Drug A Interaction with drug B Effect on A (mechanism)
Carbamazepine enzymatic inhibitors, verapamil (↓ biotransformation of A)
Cyclosporine enzymatic inhibitors (↓ biotransformation of A)
  enzymatic inducers (↑ biotransformation of A)
Digoxin amiodarone, diltiazem, verapamil, ACEi, NSAIDs (↓ excretion of A)
atorvastatin (unknown)
antiacids (with Mg2+ or Al3+), cholestyramine, colestipol (↓ absorption of A)
Lithium NSAIDs, diuretic tiazídicos (↓ excretion of A)
Quinolones cholestyramine, colestipol (↓ absorption of A)
  enzymatic inhibitors, quinolones (↓ biotransformation of A)
Theophylline enzymatic inducers (↑ biotransformation of A)
Thyroxine enzymatic inducers (↑ biotransformation of A)
TCA enzymatic inhibitorsa (↓ biotransformation of A)
  Warfarin enzymatic inducersb (↑ biotransformation of A)
cholestyramine, colestipol (↓ absorption and ↑ excretion of A)
  enzymatic inhibitors (↑ biotransformation of A)
enzymatic inducers (↑ biotransformation of A)
clofibrate, danazol, gemfibrozil, NSAIDs, phenytoin, stanozolol, tamoxifen, thyroxine (pharmacodynamic and/or pharmacokinetic potentialization)
aExamples of well-known inhibitors: amiodarone, fluconazole, miconazole, ketoconazole, erythromycin, clarithromycin, sulfonamides, omeprazole, cimetidine and ciprofloxacin.
bExemples of well-known inducers: rifampin, phenobarbital, phenytoin, primidone and carbamazepine.
(↑) Increase; (↓) Decrease
ACEi – angiotensin converting enzyme inhibitors; NSAIDs - Non-steroidal antiinflammatory drugs; TCA – Tricyclic antidepressants
Table 3: Pharmacological interactions of clinical importance in the elderly.