PBS-Intro to Pharm and Pharmacodynamics Questions With Complete Solutions

PBS-Intro to Pharm and Pharmacodynamics Questions
With Complete Solutions


Cytochrome 450 Inducers
CYP inducers increase the activity of the CYP enzyme which
leads to:
-increased drug metabolism
-decrease systemic drug levels
-decrease therapeutic effect if drug does not have active
metabolite(s)
-increase in therapeutic effect if drug has active metabolites
ex) smoking and olanzapine
larger doses may be needed to combat lack of systemic drug
levels
Major Cytochrome P450 Inducers
PS PORCS:
Phenytoin
Smoking
Phenobarbital
Oxcarbazine
Rifamycins
Carbamazepine
St. John Wart
Cytochrome P450 Inhibitors
CYP inhibitors decrease the activity of the CYP enzyme which
leads to:

, -decrease in drug metabolism
-increase in systemic drug levels
(risk of drug-induced toxicity due to increase plasma levels)
-increase therapeutic effect if drug does not have active
metabolite(s)
-decrease therapeutic effect if drug has active metabolite(s)
Example of cytochrome P450 Inhibitor
Grapefruit juice and simvastatin
-Grapefruit juice is a strong CYP 3A4 inhibitor; simvastatin is a
CYP3A4 substrate
-Result=increase plasma concentrations of simvastatin
Major Cytochrome P450 Inhibitors
G PACMAN
Grapefruit
Protease Inhibitors
Azole anti-fungals
Cimetidine, cyclosporine
Macrolides (not azith)
Amiodarone
Non-DHP CCBs (diltiazem, verapamil)
Phase II Metabolism
Phase II metabolism involves conjugation reactions
-Drug is joined with another substance (e.g. glucuronic acid) to
yield a more water-soluble compound to be excreted
-Glucuronidation is the most common type of conjugation
reaction