Multi-Drug Interaction Checker

Check drug interactions across multiple medications with complete FDA evidence. Build safety systems for complex patients on polypharmacy with instant, verifiable interaction detection.

The Problem

Complex Drug Regimens Create Dangerous Interaction Risks

Polypharmacy patients at high risk: Elderly patients on 10+ medications face exponential interaction complexity. Manually checking all pairwise interactions is impractical.

Generic drug databases miss context: Static interaction checkers show generic warnings but don't provide FDA evidence or severity reasoning.

Alert fatigue from false positives: Systems flag every theoretical interaction, overwhelming clinicians with alerts. No way to prioritize by actual clinical significance.

No evidence trail: When adverse events occur, impossible to prove what interaction warnings were available at prescribing time.

The Solution

Comprehensive Interaction Analysis with Lemma Reasoning API

Build an interaction checker that queries Lemma's Reasoning API for every drug pair in a patient's regimen. Get structured interaction data with severity levels, mechanism descriptions, and complete FDA evidence. Prioritize alerts by clinical significance with verifiable sources.

Check all pairwise interactions instantly (100+ drug pairs in seconds)

Severity-based prioritization (life-threatening → mild)

Complete FDA evidence with mechanism explanations

Cryptographic fingerprints for audit trail and liability protection

How It Works

1

Load Patient Medication List

System receives patient's current medications: 12 drugs including warfarin, aspirin, metformin, lisinopril, and others.

2

Generate All Drug Pairs

Create all pairwise combinations: 12 drugs = 66 possible interactions to check. System queries each pair in parallel for speed.

3

Query Lemma Reasoning API

For each pair: "Does drug A interact with drug B?" Get structured results with severity, mechanism, and FDA evidence.

4

Prioritize and Alert

Sort interactions by severity. Display life-threatening and serious interactions prominently with complete FDA evidence and actionable recommendations.

Complete Interaction Check Flow

1

Patient's Current Medications

Active Medications (12 drugs):

Warfarin 5mg
Aspirin 81mg
Metformin 1000mg
Lisinopril 10mg
Atorvastatin 40mg
Omeprazole 20mg
Levothyroxine 100mcg
Amlodipine 5mg
Furosemide 40mg
Gabapentin 300mg
Albuterol PRN
Ibuprofen PRN

66 possible drug pair interactions to check

2

Query All Drug Pairs (Parallel)

POST /v1/graph - Pair 1
{
  "question": "Does warfarin interact with aspirin?"
}
POST /v1/graph - Pair 2
{
  "question": "Does warfarin interact with ibuprofen?"
}

... 64 more queries processed in parallel ...

3

Structured Interaction Results

200 OK - Interaction Found
{
  "results": [
    {
      "drug": {
        "name": "warfarin",
        "brand_names": ["Coumadin"]
      },
      "relationship": {
        "type": "interaction",
        "condition": "increased bleeding risk with antiplatelet agents",
        "severity": "serious"
      },
      "evidence": [
        {
          "text": "Antiplatelet agents (e.g., aspirin) increase the risk of bleeding...",
          "fingerprint": "11001100110011001100110011001100...",
          "section": "Drug Interactions",
          "source": {
            "url": "https://dailymed.nlm.nih.gov/..."
          }
        }
      ]
    }
  ]
}
4

Prioritized Interaction Report

Warfarin + Aspirin

SERIOUS

Increased bleeding risk with antiplatelet agents. Both drugs affect blood clotting mechanisms.

FDA Evidence:

"Antiplatelet agents (e.g., aspirin) increase the risk of bleeding..."

[fp:11001100110011001100110011001100...]

⚠️ Recommendation:Monitor INR closely. Consider alternative antiplatelet if possible.

Lisinopril + Furosemide

MODERATE

Hypotension risk when combined. Monitor blood pressure especially during initiation.

Interaction Check Complete

• Checked: 66 drug pairs

• Serious interactions: 2

• Moderate interactions: 5

• Mild interactions: 8

• All interactions backed by FDA evidence with fingerprints

Implementation Code

Python - Multi-Drug Interaction Checker
import requests
import asyncio
from itertools import combinations
from typing import List, Dict

LEMMA_API_KEY = "your_api_key"

class InteractionChecker:
    """
    Multi-drug interaction checker for polypharmacy patients.
    Checks all pairwise interactions with FDA evidence.
    """
    
    def __init__(self, api_key: str):
        self.api_key = api_key
        self.base_url = "https://api.lemma.la/v1"
    
    async def check_all_interactions(self, medications: List[str]) -> Dict:
        """
        Check all pairwise drug interactions.
        Returns: prioritized interaction report with FDA evidence.
        """
        # Generate all drug pairs
        drug_pairs = list(combinations(medications, 2))
        print(f"Checking {len(drug_pairs)} drug pairs...")
        
