Primary Drug | Interacting Drug/Mechanism | Effect | Management |
Adenosine | Theophylline/Inhibits the hemodynamic effects of adenosine | Decreases the antiarrhythmic effectiveness of adenosine | May require increased adenosine doses to control arrhythmia |
Dipyridamole/Decreased adenosine metabolism | Potentiates the pharmacologic effect of adenosine | Reduce the dose of adenosine for the treatment of arrhythmias or for diagnostic tests |
Nicotine/Increases the hemodynamic and AV nodal blocking effects of adenosine | Potentiates the pharmacologic effect of adenosine | Cigarette smokers or users of nicotine gum or patches should be monitored for a greater hemodynamic response to adenosine. Reduced adenosine doses may be required in these patients |
Aminoglycosides | Neuromuscular blocking agents/Prevent release of acetylcholine at neuromuscular junction | Prolonged paralysis | Monitor neuromuscular function with train-of-four stimulation |
Antipseudomonal penicillins/ Inactivate aminoglycosides in vitro and in vivo | Reduced aminoglycoside levels | Send specimens for aminoglycoside level determination to lab for immediate assay Inactivate aminoglycosides in vivo in patients with severe renal dysfunction |
Amiodarone | Cholestyramine/Increased amiodarone elimination | Decreased amiodarone level | Monitor amiodarone level, adjust amiodarone dose accordingly |
Cimetidine/Decreased amiodarone metabolism | Increased amiodarone level | Monitor amiodarone level, adjust amiodarone dose accordingly |
Cyclosporine/Decreased cyclosporine metabolism | Increased cyclosporine level | Monitor cyclosporine level, adjust cyclosporine dose accordingly |
Digoxin/Decreased digoxin clearance | Increased digoxin level | Monitor digoxin level, adjust digoxin dose accordingly |
Phenytoin/Decreased phenytoin metabolism Increased amiodarone metabolism | Increased phenytoin level Decreased amiodarone level | Monitor phenytoin and amiodarone levels, adjust doses accordingly |
Warfarin/Altered protein binding and decreased metabolism | Increased anticoagulant effect | Monitor PT/INR, adjust warfarin dose accordingly |
Anticoagulants | Amiodarone/Altered warfarin protein binding and decreased warfarin metabolism | Increased anticoagulant effect | Monitor PT/INR, adjust warfarin dose accordingly |
Barbiturates/Increased warfarin metabolism | Decreased anticoagulant effect | Monitor PT/INR, adjust warfarin dose accordingly |
Cholestyramine/Decreased warfarin absorption | Decreased anticoagulant effect | Separate doses |
Erythromycins (clarithro-, erythro-)/Decreased warfarin metabolism | Increased anticoagulant effect | Monitor PT/INR, adjust warfarin dose accordingly Consider alternative antibiotic |
Cimetidine/Decreased warfarin clearance | Increased anticoagulant effect | Monitor PT/INR, adjust warfarin dose accordingly |
Ciprofloxacin/Decreased warfarin metabolism | Increased anticoagulant effect | Monitor PT/INR, adjust warfarin dose accordingly Consider alternative antibiotic |
Fluconazole, itraconazole, ketoconazole/Decreased warfarin metabolism | Increased anticoagulant effect | Monitor PT/INR, adjust warfarin dose accordingly |
NSAIDS/Decreased platelet aggregation | Increased bleeding | Monitor for signs and symptoms of bleeding |
Metronidazole/Decreased warfarin metabolism | Increased anticoagulant effect | Monitor PT/INR, adjust warfarin dose accordingly Consider alternative antibiotic |
Propafenone/Decreased warfarin metabolism | Increased anticoagulant effect | Monitor PT/INR, adjust warfarin dose accordingly |
Rifampin/increased warfarin metabolism | Decreased anticoagulant effect | Monitor PT/INR, adjust warfarin dose accordingly |
Salicylates/Decreased platelet aggregation | Increased bleeding | Monitor for signs and symptoms of bleeding |
Sulfonamides/Altered warfarin protein binding | Increased anticoagulant effect | Monitor PT/INR, adjust warfarin dose accordingly Consider alternative antibiotic |
Proton Pump Inhibitors | Warfarin | Increased anticoagulant effect | Monitor PT/INR, adjust warfarin dose accordingly |
Phenytoin | Increased phenytoin level | Monitor phenytoin level, adjust phenytoin dose accordingly |
Linezolid | Adrenergic agents (i.e., dopamine, epinephrine) | Increased adrenergic response | Reduce and titrate adrenergic dose as needed to achieve desired response |
Serotonergic agents (i.e., fluoxetine, paroxetine, sertraline, etc.) | Increased risk for developing serotonin syndrome | Avoid combination; use alternative antibiotic if possible |
Ciprofloxacin | Foscarnet/Decreased seizure threshold | Increased risk of seizures | Monitor for seizure activity Adjust dose of each agent for degree of renal insufficiency |
Mexiletine/Decreased mexiletine metabolism | Increased mexiletine level | Monitor mexiletine level, adjust mexiletine dose accordingly |
Phenytoin/Decreased phenytoin metabolism | Increased phenytoin level | Monitor phenytoin level, adjust phenytoin dose accordingly |
Theophylline/Decreased theophylline metabolism | Increased theophylline level | Monitor theophylline level, adjust theophylline dose accordingly |
Warfarin/Decreased warfarin metabolism | Increased anticoagulant effect | Monitor PT/INR, adjust warfarin dose accordingly Consider alternative antibiotic |
