3 - Drug Elimination/ Elementary pharmacokinetics

Question 1

2 examples of drugs with a low TPR

Answer 1

cardiac glycosides and barbiturates

Question 2

TPR=

Answer 2

maximum tolerated conc / minimum effective conc

Question 3

the greater the Kel of a drug the ____ the concentration of drug drops

Answer 3

faster

Question 4

what is first order kinetics

Answer 4

the rate of elimination is directly proportional to the drug concentration

Question 5

the higher the conc of a drug the __ the rate of elemination - with 1st order kinetics

Answer 5

greater

Question 6

if the Kel is large the halflife is __

Answer 6

short

Question 7

halflife is ____ related to Kel

Answer 7

inversely

Question 8

t1/2 = ___/Kel

Answer 8

0.69

Question 9

1st order kinetics - when a dose is doubled the __ and __ are not affected

Answer 9

Kel and T1/2

Question 10

when you double the concentration what happens to the number of half lives?

Answer 10

one half life is added on

Question 11

define clearance

Answer 11

• the volume of plasma cleared of a drug in unit time

- a constant relating the rate of elimination to plasma concentration

Question 12

with 1st order kinetics

rate of elimination = ___ x ___

Answer 12

clearance x plasma concentration

clearnace is the constant

Question 13

clearance determines the ____ ___ rate

Answer 13

maintenence dose rate

Question 14

what are the units of clearance

Answer 14

L/hr

Question 15

what is the rate of elimination?

Answer 15

the amount of drug being eliminated per unit time

Question 16

Kel and rate of elimination are NOT the same thing

Answer 16

NOT

Question 17

how do you figure out total clearance

Answer 17

add up the clearance at each of the clearance organs

Question 18

steady state = rate of ___ = rate of ___

Answer 18

administration = elimination

Question 19

CpSS = ___ /___

Answer 19

maintenence dose rate / CL

Question 20

For drugs that exhibit first order kinetics, the steady state (ss) plasma concentration (Css) is linearly related to the _____ rate

Answer 20

infusion

Question 21

the time to reach Css is determined by __ __ but NOT the ___ ___

Answer 21

half life, not the infusion rate

Question 22

Css is reached after approx ___ half lives

Answer 22

5

Question 23

how is Css calculated with oral dosing

Css =

Answer 23

(F x dose) / (Clp x dosing interval)

Question 24

the amount of drug in the body (Ab) = ___ x ___

Answer 24

Vd x Cp (plasma conc)

Question 25

for I.V administration loading dose = __ x ___ __

Answer 25

Vd x target Cp

Question 26

for oral administration loading dose = (__ x ___ __ ) /__

Answer 26

(Vd x target Cp ) / F

Question 27

what is half life dependent on?

Answer 27

Vd and clearance

Question 28

half life =( 0.69 x __ ) /__

Answer 28

Vd/ Cl

Question 29

zero order kinetics can occur when the plasma conc of a drug is ____ than the -__ of an enzyme that metabolises it

Answer 29

greater than the Km