Coating Pan: The Ultimate Guide

Do you know a coating pan is a must-have accessory in the pharmaceutical and food industries?

Am sure, you have seen pills or even tablets that have been coated.

Whether to improve taste or change color, you need a reliable and high-quality coating pan.

That’s exactly what today’s guide focuses on. How do you find high quality, reliable, efficient coating pan?

It covers every aspect of a coating pan, from basic definition, benefits, techniques, validation, working principle, etc.

Keep reading to be an expert in this industry?

What is a Coating Pan?

Before we even discuss anything about a coating pan, it would be ideal first to understand what it entails.

So a coating pan merely refers to equipment that you use to form an aqueous or organic film around any type of tablet or pellets.

Coating pan

It is the device that is mostly used for coating tablets as well as other pharmaceutical products, and it is essential in numerous pharmacological applications.

The design of this equipment puts various factors into consideration in a bid of enhancing the overall efficiency of the coating process.

Some of these factors include temperature changes, pan volume, the angle of inclination as well as the rotational speed.

While at it, it is imperative also to understand that the use of this equipment requires your personal skill if at all you need to attain the best results.

A coating pan plays significant roles in making sure that you get the ideal results as far as coating your tablets is concerned.

Therefore let’s have a look at some of the reasons why it would be necessary to invest in this kind of equipment.

Benefits of Coating Pan

Listen, the truth is that the tablet coating of drugs is something that was once a key element in pharmaceutical production.

Even though, it seems like polymer film coating is superseding it one way or the other.

Nevertheless, it is still imperative to understand that there is a need for investing in this equipment.

Section of coated tablet

Some of the reasons for investing in this device include the following;

1) Helps significantly in masking the taste, color, and smell of the drug. This is important because it makes it possible for the drugs to easily sellable in the market.

2) Assists in protecting the drug from physical or chemical harm. You see, once you apply the coat on the drug, you seal it from any form of damage be it chemical or physical. Therefore, you probably increase its shelf days.

3) Enhances the general appearance of the tablet. You need to know that some of these drugs are sellable because they have an attractive appearance. Using this machine thus enables you to attain the same.

4) Allows you to incorporate ingredients of materials in the coating as a way of preventing any chemical incompatibility.

The best thing with this is that you’ll be able to determine the essential chemical ingredients to blend while processing the drug.

And in that regard, it becomes easy for you to ensure that you only blend chemically compatible ingredients.

5) This machine also helps in making sure that it protects the drug from disintegrating particularly when exposed to gastric fluids.

In general, therefore, you will realize that investing in this equipment is quite quintessential.

Many at times, you will benefit immensely from having and using it then it would be when you do not have it.

Most of the pharmaceutical production industries know the essence of having this machine and hence can never fail to have it.

For that reason, let’s now move a step further and look at different types of coating machines available on the market.

Types of Coating Pans

Well, if you’ve been keen enough or perhaps shopping for a coating pan, you ought to have realized that they come in different types.

What I’m trying to say here is that nowadays, the market is flooded with different types of tablet coating machines.

So in some instances, it becomes reasonably difficult to determine or choose the best one that suits your needs.

In this section, however, we want to look at the significant types of coating pans you’re likely to come across.

Coating machine

1. Standard Tablet Coating Pan

This is arguably one of the most common types of coating pans that you’ll always come across in the market.

It is at times known as conventional tablet coating pan and consists of a circular metallic pan with a diameter of between 6-80 inches.

You can always tilt this metallic pan on a bench top stand and also rotate it using an electric motor.

When dealing with a standard coating pan, you’ll need to load a batch of tablets into it and set it to rotate.

It is this rotating motion that makes the tablets to tumble within the pan.

The mounting of this coating pan is often at 40°, and it rotates on its horizontal axis by a powerful motor.

During the coating process, the heated air inside the pan is supplied by inlet air supply, and it exhausts using ducts.

The coating solution in a conventional tablet coating is applied to tablets either by lading or spraying.

