Film Coating System

Film Coating System

Film Coating System/Tablet Coating Machine are designed for film coating and sugar coating of tablets. The main area of application is film coating both with water and organic solvents.

Film Coating System: The Ultimate FAQ Guide

What is Film Coating?

A film coating is a thin cover applied around a tablet to disguise the bad taste. The process of coating is through an analytical methodology that is not harmful to the coated drug users.

It also does not interfere with the drug’s pharmacological components.

Coated tablet

 Coated tablet

Why are Some Drugs Film Coated?

There are numerous benefits of film coating drugs. The initial sugar coating significantly increased the size of the tablets.

This increased both production and shipping cost to the manufacturers.

The following are some of the reasons why tablets are film-coated.

Film coated tablets

Film Coated Tablets

  • It doesn’t increase the size of the tablet since it is thin, causing a weight gain of just between 2-3%.
  • Film coat sprayed around the tablet is safe for human consumption.
  • The thin layer protects the tongue of the drug user from the flavor content of the medicine. It gives the tablet a better taste.
  • Tablets coated with the film are protected from moisture and light that may interfere with the efficacy of the drug.
  • It prevents the esophagus and stomach from irritation that may be caused by the drug.
  • Film coating helps drug inactivation in the stomach.
  • It improves drug effectiveness and also helps in prolonging the dosing interval.
  • By making the drug “friendlier and tastier,” this technology helps in improving patient compliance with the drug.
  • The coating prevents dust formation on the drug, increases drug stability, and gives the drugs long shelf life.
  • In the current technological market, it aids in improving the product identity. It enhances the drug appearance resulting in the acceptability of the product by its users.
  • Also, tablets coated with this film break down in agitation and a significant quantity of moisture from saliva or stomach acid. This promotes a relatively good drug absorption into the body.

What is the difference between Film Coated and Enteric Coated Tablets?

Film-coated drugs dissolve in an acidic condition in the stomach.

On the other hand, Enteric-coated drugs dissolve in the non-acidic condition in the small intestines.

That is, film-coated drugs are released in the stomach, whereas the enteric-coated ones are released in the intestines.

Film coating tablets don’t protect the stomach from the drug while the enteric coating does.

Also, the enteric-coated drugs protect the drug from the stomach acid.

It does this by keeping the tablet together until it reaches the intestines where it is released.

Film-coated drugs do not have this characteristic.

Also, it takes a relatively shorter time to do film coating as compared to enteric coating.

This is because films are thin and so they dry quickly.

Film coating materials are expensive in comparison to enteric coating materials.

This makes the film coating process less cost-effective.

Enteric-coated tablets dissolve after 120 minutes, whereas the film-coated ones dissolve after 30 to 60 minutes.

Are there Disadvantages of Film Coating?

 Film coating machine

Film coating machine

Yes. Just like many other technologies, there are some shortcomings.

It is relatively expensive in comparison to other coatings technologies.

This is because of expensive film material, high machine installation costs, and high energy consumption.

Setting up of film coating equipment requires a relatively large area of production, and this also increases the cost.

Also, coating using polymers results in changes in tablet smoothness, especially if the coating is uneven.

There has to be consistent monitoring of the film quality to ensure the thickness of the coat is uniform.

Apart from these, the coating can interfere with the pharmacodynamic properties of the drug formulation.

This may result in difficulty in swallowing the drug, change in color, and odor.

Some solvents are toxic and can become hazardous to the individual, formulating the solution for coating.

The film coating can sometimes cause defects like mottling, capping, chipping, and bridging.

What is Tablet Coating Made From?

Tablet coating can be made from different materials. For example, sugar coating is a sucrose solution.

The film coat is made from a mixture of polymers, plasticizers, colorants, solvent, opacifiers, and other miscellaneous additives.

Tablet coater machine

Tablet coater machine

  • The most commonly used polymer is acrylic. Meth-acrylic aster copolymer or Ethyl-cellulose can also be used to coat tablets that are intended to have their release modified.
  • Solvents used to make film solutions are ethanol, methanol, isopropanol, chloroform acetate, Methyl ethyl ketone, and methylene chloride.
  • Plasticizers include polyethylene glycol and propylene glycol. Colorants commonly used are synthetic lakes of dyes like FD & C colorant, D & C colorant.
  • Commonly used opacifiers are titanium dioxide, silicates, carbonates, sulfates, oxides, and hydroxides.

