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IV anesthetics


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Thiopental (Pentothal)
ultra-short acting barbiturate (induction 10-15 sec.)
highly lipid soluble
distribution of thiopental
initially distributes into brain well (high blood flow), then redistributes into fatty tissues (accounts for it's rapid but short effects)
use of thiopental
used mainly for induction, or very short procedures
thiopental metabolized by what?
by P-450 system in the liver
half-life of thiopental
6 hrs
repeated administration of thiopental will cause?
will fill the body's storage sites (fats) and can lead to long duration of action
thiopental : pain threshold
thiopental lowers pain threshold, thus increasing sensitivity to pain
Does thiopental have good skeletal muscle relaxtant effects?
NO! very poor skeletal muscle relaxant effects
effects of thiopental
1) potent resp. depressant - lead to a period of apnea during induction
2) depresses myocardium
3) relaxes vascular smooth muscle - cause hypotension
Methohexital (Brevital)
similar to thiopental, but 3 times as potent
metabolism of Methohexital
metabolized faster (due to less lipid solubility) mainly via P-450 oxidation
1) loss of effect still mainly due to redistribution
2) recovery is faster than thiopental with multiple doses
Propofol (Diprivan) acts by?
acts by interaction with GABA receptor, decreasing the rate of GABA dissociation from the receptor
other actions of propofol
1) antiemetic
2) antipruritic
3) anticonvulsant
distribution of propofol
1) rapidly distributes to brain
2) induction in 15-30 sec. - give slowly due to vessel irritation
termination of anesthesia of propofol is due to?
redistribution to fatty tissues
duration of propofol
5-10 min.
metabolization of propofol
highly metabolized in liver
half life 2-3 hrs (does not accumulate as much as Thiopental)
1) does not increase pain sensitivity
2) decrease BP due to < CO and < vascular resistance
3) does not trigger malignant hyperthermic crisis
Etomidate (Amidate)
1) structure unlike any other anesthetics
2) large Vd (tissue distribution)
mechanism of etomidate
via GABA interaction like barbs and benzos
etomidate mixed with?
propylene glycol for injection
etomidate is metabolized via?
via hydroxylation by plasma esterases and HMES
induction of etomidate
induction as rapid as Thiopental, with emergence in 5-10 min.
effects of etomidate
1) minimal CV effects
2) resp. depression
3) depresses steroid synthesis in adrenals (not used long term)
Dexmedetomidine (Precedex)
1) a novel agent for the control of stress, anxiety, and pain
2) alpha-2 agonist
Dexmedetomidine used with?
used in combination with agents such as propofol, opioids, and benzo.
when used Dexmedetomidine alone, it produces what?
sedation with the ability to rouse the pt
Vd, t1/2, Cl?
1) Vd = ~118 L
2) t1/2 = ~2hrs
3) Cl = ~39L/hr
administer via continuous IV infusion
metabolism of Dexmedetomidine via
1) glucuronidation
2) P450 hydroxylation (dosage adjustment in hepatic dz)
Midazolam (Versed)
1) a benzodiazepine with strong hypnotic properties
2) good amnesic
3) minimal CV effects
duration of effects of Midazolam
15 min.
use of Midazolam
1) usally used as an adjunct, but it can be used for induction (60 sec.) and maintenance
2) usually used with opioid for longer duration
Ketamine (Ketaject)
1) similar to PCP
2) IV or IM
3) rapid induction with IV dudration of ~15 min.
Ketamine stimulates?
the CV system: increase HR, CO, and BP
2) good analgesic and amnesic
Ketamine blocks?
glutamate excitatory NMDA receptors in CNS
Ketamine triggers?
catalepsy (dissociation anesthesia), which is the appearance of being awake, even though they do not respond
recovery from Ketamine
recovery phase characterized by CNS stimulation, so keep pt. in quiet area

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