CNS Pharmacology Sedative Hypnotics

CNS pharmacology sedative hypnotics

45 cards   |   Total Attempts: 185
  

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Name the major classes of sedative hypnotics
1. Benzodiazepines (major class)
2. Barbiturates (eg phenobarbitol). ultra short, short, or long acting
3. Newer hypnotics - zolpidem, eszopiclone, zaleplon
4. Carbamates- meprobamate
5. alcohols - EtOH, chloral hydrate
6. Atypicals- buspirone (selective anxiolytic) and ramelteon (selective sleep)
Name some long-acting benzodiazepines

Name some other benzodiazepines
Diazepam, chlordiazepoxide, chlorazepate


alprazolam, clonazepam, flurazepam, lorazepam, oxazepam, triazolam
Name some barbiturates
Phenobarbital, pentobarbital,amobarbital, secobarbital, thiopental.
Which sedative hypnotic is commonly used to induce anesthesia?
Thiopental


Very high lipid solubility, enters CNS quickly. Then actions are terminated by redistribution to other tissues.
Order the five shortest acting sedative hypnotics
Zaleplon
How are benzodiazepines metabolized?
Most are converted to active metabolites by the liver. may build up. Lorazepam and oxazepam undergo hepatic conjugation but are not converted to active metabolites.
Which sedative hypnotic does not have to be metabolized by the liver prior to secretion?
Only phenobarbital is excreted partly unchanged in the urine.
Name 4 long-acting (>30hrs) sedative hypnotics
Chlordiazepoxide, chlorazepate, diazepam, phenobarbitol
How is chloral hydrate metabolized?
By liver to trichloroethanol, an active metabolite.
How do benzodiazepines work?
Bind BZ R, located in thalamus, limbic structures, and cortex. Part of GABA A receptor-chloride channel. binds between a1 and y2 subunit, also binds isoforms with a2, a3, or a5.

Leads to increased frequency of GABAA chloride channel opening
What can reverse CNS effects of benzodiazepines?
Flumazenil


Will also reverse effects of newer hypnotics (zolpidem, eszopiclone, and zaleplon) but NOT barbiturates!
What effect do some B-carbolines have?
Bind to BZ R's with high affinity, can cause anxiogenic and convulsant effects. classified as inverse agonists.
How do the barbiturates work?
Depress neurons in the midbrain reticular formation, prolonging GABA/glycine effects. Also bind to GABAA R but at different site than benzodiazepines (NOT antag. by flumazenil!).

Increase duration of chloride channel opening.
May also block glutamate (excitatory), and at high conc., Na channels.
How do the newer hypnotics (zolpidem, zaleplon, eszopiclone) work?
Also interact with BZ Receptors, but only those with a1 subunits. Called BZ1 or omega1. Antagonize with flumazenil!
Describe the dose-dependent effects of sedative-hypnotics
Sedation/anxiolysis -> hypnosis (sleep) -> anesthesia -> medullary depression -> coma.


Note that barbiturates are easier to OD on than benzodiazepines or newer hypnotics (eg zolpidem).