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Different Coatings Details

Tablets can either be ‘sugar coated’, ‘film coated’, ‘enteric coated’ or coated to modify how the drug is released into the body (modified release). Each of these coatings are there for different reasons and it is important to understand these reasons before deciding whether it is safe or appropriate to crush tablets.

This page explains why the coat may be on the tablet and what it means if you choose to crush or place the tablet in water to dissolve before swallowing.

Film and sugar coating

A sugar coating is basically is a thick, hard coating of sugar surrounding the tablet. It is no different in design to the sugar coatings placed on Smarties® or Minstrels ®. This is a traditional method used to hide the flavour of particularly unpleasant tasting drugs e.g. ibuprofen and quinine, both of which are very bitter. The other advantage of a sugar coating is that it can prevent light or moisture from entering the tablet, which causes the drug to break down too quickly.

Due to the increase in tablet size caused by sugar coating, drug manufacturers have largely changed to using ‘film coatings’. These are very thin layers of a safe ingredient placed around the tablet to again protect the tongue from the flavour of the contents and protect the contents from moisture and light. The film will break down with agitation and significant amounts of moisture (saliva or stomach acid) and therefore does not significantly affect the way in which the drug is absorbed into the body.

Crushing these tablets therefore may not seriously effect how the drug is released but may cause the resultant mixture to be unpleasant to taste.

Enteric coating

If a tablet is described as having an ‘enteric coating’ (e/c) or ‘gastro-resistant’, it means that there is a coating which is designed to hold the tablet together when in the stomach. This clever science relies on the fact that the stomach is acid and the intestines, where food goes after the stomach, are not. The coating is designed to hold together in acid conditions and break down in non-acid conditions and therefore release the drug in the intestines.

There are three reasons for putting such a coating on a tablet or capsule ingredient:

To protect the stomach from the drug

To protect the drug from the stomach

To release the drug after the stomach e.g. in the intestines

The drugs which most commonly cause stomach ulcers like aspirin, diclofenac and naproxen are frequently available with enteric coatings. Omeprazole, which is a drug which stops the stomach from producing acid, is itself broken down in acid and therefore the drug generally has an enteric coating around it either as a granule in the capsules or as a granule in the dispersible form. Sulfasalazine is used either for the treatment of arthritis or for the treatment of Crohn’s disease which is inflammation of the intestines. When used for arthritis, it is very often given without an enteric coating so that it can be absorbed more quickly. For Crohn’s, it is needed to work in the intestines so it is given an enteric coating.

It can be seen that an enteric coating has advantages and therefore such tablets or the contents of enteric coated capsules should never be crushed before being taken.

Modified release

‘Modified release’ means that the escape of the drug from the tablet has been modified in some way. Usually this is to slow the release of the drug so that the medicine does not have to be taken too often and therefore makes it easier to remember to take. The other benefit from modifying release is that the concentration of the drug in the body goes up slowly, is less likely to go very high and therefore reduces the chance of side effects.

Tablets and capsules which are designed to provide modified release often have the letters MR, LA, XL, CR or SR in their names e.g. Diffundox MR, Elantan LA, Dilzem XL Calcicard CR, Dilcardia S. Sometimes the words ‘slow’ or ‘retard’ can be used to denote modified release e.g. Diclomax retard, Voltarol retard & Slow K.

There are a number of ways in which a medicine can have its release modified. Perhaps the most famous is that used in Contac 400 capsules. The pellets inside are of different thicknesses and therefore the thinnest release the drug first and the thickest last (Figure 1). Find out best cvd coatings by clicking on cvd supplier.

Vacuum Deposition and Magnetron Sputtering

In the process of vacuum deposition, a group of processes takes place. It is used for depositing the layers of the material atom-by-atom or molecule-by-molecule on a solid surface. The definition is in accordance with the giant Wikipedia.

The pressure in the process is used below the atmospheric pressure and that is therefore, vacuum. Multiple layers of unlike materials can be used, for example to create optical coatings.

Some of the very popular and well-known things about the process are:

• This is used for the purpose of reducing the particle density and this makes sure that the mean free path for collision is long.

• This will also help in the reduction of the particle density of undesirable atoms and molecules.

• This will make sure about a low pressure plasma environment.

• It will provide a medium for controlling the gas and vapor composition.

• With the process of vacuum deposition Mass flow control into the processing chamber is also controlled.

Condensing particles can be produced in a number of manners and they are:

• Thermal evaporation, Evaporation

• Sputtering

• Cathodic arc vaporization

• laser ablation

• Chemical vapor deposition

There are a number of advantages that are associated with this process and some of them are really very useful for many of our needs. Here is a list of a few but very important advantages of this process and they are:

• With the process of vacuum deposition from the high-purity source material all the High-purity films will be deposited.

• This process is considered to be the least expensive PVD process today.

• If you go for conducting the process then Deposition rate monitoring and control are very easy to manage.

• The source of material, which is to be vaporized, may be a solid in any form and purity.

Magnetron Sputtering Technology

This is another popular and very good form of the PVD coating technology today. This is considered to be a very highly developed process which is employed for the coating of any product with high quality. You can easily categorize this method as one of the most followed in all over the world. Another very popular thing about this process is the higher level of adhesion which is very much capable of providing quality results on various objects. This is one of the most trusted methods and almost any kind of product may it be a compound, element, solid objects or alloy can be easily coated with this process.

Magnetron sputtering technology is also the most flexible and a highly practiced method in the coating industry today. It is capable of offering a number of advantages to the users. There are a number of things that are not familiar to the users but this process continues to help in the development of highly quality products with the best coating services. Some of the very popular characteristics of the technology are:

• A very little radiation heat is generated.

• Almost any martial can be sputtered.

• Non-conductive materials can be sputtered by using radio frequency.

• Excellent layer uniformity is achieved.

• Very smooth sputtered coatings can be done.

• Oxide coatings can be sputtered.

Advances In Transferring Chemical Vapor Deposition

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