Hot Melt Coating Research Articles

Improving Stability Of Sitagliptin Using Hot Melt Coating Technique

Improving Stability Of Sitagliptin Using Hot Melt Coating Technique

Effect of talc and vitamin E TPGS on manufacturability, stability and release properties of trilaurin-based formulations for hot-melt coating

This study was focused on one particular case of hot-melt coating with trilaurin – a solid medium-chain monoacid triglyceride. The challenge of using trilaurin as coating agent in melting-based processes is linked to its relatively low melting profile: 15.6 °C (Tm,α), 35.1 °C (Tm,β′) and 45.7 °C (Tm,β). From a process perspective, the only possibility to generate products coated with formulations composed of trilaurin is by setting thermal operational conditions above Tm,α. From a material perspective, this processing possibility depends principally on trilaurin crystallisation which was investigated via a set of analytical techniques including turbidimetry, calorimetry, hot-melt goniometry, and polarised light microscopy. A highly soluble drug model substrate (sodium chloride crystals) was coated with three selected trilaurin-based formulations: (i) trilaurin, (ii) trilaurin plus talc, and (iii) trilaurin plus vitamin E TPGS and talc. Coated salt crystals were then analysed to investigate processing performance, coating quality, stability and release properties under digestion effect. The results show that firstly, talc addition promotes nucleation and crystal growth and, as a consequence, it facilitates the manufacture of trilaurin-based formulations. Secondly, the formulation of a solid triglyceride and a hydrophilic surfactant could potentially cause release instability, but formula (iii) was found to be stabilised by a mechanism whereby trilaurin crystallization enhanced in the presence of talc immobilised vitamin E TPGS in its crystal lattice. Thirdly, talc addition did not significantly influence trilaurin digestion which endows products with an immediate release in lipolytic conditions instead of an extended liberation in pure water. Nor did the addition of one or two additives alter the extent of trilaurin digestion under the conditions studied. These important findings relate to product manufacturability, stability, and release properties. A good understanding of material properties (e.g. crystallisation, polymorphism, digestibility) is essential for melt-processing, lipid coating stabilising and modulation of release profile of solid lipid-coated product, as demonstrated in this case study with trilaurin.

Shear-Strained Structures Induced during Hot-Melt Coating and Their Gradual Temporal Changes in Coated Layers Composed of Block Copolymer/Tackifier Blends

Shear-Strained Structures Induced during Hot-Melt Coating and Their Gradual Temporal Changes in Coated Layers Composed of Block Copolymer/Tackifier Blends

Delamination and wetting behavior of natural hot-melt coating materials

In order to achieve a defined product behavior, the coating of particulate solids is an often used process in the food, chemical, and pharmaceutical industries. The wetting behavior affects the coating quality associated with hot-melt coating (HMC) considerably more than the quality associated with solvent-based coating. Thus, the uniformity and the effectiveness of the coating can be severely affected by process parameters. Furthermore, previous studies showed that delamination of the coating layer occurs frequently in HMC products [Mueller et al. 2018 (https://doi.org/10.1016/j.apt.2017.12.020); Woerthmann et al. 2021 (https://doi.org/10.1016/j.powtec.2020.09.065)]. Therefore, the successful use of natural coating materials requires a detailed understanding of the delamination and wetting behavior. The delamination observed for HMC-particles has, however, rarely been investigated, and the basis for and factors affecting this process remain unclear. However, a correlation between delamination and the wetting properties of the materials seems likely, since wetting properties provide information about the interaction between the coating and carrier material. In this work, the delamination frequency was investigated via laboratory coating experiments and via micro-computed tomographic measurements with different material combinations. In addition, the wetting behavior was investigated using a drop shape analyzer. No correlation between delamination and wetting behavior was found. All investigated coating agents exhibited excellent wetting properties with contact angles in a range of 10° to 18°, while palm fat coatings were more prone to delamination (>65%) than the rice bran (<10%) and carnauba wax coatings (<17%).

