Table 8.
The most common drug interactions in elderly patients [12].
| Drug | Interaction | Effect |
|---|---|---|
| ACE inhibitors | NSAIDs, Coxibs, potassium-sparing diuretics | Decreased renal function, hyperkalemia |
| Antidepressants | Enzyme inducers1 | Less antidepressant effect |
| Antihypertensives | Vasodilators, antipsychotic drug, tricyclic antidepressants | Increased antihypertensive effect |
| NSAIDs | Decreased antihypertensive effect | |
| Beta-receptor-blocking drugs | Anti-diabetic drugs | Masks hypoglycemia |
| Fluoxetine, paroxetine (especially in combination with metoprolol and propranolol) | Bradycardia | |
| Corticosteroids (oral) | NSAIDs | Gastro-duodenal ulcer disease |
| enzyme inducers1 | Decreased corticosteroid effect | |
| Digoxin | NSAIDs, diuretics, qinidine, verapamil, diltiazem, amiodarone | Digoxin intoxication |
| Fluoroquinolones | Al-Mg containing antacids, iron, calcium | Decreased bioavailability |
| Levodopa | Iron | Decreased bioavailability |
| Lithium | NSAIDs, thiazide diuretics, antipsychotics | Lithium toxicity |
| Phenytoin | Enzyme inhibitors2 | Increased toxicity |
| Sulfonylurea anti-diabetics | SSRIs, chloramphenicol, VKA's, phenylbutazone | Hypoglycemia |
| SSRIs | Diuretics, NSAIDs | Hyponatremia, gastric bleeding |
| Tetracyclines | Antacids, iron | Decreased bioavailability |
| VKA's | Acetylsalicylic acid, NSAIDs, metronidazole, miconazole and other azole-type drugs | Bleeding |
1Important enzyme inducers: carbamazepine, rifampicin, phenobarbital, phenytoin, St. John's wort.
2Important enzyme inhibitors: verapamil, diltiazem, amiodarone, fluconazole, miconazole, ketoconazole, erythromycin, claritromycin, sulfonamides, cimetidine, ciprofloxacin, and grapefruit juice.