pharmacology: sedative-hypnotic-anxiolytic drugs Flashcards
what are the sedative-hypnotic-anxiolytic drugs?
benzodiazepines, barbiturates, alcohols
what is the GABA binding site? benzo? barbiturate?
GABA: alpha
benzo: gamma
barbiturate: beta
what are the increasing CNS effects of benzos/barbiturate/alcohols?
paradoxical disinhibition –> sedation–> anxiolysis –> anticonvulsant and muscle relaxing –> hypnosis –> anesthesia –> medullary depression –> coma/death
how do benzo/barbiturates/alcohol cause paradoxical disinhibition (excitement, drunk)?
inhibiting an inhibitory neuron (causing excitation instead)
GABA A activation causes
increased Cl- influx
GABA B activation causes
increased K+ efflux
benzodiazepine mechanism
potentiate GGABA, increased frequency of CL opening with NO GABA mimetic activity!
what are the benzodiazepines?
alprazolam, diazepam, lorazepam, midazolam, temazepam, oxazepam
which benzodiazepines have a short half life? implication/clinical use?
temazepam and oxazepam - used in sleep disorders
which benzos have a long half life? implication/clinical use?
alprazolam, diazepam, lorazepam, midazolam
-used in anxiety
which benzo is used in panic/phobias?
alprazolam
which benzo is used in withdrawal states?
diazepam
which benzo is used in status epilepticus?
lorazepam
which benzo is used in anesthesia?
midazolam
what is used in benzodiazepine overdose? mechanism?
BZ receptor antagonist flumazenil
barbiturates mechanism
prolong GABA activity by increasing DURATION of Cl- channel opening and have GABA mimetic activity
what are the barbiturates? uses?
phenobarbital for seizures (long acting)
thiopental for induction of anesthesia (short acting)
what is the contraindication for barbiturates?
porphyrias - blocks enzyme used in heme synthesis D-ALA synthase (buildup of chemicals related to RBC proteins)
withdrawal signs for BZs vs withdrawal signs of barbiturates and alcohol
BZs: rebound insomnia, anxiety, seizures when used as antiepileptic or high doses
Barbiturates/ethanol: anxiety, agitation, life-threatening seizures (delirium tremens with alcohol)
drug interactions with GABA A drugs
- additive with other CNS depressants such as anesthetics, antihistamines, opiates, beta blockers
- barbiturates induce metabolism of most lipid-soluble drugs such as oral contraceptives, carbamazepine, phenytoin, warfarin
what are the non-BZ drugs?
- zolpidem and zaleplon (BZ1 receptor agonist instead of BZ2) - used in sleep disorders
- buspirone (no effect on GABA - 5-HT1A partial agonist - used in anxiety disorders)
what is used for generalized anxiety disorders?
buspirone!