Coating pan side view

Moreover, this type of coating machine uses the atomizing system to produce an equal distribution of coating solutions or suspension.

When using the standard coating pan, you can always achieve drying efficiency in several ways;

· An immersion sword

This is where the distribution of drying air takes place through a perforated metal sword immersed in the bed.

· Baffled pan and diffuser

This one enables the distribution of drying air evenly over the surface of the tablets.

· Immersion tube system

This involves immersing a tube in the bed where the tube produces heated air via the spray nozzle.

2. Perforated Tablet Coating Pan

This is yet another popular type of a coating pan that you are likely to come across when shopping for one.

It consists of a partial or full perforated drum which rotates on its horizontal axis.

At the same time, the entire system remains enclosed in a sealed housing.

Perforated coating pan

Some of the examples of perforated coating pans include the following;

· Accela-Cota

The system of this equipment allows the drying to be directed to the drum hence passing through the tablet bed.

The end is that it is released through the perforations in the drum.

In other words, the Accela-Cota pan is fully perforated and contains mixing blades.

The inlet air in this system is by a plenum in contact with the top of the pan.

· Driacoater

This one is more or less similar to the Accela-Cota.

This is in the sense that channels for directing the supply and exhaust air are integrated into drum wall.

At the same time, the introduction of reinforcing elements takes place through a hollow area is that inside the periphery of the drum.

The drum ordinarily rotates the dip during the drying process hence allowing dry air to pass through and fluidize the tablet bed.

· Glatt Coater

The design of this system utilizes fully perforated drums.

This feature is essential as it combines the maximum spray rates and short process times.

As air flows horizontally, it helps in minimizing the turbulence in the nozzle area hence contributing immensely to perfect coating result.

This machine is fully welded, and the mounting of the suspended drum is at the rear part and does not have any front support.

Essentially, these are the important types of tablet coating pans which you ought to know.

And the importance of knowing these is that it helps you in making good informed decision when it comes to acquiring one which suits your needs.

Nevertheless, let us now look at another equally essential aspect of coating pan, which is validation protocol.

Validation Protocol of a Coating Pan

You see, when dealing with tablet coating system, you need to understand that it also has other numerous elements, which you must know.

In this case, there is a need for knowing the validation protocol of a coating pan as a way of enhancing the efficiency and best results.

Validation protocol, in this case, refers to a plan describing the process which needs to be validated including production equipment and how the process occurs.

Tablet coating pan has three major elements of a validation protocol.

So let’s look at each of them briefly in this section before moving to another chapter.

a) Installation Qualification

This one is commonly abbreviated as IQ.

It is a major validation protocol which helps in establishing confidence the equipment is properly installed.

There are specific manufacturer’s guidelines that the installation process of the equipment has to meet.

Validation process

This is alongside the design challenges which often arise during the installation process of the machine.

IQ also requires that all the supporting electrical utilities must meet all the electrical codes appropriately.

IQ evaluation requires quite a number of information as a way of validating the process.

Some of these information include;

· Necessary documentation of the equipment

In this instance, you need to record the machine’s and manufacturer’s operation and maintenance manual and drawings in a, particularly given table.

The fields in the table include a number of the machine, a description as well as the date.

· Equipment identification

This merely requires recording of the equipment ID number in a table along with the following information;

• Serial number
• Model number
• Purchase order number
• Location of the equipment
• Company assigned number
• Component materials

· Equipment utility requirements

Here, you need to compare the manufacturer’s specified volts, amps as well as the compressed air pressure.

All these elements should be needed as found conditions at the time of qualification testing and once done; you should record the results in a table provided.

· Equipment safety features

Note down all the safety elements that the equipment features

· Lubricants

You need to note down the type of lubricant that the machine is using and indicate whether or not they make contact with the product.

· Major component specifications

The main components of a coating pan include;

• Coating pan motor
• Supply blower motor
• Exhaust blower motor
• Spray system

It is also vital to specify the material mode number, serial number as well as other utilities.

b) Operational qualification

This is the second aspect of validation protocol in a coating pan, commonly abbreviated as OQ.

