Pharmacokinetics Flashcards
pharmacokinetics =
branch of pharmacology
rate @ which drugs are: (4)
absorbed
distributed
metabolised
eliminated
how drugs = ____ around body
move
What are the characteristics of drug regimens? (2)
- t ≠ start @ 0
- ≠ always constant
in VENSIM = functions: (3)
STEP function
PULSE function
PULSE TRAIN function
dose =
rate x duration
What does dose represent?
amt/level/accumulation
What does rate represent?
height
What does duration represent?
width
level =
area underneath the rate curve
What is the step function? (2)
constant rate - ZOS
step function ≠ start @ 0
Example of a step function.
eg. intravenous drip
What are the applications of a pulse function? (3)
- Bolus injection
single large dose delivered = short period
generally = when meds = immediately needed in bloodstream - ingesting a single drug dose
pill/multiple pills = short period - single occurrence ≠ repeated
What does a graph for the pulse function look like?
area under rate curve = (2)
height * duration
change in level (dose)
dose =
height * duration
height =
dose * 1/duration
What are the applications of the pulse train function? (3)
- series of bolus injections
repeated single large doses over short periods - ingesting single drug dose @ regular intervals
pill/multiple pills over short period - consistent time between doses
What does the graph for a pulse train function look like?
What is the importance of the TIME STEP? (2)
- extremely important w/ pulses
- if TS = too large = miss pulse completely
What is the single-compartment model? (3)
- simplifying assumption
- allows = easier analysis
- modelling the body as = single compartment
Pharmacokinetics LRD:
Drug elimination rate =
What is clearance? (2)
- for dimensional consistency
- allows the usage of
drug concentration instead of absolute amt. of drug
FOS elimination
Clearance =
K.V
= constant value
characteristic of FOS
= modified version of rate constant (k)
= scaled by vol. of distribution (V)
how many vol. units = cleared of substance per unit time
Level =
∫ (administration - elimination) dt
concentration =
A/V
Elimination =
concentration * clearance
