Systematic error associated with apparatus 2 of the USP dissolution test III: limitations of calibrators and the USP suitability test.

The calibrator tablets now used in the USP suitability test do not reveal common sources of systematic error associated with Apparatus 2. When the apparatus was operated under conditions near or beyond USP tolerances, changes in the results of the USP calibrators were slight, whereas those of several samples of commercial prednisone tablets were significant. Thus, the USP calibrators and requirements do not guarantee suitability of the equipment for general dissolution testing of drug products.