Table 3.
Common Interacting Drug Combinations
| Severity | Combinations | Frequency | Potential Adverse Outcome |
|---|---|---|---|
| Contraindicated | Propranolol + salbutamol | 1 | Constriction of bronchi |
| Carbamazepine + nifedipine | 1 | Decrease nifedipine | |
| Major | Amlodipine + phenytoin | 6 | Increase phenytoin concentration |
| Amlodipine + simvastatin | 3 | Increase simvastatin concentration | |
| Meloxicam + furosemide | 2 | Diminish diuretic effect | |
| Risperidone + carbamazepine | 1 | Depression | |
| Indomethacin + methotrexate | 1 | Methotrexate increase | |
| Moderate | Enalapril + furosemide | 69 | Hypotension/nephrotoxicity |
| Spironolactone + enalapril | 57 | Hyperkalemia | |
| Enalapril + hydrochlorothiazide | 46 | Enhance nephrotoxicity | |
| Metformin + glibenclamide | 42 | Hypoglycemia | |
| Aspirin + enalapril | 34 | Nephrotoxicity | |
| Metformin + enalapril | 32 | Lactic acidosis | |
| Spironolactone + digoxin | 23 | Increase digoxin | |
| Metformin + HCT | 19 | Hyperglycemia | |
| Furosemide + digoxin | 19 | Increase cardiac glycoside | |
| Phenobarbital + carbamazepine | 14 | CNS Depression | |
| Phenytoin + phenobarbital | 14 | CNS depression | |
| ASA + furosemide | 13 | Decrease loop diuretics | |
| Metoprolol + digoxin | 12 | Bradycardia | |
| Atenolol + digoxin | 12 | Bradycardia | |
| ASA + metformin | 9 | Hypoglycemia | |
| ASA + NPH | 7 | Hypoglycemia | |
| Atenolol + nifedipine | 6 | Hypotension | |
| Spironolactone + atorvastatin | 5 | Increase spironolactone effect | |
| Minor | NPH + enalapril | 13 | Hypoglycemia |
| Beclomethasone + salbutamol | 5 | Hypokalemia | |
| Atenolol + PTU | 7 | Increase atenolol | |
| PTU + propranolol | 7 | Increase propranolol | |
| Aspirin + phenytoin | 5 | Increase phenytoin | |
| Indomethacin + amlodipine | 4 | Diminish hypertensive |
Abbreviations: ASA, aspirin; HCT, hydrochlorothiazide; NPH, neutral protamine hagedorn insulin; PTU, propylthiouracil.