Coating pan parameters

Ideally, an OQ needs to establish that the machine has specified limits and tolerances which it can operate within.

And in the long run, the validation is this equipment will be by its operating ability.

Some of the information that would be necessary for OQ evaluation include, calibration of the instruments utilized to control the pan.

In this instance, you need to verify that all the vital elements of the equipment are logged into the calibration systems.

At the same time, they need to have calibration procedures in place and are in calibration during qualification testing.

For that reason, you need to record all the information related to calibrated instruments used in controlling the pan.

Other information includes the control functions of the equipment and its operations such as pan speed, temperature, and spray system operation.

Talking of equipment control functions, the objective is usually to confirm that the push buttons can operate according to the manufacturer’s specifications.

You also need to know how to operate each different control that comes with the equipment and verify its appropriate operation.

c) Performance Qualification

Well, this is the third and final aspect surrounding the validation protocol of a tablet coating pan.

What happens, in this case, is that you need to establish that the machine is appropriately installed and functions within specific operating parameters.

Once you do that, it’s then your prerogative to show that the coating pan can operate reliably under routine, minimum as well as maximum operating conditions.

The essence of testing the coating pan operation is to establish its performance and its speed.

The procedure for this operation is usually straightforward, and all you need to do is ensure that you fill the pan with placebo and relevant spraying materials.

All the other aspects of performance qualifications need to be set and determined accordingly before presenting the final report.

As you can see, the validation protocol of the tablet coating pan equipment is vital from any perspective you would wish to look it from.

It is an ideal way of establishing the suitability of the machine which goes a long way to determine its efficiency.

Now let’s shift gears and look at some of the critical steps you’re likely to come across in the tablet coating process.

Step by Step Stages in Coating Process

Listen, this is one of the most fundamental details that you need to know as far as the coating of tablets is concerned.

There is always the need to understand the various aspects revolving around the coating process.

And for that matter, in this section, I want us to look at the key stages in this process to give you an idea of what it takes to finally have a coated tablet.

Coating process

Ordinarily, the coating process should involve the repetitive application of what you may refer to as sucrose- based solution in a coating pan.

The essence for this, of course, is to cover the tablet for various reasons as we did explain in the earlier sections of this guide.

So there is a sequence that this particular process often follows in a bid of attaining the best results.

For that reason, let’s have a look at these steps one by one;

· Sealing

Apparently, this is the first step in the tablet coating process.

It merely involves hardening of the tablet’s external surface by providing a moisture barrier.

In simple words, sealing majorly involves waterproofing of the tablet.

So while at it, you need to ensure that you seal and thoroughly dry the tablet before adding any component, be it syrup or sugar.

Tablet coating process

The essence of this is to enable the tablet to lose all the moisture or any residual solvents.

Now after doing this and attaining the appropriate dryness, you need to apply a sealing coat as a way of protecting the core from absorbing any moisture.

What happens is that the coating layer tends to harden the surface as a way of providing protection ideal in the ensuing process steps.

In most instances, you will find that the core of the tablet tends to be weak and has a high propensity for disintegration.

And for that reason, the chances are high that the core would likely be the first to crumble during the coating process.

When choosing the ideal sealant to use, you also need to figure out the porosity of the tablet.

It happens that highly porous tablets often soak up the sealant solution hence preventing the creation of a consistent coating over the entire tablet.

Additionally, you can as well add a second coat once the first one dries as a way of ensuring that sealing of the core is effective.

You can use a wide range of sealants available in the market only that you need to make sure that your choice is appropriate.

· Sub-Coating

Well, this is now where the actual tablet coating process often starts from.

In this stage, it happens that the sides of the tablets are shaped or rounded to the desired appearance.

It is also at this stage where smoothening of the tablets and the addition of the preferable color also takes place.

