No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Advances in pharmaceutical coatings
Abstract
Recent trends in pharmaceutical technologies are towards the development of coating methods which overcomes the various disadvantages associated with solvent based coatings. In these newer technologies coating materials are directly coated onto solid dosage forms without using any solvent and then cured by various methods to form a coat, hence these methods sometimes called as solventless coatings. Various solventless coatings are available such as photocurable coating, magnetically assisted impaction coating, compression coating, hot melt coating, powder coating, electrostatic dry coating, supercritical fluid coating, herein only magnetically assisted impaction coating and electrostatic dry coating are discussed. This review summarizes the fundamental principles and coating processes of various dry coating technologies.
... As a result of the charge difference, they are transported towards the target and deposited. Tribo-charging is another method that uses the frictional charge of powder that is delivered through a pipe made of a certain material, such as PTFE, metal, or other powder particles [213,216,217]. Because tribo-charging leaves less charge on particles than corona charging [218], corona charging is the preferred method for electrostatic powder coating [219]. ...
... As a result of the charge difference, they are transported towards the target and deposited. Tribo-charging is another method that uses the frictional charge of powder that is delivered through a pipe made of a certain material, such as PTFE, metal, or other powder particles [213,216,217]. Because tribo-charging leaves less charge on particles than corona charging [218], corona charging is the preferred method for electrostatic powder coating [219]. ...
Food sectors are facing issues as a result of food scarcity, which is exacerbated by rising populations and demand for food. Food is ordinarily wrapped and packaged using petroleum-based plastics such as polyethylene, polyvinyl chloride, and others. However, the excessive use of these polymers has environmental and health risks. As a result, much research is currently focused on the use of bio-based materials for food packaging. Biodegradable polymers that are compatible with food products are used to make edible packaging materials. These can be ingested with food and provide consumers with additional health benefits. Recent research has shifted its focus to multilayer coatings and films-based food packaging, which can provide a material with additional distinct features. The aim of this review article is to investigate the properties and applications of several bio-based polymers in food packaging. The several types of edible film and coating production technologies are also covered separately. Furthermore, the use of edible films and coatings in the food industry has been examined, and their advantages over traditional materials are also discussed.
... x) Printing process can be done easily with this coating process [6,7]. ...
A tablet can be defined as a solid unit dosage form. There are several reasons for coating of solid dosage form, the most important reason is to control the release profile & also to control the bioavailability parameters of the APIs (Active Pharmaceutical Ingredients). Tablets containing active pharmaceutical ingredients (API) can be coated with thin polymer-based film for various advantages. Generally, horizontal rotating pans are used for coating purposes & coating solution can be spread through the spraying systems over the surface of tablets. Bitter taste masking, odor masking, physical and chemical protection, and also environmental protection are all benefits of the tablet coating. Despite that, Tablet coating also plays an important role in controlling the action site. Sugar-coating, film coating, and enteric coating are some of the conventional tablet coating processes. The primary objective for creating tablet coating technologies is to eliminate the numerous disadvantages of solvent-based coating. Coating solution preferentially applied on the surface of solid dosage forms without the need for any solvent in these novel technologies. This review article provides information regarding the techniques of conventional tablet coating, the recent advancement of tablet coating procedures, and tablet coating components.
... It is also common to employ blending polymers to get suitable and desired results, as using a single polymer may not give the desired drug release profile. Owing to its hydrophobic properties, EC reduces the penetration of water into the solid polymeric matrix, hence reducing drug release [4,23]. EC can be found in different forms, such as powders with various viscosity grades or aqueous dispersions. ...
Polymers constitute the most important group of excipients utilized in modern pharmaceutical technology, playing an essential role in the development of drug dosage forms. Synthetic, semisynthetic, and natural polymeric materials offer opportunities to overcome different formulative challenges and to design novel dosage forms for controlled release or for site-specific drug delivery. They are extensively used to design therapeutic systems, modify drug release, or mask unpleasant drug taste. Cellulose derivatives are characterized by different physicochemical properties, such as swellability, viscosity, biodegradability, pH dependency, or mucoadhesion, which determine their use in industry. One cellulose derivative with widespread application is ethylcellulose. Ethylcellulose is used in pharmaceutical technology as a coating agent, flavoring fixative, binder, filler, film-former, drug carrier, or stabilizer. The aim of this article is to provide a broad overview of ethylcellulose utilization for pharmaceutical purposes, with particular emphasis on its multidirectional role in the development of oral and topical drug dosage forms.
