Gamlen compaction analysis accounts for every size and shape of tablet

A question that comes up regularly when talking to a new customer is “Do we need to match the size and shape of the tooling we use in production?” The answer is always a resounding “no!”

Size and shape is accounted for

That’s because our compaction analysis method has been developed to ensure that all our calculations account for the size and shape of the tablets used to generate accurate compaction data. This is why we always convert compaction force to compaction pressure, hardness to tensile fracture stress etc.

The reason? The aim of compaction analysis is to characterise the intrinsic compaction behaviour of the powder being tested. If size and shape is not accounted for, then the compaction behaviour has not been characterised, only measured under specific conditions. This would be like trying to characterise the density of a powder by only weighing it and not accounting for its volume i.e. the size and shape. In doing so you could compare the ‘densities’ of different powders by weighing them but would first have to ensure that they occupied the exact same amount of space each time. The drawbacks to this approach are obvious. As with compaction analysis, it is far better to account for size and shape in your calculations.

Guidelines on hardness

By doing so we can easily provide guidelines on what ideal tableting behaviour looks like. The guideline that tabletability is considered acceptable if 200 MPa of compaction pressure produces a tablet with a tensile fracture strength of 2 MPa holds true across all sizes and shapes of tablets. If tablet size and shape is not accounted for, a guideline hardness value must be established for each individual product. This is more time consuming and requires specialist knowledge of each individual product to assess it. Whereas using our approach, once provided with the guideline, even a novice can now assess the tabletability of any formulation quickly and easily.

Only one punch and die set

If your compaction analysis method depends on using the exact tooling for analysis as used in production, you will need a new set for every product you work on. Also, data produced for different projects will not be comparable. Using our approach, you do not need an assortment of tooling sets for analysis. Many of our customers use just the one punch and die set for all their testing.

Punch and die

Compare data easily

The Gamlen method also lends itself to easily comparing data generated for different projects. This allows a compaction data library to be built up. If a new project comes in say looking at an excipient you’ve worked on previously, even for a different product, the existing data can be used. Similarly, if an API is being used in products of different tablet sizes or shapes you don’t need to produce a baseline for every product.

If you are familiar with our products, you will know that we do in fact offer a range of punch and die sizes, but this is not to mimic different production tooling sets. As the pressure the powder bed experiences is determined by both the force and the area over which it is applied, different sizes of punches allow different pressure ranges to be targeted. This can be useful, for example, where the aim is to mimic roller compaction where very low compaction pressures are employed.