Week 1- Digoxin + gentamicin + vancomycin Flashcards
what is digoxin?
-its is a cardiac glycoside and works by inhibiting the NA+/K+ ATPase pump in the cardiac muscle
-it causes depolarisation that causes smooth muscle contraction
Why do we do TDM for digoxin?
- Patient compliance- check the patient is taking the drug
Multiple drug therapy- due to interaction with other drugs
Digoxin toxicity- normally renally excreted, if they have problems may need to check levels.
Altered disease state
Poor response-
what is the therapeutic window for digoxin?
0.8-2.0mcg/L
-in congested cardiac failure we aim for lower end of the range compared to AF where we aim for upper end
when is the best time for blood sampling for digoxin?
-IV= 6-8 hrs post dose
-oral pre-dose trough/ at least 8hrs post dose
so that it can distribute around the body
what is vancomycin?
Glycopeptide antibiotic
Gram-positive bacteria, including
methicillin-resistant Staphylococcus
aureus (MRSA).
Bactericidal effect by inhibiting the
polymerization of peptidoglycans in the
bacterial cell wall.
Weakness bacterial cell walls and causes
leakage of intracellular components,
resulting in bacterial cell death.
when do you give vancomycin IV?
systemic infection as it is poorly absorbed by GI tract
what is the biggest risk when taking vancomycin?
nephrotoxicity
how is vancomycin eliminated in the body? what is important for elimination?
-almost completely unchanged in the urine through kidney
- Renal function is the most important factor in
determining dose and frequency
what is the normal dosing regimens for vancomycin?
Variable dosing regimens between centers’
normally - 1g IV OD up to 1.5g BD
what is the most common side effect of vacomyocin?
Red man syndrome, which is an idiopathic
infusion reaction characterised by
flushing, erythema and itching, that can
affect the upper body, neck and face
Red man syndrome is related to the rate
of administration
The rate of infusion must not exceed
10mg/min
what is gentamicin?
Aminoglycoside
Bactericidal efficacy
Proliferation and resting stage of bacteria.
It forms a bond with the proteins of the 30S subunits of the
bacterial ribosomes, which causes “misreading” of the mRNA.
Gram negative bacteria
Concentration dependant activity
Higher the peak, faster the kill rate
Post antibiotic effect
Once daily/multiple daily dosing
when should monitoring occur for renal toxicity?
-daily
-should monitor creatinine levels for signs of renal toxicity including increase in creatinine or decrease
in urine output/oliguria
when is there an increased risk of toxicity ?
Nephrotoxins, prior exposure,
↑age, pre-existing renal
disease, prolonged therapy
what is ototoxicity? what needs to be monitored? reason for it?
is when a person develops hearing or balance problems due to a medicine
-its independent of drug concentration
-should monitor for symptoms of tinnitus, dizziness, poor
balance, hearing loss
-Normally associated with prolonged use > 10 days
-stop treatment if suspected
what is the rationale for the once daily gentamicin dosing?
-at least as efficient as multiple dose therapy (possible greater due to high peak levels)
-Significantly reduced nephrotoxicity (due to shorter exposure time)
-No greater risk of ototoxocity
-3-5mg/kg dose
