Pharm - General and Local Anesthetics Flashcards
-ane suffix indicates _____
inhaled anesthetic
what is the one inhaled anesthetic that is gas at room temperature
nitrous oxide
compare vapor pressures and boiling points between the volatile and gaseous inhaled anesthetics
volatile: low vapor pressure and high boiling points
gaseous: high vapor pressure and low boiling points
describe the relationship between the blood:gas partition coefficient and the rate of anesthesia onset
inverse relationship
the higher the blood: gas partition coefficient, the slower the onset of action
the lower the coefficient, the faster the onset of action
what inhaled anesthetics have a low blood solubility and thus a fast onset (low blood:gas partition coefficient)
nitrous oxide (0.47)
desflurane (0.42)
sevoflurane (0.69)
what inhaled anesthetics have a high blood solubility and thus a slow onset (high blood:gas partition coefficient)
halothane (2.3)
enflurane (1.8)
isoflurane (1.4)
rank the inhaled anesthetics in order of highest blood:gas partition coefficient to lowest
halothurane –> enflurane –> isoflurane –> sevoflurane –> nitrous oxide –> desflurane
what is used to measure the potency of inhaled anesthetics
minimal alveolar concentration (MAC)
what tissues in the body have a higher immediate concentration of anesthetic due to their high perfusion
brain, heart, liver, kidneys, splanchnic bed
which inhaled anesthetics are eliminated at faster rates
what is the major route of elimination from the body
those that are relatively insoluble in the blood (ex: nitrous oxide)
clearance via the lungs is the major route
rank the inhaled anesthetics from least to greatest in terms of potency
LEAST
nitrous oxide –> desflurane –> sevoflurane –> enflurane –> isoflurane –> halothane
GREATEST
what are the effects of inhaled anesthetics on the cardiovascular system
volatile liquid anesthetics decrease the mean arterial pressure in direct proportion to their alveolar concentration
ALL inhaled anesthetics increase right atrial pressure
halothane –> bradycardia
desflurance and isoflurane –> tachycardia
what are the general side effects of inhaled anesthetics
nausea and vomiting
what are the specific side effects for halothane
hepatitis
anorexia, nausea, myalgias, arthralgias, rash, eosinophilia, hepatomegaly, jaundice
what are the specific side effects for enflurane and sevoflurane
renal toxicity
when combining inhaled anesthetics with succinylcholine, what side effects can occur
malignant hyperthermia
MOA propofol
agonist at GABA-A receptors and potentiates chloride current
describe the pharmacokinetics of propofol, including rate of onset and recovery
rapid rate of onset (15-30 seconds) and rapid recovery
rapidly metabolized in liver w/ extensive extrahepatic metabolism
indications propofol
- sedation in ICU (continuous infusion)
- conscious sedation
- short-duration general anesthesia in locations outside the OR
effects of propofol on CNS
general suppression of CNS activity
no analgesic properties
decreased cerebral blood flow and cerebral metabolic rate for oxygen –> decreases intracranial pressure and intraocular pressure
effects of propofol on CV system
pronounced decreased in sympathetic blood pressure due to profound vasodilation in both arterial and venous circulation
describe the metabolism of fospropofol
water soluble pro-drug of propofol
rapidly metabolized by alk phosphatase –> produces propofol, phosphate, and formaldehyde
compare onset and recovery between propofol and fospropofol
fospropofol has prolonged onset and recovery because the pro-drug has to be converted in an active form
side effects of fospropofol
paresthesias and pruritus
MOA etomidate
enhances actions of GABA on GABA-A receptors
describe rate of onset and recovery for etomidate
rapid loss of consciousness but less rapid recovery compared to propofol
effects of etomidate on CNS
potent cerebral vasoconstrictor
decreases cerebral blood flow and intracranial pressure
effects of etomidate on CV system
minimal change in heart rate and cardiac output
effects of etomidate on endocrine system
adrenocortical suppression by inhibiting 11B-hydroxylase (converts cholesterol to cortisol)
MOA ketamine
NMDA receptor antagonist
what effects does etomidate produce
hypnotic but not analgesic effects
what effects does ketamine produce
dissociative anesthetic state with catatonia, amnesia, and analgesia w/ or w/o LOC
effects of ketamine on CNS
increased cerebral blood flow
what is the main limiting factor for use of ketamine
unpleasant emergence reactions:
vivid colorful dreams, hallucinations, out of body experiences, increased and distorted visual, tactile, and auditory sensitivity
effects of ketamine on CV system
can increase systemic BP, HR, cardiac output
what is the only IV anesthetic to produce profound analgesia, stimulation of the sympathetic nervous system, bronchodilation, and minimal respiratory depression
ketamine
MOA dexmedetomidine
alpha-2 agonist
what effects does dexmedetomidine produce
sedative effect more resembles a physiologic sleep state through activation of endogenous sleep pathways
effects of dexmedetomidine on CV system
decreased HR and systemic vascular resistance and BP
indications dexmedetomidine
short-term sedation of intubated and ventilated patients in an ICU setting
what are the three classes of drugs used in adjunct to anesthetics
opioid analgesics
barbiturates
benzodiazepines
what opioids are used in adjunct to anesthetics
fentanyl, sufentanil, remifentanil, morphine
what barbiturates are used in adjunct to anesthetics
thiopental and methohexital
what benzos are used in adjunct to anesthetics
when are they used
diazepam, lorazepam, midazolam
perioperative period because of anxiolytic properties and ability to produce anterograde amnesia
which benzo is used most frequently in adjunct to anesthetics and why
midazolam
rapid onset, shorter elimination half life, and steeper dose-response curve
-caine suffix indicates what
local anesthetic
-caine suffix with two i’s in the name indicates what
local anesthetic in the amide class
MOA local anesthetics
blocks voltage gated sodium channel currents and stops the spread of axon potentials down the nerve
what is the only “surface only” local anesthetic
benzocaine
what are local anesthetics often paired with and why
vasoconstrictors
- stop bleeding for trauma injuries
- keeps the anesthetic local (decreases absorption into the circulation)
what are the CNS effects of local anesthetics at low doses and at high doses
low doses –> sleepiness, light-headedness, visual/auditory disturbances
high doses –> nystagmus, muscular twitching, convulsions
what are the CV effects of local anesthetics
decrease electrical excitability, conduction rate, force of contraction, and cause arteriolar dilation –> systemic hypotension
what side effect is specific to ester-type local anesthetics
allergic reactions are more common
indications bupivacaine
prolonged anesthesia
indications cocaine
topical anesthetic of upper respiratory tract
indications dibucaine
topical cream for use on the skin
used to be used for injections tho, but stopped because of toxicity
indications lidocaine
anti-arrhythmic agent
indications procaine
infiltration anesthesia
local anesthesia produced by injection of procaine directly into area of terminal nerve endings
