What Drug counterfeits are fake drugs intentionally produced with a commercial outcome. Drug counterfeits are a worldwide problem that yearly causes thousands of deaths due to substitution of the active drug compound(s), limited drug production control, and reduced or no pharmaceutical effect of the counterfeited drugs. Up to 10% of all drugs are counterfeit and this number increases every year. Why Non-visual drug counterfeits (e.g. changes in chemical formula or composition) are particularly challenging to identify due to the lack of chemical methods. I hypothesize that the components and the production method of a drug leave a specific chemical fingerprint. Genuine drugs and counterfeits will have different chemical fingerprints. How In this project, I will combine knowledge and methods from geology to establish a new pharmaceutical methodology to identify and understand drug counterfeits through isotopic ratio and trace elemental analysis. My work anticipates generating new and important chemical approaches to spot non-visual drug counterfeits. Thereby, I aim to improve drug safety and ultimately reduce the number of yearly deaths related to drug counterfeits. SSR Combining the knowledge, experimental expertise, and understanding of isotopes from geochemistry (Prof. Chamberlain and Prof. Maher, Stanford University) and pharmaceutical science (Assoc. Prof. Stürup, University of Copenhagen), I expect to establish methodologies of isotopic and trace element methods to reveal non-visual drug counterfeit through this synergetic interdisciplinary project at Stanford University. The in-depth characterization and understanding of the isotopic and trace element fingerprint of drugs can improve drug safety, and reduce the numbers of yearly deaths related to counterfeits.