In sub-coating, there are two alternatives to choose from;

a) A gum based sealant or solution is coated on the tablet, and then drying takes place. In such a case, you’ll need to repeat this procedure until the moment you’ll attain the desired shape of the tablet.

b) Dry powder is applied followed by a sucrose solution. Once you apply these, the excess water or gum solution is removed by drying as a way of re-hardening the surface.

In an ideal world, sub-coating often involves alternating gum solution with dusting powder until you achieve the desired shape and consistency.

You will then remove excess water after every syrup application.

· Smoothing

In some instances, it is always referred to as grossing.

This steps apparently involves filling out and smoothing of the rough, irregular or inconsistent features of the tablet.

After every filling step, you will then smoothen the tablet by polishing and refinishing it as a way of attaining smooth and finished appearance.

This process also has a way of increasing the size of the tablet gradually which of course allows you to attain the required dimension.

If you realize that there are numerous irregularities of inconsistencies in the tablet you’re a coating, you may decide to use a grossing syrup.

Now, this type of syrup needs to have suspended solid particles which ideally can be useful in filling the voids in the tablet.

Steps in coating process

In other instances, you may also choose to add color during this grossing stage.

It is a better way of attaining or rather providing a homogenous coating layer.

· Coloring

Well, the truth of the matter is this is the most critical penultimate stage in the entire coating process of tablets.

It is the stage where different types and levels of solutions are added as a way of making sure that the tablets achieve a predetermined color.

Traditionally, most people have been using soluble dyes to provide the desired color given that they stick to the tablet’s surface during the drying process.

However, nowadays, numerous pharmaceutical manufacturers prefer using insoluble certified aluminum lake pigments.

So why are these pigments preferable?

Because they are crucial in tinting the tablets by dispersion.

As much as these pigments are produced from dyes, they are oil dispersible; hence you can mix them with oil and fats.

Possibly the most important aspect of this stage is that you need to ensure that you use colorants that comply with stipulated regulations of a particular country.

This will make it possible for you to market the products in that market without any hindrance.

· Polishing

Let’s get one point clear;

Coated tablets are naturally dull in appearance since they have a matte surface finish.

For that reason, you need to polish them as a way of making the tablets to attain a high level of gloss which exemplifies finished syrup coated drugs.

Polishing can be achieved in various ways including by applying a mixture of waxes as either powders or solutions to tablets in a coating pan.

The truth of the matter nonetheless is that the methods for achieving desirable goals often vary considerably.

For that reason, a proper recommendation is that you should tray the tablets overnight in a suitable atmosphere. This is to ensure that they are adequately dry.

And while at it, you also need to ensure that the tablets for polishing with zero levels of moisture.

You see, tablets with excessive moisture will make it difficult for you to attain the best gloss and also increase the risk of blooming and sweating of coated tablet on standing.

· Printing

Now, this is possibly the last step in the entire tablet coating process.

Of course, from time to time, you always see or come across tablets with the different product name, company logo or any other distinctive symbol.

Tablet coating process

Identification of coated tablets nonetheless involves the application of special edible inks to the surface of the coated tablet.

The means for printing this identification on a coated tablet is often known as offset rotogravure.

So what happens is that printing before polishing makes it possible for the edible ink to adhere strongly to the tablet surface.

That notwithstanding, you should also realize that the print may subsequently be removed either by friction or due to contact with organic solvents when polishing.

So in other words, printing after polishing is always recommended as it helps in eliminating issues to do with print rub-off during polishing.

The bottom line is that it is imperative to ensure that you provide a clear print which also resonates with the properties of the tablets.

So that is generally the step by step process for coating tablets using a coating pan.

As you can see, it is quite detailed and involving.

Therefore, you need to ensure that you get every bit of it appropriately.

It is what will enable you to attain the best results.

Moreover, you also need to be careful in all stages to prevent incidents of wastage and compromise of other elements of coating tablets.

Talking of compromising the coating process, in the next section, we want to look at the key challenges you’re likely to face and their possible solutions.

