It is a coating defect where pit

2022.07.31
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It is a coating defect where pit

It is a coating defect where pits appear on the surface of a tablet core without any visible disruption of the film coating.

It is well known that defects and imperfections pre-existing on the substrate surface can be easily duplicated and magnified in the hot-dipping stage, resulting in defective coatings. This problem is caused by the high surface tension of the adhesive applied on a polymer surface, such as a plastic films. In other words, it is a defect in the films coating results in craters appearing on the tablet which in turn results in the exposure of the tablets surface. Corona treatment helps to a great extent in improving the wettability of the substrate. Aulton, M. E. (2004). Other possible cause of picking may include inadequate atomization, poor product movement or poor distribution of spray.

This could be that the flash off zone before heat curing is inadequate or the oven profile is incorrect.

These problems can be avoided by increasing the nozzle air pressure (or the atomization air volume), increasing pan speed and optimizing the uniformity of solution delivery through the spray gun respectively.

The most common ionizers used in film transport systems are static bars and ionized air blowers.

Please feel free and leave your comments regarding tablet coating defects and remedies.

Loading and unloading tablets from the coating pan.

Scuffing is appeared when tablets are more sliding rather than trembling. It frequently extends entirely through the coating film.

It is defect in which the film either cracks across the crown of the tablet (cracking) or splits around the edges of the tablet (Splitting). Too little air pressure, wide fan patterns or spraying at excessive nozzle distances causes droplets to become too dry during their travel time to the work surface and they remain as formed by gun nozzle. Applying (especially rolling) paint too rapidly.

Depending on whether the defect occurs early or late in the coating process, the affected area may be partially obscured as coating proceeds. What are tablet coating defects and remedies?

Coating and core have different thermal expansion properties. Substrate treatment is often applied to plastics prior to coating. Temperature of the tablet core is greater than the melting point of the materials used in the tablet formulation.

Learn how your comment data is processed. Use of sorbitol in coating formulation which causes major fall in the thermal gelation temperature of the HPMC (Hydroxy Propyl Methyl Cellulose), HPC (Hydroxy Propyl Cellulose), Cellulose ethers, and Methyl Cellulose.

Common Tablet Defects:Causes and Remedies, Advantages and Disadvantages of Pharmaceutical Emulsions, Problems Encountered During Trituration and Possible Solutions, Mechanisms Involved in the Mixing of Pharmaceutical Powders, Mixing of Pharmaceutical Powders in Small-Scale Operations, 9 Reasons Why Customers Choose Your Competitors Products Over Yours, Common Medical Abbreviations and Their Meaning, Understanding the Various Types of Hepatitis Virus, Six Reasons for the Importance of Primary Care for the Elderly, National Agency for Food & Drugs Admin & Control, Journal of Pharmaceutical Development and Industrial Pharmacy, Coated product performance and functionality, Processing efficiencies and manufacturing costs, Optimizing spray rate and/or drying air temperatures and volumes to achieve better atomization of the coating liquid and improve drying, Thinning of coating solution with additional solvent to reduce viscosity and thus improve atomization.

A defect which involves variation in colour of the film.

Coating droplets are over-dried before contacting tablet surface, increasing tablet surface roughness and filling the logo. Inadequate coating or migration of soluble dyes-plasticizers and other additives during drying.

These problems are, of course, totally unacceptable for products where the applied coating is a major factor in modifying drug-release characteristics. It is a coating defect where part of film of tablets momentarily stick together or stick to the pan, often just after they pass through the spray zone, and then sticked area being detached from the tablet surface. Read Also: Common defects in sugar-coated tablets. Under static conditions, the contact angle Q of a liquid drop placed on a given substrate determines whether wetting is good or poor.

A pre-condition that has to be met in order to obtain complete wetting is that the substrate is clean.

Orange Peel is Uneven , rough irregularities in the surface of a coated film. However, poor operator techniques, or too much adhesive coating thickness , will also produce a rough finish. Very high spray rate with low temperature.

High molecular weight polymeric blends or polymers.

