When pharmaceutical companies manufacture a drug, finding the drug’s most stable form is important. Not only do drugs become less effective as they degrade, limiting their useful shelf life, but if a more stable version of a drug is discovered after it has reached the market, products may end up being withdrawn, costing money. As a result, chemists are developing methods to evaluate drug stability, and using a “Full Interaction Maps” tool is one such computational method.
90% of small molecule drugs are delivered in the crystalline state – a solid state where the individual molecules are arranged in a highly ordered manner. However, there’s often more than one way in which the molecules can arrange themselves in crystal structure. We refer to these different arrangements as ‘polymorphs’, and some can be more stable than others. It’s not just medicinal drugs that exhibit polymorphism, either: Chocolate is an excellent everyday example!
Full Interaction Maps are a computational method that allow the relative stabilities of different crystal structures to be visually evaluated. They are generated by identifying active functional groups within molecules, and then mapping preferred possible interactions of these functional groups with other molecules. How well neighbouring molecules satisfy these interactions in different possible arrangements can then be assessed.
Using the Full Interaction Maps tool the stabilities of different drug families has been analysed, and the results returned match up with known stabilities. The method is by no means perfect, but it can help mitigate the risk of a more stable form of a drug emerging after it has reached the market, saving both time and money.
More detail on the Full Interaction Maps tool can be found on the Cambridge Crystallographic Data Centre here. There’s also further information contained in the paper this graphic is based on.
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