You can make the enteric coat from cellulose acetate phthalate, hydroxypropyl methylcellulose phthalate.

A compression coat is a polymer you can choose according to the release desired for the drug. For example, you can coat a tablet with polymers for extended, rapid, or controlled release.

Lastly, a gelatin coat is a gelatin layer.

How Many Types of Tablets Coating Are There?

There are many types of tablet coating.

These include sugar, film, enteric, compression, and gelatin tablet coating.

· Sugar-Coating

Sugar coating machine

Sugar coating machine

This type of coating was common in the past until its recent replacement and preference for film coating.

You can cover the tablet with sucrose-based coating formulations using an appropriate coating machine.

It is passed through hot air so that water can evaporate, leaving a thick sugar layer around individual tablets.

The tablet has a sweet taste because sugar has hidden the bitter taste.

This type of tablet coating is also suitable for drugs with unfriendly odor.

Sugar coats are usually shiny and colored, thus making them more appealing to young children.

It leaves the tablet smooth, rounded, and polished.

The process of sugar coating involves a series of stages with six different operations.

Some of the operations include:

i. Sealing of tablet core

ii. Smoothing

iii. Sub-coating

iv. Coloring

v. Polishing and printing

· Film-coated Tablets

 Film coating system

Film coating system

This is currently the most widely adopted coating method by many pharmaceutical companies.

It beautifies the tablet with different colors and aids in stabilizing it.

Also, it disguises the foul odor and unfriendly taste of the tablet.

Example of tablets that use film coating is herbal extracts or drugs with uneven color.

The process of film coating involves depositing film solutions via a sprayer on tablets.

This process is done once with a solution of polymer, plasticizers, solvent, and colorant.

Tablets are sprayed in a rotating tablet pan and immediately dried.

It results in a thin layer of polymer around a tablet after it has dried.

Sometimes the tablet can retain its color, but this can be changed if you mix the solution with different colorants.

The advantage of this coating method is that the entire process is short.

Therefore, many tablets you can coat within a short time.

Also, the coating process can easily be included in the dosage form.

However, there are some challenges in using this type of coating.

For instance, using organic solvents may have safety and environmental implications.

Film coating is also relatively expensive as compared to other types.

Film coating is available in two types: immediate and modifier release.

Materials used for film coating are non-enteric and enteric materials.

Non-enteric ones include hydroxypropyl methylcellulose and hydroxypropyl cellulose, while enteric ones include cellulose acetate, among others.

· Compression Coating

Compression coating

 Compression coating

This type of coating has been less popular, although industries have recently developed more interest in using it.

It is suitable for coating modifier release tablets using a dry process.

The process involves the compacting of granular materials around a tablet that has not been fully formed.

It is a useful process when you want to separate materials that are not chemically compatible.

Therefore, you can have one as a coating layer while the other as a core.

Compressing can be done more than once using a suitable machine.

It leaves the tablet with a good separation of an inner middle layer between the core and the coating.

· Enteric-coated Tablets

The technology is ideal for tablets that are absorbed in the small intestines but not in the stomach.

For example, drugs like Zantac and diclofenac sodium.

Enteric coat helps the tablets to pass through the stomach acid into the small intestines without being dissolved.

When the drug reaches the intestines, it is slowly released.

For this reason, enteric-coated drugs should not be crushed or chewed.

It is because they may result in stomach irritation, and this, together with acid, may damage the drug effect.

· Gelatin Coated Tablets

In this technology, you can coat tablets with a gelatin layer.

Normally, they acquire a capsule shape when compressed.

You can coat tablets with one or two colors, and you can print them if you like.

They have custom branding, counterfeiting can be prevented, and swallowing is much easy.

When you interfere with the tablets, it will be evident.

It also masks unpleasant smell and flavor, and aids in improving tablet stability.

This type of coating is relevant for double-blind clinical studies or tablets that can irritate the stomach when released immediately.

