Benzos (Ex1) Flashcards
Sedative/hypnotics definition
Drug that induces sleep, calm or hypnosis
Used fairly interchangeable
How is EEG monitoring used to measure drug effects
Anesthesia alters CBF and CMRO2
-CBF and CMRO2 relate to EEG activity
BIS monitoring explanation
Processed EEG compacted into one waveform
Helps determine level of sedation/consciousness
BIS # showing unconsciousness
Less than 58
BIS # less than 65
5% chance of consciousness within 50 seconds
SQI on BIS monitor
Signal quality index
-measures quality or lack of interference
SR on BIS monitor
Suppression Ratio
-number of times EEG flatlined
Examples of BIS suppressants (5)
Hypnotics, volatiles, NMBD, opioids, beta blockers
Examples of BIS stimulants (2)
Ketamine
Epinephrine
Ideal range for BIS# general anesthesia
40-60
Pharmacologic effects of BZDs (5)
-Anxiolytic
-Sedation
-Anterograde amnesia (forward)
-Anticonvulsant
-Skeletal muscle relaxation (not paralysis)
BZD benefit over barbiturates (3)
-Less tolerance or abuse potential
-Fewer/less severe side effects
-Don’t induce CYP450
BZD MOA
Facilitates actions of GABA-A => enhanced open of chloride channels => hyperpolarization of postsynaptic membrane
GABA alpha-1 effects (3)
Sedative
Amnesia
Anticonvulsant
GABA alpha-2 effects (2)
Anxiolytic
Skeletel muscle relaxation
Synergistic drugs also acting on GABA-A (4)
Barbiturates
Etomidate
Propofol
Alcohol
BZD EEG effects (2)
-Decrease alpha wave activity => relaxation
-Some able to flattened brain waves
Midazolam trade name
Versed
Versed amnesia vs sedation effects
Amnestic effects last longer than sedation effects
Versed solubility with pH
In less than 3.5 pH => water soluble (ring open)
In more than 4 pH => lipid soluble (ring closed)
Versed onset and peak effect
Onset: 1-2 min
Peak: 5 min
Versed protein binding
Extensively bound 96-98%
BZD reversal drug
Flumazenil (Romazicon)
Versed E 1/2 time
2 hours
Doubled in elderly pts
Versed Vd
Large
Versed metabolism
CYP3A4 (hepatic Microsomal enzymes)
Significant Drugs that can decrease BZD metabolism by CYP inhibition (3)
Cimetidine (Tagamet)
Calcium channel blockers
Fentanyl
Versed cerebral flow effects
Decrease CMRO2
Decrease CBF
(Both dose related)
Versed EEG effects
-Potential anticonvulsant
-Unable to produce isoelectric EEG (flatline)
CO2 cerebral flow effects
High CO2 => cerebral vasodilation
Low CO2 => cerebral vasoconstriction
Versed ICP effects
No effect on ICP (neuro-safe)
Versed pulmonary effects
Dose dependent decrease in ventilation
Versed airway effects
Depresses swallow reflex and upper airway activity => increased risk of aspiration
Versed CV effects
Dose dependent increase HR and decreased BP
(CO unchanged d/t compensation)
Versed sedation/anxiolysis dosing (adult)
1-5 mg IV
Peaks 5 min
Versed sedation/anxiolysis children dose
0.25-0.5 mg/kg oral
Peak 20-30 min
Versed induction dose
Not common as induction
0.1-0.2 mg/kg IV over 30-60 sec
Versed Postoperative sedation dose
1-7 mg/hr IV
Not recommended for use more than 2 days d/t immune/T cell effects
Diazepam trade name
Valium
Valium protein binding
Highly protein bound
Valium duration (comp)
More prolonged duration than versed
Rarely used in anesthesia
Valium solubility
Insoluble in water
-need propylene glycol => pain on injection
Valium onset and duration (comp)
Onset: 1-5 minutes
Duration longer than versed
Valium E 1/2 time
20-40 hours
Valium metabolism
CYP3A
-active metabolite nearly as potent (48-96 hr)
Valium cerebral flow effects
Dose related decrease in CMRO2 and CBF
Valium anticonvulsant dose
0.1 mg/kg IV
Valium EEG effects
Can produce isoelectric EEG (flatline)
Valium pulmonary effects
Minimal effects on ventilation
Slight decrease in Vt
Valium CV effects
Minimal decrease in BP, CO, and SVR
Valium induction dose
0.5-1 mg/kg IV
Decrease 25-50% in:
-elderly
-Liver disease
-Presence of opioids
Lorazepam trade name
Ativan
Ativan potency (comp)
More potent compared to other BZDs
Ativan solubility
Insoluble in water
-requires polyethylene glycol => burns on injection
Ativan onset (comp) and peak
-Slower onset than versed and Valium
Peak: 20-30 min with IV dose
Ativan E 1/2 time
14 hours
Ativan metabolism
Conjugated to inactive metabolites
-less dependent on hepatic enzymes
Ativan dose
1-4 mg IV
Flumazenil trade name
Romazicon
Flumazenil MOA
Competitive antagonist for BZD receptor
-prevents/reverses BZD agonist activity
Flumazenil metabolism
Hepatic Microsomal enzymes
Flumazenil dose
0.2 mg IV
-repeat 0.1 mg q1 min to 1 mg total
To consciousness
Flumazenil duration
30-60 min (shorter than BZD => resedation from BZD)
Flumazenil side effects
No significant side effects
Flumazenil cautions
Contraindicated in pt taking antiepileptic drugs