. MS-layered cores with high drug-layering efficiency (97% w/w) were first prepared by spraying a highly concentrated drug aqueous solution (60% w/w, 70°C) on non-pareils without using other binders. The presence of MS in ethylcellulose (EC) coating solution significantly improved the coating process by reducing pellets sticking, which often occurs during organic coating. There may be a maximum physical compatibility of MS with EC, and the physical state of the drug in the functional coating layer of EC/MS (80:20) was simultaneously crystalline and non-crystalline (amorphous or solid molecule solution). The lag phase associated with hydroxypropylcellulose (HPC) as a pore former was not observed when MS was used as a pore former. The drug release from EC/MS-coated pellets was pH independent, inversely proportional to the coating levels, and directly related to the pore former levels. The functional coating layer with MS as a pore former was not completely stabilized without curing. Curing at 60°C for 1 day could substantially improve the stability of EC/MS-coated pellets. The physical state of the drug in the free film of EC/MS (85:15) changed partially from amorphous to crystal when cured at 60°C for 1 day, which should be attributed to the incompatibility of the drug with EC.

Impact of anti-tacking agents on properties of gas-entrapped membrane and effervescent floating tablets

Tackiness caused by the gas-entrapped membrane (Eudragit(®)RL 30D) was usually observed during storage of the effervescent floating tablets, leading to failure in floatation and sustained release. In this work, common anti-tacking agents (glyceryl monostearate (GMS) and talc) were used to solve this tackiness problem. The impact of anti-tacking agent on the properties of free films and corresponding floating tablets was investigated. GMS was more effective than talc in reducing tackiness of the film. Addition and increasing amount of anti-tacking agents lowered the film mechanical strength, but the coating films were still strong and flexible enough to resist the generated gas pressure inside the floating tablet. Wettability and water vapor permeability of the film decreased with increasing level of anti-tacking agents as a result of their hydrophobicity. No interaction between anti-tacking agents and polymer was observed as confirmed by Fourier transform infrared spectroscopy, powder X-ray diffractometry, and differential scanning calorimetry studies. Increasing amount of anti-tacking agents decreased time to float and tended to retard drug release of the floating tablets. Floating properties and drug release were also influenced by type of anti-tacking agents. The obtained floating tablets still possessed good floating properties and controlled drug release even though anti-tacking agent had some effects. The results demonstrated that the tackiness problem of the floating tablets could be solved by incorporating anti-tacking agent into the gas-entrapped membrane.

The reality of in-line tablet coating

The possibility of continuous processing in pharmaceutical tablet manufacturing is hampered by the viscoelastic recovery of tablets post-compaction. Compacted tablets are typically aged before coating to allow complete viscoelastic recovery so as to avoid subsequent coating defects. There has been little attempt to overcome tablet recovery in order to enable continuous processing and improve manufacturing efficiency. However, with the introduction of improved or newly developed types of tablet-coating equipment, there is renewed interest in the coating of tablets in-line. In-line tablet coating is defined as the coating of tablets immediately after compaction. It is a one-step highly integrated system that circumvents the delay in processing time typically given to allow viscoelastic recovery of tablets. This review aims to summarize the requirements of an in-line tablet-coating system. The possibility of carrying out in-line tablet coating in the near future will also be discussed.

Study of the Effect of Stirring on Foam Formation from Various Aqueous Acrylic Dispersions

Acrylic polymers in aqueous dispersions are very often used to prepare coating suspensions which contain insoluble particles. The mixing of the pigment suspension and the polymer dispersion is a very important step in the preparation of the liquid. The stirring can cause precipitation of the polymer and foam formation. Foam formation from different Eudragit dispersions was evaluated in this study. A high-speed mixer was applied and the foam and liquid phases formed were separated. The changes in concentration of the polymer in the two phases were studied by FT-IR with a horizontal attenuated total reflection (HATR) accessory. The presence of shape-holding foam can be detected at very different rates of stirring. The most intensive foam formation was detected for Eudragit FS 30 D. The Eudragit RL 30 D dispersion was the least sensitive to high-speed mixing. The relative content of the polymer in the foam was higher than that in the liquid. This is indicated by the accumulation of surface-active agent on the surface of the bubbles formed in the foam. This phenomenon differed considerably for the various dispersions. An exact knowledge of the foam formation from aqueous acrylic dispersions is very important in order to determine the parameters of mixing and the quantity of antifoaming agent.

