PK

Question 1

Important sources of variability on pharmacokinetics

Answer 1

1. Genetics
2. Organ Impairment
3. Critical Illness
4. Age and body size
5. Concomitant Drugs
6. Sex
7. Pregnancy
8. Adherence
9. Environmental

Question 2

When is TDM useful?

Answer 2

-Experimentally determined relationship
-High variability in PK
-Narrow therapeutic window
-No competing drugs that DONT need monitoring

Question 3

TDM is used for these drugs:

Answer 3

-ABX
-Cardiac (procain/dig/lido)
-Bronchodilators (theo)
-Seizure (carb/pheny/val)
-Mood (lithium)
-Psychotics
-IS (CTS)

ABC SIMP

Question 4

What is monitored and when?

Answer 4

-serum/plasma
-whole blood
-oral fluid, urine

samples can be collected after SS but not necessary

specimens at peak/pre dose/random

Question 5

If observed and expected values differ, determine possible reasons:

Answer 5

Pre analytical
* Hemolyzed specimens
* Clotted specimens
* Interferences
* Collection conditions (temperature, light, freeze/thaw)

Non adherence

Dosing issues

Altered abs (food)

Drug interactions

Question 6

TDM in Outpatient Setting

Answer 6

-Missed doses
-Dose time relative to sampling time
-Previous drug conc
-Formulation changes
-Diet changes
-Assay differences
-Pt characteristics, lab data

Question 7

Individualized dose recommendations using Bayesian estimation of PK parameters

Answer 7

uses drug clearance, VD, body weight, renal function, PK parameters to develop precise dosing recommendation

Question 8

Bayesian

Answer 8

-utilizes drug’s behavior in previous patient populations (Vd/Cl) with pt specific info (BW/RF), measured drug concentrations, and PK parameters
-calculated based on the administered dosing regimen (a posteriori), to develop a precise dose recommendation for a specific patient