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 – Chlorpromazine

Piperidine side chain – thioridazine 

Piperazine side chain – Perphenazine 

Aliphatic & piperidine compounds – Low potency, little EPS, severe sedation, strong anti-cholinergic effects, strong alpha-lytic effects and are cardiotoxic. 

Piperazine compounds – Higher potency, more EPS, less sedation, weaker alpha-lytic effects, weaker anti-cholinergic effects and less cardiovascular side effects. 

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

Typical antipsychotic drugs block the mesolimbic D2 receptors.

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

Atypical drugs block the 5-HT2a receptors MORE than the D2 receptors. 

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

The low affinity for blockade of D2 receptors reduces the risk of extra-pyramidal side effects. 

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

Piperazine compounds, because they have a high potency and a high affinity for D2 receptors. 

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

Muscarinic receptor blockade