clinical pharmacology notes
takes 3 half lives of elimination to achieve steady state, so drugs w/long half lives o elimination (amiodarone - 40 days) can fool one into changing them before they've reached steady state. don't make any changes to meds unless they have been in patient for greater than 3 half lives.
aminoglycosides and fluoroquinolones are concentration dependent for bacterial infections
penicillins are time dependent
thus don't underdose fluoroquinolones, don't short course penicillins
quinidine is the most potent inhibitor of CYP2D6 in man
clinical clue: nail through the tennis shoe- think s. aureus or p. aeruginosa because these bacteria grow great in sneakers.
fluoroquinolone with Ca2+ (as in milk or iron fortified OJ) going to form Ca fluoroquinolone precipitates in the gut and less antibiotic will be available. this is bad because fluoroquinolones are concentration dependent anti-bacterial agents
interesting findings surrounding acetaminophen and EtOH. Chronic EtOH induces CYP2E1 for which acetaminophen is a substrate. the acetaminophen is metabolized to a hepatotoxic byproduct associated w/liver failure, thus the total recommended daily dosage for acetaminophen for someone who has at least 2 drinks a day is 2gms! interestingly, in binge drinking college kids - EtOH acutely inhibits CYP2E1, thus they are not bound by the same restriction of 2gm/day of acetaminophen-
No comments:
Post a Comment