What are the Most Common Film Coating Systems?

There are three main film coating systems.

They include a perforated pan coating system, standard coating pan, and fluidized bed coating system.

Perforated Pan Coating System

The main parts of these coating systems are six.

These are inner air supply, exhaust, spray, perforated coating pan, air suck, and tablet bed.

Perforated Pan Coating system

The perforated pan coating system

Here, you can get either fully or partially perforated drum. Besides, the drum is always in an enclosed housing that will rotate in a horizontal axis.

Also, it has a spraying mechanism that applies the coating solution to the tablet’s bed.

The system drying air passes directly to the drum. For most perforated pan coating systems, you can configure the airflow.

This system has an efficient coating capability, and it dries the tablet bed more efficiently than other methods.

· Standard Coating Pan

Pan coating system

Pan coating system

They include:

  • Pellegrino pan
  • Immersion sword
  • Immersion tube systems

The system has Inner air supply, Exhaust, pan, liquid, atomizing air, spray nozzle, air suck, and tablet bed.

It has a metallic pan that has a diameter ranging between 15 and 200 cm.

This pan is inclined on a benchtop stand and can be rotated using a motor.

By switching the machine, tablets on the pan will begin to tumble

Once you atomize the system, you can spray the tablets with the coating solution.

As air distributes through the inbuilt perforated metal sword within the tablet coating bed, the drying process is more efficient.

Alternatively, when it comes to distributing air over the tablet surface, you can use a baffled pan.

Also, by immersing air tube in tablet bed, heated air can reach the tablet coating bed through the spray nozzle.

A standard coating pan is a continuous process that works with low drying time.

You can use it for either film coating or sugar coating.

This system facilitates coating tablets in a short time.

· Fluidized Bed Coating

Fluid bed coating system has an exhaust duct, coating chamber, and funnel-like modifier.

It also has a support screen, air atomizing nozzle, atomizing air supply, nozzle liquid feed, and fluidizing air supply.

The system has a chamber with a vertical cylinder.

You can achieve fluidization is by allowing air to flow from the bottom of the cylinder in an upward direction.

Spray nozzles for applying the coating solution are in both the top and bottom chambers.

The tablets placed at the chamber center move upwardly in the airflow.

They then fall outside the bottom of the chamber wall.

They are forced to re-enter the air stream from the bottom of the column.

The spray nozzle continuously applies the coating solution.

Fluidization uses high pressure airless and low-pressure atomizer system to produce a fine spray that results in uniform thin films.

What Are the Main Parts of the Film Coating System?

Parts of tablets coating machine

Parts of tablet coating machine

This system has six main parts. They include:

· Automatic Control System (PLC)

You can configure the accuracy, efficiency, and consistency of the system at this point.

It has an inbuilt programmable control system where all desired parameters are determined before running the coating process. It displays process data and can record and print the working state of the equipment.

· Electronic Motors

It generates power that is used to create negative pressure, blowing air, and mixing tablets.

You can have motors in the following key areas:

  • Peristaltic pump systems
  • Exhaust air system
  • Hot air equipment or,
  • Coating drum

All these will depend on the design of the film coating system.

In most cases, you can find more than three motors in one coating system.

· Touch Screen Operation Panel

It has a human-friendly enclosed system interface.

Also, it is the part where you do and read the configurations.

· Guide Plate

It gives directions for mixing tablets with the solution.

This part prevents the breakage of tablets during coating by preventing the possibility of adhesion of coating materials.

· Peristaltic Pump

It helps to simplify the sprayer, and in turn, stabilize atomization.

This results in thin-film coats over the tablets.

· Spraying System

It includes the tank, nozzle, and pump.

Besides, it has been made simple to facilitate ease in cleaning and maintenance of the spray gun.

This part helps in saving a coating solution and prevents plugging- up of spray gun.

Other parts include Inner air supply, Exhaust, tablet pan, atomizing air, air suck, and tablet bed.

How Does Film Coating System Work?

Usually, the more advanced the equipment is, the more automated and efficient it is.

A polymer is dissolved into a solvent, and other ingredients like plasticizers, colorant, opacifiers, and pigment are also added.

To operate the film coating system, you have to load the tablets continuously into the coating drum.

