• 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, eg chlorpromazine – low potency, little EPS, severe sedation, strong anti-cholinergic effects, strong alpha-lytic effects, cardiotoxic.

Piperidine side chain, eg thioridazine – low potency, little EPS, severe sedation, strong anti-cholinergic effects, strong alpha-lytic effects, cardiotoxic.

Piperazine side chain, eg fluphenazine – high potency, strong EPS, less anti-cholinergic effects, less sedation, less alpha-lytic effects, less cardiotoxic.

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

D2 receptors in the mesolimbic pathway

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

It has a higher affinity for 5-HT2a receptors (blocks more) than D2 receptors.

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

Low affinity for D2 receptors

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

Piperazine side chain phenothiazines – its high affinity for D2 receptors.

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

Muscarinic and alpha receptors.