pharmacology of anxiolytic drugs Flashcards
drugs used to treat anxiety
-benzodiazepines
-antidepressant drugs
-buspirone
-pregabalin
-beta blockers
where does fear and phobia come from in the brain
amygdala - centered circuit
where does anxiety, apprehension and obsessions come from in the brain
cortico-striatal-thalamic-cortical circuit
where in the brain is affect of fear
anterior cingulate cortex/orbitofrontal cortex
where is avoidance (fight/flight) in the brain
periaqueductal gray
endocrine effects of fear
increase in cortisol
where is re-experiencing (traumatic memories) created
hippocampus
neurotransmitters involved in amygdala centred circuits
5HT (Serotonin)
GABA (Gamma-aminobutyric acid)
Glutamate
CRF (Corticotrophin releasing factor)
NE (Norepinephrine)
Voltage gated ion channels
GABA
-Main inhibitory transmitter in the brain
-Reduces activity of neurons in amygdala and CSTC circuit
-Benzodiazepines (anxiolytic) enhance GABA action
what are the main GABA receptors
– GABA-A, GABA-B & GABA-C
which GABA receptor is the target of benzodiazepines, barbiturates and alcohol
GABA-A
benzodiazepines mechanism of action
-Benzodiazepines bind at a separate site to GABA
-Increases the likelihood that GABA binding will activate the receptor and/or increases the effect that GABA has when it binds to the receptor
-Increased frequency of opening allows more chloride to pass through which hyperpolarises the membrane potential and makes it less likely the neuron will fire an action potential
pharmacological effects of benzodiazepines
-reduce anxiety and depression
-hypnosis/sedation
-muscle relaxation
-anticonvulsant effect
-anterograde amnesia
clinical uses of benzodiazepines
Acute treatment of extreme anxiety
Hypnosis
Alcohol withdrawal
Mania
Delirium
Rapid tranquillisation
Premedication before surgery or during minor procedures
Status epilepticus
problems with benzodiazepines
-Paradoxical aggression
-Anterograde amnesia & impaired coordination
-Tolerance and dependence
symptoms of benzodiazepine withdrawal
-abdo cramps
-increased anxiety, panic attacks
-physical symptoms
-blurred vision
-depression
-insomnia, nightmares
-dizziness
-headaches
-sweating, shaking
-nausea and vomiting
-inability to concentrate
-tingling in hands and feet
-restlessness
-sensory sensitivity
what causes benzodiazepine withdrawal
-Chronic treatment with benzodiazepines ↓ response to GABA
-Withdrawal results in anxiety/convulsions possibly due to ↓ density of benzodiazepine receptors
how do you withdraw benzodiazepines
- Transfer patient to equivalent daily dose of diazepam/chlordiazepoxide preferably taken at night
- Reduce dose every 2–3 weeks in steps of 2 or 2.5mg; if withdrawal symptoms occur, maintain this dose until symptoms improve
- Reduce dose further, if necessary in smaller steps; it is better to reduce too slowly rather than too quickly
- Stop completely; time needed for withdrawal can vary from about 4 weeks to a year or more
mechanism of action of SSRI’s
Transporter transports neurotransmitter out of the synaptic cleft into the neuron that released them
SSRI inhibit the reuptake of serotonin leading to increased serotonin in the synaptic cleft
how do SSRI’s treat anxiety
increase extracellular serotonin
management of GAD
-psychoeducation
-self help/psychoeducation groups
-CBT or SSRI
-SNRI
-pregabalin
-combination of CBT and drug treatment
management of panic disorder
-self help
-CBT or SSRI
-tricyclics