Adhesive Oozing / Bleeding Blistering Setting appropriate drying temp is a key to get raid of Blisters. It is a coating defect where the film becomes chipped or worn away and dented usually at the edges of the tablet as the coating is being applied. Insufficient film strength to provide resistance to edge damage. Use coating formulation with increased hiding power. Required fields are marked *.

Higher internal stresses in the film than the tensile strength of the film.

The improper application of the conformal coating. Adjust the Adhesive viscosity or the nip replace the solvent Peeling. Recoat , (avoiding temperature/humidity extremes) .

Another approach being most often used to prevent crawling is lowering the surface tension of the liquid adhesive by adding wetting agent.

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Crawling can be prevented in a number of ways.

Wetting becomes more critical when the surface energy of the substrate is low and/or when the surface tension of the liquid Adhesive is high. PEOPLE ALSO READ:SOP for Operation and Cleaning of Vibrosifter. Characterizing problems encountered in film coating.

Coating over contaminated surface (e.g., dirt or wax). It is a coating defect where tablets stick together especially when two tablets stick together.

As a matter of fact a temp gradient setting is essential. It is a coating defect that involves variation in color of the film. Avoid the use of sorbitol with HPMC (Hydroxy Propyl Methyl Cellulose), HPC (Hydroxy Propyl Cellulose), Cellulose ethers, and Methyl Cellulose.

Increasing compaction forces to reduce tablet friability. Penetration of coating solution at the surface of the tablet, often at the crown where the surface is more porous causing localized disintegration of the core. Unequal distribution of coating suspension. These charges often cause attraction of Dirt , Dust , fibre and hair on to the web material and defects in coating uniformity resulting in quality problems and customer dissatisfaction. Peeling: Loss of bond due to poor adhesion.

It can also be introduced during the application process. In some cases the substrate must be modified in such a way that the surface energy of the substrate is raised, i.e.

Lachman, L., & Liebermann, H. A. In other words, it is the fading or dulling of a coated tablet color after a prolonged period of storage at a high temperature. It is defect where isolated areas of film are pulled away from the surface when the tablet sticks together and then part. Your email address will not be published.

This causes obvious quality problems in printing, coating and laminating and cleanliness problems with food, medical and pharmaceutical packaging films.

Inappropriate drying (inlet air) temperature. Methods such as modifying the surface of the material to give it some degree of conductivity or the use of air ionization must be employed. At first, the use of surfactants should be minimized. Adjusting the type and concentration of plasticizer. Peeling refers to the formation of uneven or rough irregularities on the surface of a coating film applied on a core tablet surface. Foam and Bubble formation because of air spraying of a polymer solution.

the substrate is changed from hydrophobic to hydrophilic. It's a promise from my side to guide you , in terms of selection of a suitable additive or a process.

London: Pharmaceutical Press.

A small , dome like bulge in the coated film or a small recess in a coating film.

New Delhi: CBS Publishers & Distributors Pvt.

Use coating formulation which is less tacky. It is a coating defect where the engraved logo or break line filled with either particle of dried polymer or solidified foam. Trapped solvents can also show up as blisters. Tablet coating defects and remedies are the crucial concern of a pharmaceutical formulation scientist. It is defect of film coating whereby volcanic-like craters appears exposing the tablet surface. Foam and Bubble formation because of air spraying of a polymer solution.

While cohesive failure is often associated with brittleness of the coating, the problem is certainly exacerbated by thermal expansion effects particularly when significant differences exist between the thermal expansion coefficients for the core and coating, respectively.

Use lower molecular weight polymeric blends or polymers. 2.

Addalcoholorusespraynozzlecapableof fineratomization.

Coating droplets are over-dried before contacting tablet surface, increasing tablet surface roughness and filling the logo.

Raising relative humidity is sometimes used to increase surface conductivity of some normally insulate materials in an effort to reduce static charging.

Exposure of the Adhesive film to high temperature , humidity or moisture shortly after adhesive is coated , especially if there was inadequate exhaust.

Insufficient film strength to provide resistance to edge damage.

