The WHO Drug Dictionary (WHO-DD) is an internationally recognized database of medicinal products and their related information, developed and maintained by the Uppsala Monitoring Centre (UMC), the World Health Organization’s Collaborating Centre for International Drug Monitoring. It is primarily used in pharmacovigilance, clinical trials, and drug safety monitoring for identifying and coding medications across various regulatory, clinical, and safety databases.
This dictionary serves as a key tool for ensuring the standardization of drug names and codes across different countries and health systems, facilitating the accurate collection, comparison, and analysis of adverse drug reactions (ADRs), clinical trial data, and regulatory submissions.
1. Purpose and Use of WHO Drug Dictionary
The WHO Drug Dictionary is widely used in:
Pharmacovigilance: To identify and code drugs associated with adverse reactions in pharmacovigilance databases like the WHO’s VigiBase, national pharmacovigilance systems, or corporate databases.
Clinical Trials: For coding investigational drugs and concomitant medications in clinical trials, allowing for consistent and accurate drug identification across multi-center studies.
Drug Safety Databases: Used by pharmaceutical companies, regulatory bodies (such as the FDA, EMA), and healthcare providers for safety monitoring, signal detection, and compliance with regulatory requirements.
2. Structure of the WHO Drug Dictionary
The WHO Drug Dictionary contains detailed information on medicines, including:
Active ingredients: The chemical or biological substances that have therapeutic effects.
Brand names: Commercial names of drugs, also known as proprietary or trade names.
ATC (Anatomical Therapeutic Chemical) classification codes: Standardized codes for classifying drugs according to their site of action, therapeutic use, and chemical properties.
Pharmaceutical forms: Forms in which the drug is available (e.g., tablets, injections).
Strengths: Dosages of active ingredients in the medicinal product.
Country information: Drug availability in different countries, including variations in brand names and formulations.
3. Key Features of the WHO Drug Dictionary
Global Standardization: The WHO-DD helps ensure that drug names and codes are standardized across different countries, languages, and healthcare systems.
Comprehensive Drug Coverage: It includes information on drugs marketed worldwide, making it a valuable resource for multinational clinical trials and post-marketing surveillance.
Integration with Pharmacovigilance Systems: The WHO-DD is integrated with pharmacovigilance databases like VigiBase (the WHO’s global database for individual case safety reports or ICSRs) to ensure that ADRs can be linked to specific drugs in a standardized way.
Version Control: The dictionary is regularly updated to reflect new drug approvals, changes in drug formulations, and updates to regulatory information, making it reliable for current pharmacovigilance activities.
4. Applications of the WHO Drug Dictionary in Pharmacovigilance
The WHO-DD is a critical tool for several pharmacovigilance-related tasks, including:
a) Coding of Drugs in Individual Case Safety Reports (ICSRs)
When adverse drug reactions (ADRs) are reported, the drugs involved need to be coded and recorded in a standardized manner. The WHO-DD provides unique identifiers and codes for each drug, which are used to standardize the reporting of these cases in safety databases like VigiBase.
b) Signal Detection
Pharmacovigilance professionals use the WHO-DD to identify potential safety signals by linking ADRs to specific drugs. By ensuring accurate identification of drugs, it reduces the risk of misattributing ADRs to the wrong products or ingredients.
c) Clinical Trial Data Management
In clinical trials, the WHO-DD is used to code investigational and concomitant medications. This standardization ensures consistency in data collection, facilitates comparison of results across studies, and enhances the reliability of safety and efficacy data.
d) Regulatory Submissions
Pharmaceutical companies and regulatory agencies use the WHO-DD to ensure that drug names are accurately coded in regulatory submissions, such as New Drug Applications (NDAs) or Biologic License Applications (BLAs), as well as in safety reports submitted to agencies like the FDA or EMA.
5. ATC Classification System in WHO Drug Dictionary
A key component of the WHO-DD is the Anatomical Therapeutic Chemical (ATC) Classification System, which provides a standardized way of categorizing drugs based on their:
Anatomical group: The part of the body or organ system affected by the drug.
Therapeutic use: The condition or disease the drug is used to treat.
Chemical properties: The chemical composition or structure of the drug.
Example of ATC Classification:
For the drug paracetamol (acetaminophen):
ATC Code: N02BE01
N: Nervous system
02: Analgesics
B: Other analgesics and antipyretics
E: Anilides
01: Paracetamol
The ATC system is essential for identifying drugs in a global context, as the same medication may be marketed under different brand names in different countries.
6. Examples of WHO Drug Dictionary Entries
Example 1: Paracetamol
Active ingredient: Paracetamol
Brand names: Tylenol, Panadol, etc.
ATC Code: N02BE01
Form: Tablet, injection, syrup
Strength: 500 mg, 1 g
Country-specific information: Available in different formulations and brand names across countries.
Example 2: Metformin
Active ingredient: Metformin
Brand names: Glucophage, Fortamet, etc.
ATC Code: A10BA02
Form: Tablet, extended-release tablet
Strength: 500 mg, 850 mg, 1000 mg
Country-specific information: Approved for use in different formulations globally for type 2 diabetes management.
7. Benefits of WHO Drug Dictionary
Consistency and Accuracy: Ensures consistent and accurate coding of drugs in pharmacovigilance, regulatory submissions, and clinical trials.
Global Applicability: Facilitates global collaboration by standardizing drug names and codes across countries, making it easier to share safety data and regulatory information.
Improved Signal Detection: Enables better identification of safety signals in large pharmacovigilance databases, as ADRs can be consistently linked to specific drugs.
Efficiency in Drug Safety Reporting: Reduces the complexity of drug safety reporting and analysis by providing a standardized vocabulary for drugs and their related information.
8. WHO-DD vs. Other Drug Dictionaries
While the WHO Drug Dictionary is widely used in international pharmacovigilance, there are other drug dictionaries used by pharmaceutical companies and regulatory agencies. Some common alternatives include:
MedDRA: Primarily focused on adverse event terminology but does not provide detailed information on drug names or formulations.
FDA’s NDC Directory: Focuses on drug products marketed in the United States and includes unique product identifiers for regulatory use.
EMA’s EudraVigilance Medicinal Product Dictionary (EVMPD): Used in the European Union for pharmacovigilance purposes.
Conclusion
The WHO Drug Dictionary (WHO-DD) is a fundamental tool in pharmacovigilance, clinical trials, and regulatory submissions. It provides standardized terminology for medicinal products, allowing for consistent drug identification and coding. Its integration with the ATC classification system and use in global pharmacovigilance networks such as VigiBase makes it a cornerstone of international drug safety efforts. By ensuring consistent and accurate drug identification, the WHO-DD supports effective signal detection, safety monitoring, and regulatory compliance.
