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MSII Pharmacology > Unit 3 - Sedative-Hypnotic Drugs > Flashcards

Unit 3 - Sedative-Hypnotic Drugs Flashcards

1
Q

what does sedative mean?

A

calming, anxiolytic effect (ideally with little effect on motor or mental functions)

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2
Q

what does hypnotic mean?

A

induce sleep (more pronounced CNS depression than sedation; can be achieved with most sedative drugs simply by increasing dose)

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3
Q

what are the uses of sedative hypnotic drugs?

A
  1. acute treatment of anxiety disorders (anxiolytic)
  2. muscle relaxant (often diazepam)
  3. anticonvulsant
  4. pre-anesthetic
  5. recreation
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4
Q

what are the classes of sedative-hypnotic drugs?

A
  1. ethyl alcohol
  2. benzodiazepines (and pseudo-benzos)
  3. barbiturates
  4. antihistamines
  5. others, including non-sedating anxiolytics
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5
Q

what is the mechanism of sedative-hypnotic drugs?

A

bind to some site on GABA-A receptor complex to potentiate GABA-mediated inhibition

  • opens Cl- channel –> hyperpolarize cell –> cell is inhibited
  • receptor specificity is the key to selectivity of drug effects
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6
Q

what are the agents that allosterically enhance GABA binding to GABA-A receptor?

A
  1. benzodiazepines - binding site between a1 and gamma2 subunits
  2. barbiturates - bind to alpha or beta subunit
  3. ethanol - binds to alpha
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7
Q

where is the GABA binding site?

A

between a1 and B2 subunits

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8
Q

what does picrotoxin do?

A

from berries of east Indies shrub

-blocks GABA-A Cl- channel directly (non-competitive antagonist) that causes convulsions

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9
Q

what are the benzodiazepine/GABA-A receptor subtypes? what does this mean?

A

2 main families

  • BDZ1 = omega 1
  • BDZ2 = omega 2
  • most clinically used benzos bind to BOTH subtypes

different receptor subunit compositions have different functions and different binding affinities for different benzodiazepines
-thus, some differences in pharmacological profiles of various benzos

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10
Q

what are properties of diazepam?

A
  1. sedation&raquo_space; hypnosis (dose-related –> anti-anxiety and sleep)
  2. muscle relaxation
  3. anticonvulsant activity
  4. often anterograde amnesia
  5. very little cardiovascular or respiratory effects
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11
Q

degree of CNS depression in benzos VS barbiturates? if combined?

A

benzos = ceiling effect (limited depression)

  • don’t produce respiratory depression, coma, or death at OD-levels
  • augment action of GABA

barbs (and alcohol, general anesthetics) = full CNS depression –> coma and death at OD
-augment action of GABA, and at high doses can directly open Cl- channel

synergistic effects if benzo + alcohol, meaning less alcohol is needed to cause coma/death

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12
Q

what are the pharmacokinetic and pharmacodynamic differences between benzodiazepines?

A
  1. some have active metabolites, meaning some are longer acting than others
  2. differences in GABA-A subtype affinity and location
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13
Q

what are diazepam, chlorodiazepoxide, lorazepam, alprazolam, midazolam, and triazolam? which ones have active metabolites and what does this do?

A

benzodiazepines
-chlordiazepoxide, diazepam, and flurazepam have active metabolites, meaning their half lives are much higher than others (100 hrs VS 10 hrs)

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14
Q

what are pseudo-benzos?

A

sleeping pills that are BDZ (omega) 1 selective

  • sedation and hypnosis without muscle relaxation or anticonvulsant activity
  • short half-life (~2 hrs) so little hang-over for many users
  • have largely replaced sleeping benzos
  • all insomnia medicines (OTC or Rx) have a risk for next-morning impairment
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15
Q

what are zolpidem, eszopiclone, zaleplon, and zolpiclone?

A

BDZ (omega) 1 agonists; pseudo-benzos; sleeping pills

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16
Q

what is flumazenil?

A

synthetic benzodiazepine antagonist used to reverse benzo and pseudo-benzo OD
-no effect on GABA-A receptor function per se

17
Q

explain barbiturate metabolism?

A

Phase I: oxidation at several different P450s (significant enzyme induction)
Phase II: subsequent glucuronide formation

18
Q

what are phenobarbital and thiopental and how do they work?

A

both are barbiturates
PB: less lipid soluble, slower onset, slow elimination (t 1/2 = 4-5 days), so longer-acting
-used as anti-epileptic or anti-convulsant
TP: highly lipid-soluble, fast-on/off (due to tissue redistribution)
-used to induce anesthesia

19
Q

between antidepressants and benzodiazepines, which are for long term VS short term?

A

AD for long-term treatment (esp. SSRIs) that takes effect in weeks
BD for short-term treatment (due to addictive potential)

20
Q

what is used in:

  • acute anxiety
  • generalized anxiety disorder
  • panic disorder
  • OCD
  • PTSD
A 
AA: benzodiazepines
GAD: SSRIs and/or benzos; buspirone relieves w/o sedation
PD: SSRIs or benzodiazepines
OCD: SSRIs
PTSD: antidepressants
21
Q

what is buspirone?

A

relieves anxiety without marked sedation

  • euphoric, hypnotic, anticonvulsant, or muscle relaxant effects
  • no interaction with GABA-A receptor complex
  • may act as partial agonist at 5-HT1A receptors
22
Q

what drugs are used for sedation?

A

short-acting benzos: alprazolam, lorazepam

23
Q

what drugs are used for hypnosis?

A

triazolam (short-acting benzo) or zolpidem (pseudo-benzo)

24
Q

what drugs are used for anesthesia?

A
  • barbiturate thiopental for induction

- benzos for calming and anterograde amnesia (short acting midazolam

25
Q

what drugs are used for anticonvulsion?

A

lorazepam, diazepam, phenobarbital

-these aren’t for chronic seizures, but if someone presents in ER with status epilepticus

26
Q

what drugs are used for muscle relaxation?

A

diazepam

-inhibitory effects on polysynaptic reflexes and inter-neuron transmissions

27
Q

what are general adverse effects of sedative-hypnotics?

A
  1. dose-related CNS depression (additive if >1 agent)
    - drowsiness/hangover
    - may cause falls especially in elderly
    - produces confusion, sedation, and unsteadiness
  2. tolerance (cross-tolerance, metabolic tolerance, or dynamic tolerance)
  3. psychologic and physiologic dependence
28
Q

what is important to remember if withdrawing non-benzo sedative-hypnotics?

A

alcohol and barbiturates can have psychologic and physiologic dependence, so abrupt withdrawal is life-treatening
-must do tapered withdrawal

29
Q

what is the difference between metabolic tolerance and dynamic tolerance?

A

MT: induces enzymes (notably with barbiturates and alcohol)
DT: decreased CNS responsiveness (receptor down-regulation)

30
Q

what are adverse effects of benzodiazepines?

A
  1. daytime sedation and drowsiness
  2. additive or synergistic depression of CNS with other drugs (notably alcohol)
  3. significant dose-related anterograde amnesia
  4. psychologic and physiologic dependence with chronic use
    - no significant effects on respiration or cardiovascular function with normal dosing

MSII Pharmacology (43 decks)

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