Drug therapy

• What are atypical antipsychotics?

  • Combat positive and claim to combat negative symptoms of schizophrenia
  • Carry a lower risk of side effects
• what are typical antipsychotics?

  • used primarily to combat positive symptoms of schizophrenia eg hallucinations
  • dopamine antagonists (bind to but don’t stimulate dopamine receptors)
• what is the general action of antipsychotics?

  reduce dopimanergic transmission
• What receptors do typical antipsychotics bind to?

  • D2 receptors
  • In the Mesolimbic dopamine pathway
  • example = chlorpromazine
• How long does it take for hallucinations and delusions to diminish after taking typical antipsychotics?

  A few days- several weeks
• what did kapur et Al estimate about the effectiveness of typical antipsychotics?

  60-75% of D2 receptors in the Mesolimbic dopamine pathway must be blocked for antipsychotics to be effective
• why are typical antipsychotics considered high risk?

  • 60-75% of D2 receptors must be blocked in order for them to be effective
  • unfortunately to do this a similar number of D2 receptors in other areas of the brain must also be blocked, which can lead to undesirable effects
  • Blocking dopamine receptors in one dopamine pathway is useful, but in other pathways it’s harmful
• What are the three main differences between atypical and typical antipsychotics?

  • Atypical antipsychotics carry a lower risk of extrapyramidal side effects
  • Atypical antipsychotics have a beneficial effects on negative symptoms and cognitive impairment
  • They are suitable for treatment resistant patients
• in terms of their action, how are atypical antipsychotics different to typical antipsychotics?

  • atypical antipsychotics only temporarily occupy the D2 receptors and then rapidly dissociate to allow normal dopamine transmission
  • this is thought to be responsible for the reduced risk of side effects AtAs have
  • tend not to cause movement problems like TAs because they have little effect on dopamine systems that control movement
  • AtAs have stronger affinity for sensory receptors, and lower affinity for D2 receptors than TAs
• What effects do AtAs and TAs have on reducing schizophrenic symptoms?

  • TAs- tackle the positive symptoms of schizophrenia
  • AtAs- tackle the positive symptoms of schizophrenia and claim to tackle the negative symptoms of schizophrenia and cognitive impairment

  
• three advantages of antipsychotics?

  • 😊antipsychotics vs placebo- Leucht et al- meta analysis, 65 studies, about 6000 patients, some taken off antipsychotics and given placebo, 64% relapsed, compared to 27% that remained on antipsychotics
  • 😊atypical better than typical- reduces side effects- people more likely to finish meds and reduce symptoms
  • 😊drugs beneficial for economy- cheaper than therapy, reduces cost to the NHS, less ppl hospitalised so more people in work .
• one disadvantage of drug therapy?

  • ☹️ extrapyramidal side effects- TAs affect the extrapyramidal area of brain responsible for motor skills. Parkinsonian related symptoms- can make patient stop taking TAs.