The Influence of Different Plasticizers and Polymers on the Mechanical and Thermal Properties, Porosity and Drug Permeability of Free Shellac Films

The effect of triethyl citrate (TEC) and different molecular weights and concentrations of polyethylene glycol (PEG), in addition to the effect of different water-soluble polymers and dispersions at different levels, hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), carbomer 940, polyvinyl alcohol (PVA), ethyl cellulose (EC), on the mechanical and thermal properties, drug permeability, and porosity of free shellac films were investigated. Shellac films were cast from aqueous solutions, and their mechanical properties were studied by tensile test. Thermal analyses were performed using differential scanning calorimetry (DSC). The results showed that the addition of plasticizer caused a decrease in both elastic modulus and glass transition temperature (T(g)) and an increase in elongation at break of free shellac films. This effect was related to the concentrations of plasticizers. Different molecular weights of PEGs have different plasticization mechanisms.Moreover, the incorporation of different amounts of HPMC, MC, or carbomer in free shellac films caused an increase in the flexibility, decrease in T(g), and a marked increase in drug permeability of free shellac films, whereas the addition of PVA caused a decrease in flexibility and drug permeability and an increase in T(g). Addition of EC resulted in a slight decrease of the elasticity and a small decrease in drug permeability. However it does not show a considerable effect on the T(g). In addition, it was found that the drug permeability is directly related to the mechanical properties and T(g) of shellac films.

Investigation of PEGylated derivatives of rosin as sustained release film formers

The purpose of the present study was to investigate the potential use of two PEGylated derivatives of rosin (PD) as sustained release film forming materials. The derivatives differed chemically by their acid numbers--PD-1 with 120.93 and PD-2 with 88.19. The derivative films were characterized for surface morphology, water uptake-weight loss, angle of contact, water vapor transmission rate, mechanical properties and permeability study. Dissolution of diclofenac sodium (DS) and propranolol hydrochloride (PHL) as model drugs was studied from coated pellets. The films of derivatives with and without plasticizers were smooth and continuous. PD-2 films developed greater numbers of pores when in contact with phosphate buffer pH 6.8. The low weight loss, low angles of contact and high water vapor transmission rate of PD-2 films were related to presence of higher concentration of PEG esters. Higher tensile strength and percent elongation of PD-2 films was due to greater degree of internal plasticization of the derivative. The permeability of films to model drugs propranolol hydrochloride and diclofenac sodium was inversely proportional to the film thickness and dibutyl phthalate concentration in them; the permeability being greatest in PD-2 films containing 10% PEG 200. Dissolution rate of propranolol hydrochloride was higher from the coated pellets. The dissolution data followed zero order, Baker-Lonsdale equation and Hixon-Crowell equation of release kinetics with high correlation coefficients. The mechanism of drug release from these coated systems however followed class II transport (n > 1.0). The derivatives investigated could successfully retard release of the model drugs and offers an alternative to the conventionally used polymers.

Rapid method to study the sedimentation of a pigment suspension prepared for coating fluids

Film coating fluids commonly contain a pigment suspension. The sedimentation of insoluble particles in the coating suspension is one of the main problems during the formulation of the coating fluid. The aims of this work were to investigate the suitability of an energy-dispersive X-ray fluorescence analyser for rapid measurement of the sedimentation of titanium dioxide in aqueous suspensions. The suspensions were produced with a high-speed Ultra-Turrax. The process factors evaluated were the stirring rate, time and volume, and the process of sedimentation of the pigment. The enrichment of the pigment at the bottom of the sample holder was followed by means of the very rapid method of energy-dispersive X-ray fluorescence analysis. It can be concluded that the sedimentation of the particles is described by the Weibull equation. With an appropriate combination of the factors, a threefold increase in the sedimentation time was achieved. The mathematically based information (sedimentation time, kinetics of sedimentation, etc.) is essential for an exact evaluation of the preparation of the coating fluid. The understanding of the process through use of this test method leads to the ability to identify the critical control points of film coating.

Dry coating in a rotary fluid bed

A highly efficient dry coating process was developed to obtain an enteric film avoiding completely the use of organic solvents and water. Using hydroxypropyl methylcellulose acetate succinate (HPMCAS) an enteric coat should be obtained without adding talc as anti-tacking agent because of problems arising from microbiological contamination. Further on, a method was developed preparing isolated films in order to determine the glass transition temperature (T(g)) and the required process temperature. The process was conducted in the rotary fluid bed with a gravimetric powder feeder achieving an exact dosage in contrast to volumetric powder feeder. A three way nozzle was aligned tangential to the pellet bed movement feeding simultaneously powder and plasticizer into the rotary fluid bed. The determined coating efficiency of the talc-free formulation was high with 94% and storage stability regarding tacking could be achieved using colloidal silicium dioxide as top powder. The T(g) of the enteric coat could be determined analyzing the T(g) of isolated films obtained by coating celluloid spheres instead of pellets using the dry coating process in rotary fluid bed. The dry coating process has been demonstrated to be a serious alternative to conventional solvent or water based coating processes.

