Antipsychotic Drugs

Question 1

What are the 2 categories of antipsychotic medication?

Answer 1

Conventional antipsychotics and atypical antipsychotics.

Question 2

What are conventional antipsychotics known as?

Answer 2

Typical, older, or first generation antipsychotics.

Question 3

When were conventional antipsychotics first developed?

Answer 3

In the 1950s.

Question 4

Give an example of conventional antipsychotics.

Answer 4

Chlorpromazine

Question 5

How do conventional antipsychotics work?

Answer 5

Affecting neurotransmission, specifically blocking the action of neurotransmitter dopamine.

Question 6

What does Chlorpromazine do?

Answer 6

Acts primarily as an antagonist (blocking agent) of D2 receptors. It also blocks other dopamine receptor sub-types D1, D3, D4, and D5 receptor sites.

Question 7

How does Chlorpromazine work?

Answer 7

After the presynaptic neuron releases dopamine into the synapse, the receptor sites on the postsynaptic neuron are blocked by chlorpromazine, reducing activity in the postsynaptic neuron. This causes the presynaptic neuron to increase its release of dopamine into the synapse, meaning a rise in the amount of dopamine being secreted.

Question 8

What is a reduction in dopamine activity in the mesolimbic pathway responsible for?

Answer 8

The decline of positive symptoms such as hallucinations and delusions.

Question 9

What does chlorpromazine also affect?

Answer 9

The serotonin receptors (5-HT1 and 5-HT-2) as well as other receptor sites around the brain, but mainly blocks dopamine.

Question 10

What are atypical antipsychotics known as?

Answer 10

Newer or second generation antipsychotics.

Question 11

Give an example of atypical antipsychotics.

Answer 11

Clozapine

Question 12

When were atypical antipsychotics developed?

Answer 12

The 1990s.

Question 13

How do atypical antipsychotics work?

Answer 13

Like conventional antipsychotics, by acting as a dopamine antagonist, but the precise mechanism is not yet clear.

Question 14

What is the first difference between the 2 types?

Answer 14

Atypical antipsychotics are received at fewer dopamine D2 receptor sites and at more D1 and D4 sites.

Question 15

What is the second difference between the 2 types?

Answer 15

Most atypical antipsychotics also antagonise the serotonin receptor 5-HT2A, to the same degree as they antagonise the dopamine D2 receptor.

Question 16

What is the third difference between the 2 types?

Answer 16

The actual amount of time they occupy the D2 receptor sites.

Question 17

What did Philip Seeman (2002) report?

Answer 17

The fast-off theory. This proposes that atypical antipsychotics bind more loosely to the D2 receptor sites. This means it does not last long enough to also produce the side effects seen in conventional antipsychotics, such as tic-like movements.

Question 18

What is the half-life of atypical medication thought to be?

Answer 18

Less than conventional antipsychotic medication - with atypical the occupancy of D2 receptors falls off within 24 hours, however with conventional, the fall-off is longer than 24 hours.