Target concentration and interventions

Question 1

How do you find/establish the target concentration

Answer 1

RCT gold standard

Question 2

What is target concentration intervention

Answer 2

NH concept of dose individulisation

Question 3

Three ways to dose

Answer 3

Population dosing (same for everyone)
Group dosing, covariate based (same dose for similar group)
Individual dosing (dose determined by individual response)

Question 4

Why is there variation in pharmacokinetics and pharmacodynmaics between individuals. Predicatable and non predictable reasons.

Answer 4

Systemic or predictable reasons- body size, disease state, genotype, etc.
Random/ non predictable. Can be between subject variability and within subject variability

Question 5

Steps for TCI (algorithm)

Answer 5

1) Choose initial target concentration based on pharmacodynamic studies
2) Determine Vd and Cl using weight etc.
3) Calculate loading dose and maintenance dose rate
4) measure response and revise target concentration
5) Measure concentration and revise Vd and Cl
6) repeat step 3

Question 6

Why is it difficult to understand pharmacodynamic parameters

Answer 6

It is difficult to measure a clinical response that can be related to concentration.

Question 7

When calculating Volume of distribution for the individual what needs to be considered

Answer 7

Vd (patient) = Vd (standard pop) but with their own weight considered… so
Vd (pt)= Vd (std) * Wt (pt)/ Wt (standard 70kg)

Question 8

When calculating individualised clearance what needs to be considered

Answer 8

Cl (pt) = Cl (pop)* (Weight Pt/ Weight std)*3/4

Question 9

When should drug concentration be measured

Answer 9

In the middle of the dosing interval as this is closest to average steady state concentration than either the peak or trough concentrations