Therapeutic Drug Monitoring (TDM): Gentamicin & Vancomycin Flashcards
What is the difference between pharmacokinetics & pharmacodynamics?
Pharmacokinetics: focuses on measuring the time course of drug conc. in the serum & tissues (WHAT THE BODY DOES TO THE DRUG)
Pharmacodynamics: focuses on measurement of microbial exposure (WHAT THE DRUG DOES TO THE BODY)
What is MIC?
Minimum inhibitory concentration.
It is the minimum amount of drug used to inhibit microbial activity.
When is therapeutic drug monitoring (TDM) used?
- Drugs with a narrow therapeutic window
- People with altered physiology
- To ensure efficacy
- To avoid toxicity
- For patients with compliance issues
Where is gentamicin (an aminoglycoside) mostly excreted & what is its half life?
Mostly excreted via kidneys.
It has a half-life of 2-3h
What can gentamicin cause if given incorrectly?
Ototoxicity, and nephrotoxicity.
What is the benefit of having gentamicin OD?
- It is a once daily dose.
- Less oto/nephrotoxic
- Peak levels are not required
- One dose is usually enough, but 2nd dose can also be given if source of infection is not clear
What is the usual dose for gentamicin OD?
5mg/kg
What should the trough levels (lowest point) on a graph need to be of gentamicin OD?
It needs to be <1mg/L
What needs to be achieved in MD gentamicin (multiple dose)?
Steady state needs to be achieved.
What is the usual dose for gentamicin MD?
3-5mg/kg per day in divided doses.
What should peak levels aim to be in gentamicin MD?
3-5 or 5-10mg/L
What is the spectrum of activity for vancomycin?
For gram positive bacteria & narrow spectrum of activity (staphylococcus/streptococcus).
What types of infections is vancomycin used for?
- Complicated soft tissue
- Bone/joint
- Pneumonia
- MRSA
What is the alpha and beta phase of vancomycin?
Alpha phase: distribution
Beta phase: elimination
What is the half-life of vancomycin?
6h.
