GLIMPSE OF PHARMACEUTICAL COATING PROCESSES

GLIMPSE OF PHARMACEUTICAL COATING PROCESSES

Mahammed Athar Alli Saikh

Department of Pharmaceutics, Jeypore College of Pharmacy, Jeypore, Koraput, Odisha, India.

ABSTRACT: Manuscript aims to furnish glimpse on coating processes (CoPr). The coating is the process of applying coating materials (CoMa) onto the substrate surface (S-S). With time and space dimension of CoPr, that upraised as sugar-coating (S-C) expanded to film-coating (F-C) and specialized one. Lengthy and wearisome processing and skilled operators issues inherited to S-C spring-up F-C and its improvement from non-aqueous F-C to aqueous film-coating (AF-C). Non-aqueous film-coating processes (F-CP) make use of a volatile organic solvent (VOS) while AF-C processes uses aqueous solvent (AS), as a solvent system for coating formulations (C-F). VOS is preferred over AS in F-CP, and momentum for using AS has been accelerating from past few decades. Issues from VOS’s use upraised relating to safety; worker hygiene & safety; toxicity; environmental pollution; etc. These upraised issues intensified, thus, nowadays, AF-C processes are replacing VOS-based F-CP. Later on, finding the novelty of coating and CoPr thru coating of particulates became another dimension of expansion. This involves modification and/or alteration in innate properties of particulates, chemically and/or physically, thru coating, is for find their worthy attributes and functionalities. This dimensional expansion exploits the applicability of the dry-coating process (D-CP) and wet-coating process (W-CP). D-CP comprises novel and specialized CoPr based on novel technologies while W-CP comprises conventional and novel CoPr. Some state-of-art CoPr are AF-C process, hot-melt coating (H-MC) process, electrical-electrostatic deposition process, gas-/vapor-phase process, aerosolized CoPr, photo-curable CoPr, Resonant acoustic CoPr, thermal and mechanical process, thermo-mechanical CoPr, fluidized-bed processes, Supercell^® CoPr, etc. CoPr and its dimensional expansion briefed for updating professionals.

Keywords: Coating, Film-coating, novel, Process, Specialized

INTRODUCTION: Solid dosage forms comprise a major fraction of pharmaceutical products, and their formulation ingredients, in most instances, are in particulate state ^1-6. In some instances of manufacturing processes, inevitable is a coating of themselves or component particulates ^7-11. Coating of solid dosage form or their component particulates involves deposition of CoMa, as a layer, snugly affixes on surface of said substrates ^9-11.

Said coating (layering and/or deposition) is aimed in imparting final product non-functional (protective) and/or functional attributes ^{6, 9, 10}. Through coating realizable attributes are alterations and improvement in aestheticism like color, odor and taste; stabilization; enhanced mechanical properties and tailored (i.e., controlled/ extended/ modified/ delayed) drug release profile ^{1-3, 6, 9, 10}.

Until 1950, S-C is the preferred CoPr, and at that time, there was much effort there to perfect its techniques & processes ^{1-3, 6}. Further, S-C processes have lengthy processing time and their productivity & quality mostly dependent on operator skills, are the major concern ^{1-3, 6}. Said concerns are chief contributors to spring-up F-CP that with time and space improved with technology improvement ^{4, 6, 8}.

Said improvement activity made the F-CP amenable to improving aestheticism, stability, and marketability and tailing the release profile of active(s) ^{1, 4, 6, 12}. In F-C formulations, during the early stage of development, VOS is preferred as a solvent system over AS ^{1, 2, 6, 8}. Said preference in F-CP is to forefend possible debasement of active(s) and combat diverse processing problems affiliated with AS-based CoPr like over wetting, picking, sticking, and may more ^{6, 8}. With time and space issues/ concerns affiliated with the use of VOS like residual VOS, regulatory concerns, the safety of the operator, environmental safety & concerns, and cost providing momentum for springing-up, ameliorating, and perfecting aqueous F-CP, as alternatives ^{1, 2, 4, 6-8, 11, 13}.

Aqueous F-CP in most instances, use aqua-dispersions as coating fluid ^{6, 14}. Film-former level in said dispersion is low while the quantity of AS is very high ^{6, 15}. Thus aqueous F-CP is energy and time consuming, affiliates from evaporating large amount of AS ^{6, 14-16}.

Modifying surface properties/ attributes of fine & ultra-fine particles (FUFP) and particulates is inevitable in some instances ^{9, 10, 13, 16}. Strategies of particle engineering and/or methodology thru surface modifications involving coating were devised and ameliorated to find new and/or worthy functionalities, properties, and applications of FUFP and particulates ^{13, 14, 17, 18}.

Most exploited techniques/ process for modification in surface attributes/ properties of them aims to alter their innate properties physically or chemically and to receive assorted advantage ^{10, 13, 16-18}. Amongst them, pharmaceutical applications frequently aim for protective (non-functional) and/or functional purposes ^16-18.

For these purposes exploiting is chemical & physical deposition methods ^{13, 16}. These methods alter the innate properties of FUFP and particulates chemically or physically ^{10, 13, 16}. The physical method realizes physical deposition and/or embedding of coating material particles (CoMaP) at surfaces of FUFP and particulates ^{10, 13, 16}. Physical methods exploiting are mechanical, thermal, thermo-mechanical, electro-mechanical, thermodynamic, many others ^{7, 9, 13}.

The chemical method realizes chemical changes at the surface of FUFP and particulates by making usage of liquid/ gaseous precursor, thereby realizing coating ^{6, 11, 13}. The technology of physical deposition methods involves the usage of high pressures, elevated temperatures, high-shear and/or solvents ^{9, 13}. Solvent-based W-CP inherits issues like cost, undesirable waste stream and regulatory limitations on VOS relating to their usage & residual solvent; and particle agglomeration reduced stability, and energy & time requirement of AS-based CoPr ^{1, 6, 7, 13}.

These thus are preferred to a lesser extent ^{7, 13}. The strategy of chemical deposition methods inherits issues of relatively costlier, complex and challenging scale-up ^{10, 13}. Thus some physical and chemical methods are not-suits active(s) that labile to involve ambient processing conditions ^{9, 10, 13}. These facts spring-up specialized D-CP and techniques and their amelioration, over last-few decades ^{1, 5, 12, 19, 20}.

