What is drug coating?
In the modern pharmaceutical industry, film coating is generally referred to as a process by which a thin continuous layer of solid is applied onto the surface of a dosage form or its intermediate.
What is the principle of coating?
Coating process: - The basic principle of tablet coating is simple. Tablet coating is an application of coating composition to a moving bed of tablets with the concurrent use of heated air to facilitate evaporation of the solvent.
What is the purpose of coating tablets?
Stability: to protect the active ingredient from moisture, light, and/or acidic environment of the stomach. Taste and/or odor masking: to provide an easy to swallow tablet without the bitter taste of many active ingredients.
What are the methods of coating?
Several coating techniques including drop casting, dip coating, optical deposition, electrospinning/electrospraying, and layer-by-layer deposition are known. These methods have their own advantages and disadvantages as shown in Table 10.2.
How many types of coating are there?
Coatings are varied, but primarily fall into three categories: Architectural, Industrial, and Special Purpose.
What are the types of coated tablets?
Tablet coating is the outer covering of a tablet with a layer/substance....Sugar Coated Tablets. ... Film Coated Tablets. ... Gelatin Coated Tablets. ... Enteric Coated Tablets. ... Compression Coating Tablets. ... Other Types.
What are coating materials?
Typical coating materials are: Pure metals, such as Aluminum (Al), Copper (Cu), Molybdenum (Mo), etc. Alloys, such as Nickel Chrome (NiCr), Nickel Aluminum (NiAl), Aluminum Bronze (CuAl), etc. Ceramic (Oxide), such as Aluminum Oxide (Al2O3), Chrome Oxide (Cr2O3), Zirconium Oxide (ZrO2), Titanium Oxide (TiO2), etc.
What is the difference between coated and uncoated tablets?
Coated tablets reduce dust, so your cleaning burden will be lower and workers better protected. Another side benefit is that glossy, coated tablets also tend to run faster through packaging lines because they are more slippery than uncoated tablets.
What is coating solution?
Solution coating is used to place a very thin layer of plastic onto a substrate; often fabric, paper, and electronic devices. A plastic is first dissolved in a suitable solvent, forming the solution with which to coat the substrate.
What are the coating characteristics?
properties of a coating, such as increased chemical resistance, increased abrasion, and impact resistance. The body coat or intermediate coat must also provide strong adhesion to the primer, as well as a good base for the topcoats.
What is direct coating?
Direct coating uses a blade or fixed knife to spread a liquid polymer coating onto a textile. The height of the blade above the fabric determines the coating's thickness. After application, the fabric is completely or partially oven-cured.
What is the principle of compression machine?
The basic principle behind working with the Tablet Compression Machine is the hydraulic pressure. The pressure is been transmitted via static fluid to all directions in the same proportion. Multiple force is also been applied if needed.
What is the first coat of paint called?
PRIMERPRIME COAT OR PRIMER: The first coat or undercoat that helps bind the topcoat to the substrate.
What is coating machine?
Coating machine allows the drug release to be regulated. This ensures that the drug is supplied to the body in safe amounts that the body can handle and also optimizes their effect on the body.
How are typical coating formulas applied?
The coating process begins with the preparation of a suspension that consists of the coating formulation (primarily solid ingredients) and a liquid solvent which is water, alcohol or an organic solvent. In house formulations prepared from individual components often require the use of multiple mixers and kettles (low shear and high shear mixers) over the course of several hours. In contrast, a commercially supplied, fully formulated film coating is dispersed in water with a low shear mixer, with only approximately 45 minutes of stirring required.
Why is coating important in APIs?
to improve the strength of the tablet – the coating increases the mechanical resistance of the tablets. to improve the taste and mask odors associated with APIs, which are often bitter. Controlled release of drug (often referred to as functional coatings): making the release of the drug in various GI sites depending on the pH.
What are the main reasons we coat tablets?
Aesthetic and protective coatings which allow for immediate release of the API
Why should tablets be formulated carefully?
Tablets should be formulated carefully in order to provide a good surface for coating adhesion.
What is an enteric or gastro-resistant coating?
Example: the enteric or gastro-resistant coating which protects the API of the acidic media of the stomach or protects the stomach from the irritation of the API. an HPMC based subcoating is justified for both isolation and cost reasons before the gastroenteric layer
What are viscosity modifiers?
