Antipsychotic Drugs

Question 1

Positive versus Negative Symptoms of Schizophrenia

Answer 1

Positive: Psychosis - with hallucinations and delusions
Negative: Social withdrawal, inability to experience pleasure, loss of motivation
Also cognitive symptoms (disorganization of thought and speech)

Question 2

Which pathways play a role in psychosis? How?

Answer 2

1. Mesolimbic pathway: increased activity may cause positive symptoms
2. Mesocortical pathway: decreased activity associated with negative symptoms

Question 3

Dopamine Hypothesis

Answer 3

Schizophrenia may result from a functional excess of DA in CNS
Evidence:
Drugs that block DA receptors can relieve symptoms
Drugs that activate DA receptors aggravate symptoms and case psychosis

Question 4

Antipsychotic Drugs

Answer 4

Agents that reduce symptoms and improve behaviour of patients
Also called neuroleptic drugs (suppress motor activity and emotion)

Question 5

Chlorpromazine

Answer 5

First antipsychotic drug
Prevents hallucinations and delusions
Blocks D2 receptors

Question 6

Typical Antipsychotic Drugs

Answer 6

First generation (chloropromazine, haloperidol)
Relieve positive symptoms
Correlates with affinity for antagonism of D2 receptors (mesolimbic pathway)
Extrapyramidal side-effects

Question 7

Atypical Antipsychotic Drugs

Answer 7

Second generation (clozapine, olanzepine)
Higher affinity for 5-Ht2 receptors than for D2 receptors (mesocortical pathway)
Less extrapyramidal side effects
Cause metabolic dysfunction (weight gain) and agranulosis (decrease in white blood cells (clozapine))
More expensive

Question 8

Pharmacokinetics and Pharmacodynamics of Antipsychotics

Answer 8

Well absorbed orally
Sequester in body tissues
Require metabolism for elimination
Dopamine receptor antagonism

Question 9

Extrapyramidal Side Effects

Answer 9

Acute: parkinson like symptoms that go away when you stop taking the drugs
Long term: increased sensitivity of the receptors (upregulation) causes tardive dyskinesia
Due to D2 block