Stability-indicating method

Since its creation around 1973, modern high-pressure liquid chromatography (HPLC) has played a dominant role in the analysis of pharmaceuticals. It is used in many different applications for example, in content uniformity assays and stability-indicating methods, for the purity profiles of drug substances, or in the analysis of drug metabolism in animals and humans. The heart of all of these assays is the HPLC column. In this chapter, we will describe the fundamental properties of HPLC columns as well as how these properties influence column performance and separation characteristics in pharmaceutical assays. 

ICH guidelines, and is generally 0.05% for DS and 0.10% for DP methods. Any impurity above this level should be reported. Especially for stability indicating methods, it may be valuable to apply a lower level as the reporting threshold to allow for a better trending process for degradation products at levels below 0.05% and 0.10% for DS and DP methods, respectively. 

In addition to online resources, other texts and references have discussed the process of validation for methods used in the pharmaceutical industry in relation to the regulatory guidance documents. These guides include discussions on method development in relation to method validation, the validation of non-chromatographic methods and stability indicating methods. 

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... 

In combining the optimized chromatography parameters and the appropriate detector, the accuracy, precision, and robustness (including standard and sample stability) of the method must be tested to ensure that it can be defined as a stability-indicating method. (See section V and VI of chapter 3.)... 

To develop an HPLC stability-indicating method for Type I or II dissolution, the linearity must be wide enough, in combination with good sensitivity and minimal interference, to accommodate concentrations from low (possibly LOQ) to very high end, as the samples drawn represent the cumulative drug amount dissolved over time. As for an FiPLC method that is designed for Type VII dissolution, the linearity should accommodate the lower concentrations since it is a drug measurement of a controlled-release system. 

Case study 1 Stability-indicating method development for dual drug system... 

Even if HPLC is chosen as the main stability indicating method, CE will be useful as orthogonal technique, especially in cases where the reason of mass balance deviations is unclear. In addition, due to its increased peak capacity and selectivity in comparison to HPLC, the detection of possible enantiomers, stereoisomers, and position isomers, having the same molecular weight and equal/similar spectra as the drug substance may be separated by a secondary CE method. 

Eurther examples for validated stability indicating methods can be found in literature, please refer also to the literature section. 

System suitability Use of appropriate assay controls to determine if a particular run is valid. May also include assay fit-for-purpose evaluations, such as stability indicating methods, etc. 

The ability of reduced CE-SDS to be used as a stability-indicating method was studied using an antibody stressed at pH 4 and 37°C for up to four weeks. The e-grams show that additional peaks were generated which increased with time, demonstrating that the rCE-SDS is a stability-indicating method (Figure 14). 

Stress Studies and Stability-Indicating Methods for Analysis of Stability... 

Functional Requirements. Based on the user requirements, more detailed functional requirements can then be defined. Take as an example a gradient HPLC system with UV-Vis detection required to run a stability-indicating method. The functions of each of the hardware and software components required to perform the tasks in the user requirements should be specified. The functional specifications typically include ... 

Bridle JH, Brimble MT. A stability indicating method for dipyridamole. Drug Dev Ind Pharm 1993 19 371-381. 

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