Tablet and different methods for preparing tablet.
Tablet:
Pharmaceutical tablets are solid unit dosage form which are flat, biconvex discs.
Tablets generally prepared by compressing of drugs and mixtures of drugs with or without the use of diluents. Tablets are oral dosage form and they vary in different size and shape which is totally depend on the weight, type of medicinal substance and route of administration.
Properties of an ideal tablet:
- Tablet should have its own identity and should not have any defects like: cracking, chips, contamination, discoloration etc.
- Tablet should have both chemical and physical stability to maintain its form for a long time.
- There should not be any alteration occurs in the chemical and physical form of tablet.
- It should be stable at given parameters and it should be release the medicament at the right place.
Advantages of tablet:
- Tablets are easy to handle and use and easily taken by patient.
- The transportation and shipping of tablet is easy.
- By the use of coating, bitter drugs can easily administered to the patients.
- The tablet preparation cost and the final price of the tablet is lower if compare to other dosage forms.
- Tablet provide uniformity in administration of medicament to the patient.
Different methods of preparing tablets
There are three general methods of tablet preparation:
- Direct compression method
- Dry granulation method
- Wet granulation method
Direct compression method:
In this method the tablet is manufactured by direct compression.
When we prepare tablet, there is no changes occurs in physical nature of the material for the preparation of the tablets. Many substances like chlorides,bromides having cohesive properties so they are prepare by direct compression method.
Steps of process:
Milling of excipients and drugs
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Mixing of ingredients
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Tablet compression
Advantages:
- This process is simple.
- There is no need of granulation process.
- Absence of moisture and drying steps.
- Less material handling.
- The process is easy and not taking too much time.
Dry granulation method:
The dry granulation is also known as double compression, slugging, or recompression method. The dry granulation commonly used when preparation contains materials which are sensitive to moisture or they are unstable to withstand elevated temperature during drying.
Steps of process:
Milling of drugs and excipients.
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Milling of milled powder.
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Compression into large, hard tablets called slugs.
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Screening of slugs
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Mixing with lubricant and disintegrating agents.
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Tablet compression.
Wet granulation method:
The wet granulation method is an oldest and mostly used method for the tablet preparation.
Firstly a moist coherent mass is prepared by the mixing of powder and mixed tablet ingredients and converted into granules before compression into tablet.
There are some steps which are essential and involved during the preparation of tablet are: weighing, mixing, granulation, screening, the damp mass, drying, dry screening, lubrication and last one compression. This method is time consuming.
Steps of process:
Milling of drugs and excipients
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Mixing of milled powders
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Preparation of binder solution
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Mixing binder solution with powder mixture of form wet mass
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Coarse screening of wet mass using 6- to 12- mesh.
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Drying moist granules
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Screening dry granules
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Mixing screened granules with lubricant and disintegrant
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Tablet compression.
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