Antipyschotics Flashcards
what are the four dopamine pathways in the brain
- mesolimbic pathway
- nigrostriatal pathway
- mesocortical pathway
- tuberoinfundibular pathway
explain the mesolimbic and nigrostriatal pathway in terms of schizophrenia
- hyperactivity in the mesolimbic pathway account for the positive psychotic symptoms so blocking D2 receptors alleviates the positive psychotic symptoms
- nigrostriatal pathway controls motor movement –> blocking D2 receptors –> extrapyramidal reactions –> acute dystonia, akathisia (uncontrollable restlessness), parkinsonian like symptoms (bradykinesia, tremors, rigidity)
explain the mesocortical and tuberoinfundibular pathway
- reduced activity in mesocortical –> negative psychotic symptoms –> blockade of D2 receptors in this pathway –> cause or worsen negative symptoms such as emotional blunting and cognitive problems
- dopamine released from tuberoinfundibular pathway inhibits prolactin secretion –> blockade of D2 receptors –> increase in prolactin –> galactorrhea
what are the classical antipsychotics and how are they sub classified
high potency: Haloperidol and Fluphenazine
low potency: Chlorpromazine and Thioridazine
what does it mean to be a high potency and low potency antipsychotic
- high potency: haloperidol and fluphenazine are more likely to produce extrapyramidal symptoms because of higher affinity for D2 receptors
- low potency: Chlorpromazine and Thioridazine are less likely to produce extrapyramidal symptoms and more likely to produce sedation and postural hypotension
what are the atypical antipsychotics
CROAQ
Clozapine Risperidone Olanzapine Aripiprazole Quetiapine
mechanism of classical antipsychotics (name them)
high: haloperidol and fluphenazine
low: chlorpromazine and thioridazine
block dopamine receptors in the brain and in the periphery
what are the D1-like and D2-like dopamine receptors and what type of G proteins do they use for their mechanism
D1 like dopamine receptors: D1 and D5 –> Gs and they activate adenylyl cyclase
D2 like dopamine receptors: D2, D3, D4 –> Gi and they inhibit adenylyl cyclase
receptors does clozapine have a high affinity towards
D1, D2, D4, 5HT-2, muscarinic, and alpha adrenergic
receptors does risperidone have a high affinity towards
higher affinity towards 5-HT2 than D2
what are common properties of atypical antipsychotics
- dual antagonism for 5-HT2A and D2
- exert part of their action by antagonizing 5-HT
- less likely to have extrapyramidal reactions than the classical agents
- less likely to have tardive dyskinesia
- less likely to increase prolactin
- more effective at treating negative symptoms
- effective in treatment of refractory population
mechanism of action of Aripiprazole
- partial agonist at 5-HT1A and D2
- antagonist at 5-HT2A
How do most of the antipsychotics have anti emetic effect and what are the exceptions
- anti emetic effect due to blockade of D2 receptors
- exception is Aripiprazole (agonist at D2) and Thioridazine
what antipsychotics are used to treat outpatients and individuals who are not compliant with medication
Fluphenzine decanoate
Risperidone decanoate
Haloperidol decanoate
they are all slow releasing formulations
why are low potency classical agents less likely to have extrapyramidal reactions (name them)
Chlorpromazine and Thioridazine
less affinity for D2 receptors and have stronger anti cholinergic effects (hence why they are more likely to have sedation and postural hypotension)
