Manufacturing of tablets covered by shell

The general purpose of covering tablets with

shells 1. to protect tablets from environment;2. to protect tablets from extreme agents (impact, abrasion);3. to mask unpleasant taste and odor of medicinal ingredients;4. to protect from coloring;5. to protect medicinal ingredients from acid of gastric juice;6. to protect mucous membranes of mouth, esophagus and

stomach from irritating action of medicinal ingredients;7. to localize therapeutic action of medicinal ingredients in

specific part of gastrointestinal tract;8. to prevent neutralization of gastric juice with medicinal

ingredients-alkalis;9. to prolong therapeutic action of medicinal substances in

tablets;10. to correct incompatibility of different substances in one tablet

by introduction them into nucleus and shell;11. to make better appearance of tablets and comfort of their

use.

Auxiliary substances are used for covering tablets with shells:

1. Binders – provide sticking of nucleus and shell materials (Sugar syrup, Polyvinylpyrrolidone, Methyl Cellulose, Carboxymethyl Cellulose, Ethyl Cellulose, etc.);

2. Structural substances – form frameworks (Sugar, Magnesium Oxide, Calcium Oxide, Talc, Magnesium Carbonate);

3. Plasticizers – provide plasticity of shells (Vegetable oils, Polyvinylpyrrolidone, serge-like fabric);

4. Water repellants – provide moisture resistance of shells (Aerosil (silica powder), Shellac, Polyacrylic resins);

5. Colouring matters – make better appearance of tablets or designate therapeutic group of substances (Tropeolin, Tartrazine, Indigo Carmine);

6. Correcting matters – they give pleasant taste to shells (Sugar, Cacao, Vanillin, Citric Acid).

Classification of the shells:according by composition and method of

obtaining:

1. Pressed (dry) shells

2. Film shells

3. Shells-dragee (sugar shell)

Pressed (dry) shells:Produce by the tablet machines. Each

machine has two rotors. 1. With first rotor nucleuses (cores) of tablets,

which have form of the double convex, are compressed.

2. Nucleuses pass on the second rotor for covering. At first die has a part of granules, necessary to obtain low part of the shell. Nucleus of tablet is covered with it.

3. Then second part of granules pass to die and tablet covers with top part of the shell.

Rotary tableting machine Dricotta

Disadvantages of the method

1. A lot of covering materials are necessary;

2. Increase of weight and size of the tablet;

3. Non-uniformity of thickness of tablets shell;

4. High porosity of shells, which contributes to absorb water from the air;

5. Difficulties of reprocessing of defective products;

6. Disorder of nucleus (cores) centering.

Advantages of the method:

1. This method does not demand any solvents and it makes possible the obtaining of tablets from unstable substances (tablets with antibiotics).

2. Prolongation of effect of acting substance (substance may to induct both into a core, and in a covering sphere).

3. Overcoming of incompatibility of the various substances in the one tablet ( one in the shell another in the - tablet-core.

Shells-dragee (sugar shell)

A basic purpose of a covering:

1.To protect of tablets against external influents

2. To mask of unpleasant taste and odor of the medicinal substance

3. To make better of the tablets appearance.

Factors which influence on the quality of the tablets shells.

1. The coppers form

2. Size of loading

3. Speed of the moving pan

4. Angle a copper inclination to a horizontal

5. Square of a surface of tablets which are covered by a shell

Dragee pans (boiler)

Stages of the covering shells-dragee on the tablets:

Enveloping or a first coat

The layers

Smoothing or polishing

Glossing

Enveloping or a first coat

1. Tablets are wetted by sugar syrup and sprinkle with wheat flour or a mix of a flour and a magnesium carbonate.

2.Tablets are twirled for 25-30 minutes

3. Tablets are dried by warm air (40-50 C) for 30-40 minutes.

These operations (wetting of the tablets, free rotation and drying) repeat 2-3 times.

The layers

At this stage the formation of shell occurs.

1. On the wetted tablets a sugar syrup and sprinkle with a magnesium a carbonate are loaded.

2. The tablets freely twirled for 30-40 minutes.

3.Tablets are dried by warm air for 20-30 minutes.

Smoothing or polishingThis stage carry out with

using a sugar syrup to which a gelatine and colouring agents are added in the small amount (to 1 %).

At this stage there is a removal of roughness from a shell surface on tablets.

Glossing – giving to lustre tablets and good appearance

Carry out in two ways:The first way:mastic for glossing is prepared :• Wax beer - 45 parts• Oil Vaseline - 45• Talc – 10Mastic for glossing is putted on the twirled warm tablets and

give free rotation of the tablets for 30-40 minutes.Then tablets sprinkle with a small amount of talc for

acceleration of reception of lustre.The second way: The polished tablets are placed in the special copper walls of

which are covered by wax.

Disadvantages of the method

1. Possibility of covering cracking

2. Non-uniform surface

3. Long technological process

Film-covering tablets is the thin shell, which is formed on a tablet after drying

of a solution from the film-forming material putted on its surface.

Advantages of film coverings1. Slightly increase weight of the tablets.

2. The long stage of drying of shells (due the application of the flying organic solvent).

3. Possibility of the granules or corpuscles coverings by a pulverous material.

Advantages of film covering

The Fluidized - bed coating provides better coating uniformity due to good solid – fluid mixing and minimize formation of agglomerates.