Adhesive might be too viscous ( high viscosity ) Or The coating nip is too tight solvent evaporation too fast Origin and Potential Causes: Improper gun adjustment and techniques.

Select a more flexible coating Contamination Dirt Pickup: NEUTRALIZING CHARGES ON THE FILM WEB If static charges on the film web can be controlled to a low level, most electrostatic related problems can be eliminated. Cracking of applied film coating can be microscopic or macroscopic in nature.

Permeability to moisture 4. It is a coating defect where the film becomes chipped or worn away and dented usually at the edges of the tablet as the coating is being applied. After being flattened in temper rolling, these areas reflect light differently, appearing as either dark or bright spots depending on the lighting condition.

Mainly, tablet coating is to be done for masking unpleasant taste and odor, protection, identification, improvement of patient compliance, and delivering to the targeted part of GIT. Avoid the use of sorbitol with HPMC (Hydroxy Propyl Methyl Cellulose), HPC (Hydroxy Propyl Cellulose), Cellulose ethers, and Methyl Cellulose.

Although problems encountered during film coating process can fall into a broad range of categories, by far the largest category is that associated with visual defects, often purely cosmetic in nature, which rarely impact the efficacy of the finished dosage form, except in the sense that they might lead to reduced patient confidence. Reducing pan speed throughout the coating process (or at least until sufficient coating has been applied so that the tablets receive some protection from the applied coating). Migration and melting of ingredients in the core. Use lower molecular weight polymeric blends or polymers.

This manifests in aerosol or spray gun application where the coating is applied too far away from the substrate and the coating is too "dry" on the surface to level out.

Blisters will occur as a result of humidity testing on test panels, indicating moisture penetration through the film.

Larger the tablets and the denser the core formulation.

Coatingisrubbingoffduetoexcessive attritionaleffects.

PEOPLE ALSO READ:Working Principle of Vibratory Sifter.

Because the stress increases with increasing coating thickness, logo bridging of pharmaceutical tablets becomes progressively worse as more coating is gradually applied. It is surface defect resulting in the film being rough and nonglossy. Increase solids content of coating liquid, Improve mechanical strength of core by increasing compaction force, changing tablet shape, modifying core formulation or changing process by which core is produced (e.g.

The resultant coating is rough with numerous areas of localized thick coatings. Although such problems may under many circumstances be purely cosmetic, cohesive failure of the coating certainly detracts from many of the functional qualities of the coating. coating of top coat of adhesive to insufficiently cured primer. Internal stress in the film exceeds tensile strength of the film. Although some degree of roughness is always evident with film-coated tablets, coating process adjustments that might allow this characteristic to be kept to a minimum such that it is not readily visible to the naked eye include: Although the adjustments listed above may fall outside compliance with the registered process, they likely should be considered to be part of the original process design process.

Chipping/ Edge Erosion: a common tablet coating defect, 11.

Wrinkling: A rough, crinkled adhesive surface, which occurs when uncured adhesive forms a "skin.". Causes and Remedies of Scuffing of Film-coated Tablets.

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Effect of temperature on the adhesion, elasticity, and strength of the film. It is a coating defect where whitish specks or haziness in the film appear.

Be aware that the use of defoamer, being an approach that cannot always be prevented, increases the risk of cratering , as well as reduction in Peel adhesion values. It occurs when the internal stress (that develops within the film as it dries) exceeds the tensile strength of the film. Increase viscosity of coating solution to decrease spray application rate. To high processing temperaturelow molecular weight of Plasticiser.

On fast-running printing presses or roller-coater application, for example, wetting must be very fast to obtain good results. Alteration of the frequency and duration of appearance of tablets in the spray zone or the size/shape of the spray zone. Uneven coatings and "wicking" of adhesive are often the result of static charges.

Why Pharmacists are not Dispense Prescription Order? Selection of different tablet core design/ surface profile. To browse Academia.edu and the wider internet faster and more securely, please take a few seconds toupgrade your browser. "Fish-eyes" are areas in a freshly applied surface coat that tends to thin or open up on their own accord.