Pharmaceutical
With its advanced scheduling capability enabling fully-automatic testing over an extended period, the NanoTest is ideally suited to R&D and quality assurance in a highly competitive industry where both high data throughput and reliability of results are essential.
NanoTest applications include:-
- Tablet testing - hardness, modulus, fracture properties
- Brittleness index (H/Kc)
- Mapping uneven compaction
- Nanoindentation of single crystals of pharma actives
- Powder adhesion
- Mechanical behaviour of powder agglomerates
- Fatigue and high strain rate testing
The flow chart above illustrates the range of applications within the manufacturing process.
Case study: Relating brittleness index from nanoindentation to size reduction ratio in hammer milling
Researchers from Pfizer have used their NanoTest to show that a brittleness index (H/Kc) determined from measurements on single crystals can be used in the effective prediction of the milling of pharmaceutical materials. The first step was to determine the fracture toughness. The large load range possible in the NanoTest allows production of fully developed radial/median crack systems with a wide range of indenter geometries (e.g. cube corner, Berkovich, Vickers). Using the standard fracture mechanics equation to determine fracture toughness:-
Where P is the peak load, α= 0.032 for a cube corner or 0.016 for a Berkovich, and c is the average measured crack length for the radial/median crack system. The fracture toughness, together with the hardness derived from the nanoindentation, is used to determine the brittleness index.
Excellent correlation between the NanoTest nanoindentation data on single crystals and large pilot scale results have now been obtained for a wide range of materials providing significant cost savings for Pfizer.
Advantages of the NanoTest method include:-
- Very small volumes of material needed - results from 5 crystals sufficient
- Can provide information on ease of milling earlier in the development process thus saving time and material
- Working on the actual crystals of pharmaceutical materials themselves - not on compacted material - so results are easier to directly relate to the actual application
Further reading
Predictive milling of pharmaceutical materials using nanoindentation of single crystals, LJ Taylor et al, Org. Process. Res. Dev. 8 (2004) 674-679.