Levofloxacin | Warfarin/Decreased warfarin metabolism | Increased anticoagulant effect | Monitor PT/INR, adjust warfarin dose accordingly Consider alternative antibiotic |
Cyclosporine | Anticonvulsants (phenytoin, phenobarbital, carbamazepine)/Increased cyclosporine metabolism | Decreased cyclosporine level | Monitor cyclosporine level, adjust cyclosporine dose accordingly |
Diltiazem/Decreased cyclosporine metabolism | Increased cyclosporine level | Monitor cyclosporine level, adjust cyclosporine dose accordingly Consider an alternative calcium channel blocker |
Rifampin/Increased cyclosporine metabolism | Decreased cyclosporine level | Monitor cyclosporine level, adjust cyclosporine dose accordingly |
Ketoconazole, fluconazole, itraconazole/Decreased cyclosporine metabolism | Increased cyclosporine level | Monitor cyclosporine level, adjust cyclosporine dose accordingly |
Erythromycin, clarithromycin/ Decreased cyclosporine metabolism | Increased cyclosporine level | Monitor cyclosporine level, adjust cyclosporine dose accordingly |
Aminoglycosides/ Increased nephrotoxicity | Decreased renal function | Monitor renal function |
Amphotericin B/Increased nephrotoxicity | Decreased renal function | Monitor renal function |
Metoclopramide, cisapride/Increased cyclosporine absorption | Increased cyclosporine level | Monitor cyclosporine level, adjust cyclosporine dose accordingly |
Octreotide/Decreased cyclosporine absorption | Decreased cyclosporine level | Monitor cyclosporine level, adjust cyclosporine dose accordingly |
Cimetidine, famotidine, omeprazole/Decreased cyclosporine metabolism | Increased cyclosporine level | Monitor cyclosporine level, adjust cyclosporine dose accordingly |
Digoxin | Amiodarone/Decreased elimination | Increased digoxin level | Monitor digoxin level, adjust digoxin dose accordingly |
Diuretics/Increased potassium excretion | Increased potential for digoxin toxicity | Monitor potassium level Consider the need for potassium supplements or potassium sparing diuretics |
Propafenone/Decreased volume of distribution and nonrenal clearance | Increased digoxin level | Monitor digoxin level, adjust digoxin dose accordingly |
Quinidine/Decreased binding and elimination | Increased digoxin level | Monitor digoxin level, adjust digoxin dose accordingly |
Verapamil/Decreased digoxin elimination | Increased digoxin level | Monitor digoxin level, adjust digoxin dose accordingly |
Heparin | Nitroglycerin/Altered heparin clearance | Decreased anticoagulant effect | Monitor PTT, adjust heparin infusion accordingly |
Meperidine | Monoamine oxidase inhibitors (phenelzine, tranylcypromine)/ Block the reuptake of serotonin | Increased agitation, blood pressure, heart rate, temperature, development of seizures | Avoid drug combination Consider an alternative analgesic |
Phenytoin | Cimetidine/Decreased phenytoin metabolism | Increased phenytoin level | Monitor phenytoin level, adjust phenytoin dose accordingly |
Fluconazole/Decreased phenytoin metabolism | Increased phenytoin level | Monitor phenytoin level, adjust phenytoin dose accordingly |
Potassium-sparing diuretics/ (amiloride, spironolactone, triamterene) | Potassium supplements/Increased potassium intake Angiotensin converting enzyme inhibitors/Decrease potassium elimination Salt substitutes/Increase potassium intake Theophylline/Increased theophylline metabolism | Increased potassium level Increased potassium level Increased potassium level Decreased theophylline level | Monitor potassium level Review medication profile Monitor potassium level Review medication profile Monitor potassium level Review medication profile Monitor theophylline level, adjust theophylline dose accordingly |
Tacrolimus | Aluminum hydroxide/Impaired tacrolimus absorption | Decreased tacrolimus level | Monitor tacrolimus level, adjust tacrolimus dose accordingly |
Dexamethasone/ Increased tacrolimus metabolism | Decreased tacrolimus level | Monitor tacrolimus level, adjust tacrolimus dose accordingly |
Erythromycin/Decreased tacrolimus metabolism | Increased tacrolimus level | Monitor tacrolimus level, adjust tacrolimus dose accordingly |
Fluconazole, itraconazole, ketoconazole/ Decreased tacrolimus metabolism | Increased tacrolimus level | Monitor tacrolimus level, adjust tacrolimus dose accordingly |
Magnesium oxide/pH mediated tacrolimus degradation | Decreased tacrolimus level | Monitor tacrolimus level, adjust tacrolimus dose accordingly |
Rifampin/Increased tacrolimus metabolism | Decreased tacrolimus level | Monitor tacrolimus level, adjust tacrolimus dose accordingly |
Sodium bicarbonate/pH mediated tacrolimus degradation | Decreased tacrolimus level | Monitor tacrolimus level, adjust tacrolimus dose accordingly |
Theophylline | See Table 4.6 |
AV, atrioventricular; INR, international normalized ratio; NSAIDS, nonsteroid anti-inflammatory drug; PT, prothrombin time; PTT, partial prothrombin time For a complete review of HIV/AIDS drug interactions (see: Piscitelli SC, Flexner C, Minor JR, et al. Drug interactions in patients infected with human immunodeficiency virus. Clin Inf Dis 1996;23:685 93.) |