Characterization of latex particles for aqueous polymeric coating by electroacoustic method

Concentrated dispersions are used as coating dispersions for aqueous polymeric coatings, and characterization of the actual concentrated dispersions is an important in the pharmaceutical industry. The commonly used aqueous coating polymers are acrylic polymers and cellulose derivatives. We conducted a characterization study of polymethacrylate-based aqueous polymeric latex for aqueous coating, Eudragit L30D-55 (A-latex) and Eudragit RL30D (C-latex), by electroacoustic method. Colloidal Vibration Current (CVI) is one of the most important parameters relating to dynamic electrophoretic mobility and zeta potential, so we evaluated this parameter first. Volume fractions var of the latex in concentrated dispersions affect the CVIs according to the theory of Dukhin et al. The A-latex and C-latex CVI(*)s which were corrected with regard to the effect of volume fraction by the theoretical equation were nearly constant independent of phi in the ranges >0.04 and >0.03, respectively. The zeta potentials and colloidal stabilities of the concentrated dispersions were evaluated using an electroacoustic method by altering the pH and salt concentration. A-latex strongly aggregated at and below pH 2.5 and at and beyond 0.06 mol/L of electrolyte concentration. Regarding C-latex, instable dispersion was observed at 0.3 and 1 mol/L of NaCl concentration. The total potential energy of interaction between pairs of latex particles was changed by altering the salt concentration in this dispersion based on DLVO theory. The experimental results of stability in the concentrated latex dispersions can be explained by the total interaction energies.

Colloidal stability of aqueous polymeric dispersions: effect of water insoluble excipients

An important issue in the aqueous coating process is dispersion stability. An unstable dispersion results in aggregation of the colloidal particles, thereby affecting the film coating process. In the coating suspension containing pigment, a latex for aqueous film coating might interact with pigment, resulting in unstable dispersion. We therefore conducted a stability investigation in a mixed dispersion including latexes, EudragitL30D-55 (A-latex), EudragitRL30D (C-latex) and EudragitNE30D (N-latex) and pigments, titanium dioxide and iron oxide yellow. An aggregation of the dispersion containing A-latex was observed at pH 2. Regarding the dispersions with C-latex and N-latex, no aggregation was observed in the range pH 2-11. We calculated total interaction energy between latex-latex particles, pigment-pigment particles and latex-pigment particles based on DLVO theory. The calculated results explained two mechanisms of the stable mixed dispersion. The first was that the individual latex particle and the pigment particle dispersed without aggregation in the mixed dispersion because of the electrostatic interaction. The next was that the latexes adsorbed onto the surface of the pigments, making electrostatically stable heterocoaggregates. We also calculated the binding constant of iron oxide yellow for C-latex at pH 10. The value of the constant was determined to be 1.1 x 10(-2).

Investigation of novel alginate−magnesium aluminum silicate microcomposite films for modified-release tablets

Physicochemical properties of sodium alginate-magnesium aluminum silicate (SA-MAS) composite films were investigated and a potential as a film former of SA-MAS dispersion for modifying drug release from tablets was evaluated as well. Interaction between SA and MAS in the composite films was revealed using FTIR spectroscopy. Thermal behavior of the composite films was changed due to the complexation of SA and MAS. Powder X-ray diffractometry data suggested that a higher crystallinity of the composite film and a phase-separated microcomposite were formed. The composite films in the ratios of 1:0.5 and 1:1 showed the increases of tensile strength and percentage of elongation when compared with SA films. Water vapor permeability of the composite films tended to increase with increasing ratio of MAS. The decreases in water uptake and drug permeability in 0.1 M HCl were found in the composite films. A positive charge drug, propranolol HCl, provided a higher affinity on the composite films than a weakly acidic nonelectrolyte, acetaminophen, resulting in a longer lag time and a higher partition coefficient depending on the content of MAS in the composite films. This was due to the complex formation of propranolol HCl and MAS. Using SEM, the tablets coated with SA-MAS dispersion had a smooth surface, while those with SA dispersion showed a pinholing on the surface, resulting in a faster drug release. The drug release profiles of the tablets could be modified by coating with the composite film at different coating levels. This finding suggests that MAS could improve physicochemical properties of the SA films, leading to a novel coating material of the SA-MAS dispersion for modifying drug release from tablets.