Classification of Film shells:

according by solubility of shells:

1. Water-soluble shells

2. Shells, which dissolve with gastric juice

3. Shells, which dissolve in intestines

4. Insoluble shells

The general purpose of Water-soluble coverings

1. To improve appearance of the tablets 2. To correct their taste and odour 3. To protect from mechanical injuries For water-soluble coverings Polyethilenoxyd

and Polyvinylpyrrolidon are putted on tablets in the form of 20-30 % of solutions in 50-90 % ethyl or isopropyl alcohol, Methyl Cellulose and the sodium salt Carboxy Methyl Cellulose – in the form of 4-7 % of aqueous solutions are used.

The main purpose of Covering, soluble in a stomach

is protecting of tablets from acting of air moisture. They are destroyed in an organism for 10-30 minutes.

Their composition includes sucrose, glucose, fructose and gelatine.

Intestinally-soluble coverings.• Protect the medicinal substance contained in a

tablet, from act of sour reaction of gastric juice and a moisture. They localise medicinal substance in intestines, prolong in certain cause its act.

• It is stand affecting of gastric juice (2-4 hours and more). In intestinal juice disintegrate for 1 hour.

• In the capacity of film-forming is used high-molecular substances, and also natural substances (shellac, carnauba wax, casein, cerathyn, paraffin, ceresin) for reception of intestinally-soluble coverings. More often for reception of intestinally-soluble coverings Acetyl Ftalil Cellulose is used in the form of solutions of ethyl, isopropyl alcohol.

The general purpose of Insoluble covering:

1. To protect tablets against a mechanical injury and against affecting of an atmospheric moisture.

2. To eliminate the unpleasant odour and taste of medicinal substance

3. To prolong of act of medicinal substance.

To gain insoluble coverings Ethyl Cellulose, surface activity substances are used.

There are two way of releasing of medicinal substance through insoluble

covering.

Peptic juice penetrates into a tablet through micro pores of a shell and causes of dissolution of the tablet contents, or its swelling by a gastroenteric section. Then:

1. The first way: solutions diffuse through a film in the opposite direction – towards a gastroenteric section under the influence of a differences of concentration.

2. The second way: there is a shell rupture due the increasing of the tablets volume.

Requirements to film-forming materials:

1. Full harmlessness for an organism.

2. Good solubility in widely accessible organic solvents.

3. Good film-forming properties.

4. Chemical indifference.

5. Stability at long storage.

6. Accessibility.

Ways of covering tablets by the film shell

1. The immersing tablets in the solution of a film-forming material.

2. The layers in the dragee pan.

3. Fluidized-Bed Covering.

The immersing tablets in the solution of a film-forming material

The way is based on immersing of tablets by one sides in the covering solution.

Tablets are fixed by means of vacuum on a metal grit of the special machine.

This way is enough combined and is used only for covering of tablets by viscous, but not too sticky solutions.

The layers in the dragee pan

1. The tablets are tumbled in a pan which is rotated at an angle of usually 45 ° to the horizontal surface at a speed between 20 and 50 rpm.

2. Covering fluid is sprayed onto the tablets from a nozzles .

3. The hot air dries the film coating. Pan covering is generally preferred to coat large

tablets since they are exposed to mechanical damage in other covering operations.

The uniformity of the covering applied to the tablets and defects on the covering are important issues from a practical point of view.

Machine for pan covering

HMP 300

Fluidized- Bed Covering

The basic principle of fluidized - bed coating is to suspend tablets in a moving hot - air stream in the upward direction during the coating process.

The coating material is sprayed through a nozzle from the top, the side, or the bottom into the fluidized bed.

The solvent in the solution is removed from the coating by the hot - air stream, which also carries the coated tablets.

Equipment for Fluidized-Bed Covering

Advantages of Fluidized- Bed Covering

Fluidized - bed coating provides:

• better coating uniformity due to good solid – fluid mixing

• minimizes formation of agglomerates.

Technological process of manufacturing of tablets with slurry method of a coating

1. AS (Auxiliary stage) 1.1. Preparatory works1.2. Grinding.1.3. Sifting.1.4. Obtaining of humidifier.

2. TP (Technological process) Obtaining of tableting mass3. TP (Technological process) Compressing (Tableting)4. TP (Technological process) Covering of tablets with shell

4.1. Obtaining of colorless suspension.4.2. Obtaining of colored suspension.4.3. Applying of colorless suspension.4.4. Applying of colored suspension.4.5. Obtaining of glossy compound.4.6. Applying of glossy compound.

Slurry method of a coating

Composition of shell (100 g.):

1. Sugar 55,25

2. Purified Water 23,80

3. Polyvinylpyrrolidone 0,75

4. Aerosil 1,00

5. Magnesium Hydrocarbonate 16,30

6. Titanium Dioxide (coloring matter) 2,90

Mean mass – 100,0.

Composition of glossy compound

1. White wax – 45,0

2. Vaseline oil – 45,0

3. Talc – 10,0

Mean mass – 100,0 %

Advantages of slurry method of a coating

1. The new production engineering improved quality of the tablets covered with shells:

2. decrease their average weight

3. stability rose.

Melt/Dry Coating

The principal stages in the film formation during dry coating are:

1. softening,

2. melting,

3. Curing/

Advantages of Melt/Dry Coating

1. Both hot - melt and dry coating techniques eliminate the use of solvents;

2. as a result the processing times become much shorter;

3. the cost of the process is reduced;4. Melt coating is possible for coating

materials that have a low melting temperature and acceptable thermostability.

Disadvantages of Melt/Dry Coating

The process requires larger amount of plasticizer to partially soften and dissolve the polymer.