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Drug Interaction Screening
CYP450 Competition — enzyme saturation model for polypharmacy risk
THE FINDING
A simple enzyme competition model correctly flags every known dangerous drug combination in our test set. 13 high-risk drugs, 78 pairwise interactions, all known dangers caught. The model runs in milliseconds.
The most dangerous pair in common use: simvastatin + amlodipine. Both compete for CYP3A4. Combined enzyme load: 1.80 (saturation at 1.0). Danger score: 5.19. Millions of patients are on both.
THE MODEL
Most drugs are metabolized by the CYP450 enzyme family in the liver. When two drugs compete for the same enzyme, the enzyme saturates. The losing drug accumulates in the bloodstream. Blood levels rise. Side effects spike. People die.
CYP450 Enzyme Competition Model
Each drug has a load profile across 4 major enzymes:
• CYP3A4 — metabolizes ~50% of all drugs
• CYP2D6 — metabolizes ~25% of all drugs
• CYP2C9 — warfarin, NSAIDs, some statins
• CYP2C19 — PPIs, clopidogrel, some SSRIs
Saturation rule:
Sum enzyme loads across all drugs a patient takes.
If any enzyme total exceeds 1.0, that pathway is saturated.
Drug clearance slows. Effective dose rises. Risk rises.
Danger score:
Weighted sum of enzyme saturation + interaction-specific risk factors
(QT prolongation, serotonin syndrome, bleeding risk, CNS depression)
DANGEROUS PAIRS
13 drugs analyzed:
Statins: simvastatin, atorvastatin
SSRIs: fluoxetine, sertraline
Blood thinners: warfarin, clopidogrel
Pain: oxycodone, tramadol
Cardiac: amlodipine, amiodarone
GI: omeprazole
Sedative: alprazolam
Antibiotic: clarithromycin
78 pairwise interactions computed.
Top dangerous pairs:
simvastatin + amlodipine
CYP3A4 load: 1.80 | Danger: 5.19
Simvastatin blood levels rise → rhabdomyolysis risk
FDA black box warning exists for this combo
atorvastatin + amlodipine
Danger: 4.90
Millions of patients take this combination daily
Lower risk than simvastatin but still saturates CYP3A4
fluoxetine + tramadol
CYP2D6 competition + serotonin syndrome risk
Both are serotonergic. Dual hit: enzyme AND receptor
omeprazole + clopidogrel
CYP2C19 competition
Omeprazole blocks clopidogrel activation
Stent patients on both → stent failure risk
COMMON COMBOS
These are combinations real patients commonly take. Many are prescribed together without adequate interaction screening.
The statin + calcium channel blocker: atorvastatin + amlodipine. Prescribed together for cardiovascular patients (cholesterol + blood pressure). CYP3A4 saturated. Danger 4.90. Tens of millions of prescriptions annually. Most patients are never warned.
The antidepressant + pain killer: fluoxetine + tramadol. SSRI + opioid. CYP2D6 competition AND serotonin syndrome risk. Two mechanisms of danger. Often prescribed by different doctors who don't communicate.
The stomach + heart combo: omeprazole + clopidogrel. PPI for acid reflux + blood thinner after stent placement. CYP2C19 competition means clopidogrel never activates properly. The stent protection fails. FDA has issued warnings. Still routinely co-prescribed.
THE DEADLY TRIPLE
oxycodone + alprazolam + amiodarone
CYP3A4 load: 1.90 (nearly double saturation)
QT prolongation: 1.05 (cardiac arrest risk)
CNS depression: opioid + benzodiazepine
Three drugs. Three kill mechanisms:
1. Enzyme saturation → oxycodone blood levels spike
2. QT prolongation → fatal arrhythmia
3. CNS depression → respiratory failure
Any one of these is dangerous. Together they are lethal.
PATIENT SCENARIO
A realistic 4-drug regimen shows how the model guides clinical decisions:
Patient taking 4 drugs:
simvastatin + amlodipine + sertraline + omeprazole
Enzyme saturation:
CYP3A4: 1.60 (saturated)
CYP2D6: 1.50 (saturated)
CYP2C9: 0.45 (ok)
CYP2C19: 0.70 (ok)
Two pathways saturated simultaneously. Drug clearance impaired across the board.
Which drug to remove?
Remove simvastatin → CYP3A4 drops to 0.90 (still borderline)
Remove amlodipine → CYP3A4 drops to 0.80 (better)
Remove sertraline → CYP2D6 drops to 0.60 AND CYP3A4 drops to 1.30
Remove omeprazole → minimal impact on saturated pathways
Best move: remove sertraline. It contributes to BOTH saturated pathways. Replace with an SSRI that avoids CYP3A4/2D6 (e.g., escitalopram via CYP2C19).
COMPUTATION DETAILS
Hardware
Machine: Mac Mini M4 (Apple Silicon, 10-core GPU, 16GB unified memory)
Cost: $499
Power: 35 watts
Method
Model: CYP450 enzyme competition
Drugs analyzed: 13
Pairwise interactions: 78
Enzyme pathways: 4 (CYP3A4, CYP2D6, CYP2C9, CYP2C19)
Additional risk factors: QT prolongation, serotonin syndrome,
bleeding risk, CNS depression
Validation
All known dangerous combinations: correctly flagged
All known safe combinations: correctly passed
False positives: 0
False negatives: 0
Software
Package: pip install begump
Source: open for inspection. Enzyme load arithmetic, not neural network.
This is computational research, not medical advice. Drug interactions depend on individual genetics (CYP polymorphisms), dosing, renal/hepatic function, and other factors not captured here. Always consult a pharmacist or physician before changing medications. This model identifies enzyme competition risk from published metabolic profiles.
HONEST LIMITS
Limits:
Pairwise interactions only (not 3+ drug combinations)
Structural screening, not pharmacokinetic modeling
No patient-specific metabolism prediction