Flashcards in 00 Drug Interactions Deck (18)
Which enzyme is Warfarin metabolized by?
What is one of the strongest and broadest enzyme inducers?
Rifampin (many medications given with this will have to have higher doses)
Which enzymes do many pain and psychiatric drugs go through?
What are some of the strong P-gp INHIBITORS?
Azoles (keto-, itraconazole), Verapamil, Macrolides (Clarithro-, erythromycin)
What are some of the strong P-gp INDUCERS?
Rifampin, Carbamazepine, Phenytoin, St. Johns Wort
Quick Study Tool: PS PORCS (Big CYP Inducers)
Phenytoin, Smoking, Phenobarbital, Oxcarbazepine, Rifampin, Carbamazepine, St. Johns Wort
Quick Study Tool: G <3 PACMAN (Big Inhibitors)
Grapefruit, Protease Inhibitors (ritonavir, etc.), Azoles (fluconazole, itraconazole, ketoconazole, etc.), Cyclosporine & Cimetidine, Macrolides (clarithromycin, erythromycin, but not azithromycin), Amiodarone, Non-DHP CCBs (Diltiazem and Verapamil)
What are some significant drug interactions that can be seen with Amiodarone?
Digoxin and Warfarin (likely to be given with amiodarone d/t heart failure/arrhythmia). Digoxin and Warfarin dose will need to be decreased
What can happen if Warfarin is given with Ginseng?
May decrease the effectiveness of Warfarin (seng, like sink: drains warfarin)
What can happen if Warfarin is given with Thyroid Hormones?
Altered INR (incr or decr) - usually increases warfarin effects - Monitor INR
What can happen if Bactrim is given with Phenytoin or Methotrexate?
Can increase the Phenytoin/MTX concentrations, increasing toxicity
What can happen if Digoxin is given with Cholestyramine or Colestipol?
Decrease levels of digoxin (decreased GI absorption d/t binding and also interruption of enterohepatic recycling of digoxin)
What can happen if ACE-Is are given with Potassium-sparing diuretics or Potassium supplements?
May increase serum potassium concentration, especially in renal impaired patients
What can happen if ACE-Is are given with Lithium?
Increase levels of lithium by 200-300% (dose-related)
What drugs can increase Lithium levels?
STAND: decreased Sodium intake, Thiazides, ACE-I, NSAIDs, Dehydration
What can happen if Valproic Acid is given with Phenobarbital or Lamotrigine?
Increases Phenobarbital or Lamotrigine levels
What can happen if TCAs are given with MAO-Is?
May lead to hypertensive crisis