Modes of action of antipsychotics

Question 1

Amisulpride

Answer 1

• D2 and D3 antagonism

- competitive

Question 2

Aripiprazole

Answer 2

• partial dopamine agonist at D2
• also 5-HT2A antagonist
• antagonising DA at sites of excessive dopamine such as misolimbic areas
• agonist (mimic) at dopamine deificient zones such as mesocortical areas (goldilocks effect)
• does not produce any change in tuberoinfundibulum
• acts on both post-synaptic D2 receptors and presynaptic autoreceptors

Question 3

Asenapine

Answer 3

• D2 antagonist
• Serotonin 5-HT2A blocker
• potent alpha-2 blockade effect

Question 4

Chlorpromazine, promazine

Answer 4

• moderate antimuscarinic effect
• D2 blockade
• v.sedating

Question 5

Clozapine

Answer 5

• antagonist at the 5-HT2A subunit of the serotonin receptor
• D2 antagonist-weak
• also blocks D4 and 5-HT6
• alpha 1 antagonist
• also has anticholinergic and antihistaminic properties
• weak D1 and D2 affinity
• also binds to 5-HT3

Question 6

Lurasidone

Answer 6

• D2 antagonist
• serotonin 5-HT2A blocker
• high affinity for 5-HT7
• partial agonist at 5-HT1A receptors
• minimal affinity for alpha-1 (less orthostatic) and histamine (weight neurtral)

Question 7

Olanzapine

Answer 7

• atypical antipsychotic
• high 5-HT2/D2 blockade ratio
• potent D4 blockade and 5-HT6 blockade
• has anticholinergic and antihistaminic effects

Question 8

Paliperidone

Answer 8

• metabolite of risperidone
• serotonin-dopamine antagonist
• high 5-HT2A antagonism
• can bind to D2 in higher doses

Question 9

Quetiapine

Answer 9

• similar to clozapine
• hit and run profile on D2
• less of a 5-HT2A blockade
• similar effects to olanzapine (anticholinergic)

Question 10

Risperidone

Answer 10

• serotonin-dopamine antagonist
• high 5-HT2A antagonistic property
• can bind to D2 at higher doses and can lead to S/E

Question 11

Sulpride

Answer 11

• pure D2 antagonist

- reduces positive symptoms

Question 12

Thioridazine, pericyazine

Answer 12

• D2 antagonists
• marker antimuscrinic effect
• less EPSEs than other atypicals

Question 13

Thioxanthenes

Answer 13

• have some stereoisomerism

- D2 antagonists

Question 14

Ziprasidone

Answer 14

• 5-HT2A and D2 blockade
• antagonises 5-HT1D, 5-HT2C, D3 and D4 receptors
• poor affinity for mscarinic effects
• some antihistaminic property noted
• agonistic at 5-HT1A
• some serotonin and norepinephrine reuptake inhibition noted

Question 15

Zotepine

Answer 15

• 5-HT2A, 5-HT2C, D1, D2, D3 and D4 antagonism
• potent noradrenaline reuptake inhibitor
• some NMDA antagonism
• potent antihistaminic activity