Schizophrenia:%20drugs

1
Schizophrenia drugs

• Synaptic transmission
• Mechanisms of drug action
• Drugs used with schizophrenia

psychlotron.org.uk
2
Neurones
Neuronal cell bodies
psychlotron.org.uk
Axons
Source science photo library
Synapses occur at the junctions
3
Synapses

• Neurones transmit signals electrically along
  their axons
• The synapses (junctions between neurones)
  transmit signals chemically
• Most drugs act by interfering with events at the
  synapse

psychlotron.org.uk
4
Synapse
Vesicles filled with neurotransmitter
psychlotron.org.uk
Synaptic cleft
Source neuroscience.wustl.edu
Location of receptors (post-synaptic density)
5
psychlotron.org.uk
Vesicles release neurotransmitter into synaptic
cleft
6
psychlotron.org.uk
Neurotransmitter binds to receptors activates
them
7
psychlotron.org.uk
Enzymes are released to break down the
neurotransmitter
8
psychlotron.org.uk
Excess neurotransmitter is taken up by the
pre-synaptic neurone
9
psychlotron.org.uk
Vesicles are replenished with new reused
neurotransmitter
10
Drug Therapies

• Increase synaptic activity by
• Causing more neurotransmitter to be released
• Introducing a chemical that acts like the
  neurotransmitter
• Preventing breakdown of neurotransmitter
• Preventing reuptake of neurotransmitter

psychlotron.org.uk
11
Drug therapies

• Decrease activity by
• Increasing rate of neurotransmitter breakdown
• Blocking off receptors

psychlotron.org.uk
12
Antipsychotic medication

• Neuroleptics (e.g. chlorpromazine) bind to DA
  receptors without activating them

psychlotron.org.uk
13
psychlotron.org.uk
14
psychlotron.org.uk
15
Effectiveness

• Older (typical) drugs (e.g. chlorpromazine)
• Short term beneficial effect in 75 of patients
  (Davis et al, 1989)
• Long term beneficial effect in 55-60 (Davis et
  al, 1993)
• Most effective against positive symptoms
• High risk of side effects

psychlotron.org.uk
16
Side effects

• Extrapyramidal side effects (EPS)
• Parkinsons-type symptoms
• Postural motor abnormalities
• Other side effects
• Sedation
• Weight gain
• Seizures

psychlotron.org.uk
17
Effectiveness

• Newer (atypical) drugs (e.g. clozapine)
• As effective as typical drugs on positive
  symptoms better for negative symptoms (Bilder et
  al, 2002)
• More effective with treatment-resistant patients
  (DeNayer et al, 2003)
• Less risk of EPS, but other side effects may
  occur (e.g. blood disorders)

psychlotron.org.uk
18
Typical vs. atypical
tightly bound slow release from receptor
loosely bound fast release from receptor
psychlotron.org.uk
DA receptor
Drug