WHODrug Global is the Uppsala Monitoring Centre’s medicinal product dictionary for the standardised coding of medicinal product information. In clinical trials, it is used in particular to capture and analyse concomitant and prior medication consistently. The dictionary assigns reported product names to a controlled medicinal product reference with information on active substances and anatomical-therapeutic classifications.
Standardisation therefore supports not only documentation, but also robust grouping of therapies.
Convert medication information into a comparable format
Participants often report medicines as brand names, incomplete designations, or locally available products. For safety or efficacy analyses, these details are only comparable to a limited extent. Coding with WHODrug Global links the documented name to standardised medicinal product information, enabling medications to be consolidated more consistently across sites, countries, and time points.
The Uppsala Monitoring Centre describes WHODrug Global as an international reference for medicinal product information. The dictionary covers conventional and herbal medicinal products, including prescription and non-prescription products, biotechnological and blood products, diagnostic substances, and contrast agents. Its hierarchy supports review at product and active-substance level as well as anatomical-therapeutic classifications.
Coding, updates, and data delivery
In a study, the documented medication term is first matched against an entry in the dictionary. The coding result is stored in the study dataset together with the original entry and, where applicable, a coding decision. This ensures it remains clear what a trial participant reported and how it was classified for analysis. Unclear or non-attributable entries require professionally documented handling.
WHODrug files are provided via subscription and, according to the Uppsala Monitoring Centre, are updated twice a year. A study project must therefore define which dictionary release is used, when an update is adopted, and how consistency of already coded data is maintained. For regulatory traceability, the version used must be included in the study documentation and in the data processing specifications.
Coding starts with sufficiently detailed source information in the eCRF. Product name, dosage form, strength, route of administration, and indication may be required to assess a medication entry reliably. If key information is missing, an apparently suitable assignment must not obscure the clinical reality. In such cases, a documented query or a predefined coding convention determines how the entry is to be handled.
For analyses, the dictionary hierarchy can provide different perspectives. An evaluation by reported product name answers a different question than a consolidation by active substance or pharmacological group. The statistics team must therefore align with Medical Coding and the analysis plan on which coding output is used for a specific table or safety assessment.
The subscription model distinguishes WHODrug Global from freely available terminology lists. Access to files and applications requires a valid organisational licence and authorised users. Delivery as a file enables integration into coding tools, but also requires controlled archiving of the release used for a study.
Distinction from MedDRA
WHODrug Global and MedDRA serve different coding purposes. MedDRA is used for the standardised representation of medical events, findings, and diseases, for example an adverse event. WHODrug Global, by contrast, codes medicinal products and their active-substance relationships. An adverse reaction and concomitant medication taken at the same time therefore generally require two different dictionaries.
This distinction is essential for safety analyses: an event term can be grouped with MedDRA, while a concomitant therapy is analysed using WHODrug Global. Both codings may occur in the same study, but they do not answer the same question. The established term MedDRA is therefore not a synonym for a medicinal product dictionary.
A traceable coding history is particularly important when changes to already captured medication entries are reviewed after an amendment, a new delivery, or a data cut.
Relevance for clinical trials
Robust medication coding influences the assessment of washout periods, concomitant treatments, potential interactions, and exclusion criteria. It requires clear rules for collection in the eCRF, handling of free text, medical queries for unclear names, and the definition of coding time points. Different dictionary versions or inconsistent active-substance assignments can result in frequencies of concomitant medications not being comparable between data snapshots.
Full-service CROs such as Mediconomics support WHODrug processes by developing coding conventions, medically coding concomitant and prior medication, managing queries for incomplete medicinal product names, controlling dictionary versions, and reviewing data for safety analyses. They can align coding results with eCRF design, SDTM mapping, and pharmacovigilance requirements.
Frequently Asked Questions (FAQ)
Are adverse events coded with WHODrug Global?
No. MedDRA is typically used for adverse events and medical diagnoses. WHODrug Global relates to documented medicinal products.
Why is the WHODrug release used important?
Dictionary releases may differ due to new entries or updated mappings. Stating the release makes the coding of a given study snapshot reproducible.
Can a brand name be analysed directly?
A brand name can remain the source entry, but it makes cross-country consolidation more difficult. Coding enables additional analyses by active substance and classification.
Regulatory References
- Uppsala Monitoring Centre WHODrug Global – defines the medicinal product dictionary and its applications.
- Uppsala Monitoring Centre WHODrug Download Area – describes the provision of the subscription-based dictionary files.
- ICH E6(R3) Good Clinical Practice – requires the integrity of generated, recorded, and reported trial data.
- CDISC SDTM Implementation Guide – provides the structure in which standardised coded concomitant medication is tabulated.
