ICU drugs Flashcards
This is the time dependency of a drug; relationship between the dose of a drug and its plasma/tissue concentration;
pharmacokinectics
What is pharmacokinectics?
relationship between dose of a drug and tissue concentration
This is what the body does to the drug; absorption, distribution, metabolism, and elimination;
pharmacokinectics
What is pharmacodynamics?
how plasma concentration of a drug exerts its effect on the body
This is what the drug does to the body;
pharmacodynamics
General anesthesia encompasses three parts:
unconsciousness (and amnesia)
analgesia
muscle relaxation
These drugs commonly used for unconsciousness and amnesia:
propofol
ketamine
etomidate
benzos/barbs
How does propofol work?
inhibits synaptic transmission thru its effects on GABA receptor
This drug is used for unconsciousness and is an alkylated phenol that inhibits synaptic transmission thru its effects on GABA receptor:
propofol
Why is propofol use attractive in smokers and asthmatics?
has bronchodilator properties
Why do we use propofol cautiously in pts with hypovolemia and CAD?
causes hypovolemia
Onset of action of propofol?
less than a minute
Propofol is metabolized by?
liver
cleared 60% by liver, 40% by kidneys
Half life of propofol?
biphasic
initially 40 minutes
terminal half life 4-7 hrs
Adverse reactions of propofol?
local pain at injection site hypotension myoclonus QT prolongation (rare) green urine (rare)
Propofol safe in pregnancy?
yes
crosses the placenta
Propofol effects on the brain?
decrease in cerebral blood flow
decrease in intracranial pressure
decrease in cerebral oxygen consumption
Propofol use for status epilepticus?
used off label for status epilepticus
suppresses seizure activity
Propofol also exerts anti-emetic effects post-op, how?
depresses chemoreceptor trigger zone and vagal nuclei
Cardiovascular effects of propofol?
causes vasodilation by inhibitis SNS vasoconstriction
can cause hypotension when given as a bolus
What is PRIS?
propofol infusion syndrome
rare side effect of prolonged prop infusion (>4 mg/kg/hr >24 hrs)
Clinical side effects of PRIS?
metabolic acidosis
hyperkalemia
hyperlipidemia
rhabdomyolysis
Onset of PRIS?
usually within 4 days of initial treatment
How do we manage PRIS?
discontinue prop
supportive care
Mortality of PRIS?
33%
Most commonly used IV benzos?
diazepam
lorazepam
midazolam
What do we use benzos for?
anxiety and amnesia
MOA of benzos?
inhibit synaptic transmission at GABA receptor
Can cause hyperlipidemia, pancreatitis, and local injection site pain;
prop
Does propofol have analgesic effects?
NO
Main disadvantages of prolonged propofol use?
high cost
dose-related hypotension
Mechanism of this syndrome thought to be decreased fatty acid metabolism coupled with damage to mitochondria resulting in cardiac and peripheral myocyte dysfunction:
PRIS
Do benzos have analgesic effects?
NO
they are sedative anxiolytic
3 main benzos?
diazepam
lorazepam
midazolam
Diazepam AKA?
valium
How do benzos work?
increase frequency of Cl channel opening at GABA-A receptors
neuron becomes hyper-polarized, reduced neuron excitability
This benzo has short onset of action and short half-life,;
diazepam (valium)
Dose of diazepam (valium) for anxiety?
PO: 2-10 mg 2-4x/day
IV: 2-10 mg Q 3-4 hrs
Lorazepam AKA?
ativan
ATIVAN AKA?
lorazepam
This benzo has slow onset, intermediate half life and most useful for medium to long-term sedation:
lorazepam (ativan)
Lorazepam and the elderly?
can accumulate in older pts with renal and hepatic dysfunction causing prolonged sedation
Midazolam AKA?
versed
Benzo of choice for acutely agitated pts?
midazolam (versed)
Rapid onset, short acting benzo?
midazolam (versed)
Benzos when used with opioids tend to cause what?
respiratory depression
This is an imidazole derivative used to IV induction?
etomidate
Etomidate is rapidly and completely hydrolized to inactive metabolites, thus;
results in rapid awakening