D-CP are in most instances, solvent-less CoPr ^{16, 20}. The technology of these processes involves the usage of mechanical forces to directly attach/ fix CoMaP, as FUFP, onto a relatively larger substrate ^{10, 16, 20}. Applied mechanical force realizes said fixing and does not call-for binder(s) and/or solvent(s), even AS ^{10, 16, 18}.

Methodology bears the novelty of enabling mixing powders of diverse chemical & physical properties to realize composites, a new-generation material with tailored attributes ^{10, 16, 18}. Resulted composites bear new functionality and/or have improved characteristics, comparing that of component materials ^{10, 16, 18, 20}.

CoPr in present days has a diversity of type & origin; refer to Fig. 1 ^{1, 6, 10, 17}. The associates and inherits complex processing steps of diverse types and origins ^{1, 6, 13, 16, 17}. Their generalization in wider terms is wispy task ^{6, 13, 17}.

Available literature summarizing information on CoPr, an area of such diversity, as a glimpse, is scarce. Thus it seemed requisite to work in this regard for the convenience & enrichment of professionals.

FIG. 1: DIVERSE COATING PROCESS WITH PHARMACEUTICAL APPLICABILITY, AS ADAPTED FROM ^{2, 11, 17}

Recent developments in the area of CoPr having pertinence in the pharmaceutical field are at this moment, attempted for outlining and briefing. This presentation hoped to provide a glimpse on CoPr, an effort that will enable to find CoPr suiting candidate pharmaceutical and their improved/ new industrial applications. The consequence is improved productivity & profit, ultimately welfares of mankind.

Basic Principle of Coating/ Deposition Process: In the present scenario, available CoPr is of diverse types & origins ^{1-3, 17}. Generalizing their basic principle in broader terms is a wispy attempt ^{4, 5, 17}.

However, in general, a principle is deposition that involves applying CoMa onto a moving substrate-bed (S-B) with the involvement of concurrent processing step facilitating fixing of CoMa on the S-S ^{4, 6, 7, 9-11, 17}. The CoPr and equipment is must have proviso for ^{7, 9-11}:

1. Application & distribution of CoMa: for evenly distributing formulation of CoMa over the whole of the available S-S ^{9, 11},
2. Rotation of the S-B: for continuous renewal of S-S to facilitate deposition of CoMa, uniformly ^{7, 9, 10},
3. Fixing/curing: to fix CoMa on S-S for realizing even and firm coat ^{9, 11} and
4. Removal of the process waste: generated process waste call-for their removal to facilitate the realization of a uniform and smooth coat and eliminate impurities from products ^{7, 9, 10}.

Sugar-Coating: S-C, a multi-step process, involves treating the substrate cores successively with coating-medium of sucrose in AS ^{1-3, 6}. The coating-medium may contain other functional ingredients like fillers, colors, etc. ^{1-3, 6}. Inclusion of other functional ingredients in coating-medium is done depending on stages of coating reached ^{1, 3, 6}. The duration of S-C processes ranges from a few hours to a few days ^{1-3, 6}. The S-C process usually out comes in elegant, highly glossed finished products 1, 3, and ⁶. The substrate with a deeply convex core and minimal edges, usual tablets, is ideal for suiting the S-C process ^{1-3, 6}. The process increases substrate weight usually by 50-100 % ^{1, 3, 6}. In fact, the quality of S-C depends upon operator’s skill ^{1-3, 6}. S-C comprises of sealing, sub-coating, grossing/ smoothing, coloring, polishing and printing steps ^{1-3, 6}. The build-up of coat in S-C is due to the transference of coating-medium from one substrate to another ^{1, 3, 6}. Typically, a single-liquid C-F application is be made, basing upon the stages of coating, refer Table 1 for major components of C-F ^{1-3, 6}. Applied C-F allows spreading on entire S-B utilizing the mingling capability of candidate equipment ^{1, 3, 6}. At this time-point drying, operation is usually performed with hot-air for, drying applied C-F ^{1-3, 6}. The entire cycle then is repeated successively ^{1, 3, 6}.

TABLE 1: COMPOSITION OF C-F USED IN DIFFERENT STEPS OF S-C ^{1-3, 6}

Enteric Sugar-coating: Enteric S-C sealcoat is modified to comprise one of the enteric polymers ^{1-3, 6}. Applied seal coat be in sufficient quantity to pass the enteric test for disintegration ^{1, 3, 6}. Herein, the subsequent coating steps, as in the conventional S-C process, should be followed, including sub-coating ^{1-3, 6}.

Film Coating: Wearisome and lengthy processing along with skilled-operator’s issues are chief amongst the reasons inherited to S-C, refer to Table 2, spring-up F-CP ^{1, 2, 5, 6, 8, 11}. Further, F-C enables substrate’s protection from light, temperature and humidity thus improves stability; enables masking the obnoxious taste and/or odor, improving the appearance and facilitating swallowing, thereby improving aestheticism; enables product identity and can tailor release profile of active(s) ^{4, 6, 8, 12}. The F-C realizing modifications in release profile are modified release F-C, whilst that achieves conventional release are conventional release F-C ^{1, 6, 12}. Conventional release F-C is for immediate release ^{4, 12}. The modified release F-C is ether for delayed/ enteric release or extended/ controlled release ^{4, 8}. Herein film-coat membrane is a barrier controlling/ tailoring drug release, thereby tailors release ^{4, 6, 8}.

TABLE 2: DIFFERENCES BETWEEN F-C AND S-C ^{2, 6, 11}

F-CP spraying of film-forming polymer (F-FP) onto the S-S realizes thin coat layer ^{6, 8}. The C-F comprising F-FP, in liquid state, is sprayed onto portion of moving S-B using one or more spray-gun ^{4, 6}. Substrates in the S-B are kept moving by their rotation or by fluidization using panning equipment that is conventional, sophisticated, or fluid-bed processor (F-BP); to accomplish automation and efficient drying, to reduce CoPr time, to improve efficiency and accomplish reproducibility of CoPr ^{4, 6, 8}. Herein CoPr makes usage of C-F comprising film-former, plasticizers, and other excipients (like pigments) in an aqueous or non-aqueous solvent system ^{1, 6, 8}. The C-F is formulated as a solution or dispersion in either aqueous or non-aqueous solvent ^{6, 8, 12}.

The type of C-F is in turn call-for changes in overall CoPr and processing requirements ^{1, 2, 6}. In broader term the F-CP can be ^{2, 6}:

• AF-C process: CoPr that make usage of water as a solvent system for preparing C-F.
• Non-aqueous F-CP: CoPr wherein VOS is the solvent system for preparing C-F.

