Benzodiazepines Flashcards
what receptor do benzodiazepines bind to
GABA-A ligand-gated chloride channel complex
what is the mechanism of action of benzodiazepines
binds to GABA-A–> enhances the inhibitory effects of GABA-regulated channels
INHIBITS neuronal activity presumably in AMYGDALA-centered fear circuits to provide therapeutic benefits in anxiety disorders
inhibitory actions in CEREBRAL CORTEX may provide therapeutic benefits in seizure disorders
how many GABA receptor subtypes are there
3–> A, B, C
what is the function of the GABA-A receptor subtype
gatekeeper for the chloride channel–> chloride goes into the cell, polarizing the action potential AWAY from activation
action is inihibitory in the amygdala and frontal cortex
the GABA-A receptor is allosterically modulated by which compounds
benzos
alcohol
Z drugs
barbiturates
list the four MAIN indications for benzodiazepines
anxiety disorder
anxiety disorder associated with depressive symptoms
initial treatment of status epilepticus (
preanesthetic
list other indications for benzodiazepines
insomnia
muscle spasm
alcohol withdrawal psychosis
headache
panic disorder
acute mania (adj)
acute psychosis (adj)
how quickly might someone notice benefit from benzodiazepines
some immediate relief with first dosing is common
can take several weeks for maximal therapeutic benefit with daily dosing
what is the usual starting dose and the typical range of the following benzodiazepine:
lorazepam
start–> 0.5mg
typical daily dosing–> 1-2mg /day
what is the usual starting dose and the typical range of the following benzodiazepine:
clonazepam
start–> 0.5mg
typical daily dosing–> 0.5-2mg /day
what is the usual starting dose and the typical range of the following benzodiazepine:
diazepam
start–> 2-10 mg
typical daily dosing –> 4-40mg/day
can you use benzodiazepines if kidney/liver function is present
monitor functioning if impairment is present
list common side effects of benzodiazepines
sedation
fatigue
depression
decreased cognitive processing
anterograde amnesia
dizziness
ataxia/visuospatial and visuomotor deficits
slurred speech
weakness
tolerance/dependence
rebound anxiety
in which patients should you not prescribe benzodiazepines (non-psychiatric reason)
those with occupational risks i.e truck drivers, pilots–> higher likelihood of crashes (OR 1.6 on any benzo)
list rare side effects from benzodiazepines
hallucinations
hypotension
paradoxical agitation
respiratory depression (esp. when Rx along with CNS depressants)
what medication can counter benzodiazepine overdose
flumazenil
what does benzodiazepine overdose look like
hypotension
rare respiratory depression
in which patients is the risk of tolerance/dependence to benzodiazepines higher
treatment periods over 12 weeks
those with polysubstance abuse
what CYP interactions does the following medication have:
lorazepam
none
what CYP interactions does the following medication have:
clonazepam
3A4 (major substrate)
what CYP interactions does the following medication have:
diazepam
3A4 (major substrate), 2C19 (major substrate)
is lorazepam safe in end stage kidney disease
no–> not recommended
which benzo should be used with caution in liver impairment
diazepam
what is the half life of lorazepam
10-20 hours
what is the half life of clonazepam
30-40 hours
what is the half life of diazepam
20-50 hours
what determines duration of action in benzodiazepines
distribution (not as much by elimination half life)
–> ie diazepam has long half life but is highly lipid soluble so actually has relatively SHORT duration of action as will distribute fairly quickly
marked inter-individual variation
how are benzos metabolized
hepatic oxidation, reduction and conjugation
how long will someone notice benefits for insomnia from benzos
about 14 days
what is the risk of rapid withdrawal of benzodiazepines
seizure
what is the recommended tapering protocol to get someone off benzos if they have been on them a long time
rec. taper length is 6-12 months (10% per month)
first half of taper usually much easier than second half
list 3 of the strongest predictors of benzo withdrawal severity
- high baseline neuroticism
- female sex
- mild to mod alcohol use
*these are more predictive than daily dose or half life of the benzo
you should evaluate patient for what medical disorder before prescribign benzos
OSA–> benzos can worsen OSA
how might you reconsider benzo use in the pediatric population
lower dosing range
higher risk of SEs
(same for geri)
which benzo is NOT recommended for use during pregnancy
lorazepam–> especially during first trimester
what are some of the considerations for benzo use during pregnancy
possible increased risk of birth defects when benzos taken during pregnancy
infants whose mothers received benzos late in pregnancy may experience withdrawal effects
neonatal FLACCIDITY has been reported in mothers who took benzo during pregnancy
some drug found in mother’s breast milk
effects on infant that have been observed: feeding difficulties, sedation, weight loss
*risk category D–> positive evidence of risk to human fetus/ benefits may still justify use