For uniform coating across the bed, accurately measure the spray gun and tablet bed distance, and make adjustments accordingly.

Parts of tablets coating machine

Parts of tablet coating machine

This system has six main parts.

They include:

· Automatic Control System (PLC)

You can configure the accuracy, efficiency, and consistency of the system at this point.

It has an inbuilt programmable control system where all desired parameters are determined before running the coating process.

It displays process data and can record and print the working state of the equipment.

· Electronic Motors

It generates power that is used to create negative pressure, blowing air, and mixing tablets.

You can have motors in the following key areas:

  • Peristaltic pump systems
  • Exhaust air system
  • Hot air equipment or,
  • Coating drum

All these will depend on the design of the film coating system.

In most cases, you can find more than three motors in one coating system.

· Touch Screen Operation Panel

It has a human-friendly enclosed system interface.

Also, it is the part where you do and read the configurations.

· Guide Plate

It gives directions for mixing tablets with the solution.

This part prevents the breakage of tablets during coating by preventing the possibility of adhesion of coating materials.

· Peristaltic Pump

It helps to simplify the sprayer, and in turn, stabilize atomization.

This results in thin-film coats over the tablets.

· Spraying System

It includes the tank, nozzle, and pump.

Besides, it has been made simple to facilitate ease in cleaning and maintenance of the spray gun.

This part helps in saving a coating solution and prevents plugging- up of spray gun.

Other parts include Inner air supply, Exhaust, tablet pan, atomizing air, air suck, and tablet bed.

How Does Film Coating System Work?

Usually, the more advanced the equipment is, the more automated and efficient it is.

A polymer is dissolved into a solvent, and other ingredients like plasticizers, colorants, opacifiers, and pigment are also added.

To operate the film coating system, you have to load the tablets continuously into the coating drum.

For uniform coating across the bed, accurately measure the spray gun and tablet bed distance, and make adjustments accordingly.

Pan coating

FPan coating – Photo courtesy: Slideshare

Normally, the coating solution can atomize to very fine droplets.

The sprayer will sprinkle the coating solution on the bed as it rotates with the materials or tablets.

Mostly, these machines have a multi-gun sprayer system.

The droplets of the solvent hit the tablet and spread into a film before hot air removes the vapor.

This happens in a single-stage process, thus maintaining a tablet weight increase of about 2-3%.

The tablets are then dried to remove the solvent, thereby producing a thin coating called film on each tablet.

When the whole process is slow, there may be a high degree of back-mixing, causing a variation in tablet coatings.

However, you can minimize this by operating short cycle batch coaters.

Alternatively, you can load or unload one coater while only one is in operation.

However, this will lower production capacity.

What Should You Consider when Importing Film Coating System?

Tablet pan coating machine

Tablet pan coating machine

There are many factors you should consider when you want to import this equipment.

The pan should have an adequate supply of process air that will facilitate the efficient drying of coated tablets.

The system should be able to maintain a narrow temperature range of between 30 to 70 degrees centigrade.

Also, with this machine, maintaining the dew point is easier – within a range of 10 to 20 degrees centigrade.

Both the pan and the spray system should be easy to clean and maintain.

You should ensure the spray system has few dead spaces to aid the dispersion of the solvent.

Make sure the spray system is automatic, and fan air can be controlled very easily, possibly from outside the pan.

If you intend to use flammable solvents, ensure the system has in-built explosion prevention.

Both inlet and exhaust air should conform to the cGMP and environmental regulations.

The pan must have sensors that will help in the monitoring of pan rotation, inlet air temperature, and inlet dew point. Sensors will also monitor:

i. Airflow rate from the fan

ii. Inlet airflow rate

iii. Spraying system of the film coating system

iv. Coating liquid spray rate

v. Temperature of coated tablets or products

What is the Difference Between Coated and Uncoated Tablets?

Tablets

 Tablets

 There are numerous differences between coated and uncoated tablets.

First, a coated tablet has a plastic-like material covering the tablet, whereas an uncoated one does not.

Also, most coated pills take a relatively long time in stomach acid to dissolve as compared to the uncoated ones.

