DrugBank 4.0 is an updated version of the comprehensive online database that provides extensive biochemical and pharmacological information about drugs, their mechanisms, and targets. This latest release includes significant enhancements to facilitate research in xenobiotic metabolism, pharmacokinetics, pharmacodynamics, and drug design/discovery. Key additions include over 1200 drug metabolites, 1300 drug metabolism reactions, and dozens of drug metabolism pathways. Additionally, 30 new or predicted ADMET parameters have been added to each DrugCard, bringing the average number of quantitative ADMET values for FDA-approved drugs close to 40. The database now also includes referential nuclear magnetic resonance and mass spectrometry spectra for nearly 400 drugs, along with spectral and mass matching tools for compound identification. New search tools, such as Reaction Browse and Category Browse, have been introduced to enhance user navigation and information retrieval. The database has also been improved with a commenting system and a news feed to engage users and provide feedback. These enhancements aim to make DrugBank a more comprehensive and user-friendly resource for a wide range of researchers and professionals.DrugBank 4.0 is an updated version of the comprehensive online database that provides extensive biochemical and pharmacological information about drugs, their mechanisms, and targets. This latest release includes significant enhancements to facilitate research in xenobiotic metabolism, pharmacokinetics, pharmacodynamics, and drug design/discovery. Key additions include over 1200 drug metabolites, 1300 drug metabolism reactions, and dozens of drug metabolism pathways. Additionally, 30 new or predicted ADMET parameters have been added to each DrugCard, bringing the average number of quantitative ADMET values for FDA-approved drugs close to 40. The database now also includes referential nuclear magnetic resonance and mass spectrometry spectra for nearly 400 drugs, along with spectral and mass matching tools for compound identification. New search tools, such as Reaction Browse and Category Browse, have been introduced to enhance user navigation and information retrieval. The database has also been improved with a commenting system and a news feed to engage users and provide feedback. These enhancements aim to make DrugBank a more comprehensive and user-friendly resource for a wide range of researchers and professionals.