... Eudragit coating provides pH dependent drug release [20]. During coating color and appearance of the spherules are being changed using appropriate colors and excipients [21].While this process appears affordable and accessible for small and large scale processes, it can lead to disadvantages as well. For example, the wet process can affect the stability of drug molecule. ...
A novel spheronisation technique is reported here for forming spherules from granules using FDA approved excipients and common pharmaceutical unit operations. The aspirin is used as a model drug to check stability during the process. For that, spherules are prepared by "bed coating during sliding" (BCDS) of granules. Spherules with two size range (sieve no 22 and 44) are compared. These spherules are further coated with polymers to show the versatility of the process. They are characterised by microscopical evaluation, flow property determination, drug content evaluation and in vitro drug release studies. Microscopical evaluation reveal that number of edges (90° and 45°) are less for spherules compared to granules. Angle of Repose sand packing parameters appeared excellent. Different polymer coating gives different release profile as per the properties of the polymer. However, the drug content is lower for 44 as compared to 22 while drug release profile appears similar. This is a robust and versatile platform delivery system for developing advanced drug delivery systems (ADDS). However, the stability of aspirin is affected by the wet process may be because aspirin is a hydrolytically labile drug.
... Particles accumulate on the substrate before the repulsion force of the deposited particles against the coming particles increase and exceed the electrostatic attraction. Finally once the said repulsion becomes equivalent to the said attraction, particles cannot adhere to the substrate any more, and the coating thickness does not increase any more [7,8,9,10] . Magnetically assisted impaction coating (MAIC) ...
Tablet coating is one of the oldest pharmaceutical processes still is existence. Coating is a process by which an essentially dry, outer layer of coating material is applied to the surface of a dosage form in order to confer specific benefits over uncoated variety. It involves application of a sugar or polymeric coat on the tablet. The advantages of tablet coating are taste masking, odor masking, physical and chemical protection, protects the drug in the stomach, and to control its release profile. Coating may be applied to a wide range of oral solid dosage form, such as particles, powders, granules, crystals, pellets and tablets. When coating composition is applied to a batch of tablets in a coating pan, the tablet surfaces become covered with a tacky polymeric film. There are several techniques for tablet coating such as sugar coating, film coating and enteric coating. The disadvantages of the older techniques of coating have been overcome with the recent advancement in coating technologies. In these technologies coating materials are directly applied on the surface of the tablet without the use of any solvent. ICH guidelines also prefer the avoidance of organic solvents in pharmaceutical dosage formulations considering products safety profile. This review discusses the basic concepts of tablet coating, the recent advancements made, the problem faced during the process, their solutions and coating evaluation.
... Infact the formulation and clinical performance of dosage form depend on the physicochemical property of the polymer used in the formulations [1] .They are used as taste-masking agent, stabilizer, and protective agent in oral drug delivery. Polymers can bind the particles of a solid dosage form and also change the flow properties of a liquid dosage form [2]. Coating with water insoluble polymers is an important technique for targeted or controlled release formulations and the tastemasking of drugs, during which the aqueous polymer dispersions are widely used as an alternative to an organic polymer coating system [3] .Water soluble polymers are always being in good demand because of their certain advantages over organic solvents with respect to ecological, toxicological and manufacturing safety concern, high cost of organic solvents, solvent toxicity [4]. Aqueous polymeric dispersions, latexes, or pseudo latexes are all colloidal systems in which high molecular weight polymers are homogeneously dispersed in submicron sizes with the aid of surfactant(s) and other stabilizing agents. ...
... Subsequently, they are transported towards target and deposited due to the charge difference (Fig. 1). Another method is tribo-charging, which relies on frictional charging of powder that is transported through a pipe of a specific material, such as PTFE, metal or other powder particles (Fig. 2) (Bailey, 1998;Luo et al., 2008;Pawar et al., 2010). Tribo-charging produces less charge on particles than corona charging (Sumonsiri and Barringer, 2010), thus the corona charging mechanism is mostly used for electrostatic powder coating (Mazumder et al., 2006). ...