Non-aqueous F-CP is preferred over the AF-C process in earlier days due to various issues, as discussed in sections 1, 6, and ⁸. Latter, on the usage of VOS invoked concerns; following are major one ^{4, 8}:

1. Restriction on Venting of Untreated VOS: Regulatory authorities imposed restrictions on venting VOS vapors into the atmosphere, which it is ecologically detrimental ^{1, 6}. Further, treatment of gaseous effluent as regulation-mandate is an add-on cost and a costly affair ^{1, 2, 6}.
2. Compliance of Hazard Proof (Fire and Safety): VOS are flammable, toxic, and explosive; thus, their usage call-for infrastructure facilitated with hazard proof facilities for fire, explosion, and chemical and hygiene ^{1, 2, 6}.
3. Cost: VOS are relatively costly, and in the future, they are likely to be costlier ^{1, 6}. They have a higher storage cost ⁶. Insurance premium now-day is much higher for facilities using and storing VOS ^{1, 6}.
4. Residual Solvent: Quantifying the residual VOS for products of F-C are must ^{1, 6}.

Aforesaid concerns restricted VOS’s use to CoPr demanding rapid drying characteristics, especially when ^{1, 6}:

• CoPr is unable to accommodate the use of AS; for instance, causes like poor drying rate, attained adhesion is unacceptable, instability, and many other ^{1, 2, 6} and
• CoPr cannot avoid the use of aqua-insoluble F-FP, which is unavailable as a pseudo-latex/ latex system ^{1, 2, 6}.

Process Basis: CoPr involves spraying liquid C-F, using a liquid atomizing/ spraying system, onto the moving S-B ^{1, 6}. Atomizing/ spraying system is here to atomize the bulk coating fluid as fine droplets and deliver them onto the S-B, kept in moving ^{6, 11}. Said droplet’s delivery is in a state that they retain sufficient fluidity ^{1, 2, 11}. Their fluidity is sufficient enough to wet S-S, spread out, and coalesces to form film-coat ^{6, 11}. Drying conditions must enable solvent removal from realized film-coat ^{1, 11}. From there, the deposition of CoMa, as a thin film of 20-200 μm, around each substrate-cores/ particles (S-C/P) ^{1, 6}. An excellent and efficient film coat is smooth and uniform, ensures the product's physicochemical stability, and adheres satisfactorily to S-S ^{1, 6}.

Aqueous Film Coating: Increasing level of understandings relating pernicious-nesses of VOS with concomitant worldwide tightening-up of rules on Foods & Drugs, worker’s exposal to VOS, and industrial hygiene; is confining their usage ^{1, 2, 5, 6, 8, 21}. These issues are added with concerns like increasing cost of VOS, today’s environment of competitive business, searching for cost-cutting means to improve product’s market viability and success, etc. ^{4, 6, 21}. As a substitute & combat said untoward situations, last few decades manifested wide exploitation of AF-C systems based CoPr ^{4, 6, 21}.

Earlier days AF-C processes were seen with skepticism ^{4, 6, 21}. This is attributed to facts of lengthy-time of CoPr, dull appearance, possible decomposition of active, and troubles during coating ^{4, 6, 21}. Research conjoined industrial experience has revealed issues of skepticism are of low concerns during practical application ^{4, 6}. These troubles/ issues/ problems can be addressed thru evaluating reasons scientifically and making substantial advancements in equipment design and process technology ^{6, 8, 21}.

Most troubles/ issues/ problems could be categorized as related to material, process, instrument, and equipment ^{2, 4, 6, 21}. Following the innovation of latex & pseudo-latex systems, conjoined development and launching of improved equipment designs have been continuously seen broadening the spectrum of AF-C 1, 6, 21 always. In present-day, said innovation and improvement and perfect processing conditions have made it feasible to realize AF-C of fine particulates free from agglomeration and of tablets carrying superdisintegrants without their surface-erosion and core penetration ^{1, 6, 8}. Advancement in AF-C formulations is aqua enteric-coating systems ^{1, 6, 21}. Said systems eliminate separate inclusions of pigments, plasticizers, detackifiers, other process additives, and process aids ^{4, 6, 21}.

Aqueous Polymeric Dispersion: These enable aqua-processing of water-insoluble polymers, an important pro ^{1, 6, 8, 21}. Specialized commercial products of water-insoluble polymers are ammonium methacrylate copolymers and ethyl-cellulose ^{1, 6, 21}. Their applicability is often encountered in F-C of granules & beads and in modified-release products ^{1, 2, 4, 6, 8, 21}. However performance of aqua-dispersion depends significantly on conditions set during CoPr ^{6, 8, 21}. Variable results, like ultimate drug-release feature(s), may often attributing significantly from choice of wrong processing parameters, an incompatible one, and/or from lack of controls on processing parameters; instead from any variableness in aqua-dispersion used ^{6, 8, 21}.

Dry and Wet Coating Processes: Application of coating on the S-S is achievable by a method based on either W-CP or D-CP ^{2, 6, 7, 9-11, 16, 17}. W-CP is useful primarily to realize a barrier-coat between S-C/P and surrounding environment ^{6, 10, 16}. Realized barrier-film modify release ^{10, 16}; overcomes incompatibilities; improves stability and/or aestheticism; and many others ^{6, 17}. Enhancement of aestheticism is thru odor/ taste/ color masking ^{6, 10}. Improved stability and shelf-life is thru product’s protection from incompatible ingredients, light, atmospheric oxygen, water vapor, etc ^{6, 16}. While modifying release profile, barrier-film controls/ extends/ sustains/ delays the same ^{6, 17}.

The D-CP can achieve tailored surface properties apart from forming a barrier-film ^{16, 18}. Said tailoring surface attributes of S-C/P is to diverse degree ^{17, 18}. Amongst tailored attributes of diverse degree, attributes of pharmaceutical interest are solubility, wettability, dispersibility, hydrophilic & hydrophobic properties, sphericity, particle shape, flowability ^{10, 16, 18, 22}, solid phase reactivity, optical activity, electrostatic & magnetic property, sinterability, odor, flavor, color, taste and many others ^{2, 10, 22}.

Wet-coating Processes: The process typically involves spraying C-F as solution or dispersion of CoMa onto S-S, kept in either motion or fluidized state ^{7, 10, 11, 16,}. After that S-S are wrapped by the film of C-F, in individual-level ^{6, 10, 11}. Upon evaporation of solvent from the coating-fluid film, a new solid layer is formed ^{6, 10}. Thereby realizing coating of individual substrate ^{2, 7, 16}.