Coating Processes of Pharmaceutical Applicability: A Glimpse

Presentation of manuscript is aiming to furnish glimpse on coating processes. Coating is process of snugly covering substrate surface with coating materials (CoM). In due course coating process has gradually developed from sugar-coating to non-aqueous film-coating to aqueous film-coating to specialised-coating processes. In second half of past century sugar-coating was first choice for pharmaceutical industry. Lengthy and tedious processing along with issues of skilled-operator inherited to sugar-coating compelled them to spring-up and improve film-coating. From past five decades, volatile organic solvent (VOS) are preferred over water in film-coating. Momentum for using aqueous solvent in film-coating gets accelerated from past few decades. Nowadays these replacing the VOS based film-coating processes as later inherit issues relating toxicity; safety; worker hygiene &amp; safety; environmental pollution; etc. During process of finding novelty of coating another exploited sphere is coating of particulate substrate surfaces with CoM is to confer them worthy functionalities and applications. In this area both wet- &amp; dry-coating process finds applicability thru modifying and/or altering innate properties of substrate, physically and/or chemically. Dry-coating process basically comprises specialised and novel process &amp; technologies. Nowadays there available numerous conventional, specialised, and novel coating processes. Amongst them state-of-art process are hot-melt coating (HMC) process, aqueous film-coating process, aerosolized coating process, Supercell® coating process, gas-/ vapour-phase process, photo curable coating process, electrical-electrostatic deposition process, Resonant acoustic coating process, thermal and mechanical process, thermo-mechanical process, fluidised-bed processes, etc. Herein conventional, specialised, and novel coating processes are briefed, to update professionals.&#x0D; Keywords: Coating, film-coating, novel, process, specialised.

Going green: Development of a sustainable lipid-based enteric coating formulation for low-dose aspirin multiparticulate systems

There is a rising awareness of pharmaceutical industry of both patient-centric and sustainable product development. Manufacturing of multiparticulate systems (MPS) with functional coating via solvent-free hot melt coating (HMC) can fulfill both requirements. An innovative lipid-based formulation was developed with the composition of palmitic acid and Grindsted® citrem BC-FS (BC-FS) for enteric coating of acetylsalicylic acid (ASA). The ASA crystals were directly hot melt coated to produce user-friendly low-dose ASA MPS for thromboembolism prophylaxis. Prior to HMC, rational boundaries for the process temperature were defined based on the melting and crystallization behavior of coating blend. Stability of coating in terms of resistance to heat stress and solidstate stability were screened via Fourier-transform infrared spectroscopy and x-ray diffraction. Exposure of coating blend to 100 °C for two hours did not cause any chemical degradation. Crystal growth of palmitic acid and polymorphic transformation in BC-FS were observed after storage under accelerated conditions, however did not significantly affect the ASA release from coating. The developed formulation is a unique solvent-free, lipid-based enteric composition and paves the way for sustainable green pharmaceutical manufacturing.

Hot Melt Coating: Development and Optimization of Controlled Release Formulation and Process of Oxcarbazepine

Hot-melt coating process (HMCP) is being developed to formulate lipid based oral controlled release formulation system for anti-epileptic drug Oxcarbazepine. Pellets containing Active ingredient in the core portion were prepared by extrusion spheronization process with use of appropriate filler and binder. These core pellets were then coated using hot-melt coating technology with different levels of solid lipid material and a hydrophilic component. Formulation and Process parameters were optimized to achieve targeted drug release profile and other target product profile with particular focus on HMCP. Quality by design (QbD) with DOE approach was used for designing and development of the formulation, by putting risk assessment (FMEA, Fish-bone diagram), screening (by Plackett Burman), and optimization (by CCC) studies. Appropriate ‘design space’ was proposed based on the optimization studies. The results demonstrated that the level of Low melting coating component and a hydrophilic component influenced the drug release rate from the formulation, and the rate of release could be optimized by varying the amount of these components in the formulation. Processing parameters like Temperature of the coating solution and atomization air, Atomization air pressure and Spray rate also affects the drug release rate and other parameters like coating efficiency and mean particle size. For optimized formulation, dissolution data model fitting was also carried out which adequately fits to Higuchi model suggesting that the drug release occurred predominantly by diffusion.

