Lecture 19: Sedative-Hypnotics Flashcards
first two sleep-inducing agents
bromide and chloral hydrate
what drug was introduced in 1912?
phenobarbitol
2 drugs introduced in 1950s
meprobamate (equanil) and carisoprodol (soma)
first benzo
librium
3 benzos
valium, xanax, ativan
where do most act?
GABAa
3 nonbenzo BZRAs
zolpidem (ambien)
zaleplon (sonata)
eszopiclone (lunesta)
4 general anesthetics
nitrous oxide
halothane
isoflurane
ketamine
5HT1-A agonist
buspirone
BZRA
benzodiazepine receptor agonist
3 brain regions associated with anxiety response
- amygdala
- OF cortex
- insula
how many beta subunits?
3
how many alpha subunits?
6
how many gamma subunits?
3
bicuculline
deadly convulsant; competitive antagonist at GABA site
newer drugs are named by ___
receptors they bind to or that underlie major clinical actions
BZRAs include both ___
BZs and nonBZs
BZs act on GABA neurons in ___
limbic system
what happens when GABAergic function is blocked?
anxiety, seizures
what does hypofunctional GABAa receptor activity do?
sensitizes amygdala to anxiogenic responses
what is the general action of BZs on brain?
may reset threshold of amygdala to more normal level of responsiveness
what is an alcohol-induced blakout?
drug-induced, reversible, organic brain syndrome (state of bementia)
how many barbs between 1912 and 1950?
50 different
half life of barbs
3 min - 48 hours
ultrashort acting barb
thiopental
why is thiopental so short?
extremely lipid soluble, crossing BBB rapidly
longer acting barb; why?
amobarbital; more water soluble, slower to penetrate CNS
are barbs analgesic?
no
what do barbs due to REM sleep?
REM sleep and dreaming is suppressed; vivid and excessive dreaming during withdrawal
what kind of tolerance produced by barbs?
metabolic: induce enzymes that metabolize them
cell: adaptation of neurons to drug presence
4 reasons barbs are not widely used
- lethal in overdose
- narrow therapeutic range
- high potential for dependence/abuse
- dangerous interactions with other drugs
4 symptoms of barb withdrawal
- hallucinations
- restlessness
- disorientation
- life threatening convulsions
effects of barbs in pregnancy
possible risk of developmental abnormalities
are nonbarb sedative hypnotics safer than barbs?
no
methaqualone
quaaludes
BZ MoA
GABA agonists, increase chloride ion influx; allosteric modulators that increase GABA binding to GABAa receptor binding site
5 uses of BZs
- anxiolytic
- anticonvulsant
- insomnia
- central muscle relaxants
- potentiation of CNS depressants (anesthesia)
% of dependent users of BZs; comorbid depressive disorders?
10%; 34%
peak plasma conc of BZs
1 hour
3 negative effects of BZs on elderly
- dementing
- depressive
- increased falls
metabolite of diazepam
nordiazepam
half life of nordiazepam
60 hours
metabolite of lorazepam
glucoronide conjugated metabolite (inactive)
2 short acting benzos
- halcion (triazolam)
2. xanax (alprazolam)
intermediate acting BZ
lorazepam (ativan)
2 long acting BZs
- chlordiazepoxide (librium)
2. diazepam (valium)
6 limits of BZs
- poorly relieve stress
- limited anticonvulsant use
- complicate cog behav therapies (memory/cog problems)
- dementing
- rebounding symptoms w withdrawal
- addictive
1mg xanax impairs driving comparable to BAC of ___
0.15
ambien half life
2-2.5 hrs
sonata half life
1 hour
lunesta half life
5-7 hrs
Z drugs are more selective for GABARs with ___
a1 subunits
3 benefits of BZs
- safe
- do not induce metabolic enzymes
- act only on CNS
what kind of memory is impaired with BZs?
episodic memory
common users and abusers of BZs
older women
young male drug users
benefit of ketamine as anesthetic
doesn’t reduce blood pressure
ramelteon
selective meltaonin receptor agonist; very modest effect
buspar
selective weak 5HT1a agonist
what specific risk do barbs have for children?
trigger hyperactivity and learning problems
antiepileptic drug problem for pregnancy
higher rates of stillbirth and infant mortality; 7% risk of birth defect