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Pharmacology Exam 2
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Efflux transporters
pump things out of the cells into the intestinal lumen
P-gp
BCRP
MRP2
OCT1? Cations
P-glycoprotein (P-gp)
efflux pump for anticancer drugs
member of ATP binding cassette (ABC transporters)
P-gp location
intestine
liver
kidney
BBB
P-gp substrates
HIV Protease
Digoxin
Rifampin
Anticancer
Anticonvulsants
use of P-gp inhibitors
use inhibitor along with desired substrate to increase effect
p-gp inducers
phenobarbital
clotrimazole
bad with desired substrates!
Phase I reactions
CYP increases hydrophilicity
Phase II
conjugation reactions
use of transferases to increase water solubility
CYP3A4/5/7
40% of drug metabolism
CYP Family
>
40% identical genetic info
CYP1, CYP2...
CYP Subfamily
40-55% identical
CYP2A, CYP2B
Withing CYP subfamilies
>
55% identical
CYP2b1, CYP2b2
CYP Characterstics
Heme protein
Supporting enzymes CYP reductase and cytochrom b5
450nm in the reduced (Fe2+) form
6000 proteins
CYP System
requires cytochrome B5 and CYP reductase
important for e- transfer
outputs a more polar metabolite
CYP catalyzed reactions
C-H bond hydroxylation
Epoxidation (causes oxidative stress)
S-Oxidation
N-Hydroxylation
O-Dealkylation
N-Dealkylation
Unique characteristics of CYP
substrate diversity
enzyme diversity
substrate specificity
regio and stereoselectivity
atypical kinetics
enzyme cooperativeity
Substrate diversity of CYP
adjusts size of active site to fit multiple drugs
Atypical kinetics
one drug binding may facilitate binding of another drug (sigmoidal)
Enzyme cooperativity
Increase kCat+Decrease S50=
Increased efficacy of drug
CYP3A substrates
calcium channel blockers
HIV protease inhibitors
non sedating antihistamines
CYP3A Inhibitors
ketoconazole
erythromycin
grapefruit juice
CYP3A Inducers
rifampin
ritonavir
boosters for anti-retroviral therapies
Why is CYP 3A4 involved in majority of drug interactions?
responsible for metabolizing numerous drugs
Author
Rx2013
ID
39019
Card Set
Pharmacology Exam 2
Description
Enzymes of DI/ADR
Updated
2010-10-02T03:00:07Z
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