Drug metabolism can be difficult to visually capture when provided only in terms of structured data entries, especially for complex metabolic schemes involving multiple pathways from drug to end metabolites. To assist users in understanding drug metabolism, we have added an interactive ‘tree-like’ graphical interface to drug card entries, under the text metabolism description (Figure 2E). Individual molecules are represented as labelled ellipses connected by arrows, with each arrow pointing from the substrate to the product in an individual metabolic reaction. A single substrate can give rise to multiple possible products. When a user places their cursors over an individual ellipse, both this ellipse and its direct parent (together with the arrow connecting them) will be highlighted in pink. Any more distant ancestors, if present, will be highlighted in grey (Figure 2F). These visual cues make it easier for users to follow individual reaction pathways. Clicking on any of the metabolites will open a page detailing the metabolic reaction giving rise to the metabolite, including the involved enzyme(s), if known (Figure 2G).