For this reason, the uncoated drugs are released faster in the stomach and become active immediately.

You can realize the effect of the treatment quicker than using coated tablets.

Uncoated tablets like aspirin may cause stomach irritation, bleeding, and gastrointestinal ulcers.

It is therefore recommended to have it coated so that we can prevent it from being exposed to stomach acids.

Uncoated tablets are cost-effective as compared to the coated ones since coating increases the production cost.

This increase is as a result of additional technology involved, expertise, materials for coating, and time consumed during the coating process.

Coated tablets are not as smooth as the uncoated ones.

They may be difficult to swallow in comparison to the uncoated ones, especially when they have defects like orange peels.

The coated tablets are bigger since even the thin film coating adds a weight of between 2-3%.

The taste of uncoated tablets may not be pleasant, like the coated one.

The patient also has to bear with the unfriendly odor of the uncoated tablet.

On the other hand, coated tablets help to disguise both bad smell and taste.

Film Coating Formulations Contain Which Ingredients?

The formulation contains four main ingredients, namely: polymer, plasticizer, colorants, and solvent.

It also has other miscellaneous coating solution components.

Tablet coating chamber

Tablet coating chamber

i. Polymers

These are substances that have many repeated units with high molar masses.

You can form a chain by joining numerous monomer molecules that are subsequently joined together in a chemical reaction.

The polymer forms the major component in the film coating solution.

It possesses the following characteristics, qualifying it as a good material for film coating.

  • It can dissolve in various solvents.
  • For example, it has free water, slow water, and pH-dependent solubility characteristic.
  • Polymers are stable against light, heat, moisture, oxygen, and of course, the product you’re coating.
  • This coating material can form a continuous film with enough mechanism properties.
  • The ingredient is very much compatible with other additives for film coating besides tablets you want to coat.
  • It is non-toxic since it has no pharmacological activity.
  • It produces a good-looking product that gives it a better identification, preference, and acceptability in the current market.

Polymers used in film coating include cellulose, Vinyl polymer, Glycols, Acrylic acid polymers, and other carbohydrates.

ii. Plasticizers

These are low molecular weight coating ingredients added to polymers to modify their physical properties.

They help to weaken the attraction between polymer chains.

It also helps to facilitate pulling together polymer spheres of solvent dispersed when forming a film.

Normally, it is a reaction that increases the flexibility of the film.

Thereby reducing stress during film coating since it shrinks around tablets or material core when drying.

Plasticizers reduce the elastic modulus and tensile strength, thereby increasing film adhesion when coating under optimal conditions.

Also, the viscosity of the coating liquid increases with the weight of the plasticizer.

When the plasticizer is compatible with the polymer, the glass transition temperature of the film reduces.

Lastly, the physiochemical properties of the plasticizer influence the film permeability.

It may vary from one plasticizer to the other.

Plasticizers used in film coating include Polyols like glycerol, organic esters like diethyl phthalate and oils or glycerides like fractionated coconut oil.

Castro oil and distilled acetylated mono-glycerides are also other examples of plasticizers.

iii. Colorants

Colorants are pigments you can add during the film coating process to improve the appearance of tablets.

It also plays an important role in product differentiation in the market.

Also, they reduce the possibilities of counterfeiting tablets by improving the permeability of gas in the film.

In addition to these, colorant protects the tablet against light by increasing the opaque nature of the colors.

Colorants used in film coating formulations include water-soluble dyes, FD & C Lakes, and D&C lakes.

You can also use inorganic colors and natural colorants like the carmine lake.

Water-insoluble colorants are recommended in film coating formulations because they have better light stability.

They also give better opacity and provide a good barrier to moisture.

In addition to these, they are free from mottling.

The colorant reduces the tensile strength, increases the elastic modulus, and has minimal effect on the film adhesion.

The thickness of a coating liquid increases a little bit, and film permeability reduces unless you exceed pigment volume.

iv. Solvent

By dissolving tablet coating materials, they can easily pass them to the core of the tablets.

Solvents are the best because the coating process does not accommodate the use of water due to its poor drying ability.

Also, the achievement of adhesion with an aqueous system is unacceptable.

In addition to these, essential coating ingredients like polymers are insoluble in water.