Dry-Coating of Powder Particles is Current Trend in Pharmaceutical Field

Modification of surface attributes of particles, usually accomplished by coating, is desirous to enhance and maintain their usability. Coating is a multi-step process involves application of the coating material (CoM) onto the substrate, herein powder particles, where the process along with device/ equipment monitors surface attributes of the applied coating. Nowadays competitive market calls for cost cutting to survive product(s). Thus saving of energy and time, minimising number and quantity of additives, reducing and shortening process steps; consequently minimising the coating process cost are main goals while developing coating process for powder particle. Innovation of processes for dry-powder coating (DPC) along with their further development and refinement finds solution to said issues. Further, DPC process does not calls for liquid solvent or solution thus are viewed as cost-effective and environmentally safe, DPC process uses thermo-mechanical methods like mechanofusion, magnetic assisted impaction coating (MAIC), hybridization, rotating fluid-bed process, theta-composer, hot-melt coating (HMC), and many others. Besides these available are non-thermo-mechanical methods namely electrostatic coating; supercritical fluids (SCF) based methods like rapid expansion of supercritical fluid (RESF), gas anti-solvent (GAS), SCF anti-solvent, gas-saturated solution (GSS); vapour coating; and others. Basing on said thermo-mechanical and non-thermo-mechanical principle several DPC methods/ process had been reported in scientific literatures and patents. Said DPC method founds multidisciplinary applications like drug delivery and drug development. Diverse devices are there for the DPC process; their method of working, principle, limitations and benefits along with their applicability in pharmaceutical field are discussed and presented in this article.&#x0D; Keywords: Dry, particle, coating, pharmaceutical, process

Impact of polysorbate 65 on tripalmitin crystal growth and release stability of hot melt coated multiparticulate systems

Hydrochlorothiazide (HCT) multiparticulate systems (MPS) were hot melt coated with the binary mixture of tripalmitin (PPP) and polysorbate 65 (PS 65) to gain an immediate release profile. Once, HCT MPS were produced with a constant ratio of PPP/PS 65 (90:10) at three different coating amounts (15, 25, and 60%w/w) and once the PPP/PS 65 ratio was varied on 98:2 and 80:20, by keeping the coating amount at 60%w/w. PS 65 induced the polymorphic transformation of PPP from the α-form to its most stable β-form right after the hot melt coating (HMC). A release alteration of HCT, either accelerated or decelerated, occurred after the storage under accelerated conditions. The effect of the API core on the lipid lamellar configuration, the thermal behavior of lipid coating, and the effect of PS 65 concentration on the crystal growth of PPP were investigated via X-ray diffraction and DSC. While a low amount of PS 65 was sufficient to promote crystal growth of PPP and resulted in a decelerated release of HCT from the coating, a higher PS 65 concentration favored phase separation of PPP and PS 65 and led to an accelerated release. The increase in PS 65 reinforced the molecular interaction with the lipophilic HCT, reflected in less crystal growth and decelerated release. The knowledge presented in this study supports understanding the instability of binary emulsifier-lipid coating systems, paving the way for developing robust HMC formulations.

Development and Optimization of Controlled Release Formulation and Process of Levetiracetam with Hot Melt Coating Technology

Conventional coating processes are based on aqueous or organic solvent system, resulting in the lengthy and tedious processes where use and removal of solvents consumes lots of energy and resources. Also, solvent disposal is a critical issue considering environmental hazard.Hot melt coating process avoids use of solvent and is short and energy-efficient process. Here, Hot-melt coating process (HMCP) is being developed to formulate lipid based oral controlled release formulation system to deliver highly water soluble Biopharmaceutical Classification System (BCS) class-I drug Levetiracetam. Pellets containing Active ingredient in the core portion were prepared by extrusion spheronization process with use of appropriate filler and binder. These core pellets were then coated using hot-melt coating technology with different levels of lipid and a hydrophilic component. Formulation and Process parameters were optimized to achieve targeted drug release profile and other target product profile with particular focus onHMCP. Quality by design (QbD) with DOE approach was used for designing and development of the formulation, by putting risk assessment Failure Mode and Effect analysis (FMEA, Fish-bone diagram), screening (by Plackett Burman), and optimization by Central Composite Design (CCC) studies. Appropriate ‘design space’ was proposed based on the optimization studies. The results demonstrated that the level of Low melting coating component and a hydrophilic component influenced the drug release rate from the formulation, and the rate of release could be optimized by varying the amount of these components in the formulation. Processing parameters like Temperature of the coating solution and atomization air, Atomization air pressure and Spray rate also affects the drug release rate and other parameters like coating efficiency and mean particle size. For optimized formulation, dissolution data model fitting was also carried out which adequately fits to Higuchi model suggesting that the drug release occurred predominantly by diffusion.

