Study carried out using Gamlen Tablet Press
It is important that tablet properties such as tablet hardness be compared in a meaningful way when comparing formulations particularly when the tablets are compacted on different pieces of equipment. The properties of a tablet, both during manufacturing and in vivo, are determined by the properties of the materials used to make it; and the manufacturing conditions used to prepare the powder blend and compress the tablet.
Understanding the impact of starting material properties and manufacturing conditions on the tablet at the development stage is of paramount importance. Some material and tablet characteristics may not matter but others can have a dramatic effect on processing and in vivo behaviour. These physical and chemical properties are known as Critical Quality Attributes, and they must be established for starting materials, in-process materials, and the finished tablet.
Tablet hardness, or breaking strength, is an important and widely used parameter to control the tablet manufacturing process. In many cases it is used a surrogate measure for compression force during manufacture, often because the tablet machine is unable to measure compression force. It is a very important control parameter because compression affects every tablet property including disintegration, dissolution and friability. In some cases stability is also affected.
However, tablet hardness (or breaking force) comparisons are applicable to one tablet size and shape only. If you materially change the size, shape or thickness of a tablet then all tablet hardness comparisons become incorrect. It is intuitively obvious that it is more difficult for a small tablet to withstand a given load than a larger tablet to do so, and in engineering terms this indeed proves to be the case.
Why use a Gamlen Tablet Press?
It can save you time, money and materials. People need help to study tablets under properly controlled conditions in a laboratory.
Michael Gamlen invented the Gamlen Tablet Press (GTP) to help you understand the relationship between the properties of your drug, formulation, and manufacturing process. When you do this you can develop better products more quickly, and improve productivity of your tablet manufacturing operations.
The GTP is the first machine designed to make tablets on a small scale at a user-specified compaction force. This force determines both the physical strength and the dissolution behaviour of the tablet. These are the key properties which ensure the tablet reaches the patient and delivers the drug.
The machine works by monitoring the force in real time using a PLC. The punch force and punch position are displayed in real time on a computer which is also used to input the compaction conditions. Using the GTP we make tablets of extraordinary reproducibility and consistency, within 1-2% force, and with no wastage. Batch yields are >99%.
For the measurement of tablet breaking load, the press records both force and displacement during both compression and fracture, and also provides the ejection force profile associated with tablet ejection
In the scale-up of tablet production, the press can be used to determine the relationship between tablets developed at the bench-top scale using a few grams of material (often at the early development stage) and the final tablet manufactured on a rotary tablet press. The latter uses hundreds of kilograms of material, making process development difficult because of practical difficulties in experimentation; smaller and different shaped tablets can, however, be scaled to the final desired tablet design if TFS is used as the basis for comparison.
If you want better tablet products and processes you need the Gamlen Tablet Press.
Download full article: Importance of normalisation when comparing tablet properties
This whitepaper discusses the conversion of the typically quoted compression and breaking force units to pressure units which take into account the area over which the force is applied. We discuss how the normalisation of these measurements as compaction pressure and tensile fracture stress make a dramatic difference to interpreting results and illustrate this with a case study on a table formulation development project.
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