Benzos Flashcards
Pharmacological effects of Benzos (5)
- sedation
- anxiolysis
- anticonvulsant
- skeletal muscle relation
- antegrade amnesia
do benzos affect NMB dose?
No - Muscle relaxation is not sufficient for surgical relaxation
benzos facilitate inhibitory actions of what neurotransmitter?
GABA
benzos mimic inhibitory actions of what neurotransmitter
glycine
benzos mimic what two glycine actions?
muscle relaxation and antianxiety
benzos enhance what two GABA actions?
sedation and anticonvulsants
where are GABA and glycine located?
GABA – major inhibitory neurotransmitter in the CNS
Glycine is the major inhibitor neurotransmitter in the brainstem and spinal cord
MOA of benzos
bind to part of GABA receptor and causes an increase of binding of GABA to that receptor which
- opens Cl channels
- hyperpolarizes neuron
- causes inhibition of neuron to excitation
Do benzos affect GABA receptor directly?
Not really, they increase ability of GABA to bind to receptors which causes the effects of the benzos
2 important things to understand about the multiple sites on GABA receptor?
- Benzos don’t activate receptor, increase affinity of GABA
- dose of propofol, volatiles, etc will be reduced BC of the synergist effect of benzo and the fact that you already have something bound to that GABA receptor
The enhancement of the GABA inhibitory effect might explain what two effects?
sedation
anticonvulsant
Glycine-like inhibition in the spinal cord motor neurons accounts for muscle relaxation and anxiolysis r/t?
may be due to the inhibition of afferent conduction to anxiety centers at the brainstem level
GABA Has separate binding sites for benzodiazepine, barbiturates, and ETOH which means
If the receptor is “acted on” at more than one site, the inhibition of the CNS to excitation is synergistic
what type of agonist is benzo?
partial agonist whereas an inhaled agent is an agonist
what is the real agonist when thinking about benzos and effects?
GABA
Most commonly administered as premedication or IV sedation
Midazolam (Versed)
what is the interesting thing about versed and its ionization?
it is water soluble in the bottle, but becomes lipid soluble when in a solution with a pH>4 due to its imidazole ring
what two meds is midazolam compatible with?
opioids and LR
why is their no pain on injection (IV or IM) with midazolam?
does not need a carrying agent
Different routes of versed admin?
PO, IM, sublingual, intranasal, IV
Uses for midazolam -versed (4)
premedication, sedation, induction of anesthesia, maintenance of anesthesia
cards effects of Midazolam?
Decrease in BP r/t to SVR decrease
Increase in HR r/t SVR decrease
No change in CO
Hemodynamic effect exaggerated in hypovolemic patients
if you have a pt that is hypovolemic and you want amnesia and you have midazolam or scopalamine, what would you give?
scop because hemodynamic effects of midazolam are exaggerated with these patients
what is the cardioprotectant effect of midazolam?
makes adenosine last longer
Adenosine’s effect on cardio system?
it is an endogenous chemical
Reduces myocardial oxygen demand
Slows HR
Increase myocardial oxygen supply
Coronary vasodilation
what is verseds MOA on adenosine in body?
Decrease adenosine degradation by inhibiting the nucleoside transporter (mechanism for reuptake of adenosine into cells)
resp effects of midazolam? (3)
- Produces dose-dependent decreases in ventilation similar to diazepam (COPD worse)
- Apnea
- Depresses swallowing reflex and upper airway activity (OSA)
apnea can occur with midazolam with
Rapid injection of doses >0.15 mg/kg IV
With opioids