Benzos Flashcards
What is anxiety?
sustained state of apprehension and autonomic arousal in response to real or perceived threats. Fear of suffering and death, loss of control, and frustration caused by the inability to communicate
What is the onset of midazolam
30-60 seconds
What are the symptoms of anxiety?
headach, insomnia, nausea, anorexia, dyspnea, palpitations, dizziness, dry mouth and chest pain.
Signs include diaphoresis, hyperventilation, tachycardia, etc
what is the duration of midazolam?
15-80 min
what is the peak time of midazolam?
3-5 min
What is the route and trade name for for lorazepam?
Ativan
iIV
What is the onset of Lorazepam?
1-2 minutes
what is the peak time of lorazepam?
20-30 minutes
what is the duration of lorazepam?
6-10 hours
What is the route for diazepam
po. occasionall used in preop
What are the effects of benzodiapines?
Sedation
Anxiolysis
Anticonvulsant
Anterograde amnesia
Do benzodiazepines protect against the stress of intubation or provide anagesia?
no
Also not useful as an antidepressant or antipsychotic
How are benzo diazepines used clinically?
Relief of anxiety
Sedation and amnesia before and during medical and surgical procedures
component of balanced anesthesia
Treatment of epilepsy and siezures
Insomnia
Control of ethanol or other sedative-hypnotic withdrawal states
muscle relaxaition in specific neuromuscular disorders
diagnostic aids for treatment in psychiatry
What is the mechanism of action for benzodiazepines?
Benzodiazepines work in post synaptic neurons by binding to the GABAa receptor. This receptor opens chloride channels and hyperpolarizes the neuron increasing the difference btw resting potential and action potential making firing less likely.
their action works in these areas:
Cerebral cortex>hypothalamus>midbrain>hippocampus>medulla>spinal cord
What is the effectif 20% of receptors are bound by a benzodiazepine?
axiolysis
What is the effect if 20-50% of receptors are bound by benzodiazepine?
sedation
What is the effect if 60% of receptors are bound by benzodiazepine?
uncosciousness
What is the preop dose of midazolam for kids?
0.5 mg/kg PO 30 minutes before
15 mg max
What is the IV sedation dose for midazolam?
0.5-4 mg IV load, followed by 1-7mg/hour
What is the dose of midazolam for IV induction of anesthesia?
0.1-0.2 mg/kg
What dose of Diazepam used for supression of seizure activity?
0.1 mg/kg
Are benzodiazepine subject to cross tolerance?
yes. Alcohol also binds GABAa
How does hypoalbumenia affect benzodiapines?
Benzos are bound to protein 90-98%. In the case of hypoalbunemia you have more free drug and an increased effect
How is midazolam metabolized?
liver oxidation by CYP450
How does alcohol use affect midazolam metabolism?
Alcohol increases tolerance due to GABAa ase well as leads to increased clearance
What is the active metabolite for midazolam?
there is none
How does age affect midiazolam?
in elderly >80yo -dysphoria, impaired cognitive function, and effects last long
How is versed for end stage renal disease?
versed metabolites are excreted in urine. Because versed has no active metabolites, it will have no effect on these pts.
What effects do benzos have on the CNS?
decreased cerebral metabolic O2 requirement and decreased cerbral blood flow
No isoelectric EEG
No change in ICP
No evidence of neuroprotection
Potent anticonvulsant
What effects do benzos have on ventilation?
dose dependent decrease
What effects do benzos have on the CV system?
decrease BP and HR–minor
Do benzos cross the placenta?
YES
What are hepatic considerations for taking benzos
cross reactions with other drugs
age–elderly will not have as much blood flow to the liver
How do benzos work as anti convulsants?
ability ot facilitate the actions of GABA
(barbituates depress the CNS)
What is the dose of diazepam for lidocaine toxicity, DTs and status epilepticus?
0.1mg/kg IV
What is the pK of versed?
6.15
How does versed compare to Diazepam?
2-3x as potent
What are reasons versed is good for anesthesia?
Rapid onset
Short duration
Specific andtagonist
PO route
What are problems with Valium and Ativan in for anesthesia?
not water soluble-have preservative and additives and can cause thrombophlebitis and venous irritation
Active metabolites–this will increase effect in end stage renal disease
Slow onset
long duration
What is flunitrazepam?
rohypnol
What is flumazenil?
Specific competitive antagonist for benzos
What are potential problems of flumazenil?
Resedation-only has 30 minute duration
Withdrawl if chronically on benzos
How is flumazenil metabolized?
in liver
Wha tis the dosing for flumazenil?
0.1-0.2 mg IV repeated up to 3 mg
What percent of versed makes it to the BS after redistribution?
50%