Biomechanical and allergological characteristics of a biodegradable poly(D,L-lactic acid) coating for orthopaedic implants

A poly(D,L-lactic acid) surface coating (PDLLA) has been developed to optimize interactions at the implant-tissue interface. Mechanical and allergological characteristics were evaluated in the present study to elucidate possible indications and limitations prior to clinical application. Implants of stainless steel and Ti-6Al-4V and Co-Cr-Mo alloys were coated with PDLLA, and mechanical stability was studied during intramedullary implantation into rat and human cadaver bones and during dilation of coronary artery stents. Elongation resistance was examined on AlMgSi alloy specimens. Furthermore, proliferation of peripheral blood mononuclear cells of nickel-allergic donors and controls and interleukin-4 and interferon-gamma levels were measured in the presence of coated/uncoated implants and after stimulation with phytohemagglutinin or NiSO4. PDLLA remained stable on the implants with a minimum of 96% of the original coating mass and tolerated lengthening of at least 8%. Further lengthening was followed by microcracking and cohesive failure within the coating. PDLLA exerted no suppressive effect upon spontaneous and pan-T-cell mitogen inducible T-cell proliferation. Furthermore, specific proliferation to nickel in cells of nickel-allergic blood donors and production of interleukin-4 and IFN-gamma were not influenced by the coating. PDLLA coating proved high mechanical stability on different orthopaedic implants and did not influence in vitro T-cell reactivity towards specific biomaterials.

Characteristics of erythritol and formulation of a novel coating with erythritol termed thin-layer sugarless coating

The purpose of this study was to clarify the characteristics of erythritol and to develop the optimum basic formulation of a novel coating with erythritol termed thin-layer sugarless coating. Characteristics of erythritol were investigated compared with maltitol, mannitol, sorbitol, xylitol, and sucrose. Furthermore, the optimum basic formulation of thin-layer sugarless coating with erythritol was determined by coating glass beads. We selected a continuous spray mist method for thin-layer sugarless coating due to the formation of a thin sugarless coating layer by a simple method. We demonstrated that erythritol is a suitable coating material for thin-layer sugarless coating compared with maltitol, mannitol, sorbitol, xylitol, and sucrose because of its high water solubility, low hygroscopicity, instant crystallization, and low tackiness. We also demonstrated that thin-layer sugarless coating with erythritol can reduce coating time compared with the coating with maltitol or sucrose due to its characteristics. We developed the optimum basic formulation of thin-layer sugarless coating consists of erythritol, powdered acacia, and talc. We confirmed that a smooth coating layer and high coating efficiency were achieved using the formulation.

Lactic acid-induced modifications in films of Eudragit RL and RS aqueous dispersions

Eudragit RL (ERL) and RS (ERS) are polymethacrylate co-polymers, used in film coating of sustained release dosage forms, possessing some hydrophilic properties due to the presence of quaternary ammonium groups (QAG), where ERL contains more of such groups, hence more permeable, than ERS. However, because these groups ionize in solution, they undergo electrostatic interaction with negatively charged species. This phenomenon was utilized in this study to introduce modification in the film properties of ERL and ERS by interaction with lactic acid (LA). Thermal and mechanical analyses were carried out on polymeric free films. DSC showed a shift in Tg of the film while 1H NMR spectroscopy revealed a significant deshielding in the peak of QAGs protons after interaction with LA. Stress-strain test showed an increase in three mechanical parameters of the new film (containing LA): tensile strength to modulus ratio, relative surface energy and toughness index, indicating an enhancement in the mechanical stress resistance. Tablets coated with LA-containing films showed an increase in the release rate and extent and good stability upon aging, compared to those coated with the original film.

Evaluation of the Film-Forming Property of Hydrogenated Rosin

The film-forming and coating properties of a new biomaterial, hydrogenated rosin (HR), is investigated in the present communication. Films produced by casting method are studied for mechanical, (tensile strength, elongation, and Young's modulus), water vapor transmission, and moisture absorption characteristics. Type of plasticizer and its concentration were observed to play an important role in modifying the film characteristics. Dibutyl sebacate (DBS), a hydrophobic plasticizer, was found to be suitable for development of flexible and smooth films. Film formulations plasticized with DBS were investigated for coating the drug layered nonpareil seeds where plasticization facilitated development of smooth and uniformly coated pellets. The increase in coat buildup, however, did not sustain the drug release significantly. The studies conclude that HR films promise utility as moisture-protective hydrophobic, film-coating materials.