Traditionally, studies are performed and analysed following a univariate (one variable at a time) approach. The big advantage of this is that simple 2D plots can be used to assess cause and effect relationships, and the corresponding statistics are straightforward too. The production environment, however, is never univariate, and interactions between parameters should be expected. In the pharmaceutical arena, this situation has been well recognised — guidelines such as ICH Q8 on Pharmaceutical Development and ICH Q10 on Pharmaceutical Quality System explicatively mention the multidimensional design space in which product performance should be tested to assure quality.1,2 In this context, trend analyses of the manufacturing process performance and its products have been mentioned as an important tool for innovation and continuous improvements.3 A potential complicating factor with multidimensional data, however, is that it is not possible to visually inspect such data and so other ways are needed to represent the results.
From dull tables to essential informationFor a process running for several years, a wealth of data is usually stored in databases containing continuously measured data and routine-based quality control (QC) data, but it is extremely difficult to obtain useful information from such an intimidating amount of numbers and other data. Multivariate data analysis (MVA) is an approach that converts data into knowledge by using data exploration techniques, without narrowing down solely on allegedly unknown aspects. Representing this knowledge for human interpretation can be done visually.
Historical data can be analysed using MVA to learn from the past, which can be useful to solve current problems, avoid future ones or to make a validation study of a similar production process or compound quicker and cheaper. Analysing historical data can also avoid, or shorten, new studies, which are often expensive. When visualised properly, extended sets of data, such as dull and perhaps confusing tables, can be changed into spatial representations that clearly depict essential information that is not visible a-priori. The methods are widely applicable and can be used, for instance, for measuring the quality and authenticity of samples, or for monitoring a production process.
MVA for a pharmaceutical quality system