Canyon University
Prodrug
An inactive drug dosage form that is converted to an active metabolite by various
biochemical reactions once it is inside the body.
• Cytochrome P450
• Ex. Aspirin, psilocybin, heroin
Bioavailability
the rate at and the extent to which a nutrient is absorbed and used
• Affected by route of administration and drug dosage
• Drug clearance (rate drug leaves circulation)
• Steady state concentration
• Affected by chemical stability, solubility, and first pass
Steady state (of a drug)
stable level of drug in the body, occurs in 5 half lives of the drug
• rate of drug being added to system is equal to amount being eliminated
from system
Pharmacokinetics
The process by which drugs are absorbed, distributed within the body, metabolized, and
excreted.
• what the body does to the drug
First pass
the fact that a medication in the GI tract passes through the liver before entering
other organs
Bioequivalence
relative therapeutic effectiveness of chemically equivalent drugs. Does not affect
bioavailability
, Bioavailability (is affected by)
• chemical instability
• solubility
• first pass metabolism
Cytochrome P450 System
• enzymes that function to metabolize potentially toxic compounds, including
drugs and products of endogenous metabolism such as bilirubin, principally
in the liver.
• genetics influence presence of enzymes
• affects metabolism of warfarin, antidepressants, antiepileptics, and statins.
• the levels of these drugs are higher when taken with certain drugs that are
inhibitors (ex. warfarin with omeprazole) because there is competition for
enzyme metabolism.
• inducers lead to decreased plasma concentration of drug.
cytochrome p450 inducer
An inducer increases the metabolism of a substrate resulting in a decreased level
or effect of the substrate
cytochrome p450 inhibitor
An inhibitor decreases the metabolism of a substrate resulting in an increased
level or effect of the substrate.
HCAP
Healthcare-associated pneumonia
Clopidogrel
• Plavix
• prodrug that must be activated by hepatic CYP2C19 metabolism
• individuals who are poor metabolizers may not form the active metabolite
and have reduced antiplatelet response
half-life (determines)
how often a drug is administered
How long does it take to reach a steady?
4-5 times the half-life
Warfarin (MOA)