Edible coatings and incorporation of active ingredients can improve food quality (appearance, taste, flavours, and increased shelf life). In this paper, specific emphasis is given to electrostatic application of powder coatings that is known for high transfer efficiency and even coating. This application technique has the potential to reduce excessive use of coating material (up to 68%) and minimise dust release (up to 84%) to the environment. Different parameters (e.g. powder particle size) are discussed that influence powder coating quality and efficiency for both non-electrostatic and electrostatic powder application. Typical food processing systems are reviewed that can be combined with electrostatic powder coating. Finally, an overview of electrostatically coated food products and a short outlook of electrostatic powder coating of foods are given.
... Subsequently, they are transported towards target and deposited due to the charge difference (Fig. 1). Another method is tribo-charging, which relies on frictional charging of powder that is transported through a pipe of a specific material, such as PTFE, metal or other powder particles (Fig. 2) (Bailey, 1998;Luo et al., 2008;Pawar et al., 2010). Tribo-charging produces less charge on particles than corona charging (Sumonsiri and Barringer, 2010), thus the corona charging mechanism is mostly used for electrostatic powder coating (Mazumder et al., 2006). ...
Pharmaceutical solid dosage forms include tablets, pellets, pills, beads etc. Tablet is most commonly used pharmaceutical dosage form which has ease of administration. Tablets are coated for many reason such as masking odour, taste, colour of the drug, providing physical and chemical protection to drug, protecting drug from the gastric environment.Coating is a process by which a layer of coating material is applied to the surface of a dosage form. Coating may also contain active ingredient. There are various strategies for tablet coating which include sugar coating, film coating, and enteric coating. The amount of coating on the surface of a tablet is critical to the effectiveness of the oral dosage form. Recent trends in tablet coating focuses on overcoming disadvantage of solvent based coating. This review concerns with the coating process, equipments involved, coated tablets evaluation and specialized coating techniques. Key Words:
Controlled release preparations can be administered orally in single or multiple unit dosage forms. Among multi-component dosage forms, the most commonly used dosage form is the pellet. It is an ideal dosage form, which on oral administration, disperses or disintegrates rapidly in the stomach to release drug particles, granules and spheroids. Pellets are agglomerates of fine powders or granules of bulk drugs and excipients. They consist of small, free-flowing, spherical or semi-spherical solid units, typically from about 0.5 to 1.5 mm, and are intended usually for oral administration. Polymer-coated multi-particulates or Multiple Unit Pellet System have several therapeutic and technological advantages over single-unit dosage forms. Being small (<2 mm), pellets or multi-particulates can distribute evenly in the gastrointestinal tract, resulting in fewer adverse effects. Pellets also reduce the risk of dose dumping compared to single-unit dosage forms, and result in a reproducible bioavailability. Pellets can be either filled into capsules or compressed into tablets as a dosage form to be administered. Pellets offer great flexibility in pharmaceutical solid dosage form design and development. They flow freely and pack easily without significant difficulties, resulting in uniform and reproducible fill weight of capsules and tablets. Processing conditions play a significant role in the development of good quality pellets, but the physical forces first bind the primary particles together and initiate the pelletization process. Physical forces determine the nature of the elementary growth mechanism that forms the basis of pellet formation in any processing equipment. There are numerous publications on the theory of formation of a pellet.
Tablet coating is a common pharmaceutical technique of applying a thin polymer-based film to a tablet or a granule containing active pharmaceutical ingredients (APIs). Solid dosage forms are coated for a number of reasons, the most important of which is controlling the release profiles. The amount of coating on the surface of a tablet is critical to the effectiveness of the oral dosage form. Tablets are usually coated in horizontal rotating pans with the coating solution sprayed onto the free surface of the tablet bed. The advantages of tablet coating are taste masking, odour masking, physical and chemical protection, protects the drug from the gastric environment etc. There are various techniques for tablet coating such as sugar coating, film coating, and enteric coating. Recent trends in pharmaceutical technologies are the development of coating methods which overcomes the various disadvantages associated with solvent based coatings. In these latest technologies coating materials are directly coated onto the surface of solid dosage forms without using any solvent. Various solventless coatings are available such as electrostatic dry coating, magnetically assisted impaction coating, compression coating, hot melt coating, powder coating, and supercritical fluid coating. Supercell Coating Technology is a revolutionary tablet coating that accurately deposits controlled amounts of coating materials on tablets even if they are extremely hygroscopic or friable. Magnetically assisted impaction coating, electrostatic dry coating in solventless coatings, aqueous film coating and Supercell coating technology are also available recent technique of coating. An ideal tablet should be free from any visual defect or functional defect. The advancements and innovations in tablet manufacture have not decreased the problems, often encountered in the production, instead have increased the problems, mainly because of the complexities of tablet presses; and/or the greater demands of quality. This review deal in detail about history, recent tablet coating technique and remedies associated with the tablet coating.