Impact of Surface Properties of Core Material on the Stability of Hot Melt-Coated Multiparticulate Systems

Hot melt coating (HMC) of an active pharmaceutical ingredient (API) powder with lipid-based excipients is an innovative method for manufacturing patient-convenient dosage forms. However, drug release instability is still its main industrial challenge. The correlation between the unstable pharmaceutical product performance with the solid-state alteration of lipids is currently well-investigated. The remaining problem is the inconsistent release alteration of different APIs coated with the same lipid after storage, such as faster release in some cases and slower release in others. The interaction between API surface and lipid-based coating and its alteration during storage were investigated in this work. The surface properties of five different APIs and the coating composition of tripalmitin and polysorbate 65 were screened via Washburn and pendant drop methods, respectively. Metformin hydrochloride and hydrochlorothiazide particles were each coated with the coating composition. The water sorption alteration of coated particles and the crystal growth of tripalmitin in the coating after storage were measured via tensiometry and X-ray diffraction. The cleavage work necessary to overcome the adhesion of coating composition on the core surface was calculated for each API. The accelerated release of the polar core (metformin) after storage was correlated with a low cleavage work and a distinctive phase separation. In contrast, a decelerated release of the hydrophobic core (hydrochlorothiazide) was favored by the crystal growth of the lipid-based coating. The gained knowledge can be used to design the product stability during the formulation development.

Procena metoda za oblaganje višečestičnih supstrata topljenjem - oblaganje u pateni vs. oblaganje u bubnju

Hot-melt coating (HMC) is an alternative, solvent-free coating method generally used to modify substrate release rate and/or mask its unpleasant taste. The aim of this study was to assess two HMC methods (pan-coating and mortar-coating) by assaying functional properties of the coated material. The selected substrates included highly soluble sodium chloride (model substance) and caffeine (bitter drug), and the coating agent was glycerol distearate without/with the addition of liquid paraffin. Experiments with sodium chloride revealed that pan-coating yielded particles of more regular shape, while mortar-coating yielded samples of more uniform coating layer. The flowability of the coated material depended on the particle size. Sustained sodium chloride release was achieved for all mortar-coated and some pan-coated samples. The analysis of the results indicated mortar-coating as a preferable HMC method for caffeine coating. The resulting caffeine yield in the coated samples was high (99%), the material showed satisfactory mechanical properties and drug release from the coated particles was sustained. Overall, the obtained results suggest that both pan-and mortar-coating can be used to sustain the release of drugs with unpleasant taste, but mortar-coating can be considered as a more simple and practical method that can be potentially used in compounding pharmacies.

Hot Melt Coating of Amorphous Carvedilol.

The use of amorphous drug delivery systems is an attractive approach to improve the bioavailability of low molecular weight drug candidates that suffer from poor aqueous solubility. However, the pharmaceutical performance of many neat amorphous drugs is compromised by their tendency for recrystallization during storage and lumping upon dissolution, which may be improved by the application of coatings on amorphous surfaces. In this study, hot melt coating (HMC) as a solvent-free coating method was utilized to coat amorphous carvedilol (CRV) particles with tripalmitin containing 10% (w/w) and 20% (w/w) of polysorbate 65 (PS65) in a fluid bed coater. Lipid coated amorphous particles were assessed in terms of their physical stability during storage and their drug release during dynamic in vitro lipolysis. The release of CRV during in vitro lipolysis was shown to be mainly dependent on the PS65 concentration in the coating layer, with a PS65 concentration of 20% (w/w) resulting in an immediate release profile. The physical stability of the amorphous CRV core, however, was negatively affected by the lipid coating, resulting in the recrystallization of CRV at the interface between the crystalline lipid layer and the amorphous drug core. Our study demonstrated the feasibility of lipid spray coating of amorphous CRV as a strategy to modify the drug release from amorphous systems but at the same time highlights the importance of surface-mediated processes for the physical stability of the amorphous form.

