In pharmacovigilance, safety data is meaningful only when it is systematically classified, coded, and interpreted. Drug and disease classification systems, standardized dictionaries, and structured information resources allow regulators, healthcare professionals, and pharmaceutical companies to communicate clearly and detect safety signals efficiently. Alongside these technical frameworks, the establishment of robust pharmacovigilance programmes at hospital, industry, and national levels ensures continuous monitoring of medicine safety.
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Why Classification Systems Are Essential
Pharmacovigilance depends on the ability to compare and analyze safety data across regions, populations, and time periods. Standardized drug and disease classifications provide a common scientific language, enabling accurate aggregation of adverse drug reaction (ADR) reports and supporting global signal detection.
Anatomical, Therapeutic, and Chemical (ATC) Classification of Drugs
Structured Identification of Medicines
The Anatomical, Therapeutic, and Chemical (ATC) classification system categorizes drugs based on the organ or system they act upon, their therapeutic purpose, and their chemical characteristics. Each drug is assigned a unique ATC code, allowing consistent identification across countries and databases.
The ATC system supports pharmacovigilance by enabling comparison of ADR patterns within drug classes, rather than only individual products. This approach helps identify class effects and emerging safety trends.
International Classification of Diseases (ICD)
Standardizing Disease and Health Conditions
The International Classification of Diseases (ICD) is a globally accepted system for classifying diseases, symptoms, and health conditions. Maintained by the World Health Organization (WHO), ICD ensures uniform reporting of medical diagnoses.
In pharmacovigilance, ICD coding helps link adverse events to underlying diseases, supporting causality assessment and epidemiological analysis. Consistent disease classification improves the reliability of safety databases worldwide.
Defined Daily Dose (DDD)
Measuring Drug Utilization
The Defined Daily Dose (DDD) is a statistical unit developed to standardize drug utilization measurements. It represents the assumed average daily dose of a drug used for its main indication in adults.
DDD plays an important role in pharmacovigilance by enabling comparison of drug consumption across populations. When combined with ADR data, DDD metrics help estimate reporting rates and assess the public health impact of medicine-related risks.
International Nonproprietary Names (INN)
Universal Drug Naming System
International Nonproprietary Names (INN) provide unique, globally recognized names for pharmaceutical substances. Assigned by the WHO, INNs ensure that each active ingredient is identified consistently, regardless of brand name or manufacturer.
In pharmacovigilance, INNs reduce confusion, improve accuracy in ADR reporting, and facilitate global data exchange, especially when multiple brands exist for the same drug.
Drug Dictionaries and Coding in Pharmacovigilance
WHO Adverse Reaction Terminologies
The WHO Adverse Reaction Terminologies (WHO-ART) were among the earliest standardized coding systems for adverse reactions. They enabled structured recording and analysis of ADRs and laid the foundation for modern terminology systems.
MedDRA and Standardised MedDRA Queries (SMQs)
The Medical Dictionary for Regulatory Activities (MedDRA) is the most widely used terminology in global pharmacovigilance. Developed under the auspices of the International Council for Harmonisation (ICH), MedDRA provides a hierarchical structure for coding adverse events, indications, and medical history.
Standardised MedDRA Queries (SMQs) are predefined sets of MedDRA terms designed to identify specific safety issues, such as liver injury or cardiac disorders. SMQs enhance consistency and efficiency in signal detection and regulatory review.
WHO Drug Dictionary
The WHO Drug Dictionary is a comprehensive global database of medicinal products, including information on active ingredients, dosage forms, and ATC codes. It supports accurate drug identification and coding in pharmacovigilance systems, especially in multinational safety databases.
EudraVigilance Medicinal Product Dictionary
The EudraVigilance Medicinal Product Dictionary supports the European pharmacovigilance system by standardizing product information reported in ADR cases. Managed by the European Medicines Agency (EMA), it ensures harmonized reporting across European Union member states.
Information Resources in Pharmacovigilance
Basic Drug Information Resources
Basic pharmacovigilance resources include pharmacopoeias, drug formularies, prescribing information, and regulatory guidelines. These resources provide foundational data on drug indications, dosing, contraindications, and known adverse effects.
Specialized Resources for ADRs
Specialized ADR resources include safety databases, published literature, signal detection reports, and regulatory safety alerts. Access to these resources enables pharmacovigilance professionals to evaluate emerging risks and support evidence-based regulatory decisions.
Establishing a Pharmacovigilance Programme
Pharmacovigilance in Hospitals
Hospital-based pharmacovigilance programmes focus on detecting and reporting ADRs in clinical practice. They involve training healthcare professionals, establishing reporting systems, and analyzing local safety data to improve patient care.
Drug Safety Departments in Industry
In the pharmaceutical industry, drug safety departments manage global pharmacovigilance activities, including case processing, signal detection, and regulatory reporting. These departments ensure compliance with national and international safety requirements throughout a product’s lifecycle.
Role of Contract Research Organisations (CROs)
Contract Research Organisations (CROs) support pharmacovigilance activities by providing specialized services such as case processing, literature monitoring, and safety database management. CROs play a key role in outsourcing pharmacovigilance functions while maintaining regulatory compliance.
Establishing a National Pharmacovigilance Programme
National programmes coordinate ADR reporting, data analysis, and regulatory action at a country level. They integrate hospitals, industry, and regulators into a unified system, contributing to global pharmacovigilance networks and improving public health outcomes.