Issue link: https://www.e-digitaleditions.com/i/1295512
Tablets & Capsules October 2020 13 relating to how API variability, excipient variability, and processing variability interact. We must also take this interaction term into account if we are to develop robust drug products. Taking into account this interaction term, product variability then becomes: σ2 Product =σ2 Active +σ2 Excipients +σ2 Process +σ2 Interactions Drug product variability Now let's consider variability of the final drug product and how excipient variability may impact it. Variability is inherent in everything; our tolerance of it depends on the level of scrutiny we need to apply. Pharmaceutical prod- ucts are no exception. Pharmaceutical product variability can arise in several ways, as shown in Figure 2. However, this is not the complete picture. There is a further term Figure 1 Components of a medicinal product API Packaging Process Product Excipients Figure 2 Origins of drug product variability Bulk API variability Process variability Product variability Excipients variability