drug interactions Flashcards
def. drug interactions
effect of one drug altered by the use of another
2 types of drug interactions
pharmacokinetic - levels change
dynamic - levels don’t change
what is interaction between glyburide and sulfamethoxaloze/trimethoprim
SMX/TMP inhibits CYP2C9 and, which glyburide is a substrate for > too much glyburide > hypoglycemia
what is interaction between paroxetine and codeine
codeine normally turned into morphine by CYP2D6, but paroxetine inhibits > get less morphine > pain
2 types of natural variants in CYP2D6
absent - no use of codeine
ultrarapids - get high dose effects
what is interaction between simvastatin and grapefruit juice
CYP3A4 is inhibted by grapefruit > statin is a substrate > get high levels of simvastatin > rhabdomyolysis
where is CYP3A4 found
in liver and small interstine
3 other CYP3A4 inhibs
- macrolides
- CCBs
- Amiodarone
common inducer of CYP3A4
st. john’s wort
what is interaction between digoxin and clarythromycin
digoxin is normally pumped out by P-gp, but macrolides are inhibitors of P-gp > high levels of digoxin > heart not pumping well
what is P-gp
membrane glycoprotein that pumps drugs out of cells/enterocytes
where is P-gp located
- gut
- kidney
- bile canaliculi
- BBB
what does rifampin do to P-gp
inducer - can see them grow on cell wall
what is interaction between warfarin and tylenol
- normally, warfarin blocks the resubstitution of vitK which is a co-factor of y-carboxylase
- carboxylase activates clotting factors in cascade - clotting
- NAPQI, an intermediate of tylenol breakdown inhibits y-carboxylase, so get bleeds because can’t clot well
5 As that interact with warfarin
Amiodarone - antiarrthymic Antibiotics - SMX/TRI Antidep. - SSRIs Analgesics - Nsaid, acetominophen Antiplatelets - aspirins
