According to the BCS classification system, the differentiation of drugs is based on two essential parameters of solubility and permeability, meaning the latter is as pivotal as the former in creating marketable pharmaceutical products. Nevertheless, the indispensable role of permeability in pharmaceutical cocrystal profiles has not been sufficiently cherished, which can be most probably attributed to two principal reasons. First, responsibility may be on more user-friendly in vitro measurement procedures for solubility compared to permeability, implying the permeability measurement process seems unexpectedly difficult for researchers, whereas they have a complete understanding of solubility concepts and experiments. Besides, it may be ascribed to the undeniable attraction of introducing new crystal-based structures which mostly leaves the importance of improving the function of existing multicomponents behind. Bringing in new crystalline entities, to rephrase it, researchers have a fairly better chance of achieving high-class publications. Although the Food and Drug Administration (FDA) has provided a golden opportunity for pharmaceutical cocrystals to straightforwardly enter the market by simply considering them as derivatives of the existing active pharmaceutical ingredients, inattention to assessing and scaling up permeability which is intimately linked with solubility has resulted in limited numbers of them in the global pharmaceutical market. Casting a glance at the future, it is apprehended that further development in the field of permeability of pharmaceutical cocrystals and organic salts requires a meticulous perception of achievements to date and potentials to come. Thence, this perspective scrutinizes the pathway of permeation assessment making researchers confront their fear upfront through mapping the simplest way of permeability measurement for multicomponents of oral drugs.
Keywords: Active Pharmaceutical Ingredients (APIs); Cocrystal; Coformer (CCF); Crystal Engineering; Franz Diffusion Cell; Oral Drugs; Organic Salt; Permeability.