Specification setting for drugs in the pharmaceutical industry

In the pharmaceutical industry a drug must conform to certain limits through its shelf life period. To ensure compliance in practice we need manufacturing processes to be robust and in control, measurements systems to be in control and the measurements must be traceable. Storage conditions must be under control. In this paper we discuss the practical implications involved in setting and maintaining specifications for drugs in the pharmaceutical industry. These include statistical process control limits, release limits, shelf life limits and in-use limits. The challenge here is to make this chain of limits consistent and at the same time be practical for use. The scientific approach to establishing a chain of specifications involves normal linear mixed models and an Arrhenius model, a kinetic model, describing e.g. the temperature dependence of drug degradation. These models are applied to data from stability studies as well as data from batch release.