ANTIPSYCHOTICS

Psychiatric Uses Of Antipsychotic Drugs 

1. Schizophrenia: Acute and Chronic Maintenance 
2. Psychotic Depression (With Antidepressants) 
3. Acute Mania (With Lithium)
4. Autism (For Control of Aggressive Behaviors) 
5. Gilles de la Tourette’s Syndrome – Chronic Tics 
6. Severe Agitation In Mentally Retarded  
7.Alzheimer’s Patients


Pharmacological Actions of Antipsychotics At CNS Receptors

 • Dopamine: Antagonists at D2 or Partial Agonist at D2             (aripiprazole) 
 • Serotonin: Antagonists at 5-HT2 A
 • Histamine: Antagonists at H1 
 • Cholinergic: Antagonists at muscarinic M1-4 
 • Noradrenergic: Antagonists at α 1

Typical Antipsychotics Have Antagonist Actions That Are Greater for the Dopamine D2 Than the 5-HT2A Receptor



Phenothiazines & Derivatives                                          
                                                                                                               
Chlorpromazine                                                                       Fluphenazine 
Perphenazine

Butyrophenones     
Haloperidol 

Atypical Antipsychotics Have Antagonist Actions that are Greater for 5-HT2A than D2

Risperidone 
Olanzapine 
Quetiapine 
Clozapine 
Ziprasidone



Dopamine Hypothesis Of Schizophrenia :An Increase in Dopaminergic Activity in CNS 


1. All Antipsychotics are DA Receptor Antagonists

2. Therapeutic effects correlated with D2 affinity 

3. Dopamine Agonists (e.g., Amphetamines) Exacerbate Schizophrenic Symptoms at Low Doses 

4. Higher Doses of Amphetamines Induce Paranoid Psychotic Reactions in Normal Individuals 

5. Evidence of Changes in Dopamine Receptors in Schizophrenia is Still Controversial

Blockade of Dopamine D2 Receptors 


• Emotion - Reduces expression of emotion 
• Cognitive functions – Decreases cognitive processes in prefrontal cortex 
• Motor functions – Produces akinesia and symptoms of Parkinsonism
• Endocrine function – Produces increased release of prolactin