From a processing point of view, W-CP comprises sequential steps that usually include droplet formation, wetting, spreading, evaporation, and drying ^{6, 16}. However, there may be variations in processing steps ^{6, 17}. Said variation depends on nature of CoMa and substrate, processing conditions, and apparatus ^{6, 16}.

W-CP-based coating methods are fluidized-bed coating, pan coating, wet-chemistry-based techniques (interfacial polymerization, coacervation, formaldehyde/ urea deposition, etc.), and many more ^{6, 7, 11, 16, 23}.

CoPr following W-CP becomes less preferable as it might leave residual VOS ⁷, can reason reduced stability ^{7, 11} and particle agglomeration ⁶, and may arouse environmental concerns ^{2, 6, 17}. The fact that environmental concerns are arousing may be from the generation of unwanted waste streams and emissions of VOS ^{6, 16}.

Dry-coating processes: Methodology of D-CP involves directly fixing/ attaching CoMa (as FUFP) onto S-C/P that are relatively larger than CoMaP ^{10, 16}. Herein the CoMaP, as FUFP, is brought in close proximity with S-C/P thru the involvement of chemical and/or electrical interactions or by thermo-mechanical interactions ^{10, 13}. Said interaction realizes coating thru the deposition process ^{10, 16}. Involved deposition processes are mechanical, thermo-mechanical, electrical-electrostatic, or chemical one ^{13, 17}. The chemical deposition process is gas-phase or vapor-phase one ^{16, 17}. Thermo-mechanical one realizes embedding & layering of CoMaP thru strong force of mechanical and/or impaction type accompanied by generated heat ^{2, 10, 13-15, 18}. In some instances, D-CP might ether CoMaP or causes them to get embedded onto surfaces of substrate-particle ^{10, 16}. Said embedding and/or deformation realize firm coating side-by-side alters surface morphology and topography ^{6, 10}. Thereby reducing adhesive forces of substrate particle ^{10, 17}. The D-CP thereby creates engineered particulates are value-added composite particulates with tailored surface attributes ^{10, 16}. Thereby creating composite particles are with new & exciting applications ^{6, 17}. Comparing W-CP the D-CP does not call for any binder(s), solvent(s), or even AS ^{10, 16, 17}. Further, D-CP does not produce effluents like any organic gas, liquid waste stream, etc ^{10, 17}. However, D-CP is a potential alternate to W-CP, environmentally benign, and cost-effective ^{10, 16}. Over the past few decades, D-CP steadfastly established itself as viable method to realize composite particulates ^{2, 10, 22}.

Particulate Coating Processes: Manufacturing processes of solid dosage forms, in some instances, most inevitable is handling of particulate active(s) that are difficult to formulate ^{2, 10, 13, 16}. They call for modification of their surface and surface attributes and are made achievable by coating their surfaces with suitable CoMa ^{10, 13}. Most of CoPr, suiting surface modifications of particulates is W-CP or D-CP that alters their innate properties, physically or chemically ^{9, 16, 17}. CoPr suiting particulates are also exploited for finding particulate’s new and/or worthy functionalities/ properties, as drug carriers/ delivery systems ^{2, 9, 10, 16, 17}.

Hot-Melt Coating Process: This process involves depositing meltable CoMa, in a molten state, onto the S-C/P ^{10, 13, 16}. When the product is subjected to cooling, solidification is of meltable CoMa realizes coating ^{17, 24}. Usually, lipid, glycerides, fatty acid, wax with low melting point suit as meltable CoMa ^{25, 26}. CoPr, herein, involves simple technique and don’t require complicated and sophisticated equipment ^{10, 13, 17}. The CoPr can be performed with spheronizer, conventional pan coater, F-BP, and spouted-bed processor ^{1, 10, 13, 16}. The CoPr suits moisture labile drugs also for enhancing dissolution rate and aqua-solubility of poorly aqua-soluble drugs ^27-29. Said CoPr finds applicability for a wider range of substrates with diverse particle sizes and for realizing coating in multiple layers ^{13, 16}. The absence of solvent evaporation phase in this CoPr realizes nonporous & strong particles ^{10, 24, 27-29}.

Spray Congealing: A highly versatile CoPr follows the H-MC method suiting for particles ^{10, 16}. The CoPr realizes particles having a diameter within the range of 10-3000 μm ^{16, 17}. Processing of said CoPr involves spraying/ atomizing a hot-melt product containing substrate and CoMa into the air-chamber ^{10, 13}. The chamber's temperature is to be maintained below the melting point of meltable material(s) or at the cryogenic temperature ^{13, 16}. Granular particles are realized upon cooling of sprayed/ atomized droplets ^{6, 16}.

H-MC using F-BP: Herein mix of powdered non-meltable materials & meltable CoMa is applied onto starting seeds (starting particles or powdered particulate cores) in an F-BP for realizing coating ^{2, 30-32}. The meltable CoMa (binder) can apply onto seeds as either molten liquid or solid particles ³³. Procedure wherein particulate meltable CoMa is used that melts during the process to realize coating is termed melt-in procedure ^{13, 30}. CoPr wherein meltable CoMa sprayed on starting seeds, as a molten liquid, is termed spray-on procedure ^{16, 31}. From an industrial application angle, the procedure of melt-in process is simpler one comparing spray-on process, is favored over spray-on process ^{30, 32}.

Hot-melt Granulation and Hot-melt Pelletization: These CoPr calls-for meltable CoMa with high viscosity and small particle size ^{34, 35}. High viscosity grade meltable CoMa is required for improving the mechanical strength of coating ^{13, 36}. Smaller particle-sized meltable CoMa are required to prevent the realization of coating with rough surface ^{16, 36}.

Solid Dispersion Hot-melt Fluid-bed Coating: Said CoPr is termed Tumbling H-MC, a modified version of H-MC ¹⁶. It is F-BP based system that eliminates the spraying step but realizes coating by solid dispersion ^{10, 31, 37}. Thus the CoPr does not demand a steam jacket, heating assembly and/or nozzle ^{2, 10, 13, 16}.

Herein the nonpareils (powdered substrate particles) and powder of polyethylene glycol (size 1.41–3.36 mm) were fluidized together ^{10, 31, 32, 37}. During processing inlet-air temperature is increased ^{10, 37}. Thus the polyethylene glycol melts and thereby get transferred onto nonpareils ^{10, 37}. Then typical steps of H-MC are followed, like cooling & congealing ^{10, 37}. Following this method, multiple coatings can be realized by applying coatings as multiple layers ^{10, 37}. For this, CoMa with descending rank order of these’s melting point be using ^{10, 37}. Thus is to realizing additive coating layers, is resulting multiple layers of coatings ^{10, 37}.

