drug interactions Flashcards
Effect of interactions of Doxycycline &
Calcium carbonate
Decreased absorption of oral doxycycline
Mechanism of interaction of Doxycycline &
Calcium carbonate
Doxycycline chelates calcium cations to produce insoluble and unabsorbable complex
Effect of interactions of Ketoconazole &
Ranitidine
Decreased absorption of oral ketoconazole
Mechanism of interaction of Ketoconazole &
Ranitidine
Ranitidine decreases gastric acidity, which in turn inhibits absorption of ketoconazole
Effect of interactions of Metformin & Proton pump inhibitors
Decreased absorption of oral metformin resulting in metformin intolerance
Mechanism of interaction of Metformin & Proton pump inhibitors
PPI inhibits OCT1, which is needed for metformin oral absorption
beneficial drug-drug interactions at the absorption stage
lidocaine + norepinephrine
Norepinephrine shrinks blood vessels preventing lidocaine from being absorbed and enhancing its local action
Effect of interactions of Levodopa & Protein-rich diet
Reduced brain distribution of levodopa
Mechanism of interaction of Levodopa & Protein-rich diet
Levodopa-aminoacids competition for a transporter
Effect of interactions of Loperamide & Verapamil
Enhanced brain distribution of loperamide
Mechanism of interaction of Loperamide & Verapamil
Verapamil inhibits P-gp, which effluxes loperamide from the brain
Effect of interactions of Aspirin & Phenytoin
Enhanced but shortened action of phenytoin
Mechanism of interaction of Aspirin & Phenytoin
Aspirin displaces pehnytoin from plasma proteins.
beneficial drug-drug interactions at the stage of distribution
verapamil + antidepressant drugs in some patients
Verapamil might enhance brain deposition of some antidepressants
Effect of interactions of Carbamazepine & Warfarin
Enhanced metabolism of warfarin, reduced plasma concentration of warfarin
Mechanism of interaction of Carbamazepine & Warfarin
Carbamazepine is a CYP inhibitor
Effect of interactions of Simvastatin & Grapefruit juice
Inhibited metabolism of simvastatin, increased plasma concentration of simvastatin
Mechanism of interaction of Simvastatin & Grapefruit juice
Ingredients of grapefruit juice are CYP inhibitors
Effect of interactions of Cimetidine & Metformin
Reduced renal tubular secretion of metformin, increased plasma concentration of metformin
Mechanism of interaction of Cimetidine & Metformin
Cimetidine inhibits OCT2
beneficial drug-drug interactions at the stage of elimination
Cobicistat is the only marketed drug used only to increase systemic exposure of antiretroviral drugs by inhibiting CYP.
