Metabolism & Clearance Flashcards
glucuronidation
UDP-glucuronosyltransferase
UGT
sulfation
sulfotransferases
SULT
acetylation
N-acetyltransferases
NAT
Amino acid conjugation
ex. glycine
low activity in newborns, fatal benzyl acid toxicity
glutathione conjugation
glutathione-S-transferase
methylation
catechol O-methyl transferase or thiopurine methyl transferase
COMT or TPMT
CYP2D6 activity & polymorphism
absent or ultrarapid
no activity or buildup of codeine
CYP2C19 activity & polymorphism
defective (race dependent)
metabolizes prodrug for clopidogrel
TPMT activity & polymorphism
Caucasians have diminished or deficient activity
severe myelosuppression with azathiopurine
solute carriers (SLCs)
OAT, OCT, OATPs, & MATE
transporters responsible for bioavailability
OATP2B1
P-gp (ABCB1, MDR1)
MCT
PEPT1
OATP2B1 location & activity
uptake in gut, liver, and systemic circulation
large MW organic anions
P1B3 and P1B1 are liver specific
P-gp location & activity
kidney, liver, & BBB
protects and eliminates compounds from cells
MCT location & activity
intestine
transports low MW organic anions
can improve oral absorption
PEPT1 location & activity
intestine
transports peptides
can improve oral absorption
transporters responsible for liver activity
OATPs
BCRP (ABCG2)
P-gp
BCRP location & activity
intestine, liver, BBB, and some cancers
protects and eliminates compounds from cells
transporters responsible for renal activity
OAT
OCT
MATE
OAT location & activity
renal secretion (uptake)
organic anion transporter
OCT location & activity
renal secretion (uptake)
MATE location & activity
apical membrane of kidney
recognize cations for efflux
transporters with activity in the BBB
BCRP & P-gp
Equilibriative nucleoside transporters (ENTs)
transport nucleosides, regulate uptake of purines and pyrimidines
where does renal secretion occur
proximal tubules
where does renal reabsorption occur
along the nephron
when CLr > CLrf (excretion exceeds filtration)
secretion occurs
when CLr < CLrf (filtration exceeds excretion)
reabsorption occurs
what induces CYP1A2
smoking
what induces CYP2C19
rifampin, secobarbital
what induces CYP2E1
ethanol, isoniazid
what induces CYP3A4
carbamazepine, phenobarbital, rifampicin, phenytoin, SJW, troglitazone
what does carbamazepine do acutely and chronically
acute- inhibit 3A4
chronic- induce 3A4
SJW induces 3A4 & P-gp (ABCB1) which
increases clearance of indinavir
reduces bioavailability of talinolol
fluoxetine (prozac) inhibits CYP2C9
warfarin metabolism is lost, conc increases
itraconazole inhibits CYP3A4
increases CYP3A4 substrates
fluvoxamine (luvox) inhibits CYP1A2
increases CYP1A2 substrates
cyclosporine inhibits OATP1B1
prevents CL and leads to accumulation of rosuvastatin
talinolol is a P-gp inhibitor
leads to accumulation of digoxin
probenecid is a OAT1 inhibitor
reduces renal secretion, given with cidofovir (vistide) to reduce accumulation
clarithromycin inactivates CYP3A4
midazolam concentrations rise
furanocoumarins in GFJ inhibit CYP3A4 intestinal metabolism
increased bioavailability and systemic concentrations of CYP3A4 substrates
felodipine
naringin in GFJ is an OATP inhibitor
reduces bioavailability of fexofenadine