Turbo-jet Coating Process (Modified): A modified version of Turbo-jet CoPr adapts methodology to coat FUFP and particulates ^{2, 10}. Alteration is, suspending S-C/P in the spiral of ascending-air ¹⁰. Said spiral air-flow provisos homogeneous distribution of S-C/P as individual particle ¹⁰. The molten CoMa is lipidic one ¹⁰. The same is be dispersing from the bottom of the tank & tangentially to particle-flow ^{2, 10}. The lipid crystallization inside the nozzle expansion is prevented thru the use of microenvironment surrounding the nozzle outlet ^{2, 10}.

Aerosolized Coating Process: A one-step D-CP involves the principle of co-aerosolization under ambient temperature to realize the coating of particulates ^{2, 9, 10}. Said aerosolized state realizes clouds of individual particles ¹⁰. Realized cloudy state commences the intimate contact of individual particle clouds ⁹. Commencing interactions facilitate attachment of CoMaP (as FUFP) onto S-S, usually a coarse particle ^{9, 10}. Further, commencing interaction, in some instances, confers engineered attributes to S-S, without any untoward Physico-chemical modification, even of super sensitive active(s) ^{2, 9, 10}.

Herein coating happens in an aerosolized state thru particle-particle interactio; therefore, during processing, there is no exposure of substrate and C-F to heat, mechanical attrition, and solvent ^{2, 9, 10}. Precise control of processing parameters, herein this CoPr, can realize consistent product performance even from commercial-grade excipients ⁹.

Mechanical Deposition Processes: A simple D-CP, wherein realizing direct deposition of CoMa onto substrate thru compaction/ compression ^{2, 10, 22}. It involves compacting/ compressing CoMa around a substrate-core, usually a tablet, using the specialized machine designed/ devised specifically for said purpose ^{1, 9, 16, 22}. The process is well-suited for labile components to heat, VOS, and moisture; but calls functional or non-functional coating ^{1, 5, 16, 22}. This CoPr suits tablet substrate-cores for moisture-proofing or for separating incompatible ingredients ^{2, 5, 12, 16, 22}.

Resulted tablets are two/ three-component systems ^{5, 12}. Two-component systems are tablet-within-a-tablet ^{1, 16}. Three-component systems are tablet-within-a-tablet-within-a-tablet ^{5, 16}. Said CoPr may result non-uniform coating due to off-centre positioning of core tablet ^{5, 16}. The issue is short-out with “one-step dry-coated tablet manufacturing method” design approach ^{2, 5, 16}.

Vacuum Film Coating Process: A novel W-CP based CoPr is designed for coating the tablet substrates using non-aqueous C-F and a specially designed coating pan, a jacketed one inbuilt with baffle ^{5, 12}. There, an airless spraying nozzle is suitably positioned in the pan for spraying C-F ^{2, 5}. The pan is jacketed for its heating & cooling operation and also has the facility to get sealed to create vacuum ^{2, 5}. During processing, the contented air of the pan displaces thru purging of nitrogen until realizing the desired vacuum level ^{2, 5}. The inbuilt vacuum system is for removing evaporated solvent vapors ^{2, 5}. Major pros of equipment & process are its design featured with environment safety of highest degree ^{5, 12}.

Photo-Curable Coating Process: Photo-curable coating or photo-curing process is the chemical approach of CoPr devised to coat substrates rapidly at/or below room temperature, very quickly ^{2, 6, 17}. The CoPr was devised to rapidly convert solvent-less compositions (pre-polymers or monomer in liquid form, specifically formulated one) into solid film through the photo-curing process ^{13, 17}. The photo-curing process involves irradiating the product with ultraviolet or visible light ^{2, 6, 13, 17}.

The radiant energy of irradiated light generates free radical that initiate polymerization reaction, which realizes polymerization of functionalized liquid monomers or pre-polymers ^{2, 13, 17}. The initiated polymerization reaction of liquid monomers or pre-polymers realizes their polymerization that causes their transition to solid film ^{6, 17}. Ultraviolet light is much energetic thus is more effective to rupture chemical bonds and initiate & realizing polymerization, comparing visible light ^{13, 17}. Thus, ultraviolet light-mediated photo-curing is preferred one ^{6, 17}. Contrary visible light-mediated photo-curing process is safe, easy to handle attractive features for receive attention ^{2, 13, 17}.

Heat Dry Coating Process: Inclusion of plasticizer commonly practiced in D-CP ^{2, 10, 17}. Said practice un-suits F-FP having low glass transition temperature (Tg) ^{10, 17}. A high level of plasticizer in C-F causes pre-plasticization ^{10, 17}. Combating said issues done with devised heat-dry CoPr that uses heat only to realize coating while abandons plasticizer usage ^{2, 10, 17}.

Methodology, herein, make usage of spheronizer built with screw powder feeder and infrared lamp positioned at top, a heating source ^{2, 10, 17}. The powder feeder is to spread CoMaP continuously onto S-S, during processing ^{10, 17}. Spheronization conjoined with heat realizes the melting of CoMaP and their spreading on S-S ^{10, 17}. Herein heat-based adhesion realizes curing of spread coat ^{2, 10, 17}.

Eudragit® E PO is a CoMa that suits this process ^{10, 17}. The major challenge overcome in this CoPr are getting a smooth, uniform, and thick coating, only thru heat-based adhesion ^{2, 10, 17}.

Plasticizer Dry Coating Process: These are the CoPr based on D-CP that makes use of plasticizer(s) for realizing coating ^{6, 10}. Said CoPr are suitable for instances that call for F-FP of low Tg or where protecting actives from getting damaged during their processing at high temperature is essential ^{2, 6}.

Upon spreading powdered CoMa onto S-S, the plasticizer is sprayed simultaneously from a separate spraying nozzle ^{6, 10}. Thus then, sprayed plasticizer wets S-S and CoMaP ¹⁰. This in-turn promotes adhesion of CoMaP onto S-S ^{2, 6}. Then the realized coated substrates were cured for a preset time above Tg of F-FP, to realize continuous film ^{6, 10}. The substrates suiting said CoPr are particles, tablets, FUFP, and many others ^{2, 6, 10}.

