Therapeutic Drug Monitoring

Question 1

if adverse effects are a significant concern, how do we adjust our dosing?

Answer 1

start in lower half of dosage range and/or will see recommendations for dose escalation

Question 2

if lack of efficacy is the major concern with a drug, how do we adjust our dosing?

Answer 2

typically use upper half of dose range

Question 3

if the drug target is in a hard to access location, how do we adjust our dosing?

Answer 3

if it is safe to do so, we will go to the high end of the dosage range

Question 4

if the drug target is in a location with easy or enhanced drug access, how do we adjust our dosing?

Answer 4

start with mid to low dosage rate

Question 5

what do you lose with liver disease?

Answer 5

metabolic capacity

Question 6

what should you avoid in patients with liver disease?

Answer 6

drugs highly cleared by liver
pro-drugs
hepatotoxic drugs

Question 7

in general, how should you adjust dosage in a patient with liver disease?

Answer 7

if metabolic clearance: use low end of dosage range or even below
decrease dose and/or frequency

Question 8

what can renal disease impact?

Answer 8

marked effect on drugs highly dependent on renal clearance

Question 9

what should you avoid in patients with renal disease?

Answer 9

drugs with high renal clearance
nephrotoxic drugs

Question 10

what are some nephrotoxic drugs you should avoid using in patients with renal disease?

Answer 10

aminoglycosides
NSAIDs

Question 11

what do we use with renal disease to adjust dosing?

Answer 11

patient creatinine and normal creatinine

Question 12

how should you dose geriatrics?

Answer 12

be conservative and use low end of dose range if safety is a concern

Question 13

what do neonates tend to have?

Answer 13

higher body water and hence higher volume of distribution

Question 14

are some toxicities age dependent?

Answer 14

yes

Question 15

increasing total daily dose by increasing frequency raises ___________ more than ____________

Answer 15

trough
peak

Question 16

how is therapeutic drug monitoring performed?

Answer 16

measurement of serum or blood drug concentrations to help guide therapy

Question 17

for therapeutic drug monitoring to be helpful, what must happen?

Answer 17

correlation between serum concentration and therapeutic response

Question 18

what are some drugs in which therapeutic drug monitoring is used?

Answer 18

phenobarbital
bromide
other anti-epileptics
thyroxine

Question 19

what is the therapeutic reference range?

Answer 19

range of serum or plasma concentrations within which the majority of animals (95%) are expected to show a therapeutic response

Question 20

what is the target therapeutic range?

Answer 20

target to ensure the majority of animals will have a therapeutic benefit, without adverse effects

Question 21

if toxicity occurs, when do we want to check the concentration?

Answer 21

at peak of absorption: peak concentration

Question 22

if lack of therapeutic effect is what we are concerned with, when should we check the concentration?

Answer 22

trough concentration just before next dose

Question 23

if you double the dose for a single administration, you _________ the peak and therefore the concentration at any given time

Answer 23

double

Question 24

if you double the dose with repeated administration, under what conditions does the peak double after the first change?

Answer 24

if dosing interval is more than 3-5 half lives

Question 25

what is the equation for calculating a new dose with a single point for TDM?

Answer 25

new dose=old dose x desired concentration/observed concentration