Intro to sedative hypnotics Flashcards
Benzodiazepines drug list
Alprazolam (Xanax) Clonazepam (Klonopin) Diazepam (Valium) Lorazepam (Ativan) Midazolam (Versed) Oxazepam Quazepam Temazepam (Restoril) Triazolam
Benzodiazepine Antagonist drug list
Flumazenil
Barbiturates
drug list
Phenobarbital
Miscellaneous Sedative-Hypnotic Drugs
drug list
Buspirone (BuSpar) Eszopiclone (Lunesta) Ramelteon (Rozerem) Zaleplon (Sonata) Zolpidem (Ambien, Ambien-CR)
Sedative
Reduces anxiety, exerts calming effect
May be side effect of drugs which are not general CNS depressants (e.g., antidepressants, antihistamines, neuroleptics/antipsychotics
Hypnotic
Produces drowsiness, facilitates onset & maintenance of sleep
More pronounced CNS depression
Dose-Response Curves for Hypothetical Sedative-Hypnotics
Linear: barbiturates, alcohols, and older sedative-hypnotics
Plateau: benzodiazepines and newer sedative-hypnotics
what do Benzodiazepines
do?
Capable of: sedation, hypnosis, muscle relaxation, anxiolytic, and anticonvulsant effects
what do barbiturates do?
Capable of: mild sedation anesthesia, anxiolytic, hypnotic, and anticonvulsant effects
what do the new hypnotics do?
Useful for: sleep aid, delirium, anxiety, seizures
Mechanisms of Action
Benzodiazepines
Promote binding of GABA to GABAA receptor
Enhance GABA-induced ion currents
Increase frequency of channel opening
Barbiturates
Potentiate GABA-induced Cl- currents
Increase duration of channel opening
May activate channel directly at high concentrations
Miscellaneous
Eszopiclone, zaleplon, zolpidem: GABAA receptor agonists
Ramelteon: activates MT1 and MT2 receptors
Pharmacokinetics- Absorption & Distribution
Lipid solubility important determinant of rate of CNS entry
Most rapidly absorbed into blood following oral administration
Sedative-hypnotics cross CNS, placental barrier, and breast milk
Pharmacokinetics- Biotransformation of benzodiazepines
Hepatic drug-metabolizing enzyme systems important mediators of drug inactivation and elimination
Benzodiazepines
- Hepatic metabolism for clearance of all benzodiazepines
- Most undergo phase I reactions (CYP3A4) followed by glucuronidation (phase II)
- Cumulative toxicity
3 drugs that only require conjugation, useful for those with hepatic impairment
Lorazepam
Oxazepam
Torazepam
Pharmacokinetics: Biotransformation of barbiturates
Hepatic drug-metabolizing enzyme systems important mediators of drug inactivation and elimination
Barbiturates
Most undergo hepatic metabolism and excreted in urine as glucuronide conjugates (phenobarbital 20-30% excreted unchanged)
Long t1/2’s and cumulative toxicity