Sedatives. Anxiolytics Flashcards

1
Q

Classes of Anxiolytics

A
  • Barbituates (dependence; still in use as 3rd/4th line of AED)
  • Benzodiazepines (dependence)
  • Z-drugs
  • Beta blockers (to reduce sympathetic somatic symptoms such as tchycardia, sweating etc)
  • Antidepressants(SSRI)
  • Melatonin
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2
Q

Benzodiazepines

MOA

A

Librium

Lorazepam - short duration 8-12hrs

Diazepam - long duration 1-3days

MOA:

  • Allosterically (not the same site as endogenous agent) binding to GABAa receptors alpha 2,3 subunits
  • ligand-gated Cl- channels open - influx of Cl- - hyperpolarisation - potentiate inhibitory effect of GABA

Clinical uses:

  • Sedative/hypnotic (alpha1)
  • Anxiolytics (alpha2,3)
  • Reduce muscle tone (used to treat anxiety induced backpain)
  • AED (Lorazepam 4mg IV)
  • cause Anterograde Amnesia (not remembering after administration)
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3
Q

Benzodiazepines

Pharmacodynamics and pharmacokinetics

A

Highly lipophilic - transport across lipid membrane

Well absorbed orally, but can be given IV, intranasal and via rectal route

Highly protein bound,

Hepatic metabolism but active metabolites remain in the body, excreted as glucoronide conjugate

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4
Q

FLUMAZENIL

A

FLUMAZENIL

Inverse agonist (binds to the same receptor but induce opposite effect) of benzodiazepine.

Rarely used to reverse benzodiazepine overdose as may cause withdrawl symtoms (seizures, agitation).

Side effects including nauzea and vomiting - aspiration in unconscious patients with unprotected airway.

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5
Q

Z drugs

A

Zopiclone, Zolpidem, Zaleplon

Structurally different but same MOA as benzodiazepines

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6
Q

Tolerance

A

Tolerance:

Chronic administration leading to decrease in effect

(hence increasing dosage or frequency to achieve the same effect)

Benzodiazepines quick tolerance to sedative effects (alpha 1); Slow tolerance to anxiolytic (alpha2.3) & anticonvulsive effects

Mechanism:

  1. desensitisation of GABA receptors
  2. sensitisation of NMDA glutamate receptors
  3. Neuroadaptive processes
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7
Q

Dependance

A

Dependance: Compulsive taking due to rewarding/pleasant experience.

Can be physical - withdrawl symptoms; Psychological - craving; Genetic - alcohol related

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8
Q

Withdraw

A

As a result of physical dependence

syptoms include: anxiety/depression; insomnia, pain, stiffness, muscle aches, convulsions

therefore to avoid withdrawl symptoms, maximum 4wks of treatment

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9
Q

Indication for prescribing Anxiolytics/Sedatives

A
  1. Potentially uncomfortable medical procedures (Endoscopy)
  2. Acute alcohol withdrawl (sudden interrupted supply, anxiety/aggitation; tremor; nauzea/vomiting; sweating; palpitations; convulsions, life threatening. Librium 1-2wks)
  3. Insomnia - Caution in prescribing sedatives/hypnotics to elderly (falls, confusion); Sleep hygiene; Melantonin in children
  4. Generalised anxiety states - Guided self help; CBT; beta blockers + SSRI for somatic symptoms - sympathetic system related (tachycardia, palpitations, sweating and tremor)
  5. Prolonged seizures - Lorazepam IV 4mg or rectal diazepam if IV not available
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