Electrical-Electrostatic Coating Processes: Involved technology in these CoPr ensue electrostatic deposition of charged CoMaP onto surfaces of charged S-C/P ^{2, 17, 38}. Processing involves applying a strong electrostatic charge onto the S-C/P, to make their surfaces electrically conductive ^{5, 16}. Then CoMaP, which comprises oppositely-charged conductive ions, is sprayed ^{5, 17}. Following this product is subjected to curing thru heating it suitably until applied CoMaP fuses to form film-coat ^{1, 2, 38}.

An optimized CoPr can realize coated substrate having excellent coating uniformity ^{6, 16, 17}. Resulted in coating is smooth-surfaced continuous film ^{2, 6, 17}. Realized F-C releases drug significantly similar to that of S-C/P ^{12, 38}. Applicability of said CoPr finds to realize coating of powders, capsules, tablets and living cells ^{1, 2, 12}.

Plasticizer electrostatic coating: Feature of these CoPr is herein coating is realized by companioned use of plasticizer, heat, and electrostatic-field ^{10, 16}. In said CoPr, including a suitable liquid plasticizer in enough quantity reduces Tg of polymeric CoMa and increases substrate’s electrical conductivity ^{17, 38}. Herein this CoPr plasticizer’s inclusion promotes adhesion of CoMaP, encourages film formation, lowers-down curing temperature, and shortens processing time ^{38, 39}. This CoPr is called-upon when processing under lower curing temperature is warranted ^{2, 5, 12, 38}.

Electrostatic Fluidized-bed Coating: Herein, this CoPr, coating is realized in F-BP using electrostatic-field ^{17, 40}. During processing, the powder blend comprising CoMaP and S-C/P is kept in a fluidized state by passing fluidizing dry air through the porous base-plate of F-BP ^{10, 16}. The fluidized powder particles were subjected to electrostatic field ^{16, 17}. Fluidization companioned with repulsive effects of charged particulates creates clouds of charged particles above the S-B ^{16, 17}. Unheated and/or heated charged particulates make several passes through said charged-particle cloud, thus realizing coating ^{17, 40}. Said CoPr does not suit substrates that are elongated or pass axially or vertically across through S-B and/or charged-powder cloud ^{2, 16, 17}.

Thermo-Mechanical Deposition Processes: This CoPr comprises a group of processes that realizes coating thru the use of thermal energy and/or impaction force or by application of ambient shearing stress ^{1, 10, 13, 17}. Herein these CoPr applied ambient mechanical/ impaction force companioned with generated heat realizes embedding & layering of CoMaP onto S-S ^{10, 14, 15}. In some exempla, coating of S-C/P realizes thru deformation of CoMaP along with embedding of them onto S-S ^{10, 16}. In several instances, said embedding and/or deformation realize much stronger coating ^{10, 16}. Thereby these CoPr realizes an engineered particle with complete dissimilar functionality & surface attributes ^{2, 16}. These CoPr are resulting value-added composite particulates with tailored properties ^{10, 16}. Thus these are value-addition CoPr, as confer composite new & exciting applications to S-C/P ^{10, 16}. These CoPr are exploited thus in instances requiring significant changes in functionality and/or properties of S-C/P ^{10, 16}.

Mechanical Dry Coating Process: These are the group of D-CP involving high-shear & high-energy interactions amongst the particle-device wall and/or particle-particle for realizing coating ^{9, 10, 16, 17, 22}. These interactions aims in realize coating thru fixing of CoMaP on surfaces of S-C/P ^{16, 41}. In some instances of these CoPr physico-chemical binding and mechano-chemical interaction might contributes fixing/ adhesion ^{10, 16, 42}. Thereby these processes modify S-S attributes ^{9, 16}. These CoPr are safer, faster, simpler, straight forward, single-stepped, potentially cheaper, and environment-friendly ^{2, 9, 10, 16}.

Important CoPr of this group are Hybridization, Magnetically assisted impaction coating, Mechanofusion, Theta composing, and many more ^{10, 13, 16, 17, 42}. These are single-stepped straight forward process wherein load powdered blend of S-C/P and CoMaP into processing vessel of machine, then turns it ON ^{10, 16}. Operate the machine for preset time and speed, and then turn it OFF ¹⁶. Then unload coated powders ^{2, 10}.

Operator’s skill is of minimal concern in these groups of CoPr ^{10, 16}. Further, these CoPr bears ability for designing them to have continuous processing ^{10, 16}.

Mechanofusion^®: Herein embedding is realizing thru mechano-chemical-reaction that merges CoMaP on substrate particles by inputting mechanical energy of high degree ^{10, 13, 16, 17, 18, 43}. During processing, materials in a mechanofusion reactor are subjected to compression & simultaneous stress by intense shear ^{10, 16}. Thus, composite particulates with differing properties and controlled particle size & shape ^{16, 18, 41, 42, 44, 45}.

The process is arguably grabbing much attention, specifically in the pharmaceutical-field ^{41, 44, 45}.

Hybridization^®: A batch-operated D-CP makes use of a Hybridizer^® machine for realizing particulate coating ^{16, 42}. It enables the embedding of the CoMaP onto S-S very fast, within 1-5 minutes ^{10, 16}. The Jacketing facility facilitates control of local build-up temperature ^{2, 10, 17}.

Herein employed high impaction force induces particles of CoMaP and substrates to undergo legion collisions and build-up temperature ^{13, 16, 17}. Said collisions realize breaking-up of fine agglomerate(s) and coating thru embedding concomitant filming of CoMa onto S-S ^{2, 10, 16}. The embedding and filming are aided by the built-up temperature that aids in curing the coat ^{13, 16, 17}.

Theta-composing: A novel D-CP to coat particulate substrate using Theta-composer^{® 13, 17, 42}. Herein this CoPr, the powder blend comprising CoMaP and the particulate substrate, is subjected to strong shear stress with concomitant compaction force while their pushing up through a narrow gap within the processing chamber of the machine ^{2, 42}. The sequential formation of the narrow gap with concurrent attrition results in peculiar rotation of the inner elliptical rotor and rotating outer elliptical vessel ^{16, 42}. The inner rotor rotates very fast in an anti-clockwise direction inside the slowly rotating vessel in clockwise direction ^{16, 17, 42}.

