Appropriate prescribing in the elderly: Current perspectives

Table 6 Important drug interactions in older patients

Drug	Drug	Interaction	Effect
Anti- hypertensive agents	NSAID	NSAID antagonizes hypotensive effect	↓ antihypertensive effect
Aspirin	NSAID, oral corticosteroids	↑ risk of peptic ulceration	Peptic ulceration
Calcium channel blockers	Enzyme inducers	↑ clearance of calcium channel blocker	↓ anti-hypertensive effect
Digoxin	Diuretics	Diuretic-induced hypokalaemia	↑ effect of digoxin (arrhythmia, toxicity)
Digoxin	Amiodarone, Ditiazem, Verapamil	↓ clearance of digoxin	↑ effect of digoxin (arrhythmia, toxicity)
TCA	Enzyme inhibitors	↓ clearance of TCA	Arrhythmia, confusion, orthostatic hypotension, falls
Phenytoin	Enzyme inhibitors	↓ clearance of phenytoin	↑ effect of phenytoin, toxicity
Thyroxine	Enzyme inducers	↑ clearance of thyroxine	↓ effect of thyroxine

NSAID: Non-steroidal anti-inflammatory drug; TCA: Tricyclic anti-depressants.