Tablet Coating is a process by which an essentially dry, outer layer of coating material is applied to the surface of a dosage form in order to confer specific benefits over uncoated variety. The advantages of tablet coating are taste masking, odor masking, physical and chemical protection, protection of the drug from the gastric environment etc. The important reason to coat a pharmaceutical dosage form is to control the release profile and bioavailability of the active ingredient. The various techniques of coating such as sugar coating, film coating, enteric coating. The amount of coating solution applied and the thickness of the coating layer determines the release of the drug from the delivery system. Tablets are usually coated in conventional coating pans by spraying the coating solution on the free surface of the tablet bed and subsequent drying of the solution. The main focus of this review is, to study various key factors associated with coating, , latest techniques of coating such as dip coating, laminated coating, electrostatic, vacuum film coating and problem encountered during the coating process.
French fries were coated with smoke extract or glucose and mozzarella cheese slices with sodium erythorbate or cellulose with natamyacin at 0 kV and −25 kV. For the first three samples, transfer efficiency was higher for electrostatically coated products. When the same amount of powder on each sample was compared, electrostatically coated samples showed a greater color development and less mold growth than nonelectrostatically coated samples. This improvement in color and shelf life could be explained by improvement in coating evenness due to the charging of the powder. Cellulose with natamyacin did not show an improvement in transfer efficiency, mold suppression or charge to mass ratio with electrostatic coating. This powder did not charge well because it was cohesive and of the wrong polarity. The smaller the size of the powder, the greater the charge to mass ratio and final color development.
Ten powders, differing in protein, carbohydrate and salt contents and ranging from 19 to 165μm were coated by nonelectrostatic and electrostatic coating. Nonelectrostatic transfer efficiency (TE) increased to a maximum before leveling off with increasing particle size. Electrostatic TE either decreased or increased then decreased with increasing particle size. Powders became more free flowing as particle size increased. Since TE increases as powders become more free flowing, TE increased with particle size for both nonelectrostatic and electrostatic coating. For electrostatic coating, the effect of charge decreases with increasing particle size. Thus, the conflicting effects of ability to pick up charge and flowability caused an increase then decrease in the TE for powders coated electrostatically, and can also explain the exceptions. The average improvement in TE by electrostatic coating was 20%, with the improvement increasing as particle size decreased.
The total forces holding a layer of electrostatically charged powder onto a work piece result from the combination of an interfacial electrochemical phenomenon at the surface, inter particle/particle cohesion and a bulk electrostatic attractive force. An attempt has been made to obtain the total integrated effect by assessing the force that is required to selectively remove the powder layer from a metal substrate. This is a destructive measurement that disrupts the powder layer. All the measurements are taken with the powder layer before fusing. Powder adhesion measurements have been obtained from an impulse drop test, incorporated with a charge pick up device (CPD), Faraday cup, micro balance, Keithley Electrometer and CVI National Instrument Virtual Oscilloscope. Sample results are presented for powder coating using standard tribo and negative corona gun.
A model is developed for estimating the coating time in a magnetically assisted impaction coating (MAIC) device. The mixture of the host, guest and magnetic particles is assumed to be in a fluidized state where the distribution of velocities is a Maxwell–Boltzman type. It is assumed that the collisions among the particles are important for impinging the guest particles onto the surface of host particles, and thus forming a semi-permanent coating on the surface of host particles. The coating time is shown to depend on several parameters, including the number density of host particles, the diameter ratio of the host and guest particles, the height of the fluidized particle bed and the material properties of the host and guest particles. Our model shows that there is an optimal value of the bed height for which the coating time is a minimum. The coating time increases sharply when the bed height is smaller or larger than the optimal value, and also when the diameter of host particles is increased. A comparison of the model results with experimental data shows surprisingly good agreement for the coating time as a function of host particle surface covered considering the many assumptions that were made in deriving the model.
