This PhD position at Leiden University focuses on drug metabolism, pharmacogenetics, and phenoconversion, investigating how genetic and non-genetic factors (such as medication use and co-morbidities) influence drug-metabolizing phenotypes. The project aims to improve understanding of phenoconversion mechanisms in clinical practice and to evaluate advanced in-vitro models, endogenous biomarkers, and physiology-based pharmacokinetic modelling for holistic prediction of drug- and disease-induced phenoconversion. The position is uniquely shared between the Department of Clinical Pharmacy and Toxicology at Leiden University Medical Centre (LUMC) and the Division of Systems Pharmacology and Pharmacy at the Leiden Academic Centre for Drug Research (LACDR), providing training in both pre-clinical and clinical research environments. The successful candidate will conduct original laboratory research, publish in international journals, present at conferences, supervise Master’s students, and follow a tailored PhD training plan. Applicants must have an M.Sc. in Pharmacy or (Bio)Pharmaceutical Sciences with experimental training, strong interest in computational pharmacological modelling, proficiency in English, and excellent communication skills; hands-on LC-MS experience is preferred. The appointment is for four years, with an initial one-year contract and extension upon positive evaluation. The salary ranges from €3,059 to €3,881 per month, with additional holiday and end-of-year bonuses, career development opportunities, and support for international spouses. International candidates may be eligible for a substantial tax break. Leiden University values diversity and work/life balance, and the LACDR institute is highly diverse and supportive. Applications must be submitted online with a CV, motivation letter, and references by 4 November 2025. For enquiries, contact Dr. M.L. Manson or Prof. dr. Jesse Swen.