9. Anxiolytics & Hypnotics Flashcards
Describe the basic structure of benzos
benzene ring fused with a diazepine ring
All barbituates are related to which structure?
barbituric acid
What do benzos target?
the GABA-A receptor
What is significant about the alpha subunit on the GABA-A receptor?
- There are 5 isoforms of the alpha subunit (1-5)
- a1 –> hypnotic
- a2-5 –> sedation, psychomoto effect
Explain the MOA of benzos
- bind to GABA-A receptor and enhance GABA actions
- reduce excitability of neurons through hyperpolarization due to influx of Cl- (increases channel opening events)
- low affinity for GABA-B receptors
- acts as CNS depressant
Explain the MOA of barbiturates.
- binds to GABA-A receptor
- increases duration of channel-opening events
- GABA-mimetic at high concentration (inhibitory effects)
- inhibits glutamate AMPA receptor
What is the major determinant for the onset of CNS drugs?
- the lipophilicity of drugs
- need to pass the BBB
- more lipophilic = more rapid onset
What determines the duration of CNS drugs?
- Lipophilicity –> redistribution
- biotransformation
- conjugation
- metabolic conversion to more water-soluble metabolites (active)
What are short acting and long acting benzos used for?
short –> hypnotic
long –> anxiolytic
What considerations should be taken when thinking about benzo pharmacokinetics?
- can cross placenta
- found in breastmilk
- older pts and liver disease pts should use caution
- redistributed in fat –> obese pts
What uses do barbiturates have?
induction of anesthesis (ultra-short)
hypnotic and sedative (short)
seizures (long)
What are 6 therapeuticsc uses of benzos?
- anxiety relief
- insomnia
- sedation and amnesia before and during surgery
- epilepsy and seizures
- muscles relaxation for neuromuscular disorders
- alcohol withdrawal
Describe stage 1 of sleep?
light sleep during where the muscles begin to relax
Describe stage 2 of sleep.
brain activity slow down and eye movement stops
Describe stages 3/4 of sleep.
deep sleep
all eye and muscle movement stops
