Charlotte Cartwright, Elaine H Stone
Merlin Powder Characterisation Ltd, Brierley Hill, West Midlands, UK
The aim is to showcase how compaction science can be used to solve practical problems.
Case study 1: Disintegrants – compression of different types of disintegrant
Method. Six active DC formulations were blended containing different disintegrants at high and low levels. Compression testing was performed using a Phoenix hydraulic Compaction Simulator (Brierley Hill, UK). To assess the manufacturability of the formulations, a Korsch XL100 profile at 40 rpm was chosen with 10 mm flat faced tooling. Tablets were assessed using disintegration testing to highlight any potential differences associated with the disintegrant used.
Results. Tabletability, compactability and compressibility were looked at for all formulationsto determine the optimalsize compacts to be created and tested via disintegration. Six tablets from each formulation were then made at around 0.825 SF for disintegration testing and the time taken for the compact fragments to pass through the mesh recorded.
Case study 2: Heat of compression
Method. A placebo formulation blend composed of Avicel PH102, Lactose Fast Flo 316, Sodium Starch Glycolate and Magnesium Stearate was compressed using a hydraulic Compaction Simulator. To assess the manufacturability of the formulations a Korsch XL100 profile at 30 rpm was chosen using 10 mm flat faced tooling. A jacketed die was connected to a water-bath, heated to a set temperature and tablets compressed at a range of compression forces. The temperatures assessed were: 20oC, 30oC, 40oC, 50oC and 60oC and any effects on the tabletability of the formulation was assessed.
Results. The punch pressures over a range of forces and compact tensile strength were plotted to determine tabletability. The tensile strength at 100 MPa compaction pressure for each temperature from the tabletability graph was determined using trend line equations. and plotted against temperature to assess the effect of temperature.
Conclusions. Disintegrants: Tabletability shows that there was a marginal increase in strength in the formulations with a lower percentage of superdisintegrant. However, there were considerable differences between the 6 formulations in terms of disintegration times. Some showing more variability than others and some quicker than others giving an insight into selecting the most appropriate superdisintegrant depending on the formulation as disintegration seemed the be the most variable factor compared to the compaction.
Temperature. Increasing temperature changes the tensile strength of the formulation. The highest tensile strength was recorded at 50oC with no further increase for this formulation blend above this temperature. Ejection forces also decreased as temperature increased.
Compaction simulation is a good tool because it allows identification of problems within formulations by using a limited amount of blend. It also allows for isolation of variables to test to detect potential problems during scale up to production.