Identifies clinically significant drug-drug, drug-food, and drug-disease interactions with severity grading and management recommendations. Use when checking drug interactions, evaluating polypharmacy risks, or managing medication combinations.
Identifies clinically significant drug-drug, drug-food, and drug-disease interactions with severity grading and management recommendations.
Drug interactions account for approximately 3-5% of all in-hospital medication errors and are a leading cause of preventable adverse drug events. The clinical consequences range from therapeutic failure (e.g., reduced efficacy of oral contraceptives with rifampin) to life-threatening toxicity (e.g., serotonin syndrome from SSRI-MAOI combinations, QT prolongation from concurrent QTc-prolonging agents). Polypharmacy patients—particularly elderly individuals on 5+ medications—face exponentially increasing interaction risk.
Pharmacists are the final safety net before a drug reaches the patient. Robust interaction assessment requires knowledge of cytochrome P450 enzyme systems (CYP3A4, CYP2D6, CYP2C19, CYP1A2), P-glycoprotein transport, renal tubular secretion competition, and pharmacodynamic synergism/antagonism. Regulatory bodies including the Joint Commission (NPSG.03.05.01) and CMS Conditions of Participation mandate prospective drug utilization review for every dispensed prescription. Failure to identify a clinically significant interaction constitutes a deviation from the standard of care and carries malpractice liability.
List every active pharmaceutical ingredient the patient is receiving. Include:
Assign each substance its primary metabolic pathway:
| CYP Enzyme | Common Substrates | Common Inhibitors | Common Inducers |
|---|---|---|---|
| CYP3A4 | Simvastatin, cyclosporine, midazolam | Ketoconazole, clarithromycin, ritonavir | Rifampin, phenytoin, carbamazepine |
| CYP2D6 | Codeine, metoprolol, fluoxetine | Paroxetine, fluoxetine, bupropion | Not significantly inducible |
| CYP2C19 | Clopidogrel, omeprazole, voriconazole | Fluconazole, fluvoxamine, omeprazole | Rifampin, St. John's wort |
| CYP2C9 | Warfarin, phenytoin, losartan | Fluconazole, amiodarone, metronidazole | Rifampin |
| CYP1A2 | Theophylline, clozapine, caffeine | Fluvoxamine, ciprofloxacin | Smoking, omeprazole (minor) |
Run each combination through at least two independent drug interaction databases. Classify each identified interaction:
Severity Grading (use Lexicomp/Micromedex concordance):
Mechanism Classification:
Not all flagged interactions require intervention. Assess clinical significance by:
For each clinically significant interaction, provide one of:
Document the supporting evidence level for each recommendation (clinical guideline, pharmacokinetic study, case series, or mechanistic rationale).
Structure the final output as: