DANIKE DE VILLIERS
Default profile image
DANIKE DE VILLIERS

Blog #11

27 May 2021, 15:45 Publicly Viewable

Blog #11 (SU 9.2)

  • 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 derivatives:

Aliphatic side chain

Piperidine side chain

Piperazine side chain

Example

Chlorpromazine

Periciazine

Fluphenazine

Potency

Low potency

Low potency

High potency

Side effects

  • Little EPS
  • Sever sedation
  • Strong anti-cholinergic SE
  • Postural hypotension
  • Cardiotoxicity
  • Little EPS
  • Sever sedation
  • Strong anti-cholinergic SE
  • Postural hypotension
  • Cardiotoxicity
  • More EPS
  • Less sedation
  • Less anti-cholinergic SE
  • Less α-lytic effects
  • Less cardiovascular SE

 

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

Typical antipsychotics block mesolimbic D2 receptors.

 

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

Atypical (newer) drug’s mechanism of action is to block serotonin (5-HT2A) receptors much more potently than D2 receptors where typical drug’s mechanism of action is mainly to block dopamine (D2) receptors. Atypical drugs also block muscarinic (M1), histamine (H1) and alpha (α1) receptors more potently than typical drugs.

 

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

Dopamine (D2) receptors are blocked by the older (atypical) drugs decreasing the extrapyramidal side effects.

 

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

Haloperidol. Haloperidol has a high incidence of extrapyramidal side effects because of its high potency and affinity for D2 receptors.

 

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

The blockade of muscarinic receptors.

 

Reference list.

Brand, L. 2021. SU 9 Antipsychotic Drugs and Lithium. https://efundi.nwu.ac.za/access/lessonbuilder/item/6005036/group/dd46f2da-d3be-402e-9ba7-2c5955cedd9d/English%20power%20point/English%20PP%202021/SU%209.pdf Date of access: 26 Apr. 2021. [PowerPoint presentation]

Katzung, B.G.  2018.  Basic & Clinical Pharmacology.  14th ed.  California, San Francisco: McGraw-Hill Companies, Inc.