Oral dosing is considered to be the most desired route for drug delivery. In general, the success of oral drug delivery is heavily dependent on a compound’s ADME and physicochemical properties. Among the physicochemical properties, solubility and permeability are thought to be the most important factors. Biopharmaceutics Classification System (BCS) was proposed in the 1990s for classifying drugs based on their solubility and permeability. BCS was developed with the intention of facilitating biowaiver applications for BA/BE studies for compounds in development. In general, compounds with poor aqueous solubility or permeability are assumed to be at high risk of having low oral bioavailability. Due to its simplicity, this classification system was quickly adopted by the pharmaceutical industry to different drugs in development on the basis of their solubility and permeability. In the meantime, because of its popularity, the usage of the BCS has also been quickly expanded to the compounds that are in the pre-clinical stage of development. This expanded the usage of the system has led to the labeling of compounds in discovery stage as “BCS class X like.” In particular, one of the most common pre-labels used is “BCS Class II-like compounds,” and issues associated with such labels are discussed. This kind of labeling has been used by drug researchers to evaluate the risk associated with the development of a compound. In this commentary, we show that pre-labeling compound with BCS classification without sufficient information can lead to unnecessary confusion, added workload, and/or artificial concerns about the developability of drug candidates. To illustrate this point, an analysis of marketed BCS Class II drugs for fraction absorbed in human was coupled with theoretical considerations to show that most BCS-Class II like compounds can be easily developed with conventional formulation technologies.

Key words: BCS Classification, Drug discovery, Permeability, Solubility