25.2 Schizophrenia Flashcards
Which class of drugs are used to treat schizophrenia?
Antipsychotics
What are the two groups of antipsychotics?
Typical and atypical
Give two examples of typical antipsychotics
Haloperidol
Chlorpromazine
What is the mechanism of action of haloperidol?
- High affinity dopamine D2 receptor antagonism (as an inverse agonist)
- Reduces positive symptoms
What is the mechanism of action of chlorpromazine?
- D1, D2, D3, D4 receptor blockade (main effect)
- Reduces positive symptoms
Which drug has a greater affinity for D2, haloperidol or chlorpromazine?
Haloperidol
Give an example of an atypical antipsychotic
Clozapine
What is the mechanism of action of clozapine?
- Antagonist of serotonin and dopamine receptors
- Distinctly effective against negative symptoms (depression, negative cognition etc) plus positive symptoms
When is clozapine prescribed?
When patient’s schizophrenia is inadequately controlled despite previous use of at least one typical and atypical drug
What are general adverse effects of antipsychotics?
- Motor disturbances (dopamine nigrostriatal pathway - dopamine antagonists)
- Endocrine disturbances (increased prolactin release)
- Sedation
- Hypotension
- Weight gain
- Block of other receptors e.g. cholinergic - dry mouth, blurred vision
What are the two main types of adverse motor disturbances?
- Acute, reversible dystonias and Parkinsonism
- Slowly developing tardive dyskinesia (sudden, irregular movements of face and limbs) - often irreversible
Which antipsychotic drug has a particularly low incidence of motor disturbances?
Clozapine
