Polymorphism in pharmaceuticals may be defined as the ability of a drug substance to exist in two or more crystalline forms. The term can also be expanded to include the amorphous form and pseudopolymorphs such as solvates and hydrates.
Understanding the polymorphic landscape of a drug substance is of critical importance as polymorphs may have different physical properties (e.g. melting point, solubility, particle shape); these physical differences can impact manufacture, efficacy, stability and bioavailability of the Finished Product. Furthermore, understanding the polymorphic landscape is of commercial importance in protecting Intellectual Property. As metastable physical form can undergo structural changes or solvate / desolvate depending on environmental conditions, processing steps or with time.
The primary screening goal therefore is typically to identify the most thermodynamically stable polymorph under expected ambient and processing conditions. Getting to that point often requires a structured screen, but tailored to the specific goals of the development team. The Agenda1 screen is based on sound principles, but structured to meet that team’s goal.
The solubility of the compound in each target solvent utilised in the stable polymorph screen is also assessed during this programme.
This protocol is supported by the wide range of analytical equipment on site able to quickly characterise the differences between the identified forms (XRPD, FTIR, DSC, TGA, Polarised Light Microscopy, DVS, Raman Spectroscopy, Headspace GC and Karl Fischer). Further analytical techniques are then available to determine the solubility/bioavailability of the found forms (e.g. low volume dissolution).