Solid dosage forms such as tablets, granules, capsules, and powders represent the most widely used pharmaceutical preparations because of their stability, convenience, accurate dosing, and patient acceptability. Their manufacturing requires scientific formulation design, selection of suitable excipients, advanced machinery, and strict adherence to Good Manufacturing Practices (GMP). In hospital and industrial settings, pharmacists play a vital role in ensuring that these products meet quality, safety, and performance standards.
Manufacture of Tablets
Tablets are solid unit dosage forms prepared by compressing a mixture of active ingredients and excipients. They come in various types—chewable, effervescent, coated, sustained-release, dispersible, and sublingual tablets.
Excipients Used in Tablets
- Binders: PVP, starch paste, gelatin.
- Diluents: Lactose, microcrystalline cellulose.
- Disintegrants: Sodium starch glycolate, croscarmellose sodium.
- Lubricants: Magnesium stearate, talc.
- Glidants: Colloidal silica.
- Coloring and flavoring agents when required.
Tablet Manufacturing Methods
1. Wet Granulation
- Active ingredient mixed with diluents.
- Binder solution added to form a wet mass.
- Wet mass passed through a sieve to form granules.
- Granules dried and lubricated.
- Compressed into tablets.
2. Dry Granulation
- Used for moisture-sensitive or heat-sensitive drugs.
- Powder compacted using slugging or roller compaction.
- Compacts milled into granules and compressed.
3. Direct Compression
- Powers blended with excipients.
- Directly compressed without granulation.
- Suitable for free-flowing materials.
Tablet Coating
- Sugar coating: Improves taste and appearance.
- Film coating: Thin polymer film for protection.
- Enteric coating: Prevents dissolution in stomach acid.
Quality Control Tests for Tablets
- Uniformity of weight
- Hardness test
- Friability test
- Disintegration time
- Dissolution testing
- Assay of active ingredient
Manufacture of Granules
Granules are aggregates of powder particles used for improved flowability and compressibility. They are also used for effervescent formulations and reconstitutable suspensions.
Methods of Granule Preparation
1. Wet Granulation
The most common method—powders mixed, wetted with binder, granulated, dried, and sized.
2. Dry Granulation
Suitable for moisture-sensitive drugs; compaction followed by milling.
3. Effervescent Granulation
- Combination of acids (citric/tartaric acid) and carbonates.
- Produces effervescence when dissolved.
Quality Control for Granules
- Flow properties
- Moisture content
- Particle size distribution
- Assay of drug content
Manufacture of Capsules
Capsules are solid dosage forms in which the drug is enclosed within a gelatin or polymer shell.
Types of Capsules
- Hard gelatin capsules: Used for powders and granules.
- Soft gelatin capsules: Used for oils and semi-solids.
Steps in Capsule Manufacturing
1. Formulation of Fill Material
- Blending of powders or preparation of semi-solid.
2. Capsule Shell Preparation
Industrial process using stainless steel pins dipped into gelatin solution.
3. Filling
- Hard capsules filled using manual or automatic machines.
- Soft capsules filled during formation.
4. Sealing
- Band sealing or heat sealing for soft capsules.
5. Polishing and Packaging
- Polished to remove debris.
- Packed in blister packs or bottles.
Quality Control Tests for Capsules
- Weight variation
- Disintegration test
- Dissolution test
- Moisture content
Manufacture of Powders
Powders are mixtures of finely divided drugs and excipients used internally or externally.
Types of Powders
- Bulk powders
- Divided powders (individual doses)
- Dusting powders
- Effervescent powders
Steps in Powder Manufacturing
1. Comminution
Reducing particle size using mortars, mills, or grinders.
2. Sieving
To obtain uniform particle sizes.
3. Mixing
Using tumblers, ribbon blenders, or geometric dilution techniques.
4. Packaging
- Sachets
- Bottles
- Sprinkle containers
Quality Control Tests for Powders
- Particle size analysis
- Flow properties
- Uniformity of mixing
- Moisture testing
Role of Pharmacists in Solid Dosage Form Manufacturing
- Selection and evaluation of raw materials.
- Ensuring GMP compliance.
- Supervision of manufacturing operations.
- Quality control and documentation.
- Stability testing and storage monitoring.
- Training staff in safe and accurate handling.
Detailed Notes:
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