Pharmacokinetics and Pharmacodynamics Flashcards
Define Bioavailability
Measure of drug absorption where it can be used
IV bolus has what bioavailabilty?
100%
What affects bioavailability?
absorption and first pass metabolism
What are phase 1 enzymes catalysed by?
Cytochrome p450 enzymes
What can Cytochrome p450 do to drugs?
Activate, inactivate or convert to something else
What substances are typically eliminated by the kidneys?
Low molecular weight polar metabolites
What substances are typically eliminated by the liver?
High molecular weight - conjugated with glucuronic acid
Why is half life used?
It is independent of concentration
Define clearance
Constant proportion removed from the body not an amount
define elimination rate
Volume of blood cleared per unit time
What 2 things can cause a long half life?
Large volume of distribution or low clearance
Which type of order do most drugs exhibit?
First order
How many half lives reaches a steady state concentration?
5
How is loading dose calculated?
Steady state concentration x apparent volume of distribution