Therefore, exposing them to water may make them unstable when you use them for tablet coating.

Solvents used in film coating include alcohol like Methanol and Ethanol and Ketones like acetone.

You can also use esters like ethyl acetate and ethyl lactate solvents.

In addition to these, you can choose chlorinated hydrocarbons like methylene chloride and chloroform as solvents.

Other Minor Coating Solution Components

These are materials added to the formulation in small concentrations.

They include flavors and sweeteners.

They are added to mask the unfriendly odor or taste of some tablets so that the tablet can be palatable.

They are also added to promote the mixing of water-insoluble plasticizers.

Miscellaneous coating solutions stabilize suspensions, improve tablet wetting, and enhance the spreading of the film during application.

Other additives may include preservatives like carbonates, adhesive enhancers like polydextrose, anti-foaming agents, antioxidants, pore-forming agents like sucrose, and waxes.

Remember, whatever solution you use for the coating process must conform to the pharmacopeia standards.

Where Do Enteric Coated Medicines Dissolve?

Film tablet coating chamber

FigFilm tablet coating chamber

Enteric-coated medicines dissolve in the small intestines.

When you swallow the enteric-coated tablet, the coating protects the drug from stomach acid so that it doesn’t break here.

Instead, it moves into the small intestines for dissolution.

The duration from the time it’s swallowed to the time it gets to the intestines is 6 hours on average.

It may range from 30 minutes to 7 hours, depending on the type of food taken by the patient.

The small intestines have a high pH of between 7 and 9, which facilitates the dissolution of the enteric-coated tablets.

Tablet active ingredients are made available for absorption into the bloodstream.

That is when you can realize the effects of drugs.

How Does Enteric Release Coating Compare to Sustained Release Coating?

Enteric release coated drugs have a coat that stomach acid cannot dissolve.

Instead, they are dissolved and released in the small intestines where the environment is not acidic.

Sustained/extended/controlled release coated drugs, on the other hand, are those that dissolve at a very low pace.

It can take place over a longer period. For this reason, you cannot take them frequently.

What is Immediate Release Film Coating for Tablets?

It is also called non-functional or conventional film coating.

The coating is meant to improve tablet appearance, identity, handling, and tablet stability.

However, it does not affect the biopharmaceutical dosage properties.

This film coating for tablets enables the dissolution in an aqueous environment like the stomach, once it comes into contact with moisture.

What is the Disintegration Time for Coated Tablets?

It is the time required to dissolve the coated tablets completely.

Coated tablets disintegrate at different times.

Enteric-coated tablets like aspirin can disintegrate after 7 to 11 minutes of its arrival in the small intestine.

Other enteric tablets with 0.1M hydrochloric acid usually disintegrate after 120 minutes.

Whereas enteric-coated tablets with mixed phosphate buffer under pH 6.8 disintegrate after 60 minutes.

Film-coated ones disintegrate after 30 minutes while sugar-coated tablets disintegrate after 60 minutes.

How Does Spray Nozzle Affect the Efficiency of Film Coating System?

Spraying nozzle for tablet coating machine

Spraying nozzle for tablet coating machine

The nozzle influences machine efficiency through its unique design.

It aids in the atomization of the coating liquid application area and air.

Also, this helps in the passing of fine droplets of the solvent to the tablet surface resulting in thin films.

The spray gun can have more than one nozzle.

Its unique design feature ensures the system sprays the coating solution on a larger area.

As a result, it will reduce tablet-coating time and cost.

In the long-run, it will guarantee the efficiency of the film coating system.

What are the Most Common Film Coating Problems?

Coated tablets can be evaluated visually to detect shortcomings.

Some of the defects are minor; however, some may compromise film coating quality.

Film tablet coating process

FFilm tablet coating – Photo courtesy: Science Direct

Some of the most common film coating problems are:

Picking: The film develops isolated areas when tablets stick together.

Roughness/Orange pill: The film surface becomes rough like an orange skin, causing difficulty in swallowing.

Bridging of the logo-The film pulls out of the monogram, resulting in the formation of a bridge across the mark edges.

Chipping: This is when the film becomes dented, particularly along the edges of the tablets.

