You may have a problem with calibrating with the new 10mg Prednisone. The
lot was reformulated to make it more sensitive to deaeration technique. This
is the number one problem that causes the prednisone calibration to be
out.
For example, many labs that use helium sparging have found that this
technique does not always work with Prednisone 10mg (NCDA2). This is because
helium sparging is not really deaerating. Rather, it is replacing nitrogen
and oxygen with helium, which has a faster out gassing rate than the other
two, but still needs to out gas. So if you sparge then run you may have
helium interference. You must determine your rate of out gassing with this
technique and determine the appropriate time to start the test.
If you use the USP recommended method of heating to 41C and then vacuum
filter while stirring for 5 minutes, you remove almost all of the gas. The
media will start to reaerate over the next 30 minutes. This is the point in
which it will start to take in excess gas. It is the excess gas that will
cause the problems not dissolved gas. So if you use this technique, and run
the samples without delay. You should have no problems.
The other major source of error with disintegrating tablets is vessel
cleaning. The floating encapsulated micro particles are affected by the
hydrodynamic flow and follow an outward sink inward rise flow pattern. This
can be hindered if the glass is dirty or even has microfractures or scratches
in the glass. Determine if the failure occurs in certain glass vessels by
keeping the same vessels in the same location and noting their position.