• 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.

-Alphatic side-chain: Has Low potency (a few pyrimidial effects, severe sedation, strong anti-cholinergic effects (dry mouth constipation urine retension etc), cardiotoxic (causes arrythmias) and postural hypotension)
- Piperidine side chain: ( together with alphatic side chain effects).
- Piperazine side chain: (opposite effect of the previous 2 chains, high potency and more extra pyramidal effects, weaker anti-cholinergic, alpha lytic , sedation and cardio vascular effects.)

• Which receptors, in particular, are blocked by the typical antipsychotic drugs?
  • They block the Dopamine Receptors in the mesolymbic-pathway (D2-R) and then the D2 receptors in the Mesolymbic system

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

Typical antipsychotic drugs act on the dopaminergic system, blocking the dopamine type 2 (D2) receptors. 

VS.

Atypical antipsychotics have lower affinity and occupancy for the dopaminergic receptors and a high degree of occupancy of the serotoninergic receptors 5-HT2A.

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

Extrapyramidal symptoms (due to D2 blockade in the limbic system) are closely related to the antipsychotic potency of typical antipsychotic drugs. 

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

High potency drugs are more likely to cause extrapyramidal symptoms (maximum with haloperidol) whereas it is least common with thioridazine.

• Because of which receptor(s) blockade do the aliphatic groups of drugs have a high incidence of autonomic side effects?
  • These drugs act by blocking D2 receptors and differ significantly in potency.
  • High potency drugs have low anticholinergic and autonomic side effects as compared to low potency drugs.
    • Anticholinergic (maximum with thioridazine).