Viscosity modifiers, which often allow coatings to be applied in a more efficient process or create an improved tablet appearance. Carbohydrates, such as lactose, polydextrose, or starch. Gums, such as acacia or xanthan gum. Main reasons for tablet coating.
Which colorants increase opacity, light protection and provide coloration?
Colorants and pigments that increase opacity, light protection and provide coloration: Water insoluble lakes: Such as indigo carmine, tartrazine, allura red, and quinoline yellow (water soluble dyes of these same colors may also be used)
What is a particle coating?
Particle/ Granule or pellet coating is a thin layer of a substance that is placed around a core particle, granules or pellets. The coating application is through a physical deposition process, i.e. film coating resulting from the spraying and subsequent drying of solutions or dispersions.
What is a compression coating?
Compression coating is similar to the tablet technology, where the core or coated tablets are surrounded by compressible excipients, which prevents the drug incompatibilities and protects the drug from environmental factors like light, humidity and oxidation.
What is the thickness of a thin layer of polymer based polymer called?
A process where a thin polymer-based layer having a thickness between 20 and 100 µm is applied to the OSD which may be a tablet, granules or pellets is called film coating.
What is a pharmaceutical film coating?
The term ‘coating’ usually implies a membrane formed directly on a substrate. It separates two phases between which fluids (gases, vapours or liquids) may be exchanged.
Types of polymer film coatings
The practice of coating solid dosage forms (tablets, capsules, granules and spheroids) is a very old practice that has been undertaken for several centuries.
Materials used in polymer film coatings
A film coating is constituted from a variety of materials that include a polymer, a plasticizer, and other additives (surfactant, colorants/pigments and lubricants).
How Film Coatings Are Applied
Film coating of solid dosage forms in the pharmaceutical industry is undertaken in a specialised coating equipment, such as solid coating pans, perforated pans or fluidised coater.
The choice between water and solvent-based coatings
Even though organic solvents are much easier to process, there has been a steady move away from their use in pharmaceutical coatings due to various reasons.
Examples of Film Coating Formulae
The following are gexamples of film coating formulae based on the concepts outlined above:
Summary about Pharmaceutical Film Coatings
The oral route of drug administration is the most popular means by which people take medication.
Pan geometry for pharmaceutical film coating
With an L/D ratio >1, Bohle’s pan geometry provides a wide tablet bed surface, allowing the incorporation of a high number of spray guns.
Patented helical baffles
LB Bohle’s patented helical baffles consist of two baffle layers, responsible for the continuous and homogenous axial mixing within the tablet bed. Coupled with this, drum rotation maintains radial mixing, guaranteeing a dead zone free tablet bed.
Airflow principle
Bohle Film Coaters air principle use the drying capacity where most required – in the tablet bed. Therefore, the drying capacity of inlet air is used most effectively without heating the additional coater inner parts. Inlet air coming from underneath the tablet bed is directly sucked through the rotating tablet bed into the exhaust air funnel.
Why is coating important?
The coating itself can serve several functions – it can strengthen the tablet, control the release of active ingredients, improve its taste, provide colour, make it easier to package and handle, and protect it from moisture.
What is the first requirement during the coating process?
Spraying and distribution. The first requirement during the coating process is that the coating suspension must be distributed evenly on the tablet bed. To do this spraying guns are used. Most often these are atomizers that use compressed air to atomize the coating solution or suspension.
What is a film coating pan?
At the heart of a modern film coating facility is the coating pan or drum and a spraying system. Also, required is an air handling unit and dust collector, and the associated controls. Depending on the application, a humidifier or dehumidifier may also be necessary. The modern coating pan is usually a perforated rotating drum that is housed within a cabinet. The cabinet provides the means of controlling the environment within the drum i.e., temperature and pressure, air flow rate and rotational speed of the drum.
Why use a multi-pan coating pan?
To avoid issues caused by non optimal loading of the coating pan , manufacturers often use a multi-pan approach where different drum sizes are used to accommodate different batch sizes.
How to check spray rate?
By checking the first 3 to 5 batches in this way, the rotation speed of the peristaltic pump can be verified.