        # Query all pairs in parallel
        tasks = [
            self._check_pair(drug1, drug2)
            for drug1, drug2 in drug_pairs
        ]
        results = await asyncio.gather(*tasks)
        
        # Filter and prioritize interactions
        interactions = [r for r in results if r is not None]
        interactions.sort(key=lambda x: self._severity_score(x['severity']), reverse=True)
        
        return {
            "total_pairs_checked": len(drug_pairs),
            "interactions_found": len(interactions),
            "interactions": interactions,
            "summary": self._generate_summary(interactions)
        }
    
    async def _check_pair(self, drug1: str, drug2: str) -> Dict:
        """Check if two drugs interact using Reasoning API."""
        response = requests.post(
            f"{self.base_url}/graph",
            headers={
                "x-api-key": self.api_key,
                "Content-Type": "application/json"
            },
            json={
                "question": f"Does {drug1} interact with {drug2}?"
            }
        )
        
        response_data = response.json()
        data = response_data.get('data', response_data)
        
        if data.get('results'):
            result = data['results'][0]
            return {
                "drug1": drug1,
                "drug2": drug2,
                "severity": result['relationship']['severity'],
                "condition": result['relationship']['condition'],
                "mechanism": result['relationship'].get('mechanism', 'Not specified'),
                "evidence": result['evidence'],
                "recommendation": self._generate_recommendation(
                    result['relationship']['severity'],
                    result['relationship']['condition']
                )
            }
        return None
    
    def _severity_score(self, severity: str) -> int:
        """Convert severity to numeric score for prioritization."""
        scores = {
            "life_threatening": 4,
            "serious": 3,
            "moderate": 2,
            "mild": 1
        }
        return scores.get(severity, 0)
    
    def _generate_recommendation(self, severity: str, condition: str) -> str:
        """Generate clinical recommendation based on interaction."""
        if severity == "life_threatening":
            return "CONTRAINDICATED - Do not use together"
        elif severity == "serious":
            return "Use with caution - Monitor closely and consider alternatives"
        elif severity == "moderate":
            return "Monitor patient - Adjust doses if needed"
        else:
            return "Be aware - Inform patient of potential interaction"
    
    def _generate_summary(self, interactions: List[Dict]) -> Dict:
        """Generate summary statistics by severity."""
        summary = {
            "life_threatening": 0,
            "serious": 0,
            "moderate": 0,
            "mild": 0
        }
        
        for interaction in interactions:
            severity = interaction['severity']
            if severity in summary:
                summary[severity] += 1
        
        return summary
    
    def generate_report(self, results: Dict, patient_info: Dict = None) -> str:
        """
        Generate human-readable interaction report.
        """
        report = []
        report.append("=" * 60)
        report.append("DRUG INTERACTION ANALYSIS REPORT")
        report.append("=" * 60)
        
        if patient_info:
            report.append(f"\nPatient: {patient_info.get('name', 'Unknown')}")
            report.append(f"Age: {patient_info.get('age', 'Unknown')}")
        
        report.append(f"\nTotal pairs checked: {results['total_pairs_checked']}")
        report.append(f"Interactions found: {results['interactions_found']}")
        
        summary = results['summary']
        report.append(f"\nSeverity Breakdown:")
        report.append(f"  Life-threatening: {summary['life_threatening']}")
        report.append(f"  Serious: {summary['serious']}")
        report.append(f"  Moderate: {summary['moderate']}")
        report.append(f"  Mild: {summary['mild']}")
        
        if results['interactions']:
            report.append(f"\n{'=' * 60}")
            report.append("DETAILED INTERACTIONS")
            report.append("=" * 60)
            
            for i, interaction in enumerate(results['interactions'], 1):
                report.append(f"\n{i}. {interaction['drug1']} + {interaction['drug2']}")
                report.append(f"   Severity: {interaction['severity'].upper()}")
                report.append(f"   Condition: {interaction['condition']}")
                report.append(f"   Recommendation: {interaction['recommendation']}")
                
                if interaction['evidence']:
                    report.append(f"   FDA Evidence:")
                    for evidence in interaction['evidence'][:2]:  # Show first 2 pieces
                        report.append(f"     - {evidence['text'][:100]}...")
                        report.append(f"       [fp:{evidence['fingerprint'][:30]}...]")
        
        return "\n".join(report)

# Example usage
async def main():
    checker = InteractionChecker(LEMMA_API_KEY)
    
    patient_medications = [
        "warfarin", "aspirin", "metformin", "lisinopril",
        "atorvastatin", "omeprazole", "levothyroxine",
        "amlodipine", "furosemide", "gabapentin",
        "albuterol", "ibuprofen"
    ]
    
    print(f"Analyzing {len(patient_medications)} medications...")
    results = await checker.check_all_interactions(patient_medications)
    
    # Generate report
    report = checker.generate_report(
        results,
        patient_info={"name": "Patient #12345", "age": 72}
    )
    
    print(report)
    
    # Save fingerprints for audit trail
    with open("interaction_audit_trail.json", "w") as f:
        json.dump({
            "timestamp": datetime.now().isoformat(),
            "medications": patient_medications,
            "interactions": results['interactions']
        }, f, indent=2)

# Run
asyncio.run(main())

Why This Works

Handles Complex Polypharmacy

Checks 100+ drug pairs in seconds with parallel queries. Scales to any number of medications without performance degradation.

Severity-Based Prioritization

Automatically prioritizes life-threatening and serious interactions. Reduces alert fatigue by showing clinicians what matters most.

Complete FDA Evidence

Every interaction backed by exact FDA label text with mechanism explanations. Clinicians see why drugs interact, not just that they do.

Audit Trail for Liability

Fingerprints stored with patient record prove exactly what interaction warnings were available. Complete liability protection for adverse events.

Ready to Build?

Build interaction checkers that handle complex polypharmacy cases with complete FDA evidence and cryptographic proof.