Benzos and Barbs Flashcards
Do benzos potentiate the neuromuscular blockade?
Nope
Do benzos induce hepatic enzymes?
Nope
We’re having fun now, aren’t we? Riiiiiight?!?
Nope
Benzodiazepine structure?
Benzene ring fused with 7-member diazepine ring
Benzodiazepine MOA
Facilitate action of GABA and GABA-A receptor, enhance affinity of GABA to the receptor
(but DOES NOT activate GABA-A receptor)
This leads to Cl channels open, inc conductance, hyperpolarization of post-synaptic membrane, increased resistance of post-synaptic membrane to excitation
Benzos are highly _____ (water/lipid) soluble and _____ (high/low) protein binding
Lipid soluble
High PB
Structure of midazolam (versed)?
Water soluble preparation Imidazole ring (same compound that etomidate has)
How does potency of midazolam compare to diazepam?
Midazolam is 2-3x more potent than diazepam
Midazolam metabolism?
Extensive hepatic metabolism
ACTIVE METABOLITE: 1-hydroxy-midazolam
Conjugated and excreted in the urine
Renal failure doesn’t effect VD, E1/2t, or clearance
Midazolam CNS effects?
Decreases CBF and CMRO2
Does NOT attenuate ICP response to laryngoscopy
Anticonvulsant and amnestic
Midazolam respiratory effects?
Decrease in ventilation
Hypoxemia and hypoventilation enhanced in presence of opioid
Depress swallow reflex
Midazolam CV effects?
Cardio stable; CO unchanged
Dec SVR at induction dosage
Dec BP from anxiolysis
Doesn’t attenuate laryngoscopy HR/BP changes
Dosage of midazolam for…
Premedication peds
IV sedation adults
Induction
Premed peds: 0.25-0.5 mg/kg po (not on drug cards)
Peds po dose max 20mg
IV sedation adults (premedication): 0.5-5 mg IV or 0.04-0.08 mg/kg
Induction: 0.05-0.35 mg/kg over 30-60 sec
*Per drug cards, not powerpoint
Diazepam is prepared in what solvents?
Propylene glycol
Benzyl alcohol
Painful IV/IM injection
Diazepam metabolism?
Oxidation, n-demethylation to desmethyldiazepam (ACTIVE METABOLITE) which is oxidized, conjugated, and excreted in the urine
Diazepam E1/2t?
Diazepam is a day (21-37h) with prolonged DOA
Desmethyldiazepam is 2-4 days!
Diazepam dosages for… premedication oral and IV; induction; anticonvulsant?
Premedication oral: 10-15mg
Premedication IV: 0.2 mg/kg (reduces MAC)
Induction: 0.5-1 mg/kg IV
Anticonvulsant: 0.1 mg/kg IV
Which benzodiazepine is most potent?
Lorazepam (ativan)
It is 5-10x more potent than diazepam
Lorazepam metabolism and e1/2t?
Metabolites are INACTIVE
Metabolism effected by hepatic function and age
E1/2t 10-20h
Slow onset, IV takes 20-30 min to peak, not used as often in OR
Lorazepam solvent?
Propylene glycol
Lorazepam premedication/po dosage?
50 MCG/kg (max 4 mg)