TDM Flashcards
What is the free portion of a drug?
That which interacts with site of action and produces biological response.
Free portion of a drug best correlates with ________ and therapeutic or toxic effects
concentration
Things that can cause the free portion of a drug to be higher than anticipated (potentially causing toxic effects)
Conditions that alter binding proteins (inflammation, infection, malnutrition, etc)
Presence of substances that compete for binding sites (other drugs, hormones, etc)
Renal or liver dysfunction (not eliminated as well)
2 ways drugs are cleared from body
- Hepatic Metabolism
2. Renal filtration
Serum concentration will _______ when rate of absorbance exceeds elimination and distribution of a drug
Increase
How many half- lives does it take to reach a steady state of drug in the body?
5 & 1/2
How many half-lives does it take for a drug to clear the body?
5 & 1/2
T/F Goal of therapeutic drug monitoring is to achieve a trough below therapeutic range and keep peak below toxic range
False (partly): Trough should in therapeutic range and peak below toxic range
When is a trough sample drawn?
Right before next dose is given
When is a peak sample typically drawn?
1 hour after last dose. Can change when drugs are metabolized quicker or slower.
Would a digoxin peak level drawn 1 hour after dose be an accurate representation of the concentration?
Why/why not?
No- Digoxin is metabolized slowly. The level of drug in the sample would be low. This should be drawn 6 to 8 hours after a dose.
As a rule, what tube would we use for a TDM blood sample?
Red top tube
Generally use non-separator tubes, but that may be changing
What sample types are used for TDM testing?
Serum, plasma, whole blood
Urine
What anticoagulant(s) may be used for plasma samples?
Heparin
no EDTA or Citrate
What are some Cardioactive drugs that we test for?
Digoxin Disopyramide Procainamide Quinidine Norpace (quinidine substitute- hard to establish serum concentration and therapeutic values)
What are some TDM antibiotics?
Aminoglycosides, Vancomycin, Chloramphenicol
What is digoxin used for?
To treat CHF. It increases heart contraction.
Digoxin is eliminated by the _____
kidney
Decrease in K+ or Mg++ will ________ the effect of digoxin, whereas hyperthyroid will ______ the effect
increase
decrease
This is given to reverse toxic levels of digoxin
Digibind
How is procainamide eliminated?
What’s the active metabolite we can monitor?
Hepatic and renal function
NAPA (hepatic metabolite)
What are Aminoglycosides used to treat?
Infections with gram negative bacteria that are resistant to less toxic antibiotics
What are toxic effects of aminoglycosides (to humans)?
Nephrotoxicity and ototoxicity (irreversible effects)