25.2 Schizophrenia

Question 1

Which class of drugs are used to treat schizophrenia?

Answer 1

Antipsychotics

Question 2

What are the two groups of antipsychotics?

Answer 2

Typical and atypical

Question 3

Give two examples of typical antipsychotics

Answer 3

Haloperidol
Chlorpromazine

Question 4

What is the mechanism of action of haloperidol?

Answer 4

• High affinity dopamine D2 receptor antagonism (as an inverse agonist)
• Reduces positive symptoms

Question 5

What is the mechanism of action of chlorpromazine?

Answer 5

• D1, D2, D3, D4 receptor blockade (main effect)
• Reduces positive symptoms

Question 6

Which drug has a greater affinity for D2, haloperidol or chlorpromazine?

Answer 6

Haloperidol

Question 7

Give an example of an atypical antipsychotic

Answer 7

Clozapine

Question 8

What is the mechanism of action of clozapine?

Answer 8

• Antagonist of serotonin and dopamine receptors
• Distinctly effective against negative symptoms (depression, negative cognition etc) plus positive symptoms

Question 9

When is clozapine prescribed?

Answer 9

When patient’s schizophrenia is inadequately controlled despite previous use of at least one typical and atypical drug

Question 10

What are general adverse effects of antipsychotics?

Answer 10

• 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

Question 11

What are the two main types of adverse motor disturbances?

Answer 11

• Acute, reversible dystonias and Parkinsonism
• Slowly developing tardive dyskinesia (sudden, irregular movements of face and limbs) - often irreversible

Question 12

Which antipsychotic drug has a particularly low incidence of motor disturbances?

Answer 12

Clozapine