Clinical Pharmacology in Old Persons

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 inducers^1	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 inducers^1	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 inhibitors^2	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.