Target Concentration Intervention Flashcards
What is the formula for target concentration?
Target concentration= Target Effect x C50 / (Emax- Target Effect)
What does the ideal dose prediction require?
Individual estimates of Emax, C50, V and CL
How do we find target concentration?
Randomized concentration controlled trials
How does PKPD vary?
Systemic (predictable): body size, genotype
Random (not predictable): between subject variability and within subject variability
What factors can be combined to explain about 80% of clearance variability?
Weight and age
What are the three ways to dose?
Population:same dose for everyone
Group: same dose for similar group(children)
Individual: dose determined by individual response
What are the two key reasons for using target concentration intervention?
Usefulness of drug is hard to measure as clinical outcome is not clearly observable
Big unpredictable variability
What is the target concentration strategy?
Choose target concentration
Determine volume and clearance using weight
Calculate loading dose and maintenance dosing rate
Measure response
Measure concentrations
How do you calculate the group volume of distribution?
V=Vpop x WT/ Wtstandard
How do you calculate group clearance?
CL= Cl pop x (WT/WTstandard)^3/4
How do you calculate loading dose?
Target concentration x Volume
How do you calculate maintenance dose?
Target concentration x Clearance
When should you measure concentrations?
Just before the next dose, so hopefully will measure PK and clearance
Which is more ideal, therapeautic drug monitoring or target concentration intervention?
TDM-therapeutic range but not accurate and can be toxic
TCI-accurate and acts on a single target
