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Newer CNS depressants. Benzodiazepines, second generation anxiolytics, and antiepileptic drugs. Use of benzodiazepines. Not for chronic anxiety disorders Not for the elderly Not for depression For short-term treatment of stress-related anxiety: Acute situational grief

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newer cns depressants

Newer CNS depressants

Benzodiazepines, second generation anxiolytics, and antiepileptic drugs

use of benzodiazepines
Use of benzodiazepines
  • Not for chronic anxiety disorders
  • Not for the elderly
  • Not for depression
  • For short-term treatment of stress-related anxiety:
    • Acute situational grief
    • Acute stress reactions
    • Short-term anxiety-induced insomnia
pharmacodynamics
Pharmacodynamics
  • GABAA receptor interactions
    • Benzodiazepine agonists, eg. diazepam
    • Benzodiazepine antagonists, eg. flumazenil
    • Chloride ion channels and fast IPSPs
  • GABAB receptor interactions
    • Presynaptic for several neurotransmitters
    • Potassium ion channels and late IPSPs
    • Baclofen, a muscle relaxant and antispastic
localized pharmacodynamics
Localized pharmacodynamics
  • Low-dose antianxiety effects: hippocampus and amygdala
  • Mental confusion and amnesia: hippocampus and cerebral cortex
  • Sedative-hypnotic effects: cerebral cortex
  • Different benzodiazepines have different relative effects, perhaps due to multiple subtypes of GABAA receptors.
pharmacokinetics
Pharmacokinetics
  • Study administration, absorption and distribution in textbook.
  • Metabolism is unusual:
    • Intermediate metabolites may be psychoactive.
    • Intermediate metabolites may be long-lasting.
    • Elderly patients have difficulty metabolizing long-acting benzodiazepines, leading to profound dementia. May take 60 days to clear.
uses and side effects of benzodiazepines
Uses and side effects of benzodiazepines
  • Panic attacks and phobias: alprazolam (Xanax)
  • Alcohol withdrawal and abstinence
  • Antiepileptic
  • Dose-related side effects:
    • Drug-induced brain syndrome
    • Impaired functioning
    • Amnesia
  • Severe interactions with alcohol
benzodiazepine miscellany
Benzodiazepine miscellany
  • Fetal effects have been reported for BDZ taken in the first trimester, but other research disputes the claim.
  • If abused, BDZs are part of polydrug abuse, complicating flumazenil antagonistic effects
  • GABAA antagonists may enhance learning by facilitating cortical and hippocampal cholinergic activity
  • GABAB antagonists may enhance cognition and counter depression
second generation anxiolytics
Second generation anxiolytics
  • Zolpidem (Ambien, 1993): Not a BDZ, it is a specific agonist at GABAA1 receptors.
    • Rapid uptake and short elimination half-life make it an effective insomnia treatment
    • Little interference with normal sleep cycle
    • Safe, and high doses trigger vomiting
    • High doses produce problems in older people
    • Flumazenil antagonizes zolpidem
second generation anxiolytics9
Second generation anxiolytics
  • Buspirone (BuSpar): A weak agonist of 5-HT1A receptors, so no crossing or synergy with other CNS depressants
    • Buspirone is also antidepressant
    • No sedation, little amnesia or confusion
    • Very slow development of main effect: several weeks tid. Minimal abuse, withdrawal symptoms.
    • Useful for GAD and anxiety in older people.
    • Postsynaptic inhibition of adenyl cyclase
    • Presynaptic inhibition of 5-HT synthesis
    • Remember grapefruit juice effect on buspirone
controversial anti anxiety drugs
Controversial anti-anxiety drugs
  • Triazolam (Halcion)
  • Flunitrazepam (Rohypnol)
    • Illegal in U.S.A.
    • Produces amnesia
    • Synergistic with alcohol: “Date-rape drug”
      • Roughies, roofies, rochas
future directions in anxiety control
Future directions in anxiety control
  • Find partial agonists of BDZ receptors
    • Abecarnil, used for GAD
  • Find drugs which act on different receptor subtypes, like Zolpidem
    • Alpidem acts on GABA A1 and GABA A3 sites
    • Imidazenil has fewer side effects
  • Nonhormonal neurosteroids (epalons) as GABAA agonists: Ganaxolone
  • Serotonin (5HT1A) agonists, like buspirone: gepirone, alnespirone, ipsapirone
antiepileptic drugs
Antiepileptic drugs
  • Epileptic seizures, foci/lesions, and kindling
  • Sodium channel blocking
    • carbamazepine, phenytoin (Dilantin)
    • lamotrigine, valproate/valproic acid
  • GABA agonism
    • reduce metabolism of GABA
    • facilitate GABA release: gabapentin
    • Enhance GABA action: benzodiazepines, valproic acid
other uses of antiepileptics
Other uses of antiepileptics
  • Kindling may be part of a set of psychiatric disorders characterized by impulse control difficulty.
    • Bipolar Disorder and mania
    • Conduct Disorder
    • Borderline Personality Disorder
    • Panic Disorder
    • Intermittent Explosive Disorder
  • Antiepileptic drugs are sometimes helpful.
antiepileptic drugs14
Antiepileptic drugs
  • Identify the three main groups of antiepileptic drugs.
  • In which group would you place carbamazepine and valproic acid?
  • Construct a timeline of the drug treatment of seizure disorders, starting with bromide.
  • How do antiepileptic drugs relate to specific psychological disorders?
  • http://www.pslgroup.com/dg/2d9a6.htm