Antipsychotics Flashcards
Antipsychotic drugs
There are over 40 types of antipsychotics
- Typical = examples include chloromazine, first generation drugs, cause unwanted motor effects
- Atypical = examples include risperidone, second generation drugs, cause less unwanted motor effects
D2 receptor antagonism
Antipsychotics are antagonists of the D2 receptor
D2 antagonism in the mesolimbic pathway relieves postive symptoms
Antagonism in other brain pathways leads to side effects
5-HT(2A) antagonism
Antipsychotics are also 5-HT(2A) antagonists
5-HT(2A) receptors are Gi/o coupled
- Antagonism of these receptors results in an increase in dopamine release
- This relieves negative symptoms
5-HT(1A) partial agonism
Antipsychotics are also 5-HT(1A) partial agonists
These receptors are auto-receptors
- So agonism of these receptors leads to a decrease in 5-HT release
- This reduces 5-HT(2A) activation, reducing dopamine release
mACh antagonism
Second generation antipsychotics are mACh antagonists
activation of mACh leads to unwanted side effects of first generation antipsychotics such as motor effects
-Antagonism of these receptors therefore reduces the side effects
Acute dystonias
Extrapyramidal motor effect of antipsychotics
Involuntary muscle spasms due to inhibition of the nigrostriatal system
Appear early in treatment and decline over time
Tardrive dyskinesia
Extrapyramidal motor effect of antipsychotics
Involuntary movements of the face, tongue, trunk and limbs due to irreversible blocking of D2 receptors
Appear later in treatment and are irreversible
Endocrine side effects of antipsychotics
Antipsychotics also have endocrine effects
-Gallactorrhea = occurs because D2 activation leads to a decrease in prolactin release
Antipsychotic dosage
The concentration of antipsychotics in the plasma vs. their effect is variable
Dosage is changed on a trial/error basis
Compliance with antipsychotic drugs also tends to be poor