Novel approach for overcoming the stability challenges of lipid-based excipients. Part 2: Application of polyglycerol esters of fatty acids as hot melt coating excipients

The application of hot melt coating (HMC) as an economic and solvent-free technology is restricted in pharmaceutical development, due to the instable solid-state of HMC excipients resulting in drug release instability. We have previously introduced polyglycerol esters of fatty acids (PGFAs) with stable solid-state (Part 1). In this work we showed a novel application of PGFAs as HMC excipients with stable performance. Three PGFA compounds with a HLB range of 5.1–6.2 were selected for developing immediate-release formulations. The HMC properties were investigated. The viscosity of molten lipids at 100 °C was suitable for atomizing. The DSC data showed the absence of low solidification fractions, thus reduced risk of agglomeration during the coating process. The driving force for crystallization of selected compounds was lower and the heat flow exotherms were broader compared to conventional HMC formulations, indicating a lower energy barrier for nucleation and lower crystallization rate. Lower spray rates and a process temperature close to solidification temperature were desired to provide homogeneous coating. DSC and X-ray diffraction data revealed stable solid state during 6 months storage at 40 °C. API release was directly proportional to HLB and indirectly proportional to crystalline network density and was stable during investigated 3 months. Cytotoxicity was assessed by dehydrogenase activity and no in vitro cytotoxic effect was observed.

Tableting of hot-melt coated paracetamol granules: Material tableting properties and quality characteristics of the obtained tablets

Hot-melt coating (HMC) has been recognized as a promising technique in the production of solid dosage forms e.g., HMC of granules can be applied prior to compression in order to obtain modified drug release or taste masking. However, tableting properties of HMC granules have not been studied yet. In this work, we explored the influence of the lipid coating on granules tableting properties, and assessed quality attributes of the obtained tablets. Paracetamol granules, previously coated with the lipid excipient Precirol® ATO 5 using a hot-melt coating technique in modified fluidized-bed system, were evaluated in terms of work of compression, elastic recovery, tablets tensile strength, detachment stress and ejection stress. Regarding the product quality, tablets content uniformity, friability, disintegration time and drug release properties were tested. Our results demonstrated that tablets made of coated granules exhibited more pronounced elastic behaviour, and increased tensile strength in comparison to tablets made of uncoated granules, suggesting that lipid coating promotes elastic deformation and forms lipid matrix within the tablets. Additionally, low detachment and ejection stresses for tablets made of HMC granules indicated no need to add lubricant prior to tableting process. Evaluation of tablets properties revealed that tablets friability was not influenced by the presence of lipid coating on the compressed granules. However, formation of lipid matrix within the tablets made of HMC granules resulted in prolonged tablet disintegration time, and sustained drug release. Moreover, the performance of lipid matrix tablets, in terms of drug dissolution rate, was relatively insensitive to compression pressure variations in 104–173 MPa range. The obtained results indicate that tableting of HMC granules is a promising technique to obtain sustained release lipid matrix tablets of suitable pharmaceutical-technical properties.

Combination of a hot-melt subcoating and an enteric coating for moisture protection of hygroscopic Sennae fructus tablets

The objective of this study was to investigate the efficiency of moisture protection of hot-melt coatings solely and in combination with an enteric coating on hygroscopic tablet cores containing a spray-dried Sennae fructus extract. Tablet cores were subcoated with different hot-melt coating materials: medium chain tryglycerides, stearic acid, Precirol® ATO 5, and Compritol® 888 ATO, at varying amounts and coated with Eudragit® L 30D-55 for enteric resistance. Subcoating penetration, tablet disintegration, dissolution times, tablet hygroscopicity, and tablet properties such as weight, height, diameter, and hardness were analyzed. 3 mg/cm2 of tablet surface seemed to be sufficient if sustained release is not required. Thereby, hot-melt coating did not adversely affect the tablet properties with regard to subsequent processing steps. Compared to the tablet cores it was possible to reduce the moisture uptake by 85% at 75% relative humidity with tablets coated with a combination of Precirol® ATO 5 and Eudragit® L 30D-55. This combination was more efficient than high amounts of Eudragit® L 30D-55. Hot-melt coating proved to be a suitable technique for the application of subcoating material to tablet cores serving as a barrier against water permeation into hygroscopic tablet cores without exceeding the required disintegration times.