The aim of this work was to develop an experimental set-up allowing the measurement of tribo-charging during handling and transport of powders. The experimental set-up included a fluidisation unit, a transport pipe and two “Faraday cups” allowing continuous monitoring of particles charge. Several batches of industrial powder coatings were tested. The investigated parameters were the length and the fouling of the conveying pipe. The experimental device and procedure permitted to classify conveniently the tested powders according to their ability to be charged. More specially, a net difference between electrostatic properties of two powder primers, which behave very differently in the industrial application unit, was pointed out. Furthermore, it was established that tribo-charging is essentially governed by the nature of the flow conditioner added to powder coatings. The results showed that the net amount of acquired tribo-charge increases with the length of the conveying pipe. However the polarity of charges could change with the pipe fouling.
This paper deals with an electrostatic spray deposition (ESD) process of ‘self organizing’ TiO2-epoxy powder paints on metal substrates.The first part of the paper focuses on analyzing the influence of both electrical and aerodynamic operational parameters on ESD process. Design of experiments (DOE) was used to plan experimental trials. ANOVA tables were calculated and used as support instruments to interpret the experimental findings and to understand physical phenomena involved in the deposition process as well as the role of TiO2. As a result, several process maps were produced which report consistent trends in coating thickness versus operational parameters. Best deposition conditions could therefore be deduced. Initial attempts to produce ‘self-organizing’ TiO2-based gradient coatings are also discussed.The second part of the paper focuses on assessing the influence of the target locations in the deposition booth on coating thickness of the TiO2-epoxy films. Design of experiments (DOE) was once again used to plan experimental trials and ANOVA tables were also calculated. Experimental findings are interpreted and the role of TiO2 is also investigated. This leads to the best target locations being deduced.Finally, neural network solutions able to predict coating thickness according to settings of operational parameters were developed and validated by comparing them with experimental data and a first approximation regression model.
Properties of powder, e.g. particle size distribution, chemical composition, triboand corona charging characteristics, electrical resistivity, hygroscopicity, fluidity and shape distribution play significant roles on the performance of powder coating such as transfer efficiency, film thickness, adhesion and appearance. Our focus in this paper is on particle size distribution, fluidity, charging characteristics and their effects on the first pass transfer efficiency. Even a minor difference in powder properties showed differences in the applications process illustrating the importance of characterizing physical parameters and control techniques to achieve desirable performance.
Electrostatic spray deposition (ESD) is a recently developed technique to deposit a calcium phosphate (CaP) coating upon substrates. With this technique, an organic solvent containing calcium and phosphate is pumped through a nozzle. Between the nozzle and substrate a high voltage is applied. As a consequence, droplets coming out the nozzle disperse into a spray, and this spray is deposited upon the substrate. When the solvent has evaporated, a coating is formed on the substrate. ESD allows for a variation in coating composition and morphology. Titanium alloy (TiAl6V4) substrates were coated with a CaP layer using two different methods; radio frequency magnetron sputtering, and ESD. These surfaces were characterized with X-ray diffraction, Fourier transform infrared spectroscopy, an universal surface tester, scanning electron microscopy, and energy dispersive spectrometry. Subsequently, bone marrow cells were isolated from rat femora and cultured 1, 4, 8, 14 and 16 days. Cell proliferation, alkaline phosphatase activity, and osteocalcin concentration were assayed. RT-PCR was done for collagen type I and osteocalcin. SEM was also performed to observe cellular behaviour during culture. Two separate runs of the experiment were performed. In the first run, osteoblast-like cells on both CaP coatings showed similar results in all assays. In the second run, proliferation and osteogenic expression had increased on ESD coatings. On basis of these results, we conclude that the novel ESD coating behaved similar to, or even better than the known RF magnetron sputter coating. Thus, ESD could be a valid addition to already existing CaP coating processes.