Sedatives and Hypnotics Flashcards
Benzodiazepines- Available Drugs
diazepam
furazepam
clordiazepoxide
clonazepam
flunitrazepam
midazolam
alprazolam
triazolam
lorazepam
oxazepam
temazepam
Benzodiazepines- Mech of Action
Bind both BZ1 and BZ2
Non-selective agonist
Positive allosteric modulators of GABA receptors
increase frequency of Cl channel opening
Benzodiazepines- Absorption/Distribution
Lipid soluble (variable= different rates of absorption, onset, and redistribution)
Good bioavailability (60-100%)
High protein binding
Diazepam, Flurazepam, Clordiazepoxide- Elimination
VERY LONG HALF-LIVES
Have active metabolites
Phase I and Phase II metabolism
Clonazepam, Flunitrazepam- Elimination
Phase I and Phase II
Intermediate to long half lives
Midazolam, Alprazolam, Triazolam- Elimination
SHORT HALF LIVES
Phase I and Phase II
Lorazepam, Oxazepam, Temazepam- Elimination
INTERMEDIATE HALF LIVES
Phase II only
PREFERRED IN ELDERLY AND IMPAIRED HEPATIC FUNCTION DUE TO NO PHASE I ELIMINATION
Benzodiazepines- Clinical Use
Anxiolytic
Sedation
Some have anticonvulsant effects and are used as muscle relaxant adjuncts to anesthesia.
Short term treatment of insomnia (don’t use trizolam).
Benzodiazepines- Adverse Effects/Contraindications
CONFUSION
PARADOXICAL EXCITEMENT IN CHILDREN AND ELDERLY
PARADOXICAL RAGE REACTION
RAPID ONSET, HIGHER DOSE, SHORTER HALF LIFE, LONGER DURATION OF USE, AND HIGHER POTENCY ALL INCREASE SEVERITY OF DEPENDENCE AND WITHDRAWAL
lowerchance of extreme CNS depression and death, drowsiness, ataxia, anterograde amnesia, tolerance and dependence, withdrawals (anxiety, insomnia, irritability, muscle aches, tremor, loss of appetite, nausea, ataxia, hyperreflexia, blurred vision, fatigue; rarely confusion, delirium, psychosis, seizures, catatonia), rebound insomnia
Flunitrazepam- Rohypnol= date rape drug
Benzodiazepines- Drug Rxns
cross tolerance with EtOH and other sedative hypnotics
Imidazopyridines- Available Drugs
Zolpidem
Zaleplon
Imidazopyridines (Zolpidem, Zaleplon)- Mech of Action
Bind only the BZ1 site
Positive allosteric modulators of GABA receptor
Zolpidem- Absorption, Distribution
rapidly and completely absorbed PO
Zaleplon- Absorption, Distribution
rapidly absorbed
Zolpidem- Elimination
liver metabolism
short half-life
Zaleplon- Elimination
very short half life- even shorter than Zolpidem
hepatic metabolism
Zaleplon- Clinical Use
only for short term use for insomnia
Imidazopyridines (Zolpidem, Zaleplon)- Adverse Effects/Contraindications
Habit forming
Headache, dizziness, somnlence, nausea, vomiting, diarrhea, anterograde amnesia, rebound insomnia
sleep driving, sleep eating
Imidazopyridines (Zolpidem, Zaleplon)- Drug Rxns
Potentially fatal CNS depression when combined with other CNS depressants
Zaleplon= Metabolism is inhibited by cimetidine, an H2 histamine blocker
Pyrrolopyrazines- Available Drugs
Eszopiclone
Pyrrolopyrazines (Eszopiclone)- Mech of Action
Bind only the BZ1 site
Positive allosteric modulators of GABA receptor
S(+) isomer of Zopiclone
Pyrrolopyrazines (Eszopiclone)- Absorption, Distribution
rapid absorption
Pyrrolopyrazines (Eszopiclone)- Elimination
Short half life, but longer than Zolpidem and Zaleplon
Pyrrolopyrazines (Eszopiclone)- Clinical Use
sleep disorders (not restricted to short-term use)
Pyrrolopyrazines (Eszopiclone)- Adverse Effects/Contraindications
Habit forming
headache, dizziness, somnlence, nausea, vomiting, diarrhea, anterograde amnesia, rebound insomnia
sleep driving, sleep eating
Pyrrolopyrazines (Eszopiclone)- Drug Rxns
Cyp 3A4 inhibitor and inducers
Potentially fatal CNS depression when combined with other CNS depressants
Inverse Agonists- Available Drugs
Beta Carbanolines
Inverse Agonists (Beta Carbanolines)- Mech of Action
Bind same site as Benzos
Act as negative allosteric modulators of GABA receptor
Inverse agonist
Barbiturates- Available Drugs
Short-Acting-
Thiopental
Methohexital
Intermediate-
Amobarbital
SEcobarbital
Pentobarbital
Long-
Phenobarbital
Barbiturates- Mech of Action
bind sites on GABAa receptor distinct from BZ binding sites
No specificity for GABAa isoforms
Increases duration of Cl channel openings
Can directly open Cl channels at very high doses even in the absence of GABA. Enhances P450 enzymes= enhances its own metabolism, thus requires increasingly higher doses