SOME BASIC KNOWLEDGE ABOUT 1. Granulation Technology, 2. Compression technology, 3 Coating of Tablets

Granulation Technology

In the pharmaceutical industry, the three most common granulation processes for solid dosage form production are wet granulation, dry granulation (roll compaction) and direct blending. Given the importance of granulation in the production of oral dosage forms — most fine pharmaceutical compounds require granulation to improve their flowability and processing properties prior to tableting — and the technique’s extensive use in the industry, it’s essential to understand the principles and options, which are summarized below. An obvious advantage of roll compaction is that no moisture is involved in the process; it is therefore an ideal way to process compounds that are physically or chemically unstable when exposed to moisture. Furthermore, it’s not necessary to dry the granules produced and, hence, typically more energy efficient. 

Tablet compression

After the preparation of granules (in case of wet granulation) or sized slugs (in case of dry granulation) or mixing of ingredients (in case of direct compression), they are compressed to get final product. The compression is done either by single punch machine (stamping press) or by multi station machine (rotary press). The tablet press is a high-speed mechanical device. It 'squeezes' the ingredients into the required tablet shape with extreme precision. It can make the tablet in many shapes, although they are usually round or oval. Also, it can press the name of the manufacturer or the product into the top of the tablet.

Each tablet is made by pressing the granules inside a die, made up of hardened steel. The die is a disc shape with a hole cut through its centre. The powder is compressed in the centre of the die by two hardened steel punches that fit into the top and bottom of the die. The punches and dies are fixed to a turret that spins round. As it spins, the punches are driven together by two fixed cams - an upper cam and lower cam. The top of the upper punch (the punch head) sits on the upper cam edge .The bottom of the lower punch sits on the lower cam edge.

The shapes of the two cams determine the sequence of movements of the two punches. This sequence is repeated over and over because the turret is spinning round. The force exerted on the ingredients in the dies is very carefully controlled. This ensures that each tablet is perfectly formed. Because of the high speeds, they need very sophisticated lubrication systems. The lubricating oil is recycled and filtered to ensure a continuous supply. 

COATING

Many solid pharmaceutical dosage mediums are produced with coatings, either on the external surface of tablets, or on materials dispensed within gelatine capsules. Coating serves a number of purposes:

1. ·         Protects the tablet (or the capsule contents) from stomach acids
2. ·         Protects the stomach lining from aggressive drugs such as enteric coated aspirin
3. ·         Provides a delayed release of the medication
4. ·         Helps maintain the shape of the tablet

Ideally, the tablet should release the material gradually and the drug should be available for digestion beyond the stomach. The coating can be specially formulated to regulate how fast the tablet dissolves and where the active drugs are to be absorbed into the body after ingestion.

Many factors can affect the end-use properties of pharmaceutical tablets:

·         Chemical composition

·         Coating process

·         Drying time

·         Storage and environmental monitoring