Cracking of film coating: This defect causes the film to crack across the tablet crown.

Film flaking and peeling: The defect is visible when the tablet surface is exposed after the film peels off from the tablet edges.

Logo in-filling: The logo becomes distinct and eligible when you fill it with solidified foam.

Erosion of tablet surface: This is when the film-coated tablets exhibit a high degree of friability.

The surface becomes soft and less resistant.

Pitting of tablets-A pit is formed on the core surface.

Also, this happens without interfering with the film coating.

Breakage of the tablet: During the film coating, some tablets may end up breaking into two or many parts.

A color variation of tablets: Sometimes, there may be differences in colors of tablets coated with the same film at the same time and process.

The twinning of tablets: You can see this when two or more tablet cores stick together.

Discoloration of the tablets: There may be dark spots stuck to the coat.

For example, some of these are visible in multi-vitamin tablets.

Scuffing: You could find black or grey marks on white film-coated tablets.

How do you resolve Common Problems in Film Coating Systems?

You can minimize the problems during the film coating process by choosing a proper design and formulation of the tablet core and coating process.

Below are some of the remedies for these problems.

You can solve blistering by using a mild drying condition.

Also, make sure you have a moderate temperature at the cooling process.

You can reduce clipping when you adjust the plasticizers in the coating solution.

Alternatively, you can use polymers with high molecular weight.

Cracking is resolved by continually checking the drying process efficiency and optimize the drying conditions.

You can eliminate picking by increasing the drying efficiency through increased inlet air temperature.

Alternatively, increase solution viscosity or minimize the rate at which you apply the coating solution.

To resolve pitting, modify the inlet air temperature.

Besides, this will make sure the tablet core temperature doesn’t exceed the melting point of the batch additives.

Reducing concentration and increasing the molecular weight of plasticizers in the solution will help to resolve blooming.

To minimize color variation, ensure an even geometric mixing of tablets and the solution.

You can also reformulate with different plasticizers and additives.

For orange peels, use mild drying conditions.

You can also use additive solvents to reduce the viscosity of the polymer solutions so that the spraying rate can go down.

Reduce blushing by lowering the drying temperature so that there may be no precipitation of the polymers.

Do not use sorbitol with polymers like hydroxyl propyl cellulose, and hydroxyl methylcellulose.

To resolve to infill, add alcohol to the polymer solution to improve the dispersion of the solvent on the tablets.

Alternatively, you can use a spray nozzle that can form finer atomization.

What is the Aqueous Sugar Film Coating System?

 Coating system

 Coating system

It is a sugar film coating system that minimizes the coating time from days to hours.

It’s a safe way of coating tablets since it eliminates the use of toxic organic solvents and instead uses water.

This coating system produces colored coats that meet market demands.

It is also very ideal for areas where automatic equipment is not common.

Is Peristaltic Pump Best for Film Coating System?

Yes, it is.

It transfers solvent particles in a more precise way resulting in the formation of thin films around tablets.

You can control the spraying rate at the desired speed.

This pump is also ideal because you can use it with both toxic and non-toxic solvents.

The toxic ones are contained in the pump and not exposed to any form of contamination outside the pump.

This way, it also ensures the safety of the operator.

What is the Best Drying Mechanism for Film Coating System?

The best mechanism is to have a system that can be manipulated to increase the heat transfer coefficient.

This will help to quicken the drying process.

When it comes to drying aqueous film coated tablets, inlet air temperature, which is relatively high will increase efficiency.

Are there Benefits of Clean-in-place (CIP) for Film Coating Systems?

CIP reduces any human errors by automatically cleaning the equipment, leading to better tablet safety.

CIP also minimizes contamination through the use of monitoring sensors.

Clean-in-place also helps to minimize employee exposure to the toxic solvents since they don’t have to enter the tanks.

It offers a cost-effective cleaning process, particularly on cleaning chemicals which you need to clean repeatedly.

What are the Process Requirements for Film Coating Systems?

Every coating process is only successful if evenly applied.

A good coating should be heavy, with no cracks or mechanical damages.

There are four major process requirements for film coating systems.