So let’s get straightway to this point and find out more.

Major Problems in Coating Process and Possible Solutions

You see, from the step by step process of tablet coating, it is quite inevitable for you to experience a wide range of problems before the final product.

In many instances, these problems are always easy to prevent.

However, there are those that may happen unknowingly regardless of the numerous interventions you put in place.

In this section, I want us to keenly look at some of the inevitable challenges you’re likely to encounter when coating tablets.

Additionally, we will also figure out the possible solutions for the challenges.

It is important since it will give you an idea of how to avert or deal with them.

So let’s look at these possible problems one by one;

· Chipping of the tablet

The cause for this problem often results from excessive use of insoluble pigments and fillers.

Incidentally, it is a common challenge that you’ll always encounter especially if you do not verify the types of pigments you’re using.

However, you can resolve this problem by adding small quantities of polymers to one or more of the numerous coating formulations.

· Cracking

It is also another common problem that you’re likely to encounter in the tablet coating process.

Usually, the tablet cores which tend to expand be it during or after coating are what causes the coating to crack.

In many cases, such expansions often arise from stress-relaxation of the core after compaction or as a result of the tablet core absorbing moisture.

An ideal way of dealing with this problem is simply by considering using seal coat.

Alternatively, you may also choose to extend the time between sugar coating and compaction.

· Marbling

This is the thing;

If you want to attain high quality coated tablets, you need to make sure that there is a uniform color distribution in the color area.

Also, you have to ensure that you attain a smooth coating surface by the time you finish applying the color coating before polishing.

The moment you fail to attain the necessary smoothness, chances are high that you there will be a marbled appearance on polishing.

The cause of this problem is ordinarily as a result of the collection of wax in the small surface depressions of a somewhat rough coating.

The suitable way of resolving this problem is by making sure that you attain a smooth surface at the end of the color coating.

· Twinning

Naturally, formulations you use for coating tablets are sticky especially when they start to dry and allowing adjacent tablets to stick together.

And when the buildup of multiples occurs, it becomes quite problematic particularly when the coated tablets have flat surfaces since they can easily come into contact with each other.

The challenge here could be with high dose, capsule-shaped tablets which have high edge walls.

The suitable choice for tablet punch design is what you can effectively use to reduce this particular problem.

In other words, you can choose to modify or alter the punch design.

· Uneven coloring

Well, one fundamental aspect that you ought to know is that the color coating stage of the tablet coating process has an ultimate impact on final tablet appearance.

Inconsistent distribution of color especially the dark ones is normally visually apparent hence the primary cause for batch rejection.

Several factors may lead to this kind of problem and include the following;

Design of coating pan

a) Excessive drying during color application

Mostly, this causes erosion of the color layer and also contributes to disproportion in the color coating.

The only way of correcting this problem is by reducing the rate of drying or better still by reducing the temperature.

b) Poor coating liquids distribution during application

Normally, this arises as a result of poor mixing of tablets during the coating process.

In some instances, it can be due to failure to add sufficient liquid to coat the surface of each tablet in the batch.

The suitable way to resolve this problem is by adequate coating liquid and making sure that it’s appropriately mixed.

c) Color migration due to under/faster drying

The ideal way of solving this problem is by making sure that you alter the solvent system or better still, optimize the drying condition.

d) The unevenness of the surface of sub-coat

Well, this commonly arises especially when you are using dye-colored coatings.

What often happens is that the unevenness tends to cause variation in thickness of transparent color layer perceived to have different color intensities.

The suitable way of dealing with the issue is to attain the desired smoothness during sub coat application.

· Blooming and sweating

It is also another major challenge that you are likely to encounter during the tablet coating process.

It is often as a result of the accumulation of a large quantity of residual moisture.

Over some time this moisture tends to diffuse out and ultimately affecting the overall quality of the product.

And moderate levels of moisture egress also tends to cause the polish of the product to have a fogged appearance, which is known as blooming.

The moisture may also appear as beads of sweat on the surface of the tablet at higher levels of moisture egress.

