Assays stability-indicating methods

XRPD as a stability-indicating assay method When the phase identity, or degree of crystallinity (or lack thereof), of a drug substance is important to its performance in a drug product, XRPD can serve as a vital stability-indicating assay method. There is no doubt that XRPD can be validated to the status of any other stability-indicating assay, and that one can use the usual criteria of method validation to establish the performance parameters of the method. This aspect would... 

A stability-indicating method is a validated quantitative analytical procedure that can detect the changes with time in the pertinent properties of the drug substance and drug product under defined storage condition. A stability-indicating assay method accurately measures the active ingredient(s) without interference from other peaks and is sensitive... 

Wahbi et al. [32] used a spectrophotometric method for the determination of omeprazole in pharmaceutical formulations. The compensation method and other chemometric methods (derivative, orthogonal function, and difference spectrophotometry) have been applied to the direct determination of omeprazole in its pharmaceutical preparations. The method has been validated the limits of detection was 3.3 x 10 2 /ig/ml. The repeatability of the method was found to be 0.3-0.5%. The linearity range is 0.5-3.5 /ig/ml. The method has been applied to the determination of omeprazole in its gastro-resistant formulation. The difference spectrophotometric (AA) method is unaffected by the presence of acid induced degradation products, and can be used as a stability-indicating assay method. 

M. Bakshi and S. Singh, Development of validated stability-indicating assay methods—critical review, /. Pharm. Biomed. Anal. 28 (2002), 1011-1040. 

Chafetz, L. Stability indicating assay methods for drugs and their dosage forms. J. Pharm. Sci. 60 335-345, 1971. 

Khedr, A. and Sheha, M. 2008. Stress degradation studies on betahistine and development of a validated stability-indicating assay method, J. Chromatogr. B, 869 111-117. 

Khedr, A. 2007. High-performance liquid chromatographic stability indicating assay method of tianeptine sodium with simultaneous fluorescence and UV detection, J. Chromatogr. Sci., 45 305-310. 

There are numerous variables to consider in developing an accurate and rugged chromatorgaphic method. The extent depends on the purpose of the test that is, stability-indicating assays are the most demanding, whereas identification tests are the least demanding. 

K. Shivram, A. C. Shah, B. L. Newalhar, and B. V. Kamath, Stability indicating HPLC method for the assay of diltiazem hydrochloride in tablets, J. Liquid Chromatogr., 75 2417 (1992). 

By the time the drug product is in phase III, studies should be included to demonstrate the inherent stability of the drug product, and the ability to detect potential degradation products should be available. The analytical method should use a validated stability-indicating assay. 

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