ClinicalTrials.gov Database

Query the U.S. National Library of Medicine's clinical trials registry through API v2. Public access, no authentication required.

Triggers

• User asks about ongoing or completed clinical trials
• User needs trial details for a specific drug/intervention
• User wants to track recruitment status
• User is analyzing trial landscape for a cardiology topic
• User needs NCT numbers for references

Core Capabilities

API Technical Details

• Rate limit: ~50 requests/minute
• Response formats: JSON, CSV
• Max page size: 1000 studies per request
• Date format: ISO 8601

Example Searches

Cardiology Trial Discovery

# Find active heart failure trials
GET /studies?query.cond=heart+failure&filter.overallStatus=RECRUITING

# SGLT2 inhibitor trials in cardiology
GET /studies?query.intr=SGLT2+inhibitor&query.cond=cardiovascular

# Trials at major academic centers
GET /studies?query.locn=Cleveland+Clinic&query.cond=coronary+artery+disease

# Phase 3 trials for new anticoagulants
GET /studies?query.intr=anticoagulant&filter.phase=PHASE3

Common Status Values

• RECRUITING - Currently enrolling
• ACTIVE_NOT_RECRUITING - Ongoing, enrollment closed
• COMPLETED - Trial finished
• TERMINATED - Stopped early
• WITHDRAWN - Never started enrollment

Workflow Integration

For Newsletter/Editorial Content

1. Search for recent trial results in target area
2. Identify landmark trials by enrollment size and phase
3. Pull NCT IDs for proper citation
4. Cross-reference with PubMed for published results
5. Note primary endpoints and key secondary outcomes

For Trial Analysis Pieces

1. Retrieve full study record via NCT ID
2. Extract: design, enrollment, endpoints, sponsor
3. Compare with published results if available
4. Assess trial quality (blinding, randomization, sample size)
5. Contextualize within existing evidence

Key Fields to Extract

Best Practices

• Always cite NCT number when discussing trials
• Note enrollment numbers for context on power
• Distinguish between primary and secondary endpoints
• Check for related publications in PubMed
• Note funding source for potential bias assessment