Development of Hot Melt Coating Technique for Taste Masking of Chloroquine Phosphate Tablets

In the present study to mask the unpleasant taste of chloroquine phosphate, hot melt coating technique was used as a taste masking tool. Hot melt coating is a solvent free technology grants rapid, additionally economical coating process with reduced risk of dissolving drug during process and provide uniform application rate of coating agent. Precirol ATO 5 was used as hot melt coating material for taste masking. Tablets were prepared by wet granulation method and coated using hot melt coating technique. Coated tablets exhibited good uniformity of drug content. Amount of drug release from all batches were evaluated. Taste evaluation of hot melt coated tablets was done by using electronic tongue.PrecirolATO5 was found to be a better taste masking agent when used by hot melt coating technique.&#x0D; Keywords: Precirol ATO 5, Hot melt coating, taste masking.

Correlation between the solid state of lipid coating and release profile of API from hot melt coated microcapsules.

Solvent-free hot melt coating (HMC) provides a safer and more economic process compared to the conventional solvent coating techniques. However, drug release instability and the lack of fundamental understanding on it are limiting factors for application of HMC for industrial productions. In this work, we investigated glyceryl dibehenate, glyceryl monostearate and behenoyl polyoxyl-8 glyceride as HMC materials. The microstructure and solid state alteration of lipids were studied via polarized light microscopy, DSC and powder x-ray diffraction. Microcapsules of N-acetylcysteine particles were provided with these excipients and stored under long term and accelerated conditions for 3 months. The feasibility of selected lipids as HMC excipients was confirmed. The drug release from freshly coated microcapsules was dictated by microstructure, solid state and HLB of lipid coating. Alterations in the release profiles after storage under accelerated conditions were correlated with time-dependent structural alterations of selected lipids. The faster drug release from glyceryl dibehenate and behenoyl polyoxyl-8 glyceride microcapsules was correlated with a low-melting small fraction composed by mixed phases in glyceryl dibehenate and the amorphous region of polyoxyl part in behenoyl polyoxyl-8 glyceride, respectively. The slower drug release from glyceryl dibehenate after storage was explained by the transition of lipid crystals to the β-form with dense crystalline structure. The gained information can be used to design effective tempering strategies for providing stable pharmaceutical products.

Designing optimal formulations for hot-melt coating

Hot-melt coating (HMC) as a solvent-free technology grants faster and more economic coating processes with reduced risk of dissolving the drug during the process. Moreover, traditional coating equipment can be modified to enable the HMC process. Despite the indubitable advantages and feasibility of the process, HMC is not well-known to pharmaceutical industry and its employment is still limited. The main aspect hindering the widespread application of this technique is the need of materials alternative to the conventional polymeric coatings.The current work reviews the published HMC formulations and describes the properties that have led to their selection. As these materials are mainly solid lipid excipients, attention should be paid to their crystallization and solid state behavior, and their impact on the performance of coated drug products, particularly on the stable drug release profile.Although different drug release profiles can be easily tailored, much development work is needed to respond to the unmet requirements of a stable formulation. Ensuring stable solid-state behavior and providing a mechanistic understanding of the macroscopic properties are essential steps towards fulfilling these requirements and establishing of HMC as advanced coating technology for manufacturing of pharmaceutical products.

Monitoring of a Hot Melt Coating Process via a Novel Multipoint Near-Infrared Spectrometer

The aim of the present work was to develop a PAT strategy for the supervision of hot melt coating processes. Optical fibers were placed at various positions in the process chamber of a fluid bed device. Experiments were performed to determine the most suitable position for in-line process monitoring, taking into account such requirements as a good signal to noise ratio, the mitigation of dead zones, the ability to monitor the product over the entire process, and reproducibility. The experimental evidence suggested that the position at medium fluid bed height, looking towards the center, i.e., normal to particle movement, proved to be the most reliable position. In this study, the advantages of multipoint monitoring are shown, and an in-line-implementation was created. This enabled the real-time supervision of the process, including the fast detection of inhomogeneities and disturbances in the process chamber, and the compensation of sensor malfunction. In addition, a model for estimating the particle size distribution via NIR was successfully created. This ensures that the quality of the product and the endpoint of the coating process can be determined correctly.