CNS- Antipsychotics Flashcards
what is schizophrenia, include the symptoms and negative symptoms
shattered mind
initial symptoms=positive symptoms (hallucinations, paranoia, delusions)
later = negative (apathy, social withdrawal, inattentiveness)
what causes a drug induced phsychosis?
long-term cocaine or amphetamine can lead to schizophrenia-like symptoms; hallucinations = adverse effect of L-dopa.
supports role of dopamine imbalance in psychosis.
what is the psychosis and the Dopamine hypothesis?
- antipsychotics block D2 receptors
- drugs that ^ dopamine activity aggravate of produce psychosis
- ^ dopamine receptor density in schizophrenic patients
- decrease in dopamine metabolites in successfully treated schizophrenic patients.
what are the 3 main DA pathways?
- nigrostriatal associated with movement
- cortical
- limbic associated with behaviour
high dopamine in limbic system is linked with what kind of symptoms?
positive symptoms
low dopamine in cortex is linked with what kind of symptoms?
negative symptoms
how do newer antipsychotic drugs work?
block both the 5-HT2a and D2 receptors and normalize DA activity in limbic system and cortex.
what is the D2 receptor?
its inhibitory and G-protein linked. the presynaptic effect decreases Ca2+, and postsynaptic decreases cAMP/ ^K+
what are the 4 kinda os antipsuchotic drugs used?
- phenothiazine derivatives
- thioxanthene derivatives
- butyrophenone derivatives
- Atypical
describe how the butyrophenone derivative Haloperidol works
D2 > alpha 1 >D4 >5Ht2a>D1>H1
**D2>5HT2a
describe how the atypical Olanzapine works
5HT2a >H1 >D4 >D2> alpha 1 >D1
** 5HT2a>D2
it also increases DA in cortext
what are the theories for the delay in clinical effects when taking antipsychotic drugs?
- D2 blockade alone does not explain antipsychotic action of drug
- tolerance to presynaptic blockade develops over time and post-synaptic blockade becomes more effective.
what is the effect of PAP?
its an NMDA receptor antagonist and can lead to psychosis.
what is the glutamate hypothesis?
NMDA antagonists ^ DA neutrotransmission in limbic system -> induce psychosis
glutamate hypofunction in the cortex is associated with negative symptoms.
what are the adverse effects of antipsychotic drugs
CNS: parkinson-like symptoms (D2 antagonism)
sedation ( H1 and alpha1 antagonism)
automicL Hypotension, and atropine-like side effects (dry mouth, blurred vision, constipation)
