Drug Interactions Flashcards
Which of the lipid lowering drugs interacts with warfarin?
Fenofibrate (fibric acid derivative) causes warfarin potentiation.
What is a potential interaction between ACEi and K+ sparing diuretics?
Increased hyperkalaemia, which can lead to cardiac problems.
What is a potential interaction between aminoglycoside ABX and loop diuretics?
Ototoxicity (toxic to ear) and nephrotoxicity.
What is a potential interaction between digoxin and thiazide or loop diuretics?
Hypokalaemia
What is a potential interaction between steroids and thiazide or loop diuretics?
Increased risk of hypokalaemia.
What is the DDI for St. John’s Wart and warfarin?
St. John’s Wart increases activity of CYP450.
Warfarin is metabolised by CYP450, therefore these drugs together inhibits actions of warfarin.
What is the DDI for St. John’s Wart and COCP?
COCP is metabolised by CYP450, but St. John’s Wart increases the CYP450 enzyme. This could lead to pregnancy as the COCP is ineffective.
What is the interaction between NSAIDs and warfarin?
NSAIDs displace warfarin from albumin - increases INR.
What is the interaction between 5-flurouracil and warfarin?
5-fluorouracil inhibits metabolism of warfarin.
What is the interaction between vincristine (vinca alkaloid) and itraconazole (antifungal).
Leads to more severe neuropathy.
What is the interaction between St. John’s Wort and 5-fluorouracil?
St. John’s wort induces cyp3a4, which is used to metabolise 5-FU.
When prescribing NSAIDs what should you be cautious of?
Whether the patient is taking any highly protein bound drugs e.g. Sulfonylureas, methotrexate, warfarin, diuretics, ACEi/ARBs. This could increase the risk of ADRs.
