How Do You Prepare a Tablet Dosage?
The choice
of the tablet manufacturing process depends upon many factors, including the
compression property of that chemical substance, the particle size of the
chemical substance and excipients, and also the stability of the chemical
substance during the tablet manufacturing process.
In
the Manufacturing of Tablets many steps are
performed;
Step
1: The mixing of chemical or
therapeutic agents with the excipients.
Step
2: Methods of Granulation of
the mixed powder. (This method will not be performed during the direct
compression method.)
Step
3: Mixing granules or powders
with other excipients. (Lubricants)
Step
4: Compression into
tablets.
Method of Tablet Preparation:
For the
preparation of Tablet Dosage Forms, three Methods
of Tablet Compression are used.
1) Wet granulation method
2) Dry granulation method (slugging or roller compaction)
3) Direct compression method
1) Wet Granulation Method:
The wet granulation method is the most widely used method and one of the oldest methods used in the preparation of tablet dosage forms. In the method of wet granulation, the granulation will meet all the physical requirements for the compression of a good tablet. The main disadvantage of wet granulation methods is that this method has many separate steps involved, the process is very time-consuming, and labor is very important to carry out all these steps, especially in the case of the large-scale tablet manufacturing process in industries.
The
powdered and the active ingredients are sticking together to form a mass and
are then converted into granules before being compressed into tablets.
The
main and essential steps that have to be done during the preparation of tablets
or during the methods of granulation include weighing, mixing, granulation process, screening the damp mass, drying, dry
screening, lubrication, and finally the compression of the tablet.
The
process involved the blending and mixing of active ingredients, diluents, and
disintegrants.
The
mixed material is then sifted through a screen of suitable mesh to remove or
break the lumps.
The
sifted ingredients are transformed into a damp mass by mixing and adding to the
binder solution. The damp mass is forced through 6-8 mesh screens for
granulation.
In the
oven, wet granules are dried. The particles may form lumps, and for that reason, after drying, dry screening is required.
The
remaining quantity of lubricant and disintegrants is added to the dried
granules.
Finally,
the granules are compressed into tablets of desired shapes and sizes.
The
types of equipment that are involved in the wet granulation methods depend upon the size or quantity of the batch means how many tablets are
going to be prepared.
Advantages of Wet Granulation:
- This is a very useful method for the preparation of tablets that contain low contractions of chemical agents.
- Most of the tablet manufacturing industries are built for granulation manufacturing.
- The tablets prepared by wet granulation methods are accountable or responsible for post-processing unit operations like tablet coating methods.
Disadvantages of Wet Granulation:
- In the wet granulation process, solvents are required, due to which many concerns occur.
- In the presence of solvents (Ethanol, Isopropanol, Methyl chloride, and Water), drug degradation may occur. To minimize or overcome this, an alcoholic or hydroalcoholic granulation medium should be used.
- During the drying process, the drug may form precipitation or may crystallize due to solubility in the granulation fluid.
2) Dry Granulation Method:
The dry granulation method is also known as slugging, double compression, or roller compaction method. The manufacturing of tablets through this process is done when the ingredients used are sensitive to moisture, and also during the drying process can not withstand the temperature. Due to such conditions, the dry granulation method is used for the preparation of tablet dosage forms.
The
main steps that are used in the dry granulation methods are;
Weighing
— Mixing — Slugging — dry screening — lubrication — compression.
For the
formation of a cohesive slug, powdered binders such as acacia or
microcrystalline cellulose are added to the dry powder.
Generally,
lubricants are added to reduce powder sticking or adhesion to the punches and
to make easy ejection of an intact slug from the dies.
By compressing
powdered material with excipients, large slugs are obtained, which are then
passed through a mesh screen, breaking them into granules. The remaining
lubricants are added to the granulation by gently blending and finally
compressed into tablets.
In the
compaction method, the densified powder is passed through high-pressure rollers, which compress the powder and remove the air. The densified powder was reduced
to uniform granules. Now, lubricants are added and compressed into tablets. Due
to the excessive pressure to obtain cohesion of certain ingredients, a longer
dissolution rate may have occurred.
Advantages of Dry Granulation:
- The slugging and roller compaction require common excipient grades.
- In dry granulation methods, no solvents or heat are required.
Disadvantages of Dry Granulation:
- For granulation, through roller compaction, there are specialist types of equipment required.
- Segregation can be caused post-mixing, due to which powder flow issues may occur.
- The final tablets, which are prepared by the dry granulation method, become softer compared to the tablets prepared by the wet granulation method. Problems may occur during post-tableting techniques, for Example, film coating.
- There is a lot of dust that occurs during roller compaction and slugging, which causes a reduction in the tablet yield.
3) Direct Compression Method:
In the direct comparison method, the tablet is compressed directly from the powdered materials. As the pharmaceutical industry continuously works on increasing the efficacy of tableting operations and reducing the space occupied, as well as cost and labor, so much attention is given to these methods of tablet manufacturing.
A few substances like ammonium chloride, chlorides, bromide, iodides, chlorates,
nitrates, and permanganates, and salts of potassium, etc., have cohesive
properties as well as good flow properties, which is why these substances are
manufactured by direct compression methods.
In direct compression methods, the vehicles should also have good compressibility as well as flow properties.
Advantages of Direct Compression:
- The advantage of the direct compression method is that it is a very simple method because granulation steps are not performed in this method, and due to this, the method becomes more cost-effective as compared to the other methods.
- In the direct compression method, the use of water or solvents is not required, and heating is also not required, which is a very costly process.
- The process of lubrication is performed in the same vessel in which the powder mixing is performed, which minimizes the material transfer losses and also reduces the contamination of the types of equipment.
Disadvantages of Direct Compression:
- In the direct comparison method, expensive or specialized excipients are required.
- In this method, there may be powder flow issues arising in the tablet machine.
- The final tablets, which are prepared by the dry granulation method, become softer compared to the tablets prepared by the wet granulation method. Problems may occur during post-tableting techniques, for Example, film coating.
- In the direct compression method, the colorants are not used in the formulation because a mottled appearance can occur in the final dosage form.
Read More - Solid oral dosage forms (Tablet or Capsules)
Read More - What is tablet dosage form?
Read More - What are the excipients used in tablet manufacturing?
