• 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.

Phenothiazine with the specific sidechain	Example	Potency	Side-effects
With an aliphatic sidechain	Chlorpromazine	Low	Less extrapyramidal side-effects Severe sedation Strong anti-cholinergic effects (dry mouth, visual disturbances, urine retention etc.) Strong α-lytic effects (postural hypotension)
With a piperidine side chain	Periciazine	Low	Same as the aliphatic sidechain
With a piperazine side chain	Fluphenazine	High	More extrapyramidal side-effects Less sedation Weaker anti-cholinergic effects Weaker α-lytic effects

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

D₂ receptors are blocked by typical antipsychotic drugs

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

Atypical drugs block the 5-HT_2A receptors whereas typical drugs block the D₂ receptors

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

The receptors that are blocked by older drugs, that reduce the risk of extrapyramidal side effects, is the D₂ receptors. An example would include Sulpiride.

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

Fluphenazine has a high incidence of extrapyramidal side effects as it is a potent drug. Potency refers to how likely a drug is to bind to a specific receptor, in this case, fluphenazine is very likely to bind to D₂ receptors. The thioxanthenes have a similar pharmacological profile thus they have a high likelihood (but less than fluphenazine) to bind to D₂ receptors. Haloperidol is a potent D₂ blocker thus producing the most extrapyramidal side-effects.

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

DA, M, α, histamine and 5-HT receptors.