• 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 – example Chlorpromazine

Piperidine – example Periciazine

Piperazine – example Fluphenazine

The aliphatic and piperidine derivatives have the same properties. They have a low potency. Has little extra pyramidal side effects, causes severe sedation. May produce strong anti-cholinergic effects, may cause postural hypotension and can be cardiotoxic.

The piperazine derivative has a higher potency. Has a higher risk for the development of extra pyramidal side effects. Has weaker anti-cholinergic effects and lower chances of causing postural hypotension. Causes less sedation and is less cardiotoxic.

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

The typical anti-psychotic drugs mainly block the mesolimbic Dopamine-2 receptors.

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

The atypical drugs mainly work’s by blocking the Serotonin-2A receptors, instead of blocking the Dopamine-2 receptors while the typical drugs work by blocking the activity of the Dopamine-2 receptors.

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

The blockade of Dopamine-2 receptors reduces the risk of extrapyramidal side effects.

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

Piperazine compounds, due to its high potency and the fact that it has a high affinity for Dopamine-2 receptors.

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

Muscarinic receptors blockade

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  Unpublished lecture notes on efundi, FKLG 312.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