Sweating is also another serious problem in coating process given that the tablets stored in enclosed containers may eventually stick.

To avoid blooming and sweating, you need to ensure that you attain appropriate levels of moisture in tablet coating.

For that reason, you have to take great care at the drying stage and also thoroughly dry the tablets before polishing.

· Non-drying of the coating

It primarily refers to the inability of coatings formulations to dry appropriately.

This phenomenon is an indicator that the formulation you’re using has excessive levels of invert sucrose.

And the situation of inversion of sucrose even becomes worse when you try to maintain sucrose syrups at high levels of temperatures under acidic conditions.

The remedy for this problem is, of course, trying to avoid excessive heating of the sucrose syrup under acidic conditions for a prolonged period.

So ordinarily, these are the core challenges you’re likely to face when undertaking a tablet coating process.

Therefore, with all the possible solutions I have provided, you need to be able to counter such problems whenever you’re undertaking this process.

Factors to Consider when Buying a Coating Pan

Listen here carefully;

Buying a coating pan is not ideal as easy as you may think it is.

First of all, you need to acknowledge the fact that many manufacturers nowadays produce this equipment.

Coating pan specifications

And therefore, it becomes somewhat difficult for you to choose the best one that suits your needs ultimately.

The reason is that every manufacturer incorporates different properties and elements on the machines that they produce.

So you’re likely to get some variances from one machine to another.

In this section though, I want us to briefly look at some of those critical elements which you need to consider whenever you’re looking for or buying a coating pan.

1. Size

This is an important aspect by any consideration.

These machines come in different sizes.

Therefore, it would be ideal for ensuring that the choice you make suits your needs in terms of working space.

Most of the bigger coating pans are often for massive commercial production and are also quite pricey.

So at the end of the day depending on your needs and budget, ensure that you make the right choice as far as size is concerned.

2. Air capacity

It is also imperative to ensure that you look into the air capacity of the coating pan that you’re purchasing.

Remember that the amount of air which flows through the bed immensely determines the amount of solvent or water that you can eliminate during the coating process.

3. Speed

Speed in this instance is an important element of the coating machine.

However, you also need to note that speed varies depending on the actual stage in the coating process.

So the best thing is always to make sure that you find a coating pan which allows you to the moderate speed of various parameters in every relevant stage.

4. Conformity to GMP standards

In most instances, you’ll realize that most of these machines are regulated by a specific body which approves their suitability.

For that reason, you need to ensure that you carry out a proper background check to determine whether or not the coating pan you’re selecting conforms to the stipulated standards.

In most instances, GMP standards are usually set for such equipment.

5. Usability

Of course, when selecting a coating pan, you need to go for one that is easy to use.

The reason for this is that it makes it possible for you to enhance your efficiency when coating the tablets, which is quite fundamental.

6. Tech-oriented

With the ever advancing technology in almost all spheres of life, you have no excuse to purchase a coating machine that is not tech-oriented.

By tech-oriented here I mean equipment that incorporates different technological, operational aspects.

These are what will make it possible for you to increase the efficiency of different parameters in the coating process.

7. Serviceability

Lastly, you also need to ensure that the machine you are buying is easily serviceable.

And by this, I mean that it should be a unit which you can as well service the basic needs without essentially involving a technician.

On the same note, you should ensure that the parts and components of the machine are easily obtainable in case there is a need to replace.

Conclusion

As you can see, a coating pan is quite a fundamental unit in the pharmaceutical world.

Many pharmaceutical industries that understand the essence of this machine always ensure that they get the best for their needs.

For example, SaintyCo, a leading manufacturer of different machines offers the best coating pan in the market.

So if you are indeed in need of one, feel free to consider any of the SQY Series Sugar Coating Pan from SaintyCo.

Certainly, you’ll be sure of getting the best for your needs.

Otherwise, feel free to contact us in case of any inquiry, suggestion or purchase of this machine.

We will be glad to assist you in any way possible.