What pressure should be used for coating drums?
During the coating process, the pressure in the drum should always be less than the inlet air pressure. However, high negative pressures must be avoided to ensure that some spray is not lost via the air exhaust port. It is important therefore to keep a check on the pressure within the drum during a coating operation. At the same time, a positive pressure in the drum must also be avoided as this may cause contamination of the environment when the drum door is opened due to the release of dust particles and hot air, both of which are prohibited by GMP.
How long does it take to film coat a tablet?
This usually takes about 15 minutes. Spray guns within the drum are then activated to create a fine mist of coating solution that dries as soon as it reaches the surface of the tablets. As the water or solvent evaporates from the mist, it leaves the solids behind to form a thin film. The secret of film coating is very similar to spray-painting – it is best to spray lightly and evenly so that successive thin coatings are allowed to build up to create a robust dense layer on the surface of the tablet. The time taken to achieve this can range from a few minutes to several hours and is governed by the particular characteristics of the coating material, as well as the process parameters such as drum speed, temperature, pressure and spray rate. Above all these parameters must be carefully controlled for the whole length of the coating process. Disruption of spray rate, for example, will often produce defective tablets.
What are the two methods of coating tablets?
There are two principal methods of coating tablet: sugar coating and film coating . Both have advantages and disadvantages, and the following table provides a comparison between the two methods. The choice of which method is appropriate depends to an extent on how the tablets have been produced, the composition of the tablet and the intended market.
What is spray coating?
Spraying is the preferred method of coating tablets with film polymer. The Thomas Accela-Cota ® C and D-Series tablet coating machines is a leading series of machine for spray coating , and is representative of state-of-the-art technology. Available with several different drum sizes the machines are ideal for aqueous, solvent and sugar coating applications. The D Series offers all the advantages of the Accela-Cota ® fully perforated drum technology, including greater thermal efficiency and faster processing time. The D Series features a double wall construction which leads to better thermal efficiency, better sound absorption and ease of cleaning. The coating maxhine incorporates fluidized bed technology in which tablets are fluidized through the stream of air that enters the bottom of the cylinder. A small cylindrical insert helps the tablets to move upwards while being exposed to spray mist in the centre of the drum.
What does it mean when a polymer sticks together?
Once the solvents are removed, the polymers tend to stick together creating a 3D honeycomb look. Plasticizing techniques – internal and external are used to change the film quality and a combination of the plasticizers maybe required to achieve the desired appearance. The required concentration of plasticizer in the film formulation depends on the polymer that is being plasticized where the recommended level ranges from 1-50%, depending on the required mass of the film.
How to film coat a tablet?
Film coating starts, as for sugar coating, by enveloping the tablet’s core with a thin film of protective polymer. Traditional pans can be used for film coating, but recent innovations make use of more sophisticated equipment that provides a level of automation. These include rotating perforated drum machines and fluidized bed machines. The polymer that is to serve as the coating film is dissolved in a suitable solvent, together with additives such as pigments and plasticizers. Once these materials are mixed and homogenised the solution is then sprayed on the tablets. Finally the tablets are dried, which remove the excess solvent leaving behind a thin coating of the solvent around the core of the tablet.
What is the most commonly used colorant for film coating?
Most colourants used in film coating are available in solution or suspension form. To distribute a suspended colourant equally, the coating solution requires the use of powdered colourants. The most commonly used lakes and dyes are the certified FD, C and D/C colourants. For sugar or film coating, lakes are preferred because they produce more reproducible results.
What are the requirements for film coating?
These include the most appropriate means of atomizing the spray liquid during application, proper mixing and agitation of the tablet bed, and providing enough drying heat air to evaporate the solvent (especially for liquid-based sprays). Exhaust efficiency is also important to remove the solvent laden air and dust as well.
Why do we use sugar coating?
One purpose of the sugar coating is to protect the drug inside the tablet and act as barrier to external contaminants. It may also hide or mask the unsavoury taste of the drug that some patients may find unpalatable. Tablet coating is used to improve the tablet’s appearance and has the added benefit of providing pharmaceutical companies a surface on which to imprint information or branding. Sugar coating insulates and masks the colour and texture of the tablet’s core. It may also influence the release of the encased drug in the body.