 Pan coating system fro tablet

Pan coating system for tablet

An Adequate Spray Atomizing Means

The spray should be atomized to enable the application to the tablet core.

This is a very critical process requirement because it affects the level of moisture present during the film coating process.

Besides, it will also determine the uniformity and quality of the coating film.

Spraying should be done within a recommended rate for it to yield desired results.

Also, when the rate of the spraying coating liquid is low, it can result in inadequate wetting.

Again, when you spray the coating liquid at relatively higher rates, it may result in over-wetting.

Consequently, it may cause picking and stacking defects.

When the spraying air pressure increases, coated tablet surface roughness decreases, leading to the formation of dense and thin films.

Excess spraying air pressure leads to the formation of very fine droplets.

Consequently, it can make a solution not to spread adequately and possible coalescence.

Of course, there will be no sufficient coating solution reaching the tablet bed.

When the pressure in the spraying air is inadequate, it may result in the differentiation of film thickness.

It can be due to a change in:

  • Film density
  • Small spray loss

On the other hand, when the spraying air pressure is low, it can result in larger drops that will over-wet your table surface.

Consequently, tablets will start sticking together.

The tablets that have not undergone wetting are recycled back for spraying.

At the same time, we tablets move to the drying chamber.

Enough Mixing and Agitation of the Tablets

Increased speed of rotating tablet pan promotes proper mixing of tablets.

The speed at which a coating pan rotates will determine the time tablets will be in the spraying zone.

This will affect the uniformity of the coating solution in each tablet batch during the film coating process.

High speed will minimize any variations in the coating film thickness.

At the same time, it increases uniformity.

However, too much rotation can cause tablet attrition that can lead to breakage.

Enough Energy Input in Heated Air Form

It will affect the efficiency of the frying pan and uniformity. It helps to facilitate water/solvent evaporation leading to film formation around the tablet.

To increase tablet drying efficiency, increase the temperature of the inlet air.

It will reduce the degree at which water penetrates the tablet core making drugs less porous.

Besides, it will increase:

  • The residual moisture content of tablets
  • Tensile strength of moisture

Too much air temperature causes pre-mature spray drying, hence reducing coating efficiency.

As a recommendation, you should measure the pan air temperature to maintain the optimum conditions during the coating process.

This will also help in predicting drying and over wetting faults that may be evident in poor film appearance.

A Good Exhaust Facility

It is necessary for removing dust and solvent laden air.

This will help in keeping the equipment clean and prevent some defaults of the machine.

Which Drugs are Suitable for Film Coating?

Numerous drugs can be film-coated. Examples include Valsartan 320mg, Ranitidine 300mg, Ondansetron 8mg, Zinc 30mg, Ibuprofen 200mg, Atenolol 100mg, and Accord Clarithromycin 500mg among others.

Aqueous Film Coating vs. Solvent Film Coating; how do they compare?

In aqueous film coating, we use water. On the other hand, a solvent film coating relies on organic solvents like methanol.

Aqueous film-coating does not require the formulator to follow safety protocol since it is not toxic.

On the contrary, you should adhere to the safety protocol for film coatingfor each specific solvent.

Aqueous film-coating takes long to dry and, therefore, requires more air drying than organic solvents.

There is a possibility of aqueous coating developing mechanical problems because it takes a relatively long time to dry up.

This is not so with solvent coating since the tablets tumble for a short time in the machine.

The solvent coating requires a modification of the system and the production area to get enough ventilation for the solvent.

This is not necessary for the aqueous coating.

Because the solvent is toxic, it can affect the smell and taste of the tablet.

Aqueous coating is friendly to the tablet.

Frequent alteration of the machine is advisable for solvent film coating.

However, for aqueous coating, the equipment can be used over and over.

When using a solvent to film-coat tablets, the industry must be responsible for the disposal of waste solvents into the environment.

With aqueous coating, it is non-toxic; thus, there are no such responsibilities.

What are the Recommended Film Coating System Quality Standards?

The coating machine must have the following global quality standards for you to be sure it can function efficiently:

  • It has to be FDA licensed.
  • The system should be GMP certified.
  • It should also have ISO 9001: 2000 certification.
  • Halal and Kosher certification is also a requirement.