GMP : Tablet Manufacturing Technology Industry Certification

The manufacture of oral solid dosage forms such as tablets is a complex multi-stage process under which the starting materials change their physical characteristics a number of times before the final dosage form is produced.

Traditionally, tablets have been made by granulation, a process that imparts two primary requisites to formulate: compatibility and fluidity. Both wet granulation and dry granulation (slugging and roll compaction) are used. Regardless of whether tablets are made by direct compression or granulation, the first step, milling and mixing, is the same; subsequent steps differ.

Numerous unit processes are involved in making tablets, including particle size reduction and sizing, blending, granulation, drying, compaction, and (frequently) coating. Various factors associated with these processes can seriously affect content uniformity, bioavailability, or stability.

The manufacturing of tablet involves numerous unit processes, including:

• Particle size reduction and sizing.

• Blending.

• Granulation.

• Drying.

• Compaction.

• Testing of physical properties.

• Coating.

Following particle size reduction and blending, the formulation may be granulated, which provides homogeneity of drug distribution in the blend. This process is very important and needs experience to attain proper quality of granules before tableting. Quality of granule determines the smooth and trouble free process of tablets manufacturing. If granulation is not done in a proper manner, the resulting mixture may damage the tableting press.

After the preparation of granules (in wet granulation) or sized slugs (in dry granulation) or mixing of ingredients (in direct compression), they are compressed to get the final product. The compression is done either by a single-punch machine (stamping press) or by a 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.

Stage 1: Top punch is withdrawn from the die by the upper cam. Bottom punch is low in the die so powder falls in through the hole and fills the die.

Stage 2: Bottom punch moves up to adjust the powder weight. It raises and expels some powder.

Stage 3: Top punch is driven into the die by upper cam. Bottom punch is raised by lower cam. Both punch heads pass between heavy rollers to compress the powder.

Stage 4: Top punch is withdrawn by the upper cam. Lower punch is pushed up and expels the tablet, which is removed from the die surface by surface plate.

Stage 5: Return to stage 1.

The physical properties of a tablet are tested either by manual or automated sampling and IPC testing (in-process control). Tablet "hardness", also called "breaking force", is tested to assure that the tablet's strength will survive all further processes, such as dedusting, coating and packaging. The hardness value of a tablet gives an early indication of the tablet's disintegration time. Further measured parameters are weight, thickness, diameter, disintegration time, friability, and abrasion.

Friability and abrasion testing is performed in rotating testing drums, designed according to the pharmacopeia. The measured parameter is weight loss before and after testing and tumbling the tablets at a particular time and speed. In the friability test drum tablets are being carried up by a "shovel" and dropped. Tablets are also not allowed to fall apart during the test. In the abrasion test, drum tablets are not falling/dropping, but rolling on the ground of the test drum and losing weight due to the friction between tablets.

Tablet coating is a common pharmaceutical technique of applying a thin polymer-based film to a tablet or a granule containing active pharmaceutical ingredients (APIs).

Solid dosage forms are coated for a number of reasons, the most important of which is controlling the release profiles. The amount of coating on the surface of a tablet is critical to the effectiveness of the oral dosage form.

Tablets are usually coated in horizontal rotating pans with the coating solution sprayed onto the free surface of the tablet bed.

The advantages of tablet coating are taste masking, odour masking, physical and chemical protection, protects the drug from the gastric environment etc.

There are various techniques for tablet coating such as sugar coating, film coating, and enteric coating. Recent trends in pharmaceutical technologies are the development of coating methods which overcomes the various disadvantages associated with solvent based coatings.

In these latest technologies coating materials are directly coated onto the surface of solid dosage forms without using any solvent. Various solventless coatings are available such as electrostatic dry coating, magnetically assisted impaction coating,

Benefits of Proper Tablet Design:

• Ensure solid tablet quality

• Maximize tablet production

• Enhance product life-cycle

• Tablets are easily recognized, which builds brand equity and incorporates brand authentication

• Ease in Swallowing and administration by patient

Common Tablet Shapes

Round

Geometric

Oval

Modified Oval

Capsule

Modified Capsule

Common Tablet Profiles

Convex

Convex & Bevel

Flat Face

Flat Face Bevel

Compound Cup

Modified Ball

The monitoring of tablet hardness is especially important for drug products that possess real or potential bioavailability problems that are sensitive to altered dissolution release profiles as a function of the compressive force employed .One of the earliest testers to evaluate tablet hardness was the Monsanto hardness tester to evaluate tablet hardness tester.

Friabilator is the instrument which is used to detect the friability of the tablets .Friability is the combined effects of shock and abrasions. So to resist shock and abrasions friability test is done for the tablets. In this a no. of  tablets are put in the friabilator and revolves at 25rpm,dropping the tablets a distance of six inches with each revolutions .Conventional compressed tablets that lose less than 0.5 to 1.0% of their weight are generally considered as acceptable. When capping is considered on friability testing , the tablet should not be considered as for commercial use, regardless of the %age of loss seen.

Practical demonstration