Drug-Drug Interactions
Potential interactions between medications in the SgTxGNN database.
Overview
Drug-drug interactions (DDIs) occur when one medication affects the action of another. Understanding DDIs is crucial for:
- Safe prescribing
- Avoiding adverse effects
- Optimising therapeutic outcomes
Search Interactions
Interactive search coming soon
For now, individual drug pages include interaction information. See the Drug Reports section.
Interaction Categories
By Mechanism
| Category | Description | Example |
|---|---|---|
| Metabolic | CYP450 enzyme interactions | Ketoconazole + Simvastatin |
| Transport | P-gp and transporter effects | Cyclosporine + Digoxin |
| Receptor | Competing at same receptors | Fluoxetine + Tramadol |
| Additive | Combined similar effects | NSAIDs + Anticoagulants |
By Severity
| Level | Action Required |
|---|---|
| Critical | Combination generally contraindicated |
| Serious | Alternative recommended or close monitoring |
| Moderate | May require dose adjustment |
| Minor | Minimal clinical significance |
Common High-Risk Interactions
Anticoagulants
| Drug | Interacting Class | Effect |
|---|---|---|
| Warfarin | NSAIDs | Increased bleeding risk |
| Warfarin | Antibiotics | INR changes |
| DOACs | P-gp inhibitors | Increased levels |
Cardiovascular
| Drug | Interacting Drug | Effect |
|---|---|---|
| Statins | CYP3A4 inhibitors | Myopathy risk |
| Digoxin | Amiodarone | Toxicity risk |
| ACE inhibitors | Potassium supplements | Hyperkalaemia |
CNS Medications
| Drug | Interacting Class | Effect |
|---|---|---|
| SSRIs | MAOIs | Serotonin syndrome |
| Benzodiazepines | Opioids | Respiratory depression |
| Antipsychotics | QT-prolonging drugs | Arrhythmia risk |
Interaction Mechanisms
CYP450 System
Key enzymes and their clinical significance:
| Enzyme | Major Substrates | Notable Inhibitors |
|---|---|---|
| CYP3A4 | Statins, Calcium channel blockers | Ketoconazole, Grapefruit |
| CYP2D6 | Codeine, Tamoxifen | Fluoxetine, Paroxetine |
| CYP2C9 | Warfarin, Phenytoin | Fluconazole |
| CYP2C19 | Clopidogrel, PPIs | Omeprazole |
P-glycoprotein
| Effect | Clinical Consequence |
|---|---|
| Inhibition | Increased substrate absorption |
| Induction | Decreased substrate levels |
Data Sources
| Source | Coverage |
|---|---|
| DDInter | 240,000+ interaction pairs |
| DrugBank | Mechanism-based interactions |
| HSA Alerts | Singapore-specific warnings |
API Access
Query interactions programmatically:
# Check interaction between two drugs
curl "https://sgtxgnn.yao.care/api/ddi?drugA=DB00945&drugB=DB00374"
Response:
{
"drugA": "Aspirin",
"drugB": "Warfarin",
"interaction": true,
"severity": "serious",
"description": "Increased risk of bleeding",
"mechanism": "Additive antiplatelet and anticoagulant effects"
}
Clinical Use Warning
This database is for research purposes. Clinical decisions about drug combinations should involve pharmacist review and consideration of individual patient factors.
This database is for research purposes. Clinical decisions about drug combinations should involve pharmacist review and consideration of individual patient factors.