Magnetically Assisted Impaction CoPr: A D-CP-based soft CoPr wherein coating is realized thru mechanical impaction of oscillating magnetic beads ^{10, 13, 16, 17}. The process warranted for handling thermo-labile, easily deformable, and relatively soft CoMa and substrate ^{1, 5, 42}. The coating is realized with miser degradation of components and miser deformation in particle shape & size ^{1, 2, 5}. Herein this CoPr, generated oscillating magnetic field, surrounding processing vessel, agitates magnetic particles ^{10, 16}. Magnetic particles while agitating causes collisions among magnetic particles & CoMa/ substrate particles, CoMaP & substrate particles, and substrate particles/ CoMa & vessel wall ^{10, 17}. Concomitant occurrence of said collisions causes peening of CoMaP onto S-S, thus realizing coating ^{2, 16, 42}.

F-Bp Based Processes: The F-BP-based CoPr improved and novel processes, alternative to pan-CoPr ^{2, 17}. These CoPr bear potential pros being able to effectuate the most effectual drying of diverse products compared to any other existing CoPr ^{2, 17}. Thus, these CoPr are particularly popular for coating multi-particulates, pellets, fine particles, and microencapsulation ^{2, 17}. The use of these CoPr is uncommon for coating of tablets, especially in large scale, as associated high process attrition causes tablets to break, chip, and abrade out ^{2, 17}.

F-BP based CoPr having applicability in pharmaceutical fields are ^{2, 17}:

1. Top-spray CoPr,
2. Bottom-spray (Wurster) CoPr,
3. Tangential-spray (Rotary) CoPr,
4. Rotating (centrifugal) fluidized-bed CoPr,
5. Supercell^® coating process and
6. Huttlin Kugel coater-based CoPr.

The C-F, as liquid, is continuously applied through spray nozzle(s) located at the top of the chamber (in top-spray CoPr), the bottom of the chamber (in Wurster CoPr), or tangentially (in Rotary CoPr) onto the fluidized S-B ^{2, 17}. Amongst the said CoPr selection of suitable/ efficient one is often decided by nature & intended functionality to be realized from the coating (refer Table 3) for example ¹⁷:

17. Films produced by CoPr using top-spray F-BP are not of uniform thickness ^{2, 17}. Thus favored in instances where critical control of drug release rate is not desirous, like taste masking and barrier films ¹⁷. However, suit in hot-melt CoPr ¹⁷.
18. CoPr using Wurster F-BP is for conferring sustained/ controlled/ extended/ enteric/ delayed release property to a wide variety of multi-particulates and pellets ¹⁷. Said CoPr also suits drug layering with dose in low-to-medium range ^{2, 17}.
19. CoPr that use Rotary F-BP has applicability in modified-release (controlled/ sustained/ extended/ enteric/ delayed-release) and F-C of wide-ranged multi-particulate products ¹⁷. These CoPr are ideally suited for drug layering having dose in the medium-to-high range ¹⁷. It finds usefulness also in the extrusion & spheronizing process to get pellets with modified-release attributes ^{2, 17}.

Rotating (Centrifugal) Fluidized-bed Process: W-CP-based soft CoPr employs F-BP operating with rotating fluidization principle ^{2, 17}. They find applicability for delicate and soft particulate substrates ^{2, 17}. High rotational speed mediated centrifugal force conjoined inwardly directed radial-air-flow fluidizes the revolving S-B ^{2, 17}. Onto the fluidized S-B, a binary-fluid sprayer sprays C-F fluid onto them to realize coating ^{2, 17}. Excellent mixing is add-on pro of the CoPr thus achieving nice coating and operating in a continuous mode ^{2, 17}.

TABLE 3: DISADVANTAGES, ADVANTAGES AND APPLICATIONS OF F-BP BASED COPR ^{2, 17}

Supercell^® Coating Process: Using conventional coaters in CoPr, in most instances, outcomes inaccurate/ non-homogenous coat ^{1, 2}. CoPr based on said coaters while coating tablet substrates causes their grounding off and filling in of their integration ^{2, 5}. Further, said methodologies of CoPr are unsuitable for tablets with flat & other odd shapes, as they fail to consistently coat their corners/ edges/ faces ^{1, 2}. Thus, in a nutshell, said methodologies are unsuitable for modified release coating, friable, extremely hygroscopic, and flat & other odd-shaped tablets ^{2, 5}. Solutions to talk over issues are made with devised “Supercell coating technology^®” ^{1, 2}. It’s a novel and gentle F-BP (Wurster type) based W-CP to realize coating of hygroscopic/ friable/ flat & other odd-shaped tablets ^{1, 2, 5}.

Gas-Phase Deposition/ Coating Process: These comprise a group of D-CP that are based on Supercritical fluid (SCF) and aerosol flow reactor ^{2, 10, 16, 46-48}. CoPr of this group suits FUFP and particulate substrates ^{10, 16}. Herein C-F is prepared using SCF as solvent/ medium for carrying CoMa ^{9, 10, 46}. Basically, strategies of CoPr following gas-phase deposition are complex, relatively expensive, and challenging during scale-up ^{10, 47, 48}. SCF-based CoPr with applicability in pharmaceutical fields are based on ^{16, 17}.

49. Rapid expansion of SCF ⁴⁹.
50. SCF anti-solvent ⁴⁹.
51. Gas anti-solvent ⁵⁰.
52. Gas-saturated solution ^{49, 50, 51}.

Rapid Expansion of SCF Based CoPr: Rapid expansion of SCF companioned rapid supersaturation is the underlying principle of this approach ^{2, 10, 46, 47}. Rapid expansion of SCF consequences a rapid change in density along with solvent power of SCF ^{9, 10, 48, 49}. This thus translates into rapid crystallization rates, resulting in fast precipitation of CoMa thereby realizing coating ^{10, 48}.

SCF Anti-solvent Based CoPr: CoPr has synonym ‘Aerosol solvent extraction systems’ ^{9, 10}. ‘Solution-enhanced dispersion by supercritical fluids’ is its reported variant ^{10, 48, 49}. The design approach of the CoPr is for handling CoMa and substrate that are soluble in VOS; whilst they are insoluble in SCF and solution of VOS and SCF ^{9, 10, 17}. However, the SCF is miscible with VOS ^{2, 10, 16}.

Gas Anti-solvent Based CoPr: The design approach of the CoPr is to handle substrate and CoMa that are soluble in SCF but insoluble in inert gas ^{16, 17}. The process basis herein is an interacting solution of substrate and CoMa in SCF with an inert-gas ^{10, 50}. Used inert gas should be non-solvent for substrate and CoMa but miscible with SCF ^{10, 50}. Rapid mixing of SCF solution with inert gas during the interaction phase lowers SCF’s solvent power and causes substrate and CoMa to precipitate ^{10, 16}. Said rapid precipitation realizes deposition of CoMa on S-S ^{10, 17}. During processing, the inert gas may be kept at a pressure that is elevated or par to the pressure of SCF solution ^{2, 16, 17}.

