Antipsychotics

Question 1

Types

Answer 1

Typicals: chlorpromazine, flupenthixol
Atypicals: olanzapine, reserpine

Question 2

Indications

Answer 2

• Psychosis
• Sedation, reduction of agitation
• Non-psychiatric uses: nausea in pregnancy, intractable hiccough, terminal illness, some forms of anaesthetic

Question 3

Acute psychosis

Answer 3

Oral
Typicals: Chlorpromazine 300-800mg/day, Haloperidol 5-20mg/day
Atypicals: Olanzapine 5-20mg/day, Risperidone 1-6mg/day

Short term often require benzodiazepine such as lorazepam for agitation and hostility

Question 4

Pseudo-parkinsonism/akathisia

Answer 4

anticholinergics (procyclidine, benzhexol)

Question 5

Maintenance

Answer 5

Continue antipsychotic drugs for at least 1 year after first acute episode, usually at reduced dose.

If relapse, long term maintenance therapy is necessary.
Depot treatment which ensures better compliance
Flupenthixol 50mg every 2 weeks
Fluphenazine 25mg every 2 weeks

Question 6

Resistant patients

Answer 6

Try at least two type of antipsychotic drugs; typical and atypical

Clozapine (requires WBC monitoring due to neutropenia and agranulocytosis side effects)

Also causes postural hypotension, marked sedation, increased salivation.

Question 7

Mode of action

Answer 7

Dopamine receptor antagonism (competitive), principally at the D2 receptor

Mesolimbic - therapeutic effect
Nigrostriatal - extrapyrimidal side effects
Tuberoinfundibular tract - endocrine effects (increased prolactin leading to galactorrhea)

Question 8

Extrapyrimidal side effects

Answer 8

Acute dystonias, parkinsonism, tardive dyskinesia, akathisia

Question 9

Dopamine hypothesis

Answer 9

1. All antipsychotic drugs block dopamine receptors
2. Stimulant drugs which act through dopamine can produce schizophrenic-like behaviours (amphetamine)
3. Levodopa, a dopamine precursor, can exacerbate schizophrenic symptoms, or occasionally elicit them in non-schizophrenic patients
4. Higher levels of dopamine receptors measured in brains of schizophrenics
   Brain dopamine increases during psychotic episodes but not during remissions