1. Name an example of each of the three phenothiazine sub-families and state how they differ from one another in terms of potency and side effects.

• Aliphatic side chain:

Example: chlorpromazine.

Low potency and little EPS.

Severe sedation.

Strong anti-cholinergic effects.

• Piperidine side chain:

Example: thioridazine.

Low potency and little EPS.

Severe sedation.

Strong anti-cholinergic effects.

• Piperazine side chain:

Example: fluphenazine.

High potency and more EPS.

Less sedation.

Weaker anti-cholinergic effects.

2. Which receptors in particular are blocked by the typical antipsychotic drugs?

Mesolimbic dopamine 2 receptor are blocked.

3. How does the mechanism of action of the atypical drugs differ from that of the typical drugs?

Atypical drugs are serotonin 2A blockers, more than dopamine 2 receptor blockers, and also strong blocking effects of muscarinic 1 receptor, histamine 1 receptor and alpha 1 receptor.

4. Which of the receptors blocked by the older drugs reduce the risk of extrapyramidal side effects?

Dopamine 2 receptors are blocked and this reduces the risk of extrapyramidal side effects.

5. Which of the older drugs have a high incidence of extrapyramidal side effects? What is the reason for this?

Piperazine compounds, because it has a high potency and high affinity for dopamine 2 receptors.

6. Because of which receptor(s) blockade do the aliphatic group of drugs have a high incidence of autonomic side effects?

Muscarinic receptor blockade.

 

Reference list:

Brand, L.Prof.  2021.  Study Unit 9: Anti-psychotic Drugs and Lithium.  Unpublished lecture notes on efundi, FKLG 312.  Potchefstroom: NWU.  [PowerPoint presentation].