Relequa ERH test negates lengthy investigations
Equilibrium relative humidity test
Relequa has revealed that its equilibrium relative humidity (ERH) test can be used to solve process validation sample issues.
An investigation was begun after process validation samples were seen to be giving results that did not make any sense.
Powder-blend samples and tablet samples were all assayed for content at the same time by the same method and on the same equipment.
All the tablets' assay results range from four per cent to eight per cent higher than the powder blends.
Using Relequa, it was found that the tablet samples had high ERH.
The company powered the tablets in a mechanical grinder and saw that this instantly reduced the ERH.
The decreased ERH demonstrates that the tablets had lost moisture.
This was the first instance of tablets showing to have trapped moisture in their matrix.
In a typical HPLC assay the average weight of 20 tablets (Av) is used in the assay calculation: Std x (Av/WS) x (PS/PStd) x 100 per cent.
It is seen from this equation that the weight of the tablets is used on the top line.
The trapped moisture is instantly lost when tablets are powdered and not accounted for in the sample weight (WS).
It was concluded that the increased moisture, demonstrated by the sensitive Relequa ERH test, added to the tablet assay values.
In this case, unfortunately, the process validation results had been generated causing a lengthy investigation and considerable cost that could have been avoided by a using the simple Relequa ERH test.
Relequa is an analysis tool for looking at moisture profiles in pharmaceutical materials and products.
The Relequa ERH test has recently been used to investigate moisture profiling applications in prospective formulation and process development.
During investigation of tablets placed on stability, one company found that the tablets' moisture-related problem could not be rectified using conventional testing.
The Relequa sample moisture test has been used to investigate a problem involving inconsistencies in the stability of batches of a film-coated tablet.
Relequa Analytical Systems is giving away 500 copies of 'A Wet Look at Climate Change' by Dr Peter Moir, which explains the principles of relative humidity and equilibrium relative humidity (ERH).