Introduction
The Medical Dictionary for Regulatory Activities (MedDRA) is a standardized multilingual terminology developed by the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH).
Its main goal is to provide a single, consistent, and internationally accepted medical language for:
- Regulatory authorities (FDA, EMA, PMDA, CDSCO, etc.)
- Pharmaceutical companies
- Contract research organizations (CROs)
- Academic researchers
- Healthcare professionals
By harmonizing terminology, MedDRA ensures that adverse events, drug indications, laboratory tests, procedures, and medical history are captured and shared consistently across the globe.
The Need for MedDRA
Before MedDRA, multiple terminologies like WHO-ART (Adverse Reaction Terminology), COSTART, HARTS, J-ART were used. This created confusion and inconsistency in global pharmacovigilance and clinical trials.
MedDRA solved this by providing:
- A single global standard for regulatory activities.
- Coverage of all medical domains (not just adverse reactions).
- Regular updates to keep pace with scientific and medical advancements.
Hierarchical Structure of MedDRA (With Examples)
MedDRA’s five-level hierarchy ensures both detailed reporting and broad data analysis.
System Organ Class (SOC) – Broadest classification
Example: Cardiac disorders
High Level Group Term (HLGT) – Grouping of related medical conditions
Example: Cardiac arrhythmias
High Level Term (HLT) – Subdivision for better granularity
Example: Supraventricular arrhythmias
Preferred Term (PT) – Standard single medical concept
Example: Atrial fibrillation
Lowest Level Term (LLT) – Synonyms, spelling variations, medical slang
Example: Irregular heartbeat, AFib, Auricular fibrillation
This hierarchy allows precise data entry (LLTs) and aggregate analysis (SOCs).
MedDRA in Pharmacovigilance (Step-by-Step Usage)
Adverse Event Reporting
A patient reports “feeling dizzy with high BP.”
This is coded using MedDRA as LLT “Raised blood pressure” → PT “Hypertension.”
ICSR Coding
The event is entered in an Individual Case Safety Report (ICSR).
MedDRA ensures that regulators globally understand the same medical term.
Signal Detection
Aggregated reports coded in MedDRA are analyzed for trends.
Example: If multiple ICSRs show “QT prolongation,” regulators may issue a warning.
Regulatory Submission
NDAs, PSURs, DSURs all require adverse events coded in MedDRA.
Without MedDRA, cross-border pharmacovigilance would be inconsistent and less reliable.
MedDRA Versioning and Updates
- MedDRA is updated twice a year (March & September).
- Each update may include:
- New LLTs/PTs for emerging diseases (e.g., COVID-19 related terms were added in 2020).
- Deactivation of redundant terms.
- Reclassification within hierarchy.
- Users must synchronize their databases with the latest MedDRA version.
Training and Certification
The MSSO provides:
- Free online training courses.
- Paid advanced courses for coding experts.
- Certification exams to validate MedDRA expertise.
This is especially useful for professionals working in pharmacovigilance, clinical trials, and regulatory submissions.
Benefits of MedDRA
✅ Regulatory compliance – Required by FDA, EMA, PMDA.
✅ Global harmonization – Used in >120 countries.
✅ Detailed & comprehensive – Covers >80,000 terms.
✅ Multilingual – Available in 11+ languages.
✅ Consistency – Same AE coded in Japan, Europe, or US will mean the same thing.
Limitations of MedDRA
⚠️ License required – Commercial users must pay.
⚠️ Complexity – Large structure may overwhelm new users.
⚠️ Training essential – Incorrect coding may affect regulatory reports.
⚠️ Version management – Frequent updates require alignment.
MedDRA vs. Other Dictionaries
| Feature | MedDRA (ICH) | WHO-ART | SNOMED CT | COSTART |
| Primary Focus | Drug safety, regulatory | Drug safety (older) | Clinical care | Drug safety (older) |
| Hierarchy | 5 levels | 4 levels | Complex (multi-level) | 4 levels |
| Global Acceptance | Very High | Low | High | Very Low |
| Updates | Biannual | Minimal | Regular | Obsolete |
Future of MedDRA
- AI/NLP integration – For automatic AE coding.
- Rare diseases & gene therapies – Expanding coverage.
- Big Data analytics – Use in RWE (Real World Evidence).
- Greater globalization – Adoption in emerging markets like India, Africa, and Latin America.
Download MedDRA PDF
👉 You can access the latest MedDRA PDF and resources from the official site:
🔗 https://www.meddra.org
⚠️ Note: Since MedDRA is licensed, you may need to register for access.
Frequently Asked Questions (FAQs)
Q1: What is MedDRA used for?
✔ MedDRA is used for coding, reporting, and analyzing adverse events, indications, medical history, and procedures in pharmacovigilance and clinical trials.
Q2: Is MedDRA free?
✔ Non-commercial users (academia, regulators) can access it free, but commercial organizations need a paid license.
Q3: How often is MedDRA updated?
✔ Twice a year – in March and September.
Q4: Who maintains MedDRA?
✔ The MSSO (MedDRA Maintenance and Support Services Organization).
Q5: How many languages is MedDRA available in?
✔ More than 11 languages including English, Japanese, French, Spanish, and Chinese.
References
- Brown EG, Wood L, Wood S. The medical dictionary for regulatory activities (MedDRA). Drug Saf. 1999;20(2):109-117.
- Mozzicato P. MedDRA: an overview of the medical dictionary for regulatory activities. Pharmaceut Stat. 2009;8(4):295-301.
- International Council for Harmonisation (ICH). MedDRA official website: https://www.meddra.org