Gas-saturated Solution Based CoPr: Basis of CoPr, herein, involves mixing of polymeric CoMa in SCF and substrate particles at elevated pressure ^{10, 49, 51}. During processing, penetration is of SCF into polymeric CoMa, causing swelling of CoMa ^{51, 52}. The ensued mix is then heated at a temperature higher than Tg of polymeric CoMa, for liquefying polymer ^{10, 16}. Then the pressure is released ^{10, 17}. As when pressure is released CoMa gets deposited on S-S ^{9, 10}. The CoPr suits substrate and CoMa that may be insoluble in SCF of choice ^{2, 16, 17}.

Vapor-Phase Deposition/ Coating Process: These comprise a group of CoPr; up-roused novel D-CP for FUFP, particulates, and solid dosage forms; wherein electro-deposition is the underlying principle for realizing coating ^{2, 10, 53, 54}. Said electro-deposition involves generating vapor of desired CoMa thru electro-dispersion and then permeating generated vapor onto S-S, for realizing deposition of CoMa on S-S ^{55, 56}. The CoMa, used herein, in most cases is powder but the liquid is in minor instances ^{16, 17}. CoPr can realize uniform and durable coating of controlled thickness on particulates at the individual level, which is slow-dissolving ^{10, 20}. The terminal product has orchestrated functionalities and surface and surface-topography ^{10, 53, 55-58}. Major cons associated with CoPr based on this strategy are involvement of vacuum creation that requires huge investments arising from immense overhead costs, in process equipment ^{2, 10, 16}. CoPr, herein, comprises of dispersal-phase & maintenance-phase ^{10, 16}. Dispersal-phase realizes electro-dispersion, which is the process of dispersing powder or liquid with thru application of electrostatic-field ^{20, 53, 57, 58}. The electro-dispersion makes usage of an intense electric-field that realizes dispersal of a part of the static-bed, comprising substrate & CoMa, into a stable cloud ^{9, 57}. Said cloud is of fast-moving particles herein termed dispersed phase ^{53, 57}. A dynamic equilibrium is maintained between static and dispersed-phase during the maintenance phase; herein, electro-deposition effected ^{2, 10, 16, 57, 58}.

The involved methodology of these CoPr is as follows ^{16, 17}.

Chemical vapor deposition (CVD) ¹⁰.

• Plasma enhanced CVD ¹⁰.
• Initiated CVD ^{10, 54}.
• Fluidized-bed CVD ¹⁰

Atomic/ molecular layer deposition (AMLD) ^{10, 58, 59}. Both AMLD and CVD realize F-C using gaseous reagents ^{2, 46, 57-60}. Even though AMLD is relatively expensive which often requires toxic precursors but can realize effective fine coating with a fineness of a few atomic layers only ^{16, 61}.

Fluidized-bed CVD CoPr: The state-of-art technology combines CVD and fluidized-bed process for realizing coating ⁶⁰. CVD on fluidized S-B is an efficient technique to functionalize & to deposit CoMa on individual substrate particles ⁶⁰. CoPr herein involves two steps ⁶⁰. One process step aims to deposit CoMa on substrate by itself while the other aims to suspend CoMaP in deposition zone ⁶⁰. The suspending step is resulted most often by upwardly flowing fluidizing gas through powder-bed ^{2, 60}.

Resodyn Acoustic Coating Process: D-CP realizes particulate coating following “Resonant Acoustic Technology^®” using “Resodyn Acoustic Mixer^®” ^{2, 16, 17, 62-64}. Said mixer is a sophisticated benchtop mixer ^{16, 62}. Embedded state-of-art technology creates a low-frequency, high-intensity shear field within the mixer’s processing vessel ^{16, 17, 63}. During processing, generated acoustic energy realizes the coating of particulate substrates as they collide with each other ^{16, 62, 64}. The coating is ensured in very short time span ^{16, 17}.

CONCLUSION: W-CP and D-CP can be realized by modifying the surface, surface topography, and surface attributes of solid dosage form and FUFP thru coating. In major instances, W-CP suits CoMa that is liquid or solid, whilst D-CP suits solid CoMa. The D-CP fits for coating of FUFP, whereas W-CP is unfit for coating of FUFP. Residual VOS and handling of environmental issues along with unwanted waste streams are major concerns of VOS-based W-CP. In this regard, D-CP is novel alternatives.

D-CP is a one-step straightforward CoPr, that bears minimal concern to process deviations invoking from operator skills. Further, some of them can be designed for continuous operation. Most of D-CP inherit scale-up potentiality of a higher-degree. CoPr based on D-CP can realize composite products having novel/ new functionality and/or surface attributes.

Realization and reproduction of coating uniformity in D-CP, particle size of CoMa, and substrate play crucially. Mechanical compaction-based D-CP is unfit for elastic CoMa and substrates. The possible realization of composite products from plastic CoMa and substrates is possible through their mechanical interlocking of them.

Specialized W-CP and D-CP involve technologies that make use of ambient conditions like elevated temperature, high pressures, high shear and/or solvents. Vapor-phase and gas-phase deposition processes involve vacuum creation and/or pressure generation. CoPr based on these processes mostly requires immense capital investment & huge overhead costs, in-process equipment. Strategies like CVD, plasma-enhanced CVD, AMLD, and SCF-based CoPr are complex, expensive, and challenging scale-ups. Among the W-CP aqueous F-CP be considering the first option for realizing coating of the solid orals, regardless of conventional release and modified-release applications. It’s hoped that D-CP will become robust upon optimization & validation. These CoPr thus may have a high degree of potentiality suiting to manufacturing line-up. Finally, for finding the pharmaceutical applicability of W-CP and D-CP, their scalability potential for larger and pilot manufacturing-scale batches calls for an immense and robust investigation.

ACKNOWLEDGEMENT: However, for continual support and encouragement author will remain indebted to the administration and the staff of Jeypore College of Pharmacy, Jeypore, Koraput, Odisha, India.

CONFLICT OF INTEREST: Nil

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    How to cite this article:

    Saikh MAA: Glimpse on pharmaceutical coating processes. Int J Pharm Sci & Res 2022; 13(11): 4305-20. doi: 10.13040/IJPSR.0975-8232.13(11).4305-20.

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