The Case for Physiologically Based Biopharmaceutics Modelling (PBBM): What do Dissolution Scientists Need to Know?

The purpose of this article is to inform the dissolution scientist of a powerful emerging tool that provides in vivo linkage to dissolution methods. This tool is physiologically based biopharmaceutics modelling (PBBM). Dissolution scientists are mostly concerned with analytical sections of drug development, so exposure to modeling and other pharmacokinetics and biopharmaceutic concepts may be uncommon. PBBM is an in-silico model that focuses on the interactions between the in vivo physiology and the formulation and drug characteristics. The principles behind PBBM is that all mechanisms related to drug release, dissolution, and diffusion from the site of administration to the site of action can be described in a mechanistic way or semi-empirical way. The integration of in vitro dissolution data in PBBM is described, including examples of software and modeling applications. The expertise needed to use the software and appropriate training is discussed. The key inputs that are expected from the dissolution scientist include an understanding of the aqueous solubility across the physiological pH range, impact of in vivo relevant bile salts and phospholipids on solubilization, and the impact of surface pH on dissolution rate. An example of an advanced in vitro system, TNO intestinal model (TIM-1), will be discussed and its importance in establishing a biorelevant understanding of dissolution behavior. PBBM can evaluate the clinical relevance of a dissolution method and justify specifications and ultimately provide an approval advantage to the sponsor. A well-supported dissolution method that provides clinically relevant drug product specifications (CRDPS) will be viewed with favor by the regulators. Therefore, the partnering of a dissolution scientist and biopharmaceutics scientist to develop PBBM is clearly an important step forward in drug development.