Add ClinicalTrials.gov data source for evidence-based drug safety

[sarvanithin]

Overview

ClinicalTrials.gov has a free REST API with data on 500k+ trials. This can augment drug safety checks with real trial-level evidence — e.g., checking if a drug combination was studied in a trial and what the outcomes were.

API

GET https://clinicaltrials.gov/api/v2/studies?query.term=warfarin+aspirin&fields=protocolSection&pageSize=5

No API key required. Returns JSON.

What to build

• medguard/knowledge/clinicaltrials.py — ClinicalTrialsClient
  • search_trials(drug_a, drug_b) → list of relevant trial summaries
  • Cache results with diskcache (same pattern as RxNormClient)
• Hook into DrugSafetyChecker as an optional third source alongside OpenFDA and static table
• Add use_clinical_trials: bool = False to DrugSafetyConfig

Value

Catches drug interactions that appear in trials but not yet in FDA labeling. Especially useful for newer drug combinations.

Files to modify

• medguard/knowledge/clinicaltrials.py — new file
• medguard/guardrails/drug_safety.py — integrate as optional source
• medguard/config.py — add flag to DrugSafetyConfig
• tests/test_drug_safety.py — add mocked tests

Acceptance criteria

• ClinicalTrialsClient.search_trials("warfarin", "aspirin") returns results
• Results integrated into DrugSafetyResult
• Graceful fallback if API is down
• Tests with respx mocks (no real network in unit tests)