Chapter 12: Antipsychotic Drugs Flashcards
What are the symptoms of Schizophrenia?
- Positive: hallucinations, delusions of grandeur and persecution, disordered cognition etc
- Negative: social withdrawal, flat affect, anhedonia, alogia, catatonia, reduced motivation and poor focus
Antipsychotics only work on one type of symptoms, which one?
- Positive
- it can actually enhance negative ones
With positive symptoms there is hyperactivity in what System?
- Mesolimbic DA synapses
With negative and cognitive issues there is hypoactivity at was synapses?
- Mesocortical DA synapses
Explain why DA blockers work with Positive symptoms and not negative ones!
- with positive symptoms you have hyperactivity so DA blockers will reduce that! But with negative symptoms you have HYPOACTIVITY so you will actually be making it worse
What are the three brain abnormalities in schizophrenia ?
- enlargement of Cerebral ventricles
- shrinkage of brain tissue
- disorganized cellular development
Is the DA Hypothesis relevant?
- no its been dismissed !
- meaning: schizophrenia and other psychoses result from excessive DA activity
L> Support: drugs that increase dopamine function produce almost indistinguishable positive symptoms seen in schizophrenia
L> Antipsychotics at the time were all DA blockers
Glutamate Hypothesis?
- lack of glutamate activity
L> due to genetics…and NMDA receptor
L> many genes involved with schizophrenia are involved with development of glutamate connectivity, synaptogenesis and neurotransmission at NMDA.
Dopamine and Glutamate interactions?
- Normal
- Abnormal
-Stimulation of GA neurons in the prefrontal cortex result in the inhibition of DA neurons of the mesolimbic pathway
L> Normally cortical GA stimulates Mesocortical DA
-cortical GA activity is diminished resulting in loss of NMDA receptors, ventral tegmental area DA neurons become understimulated. The mesocortical pathway becomes hypoactive and the mesolimbic DA pathway becomes hyperactive
In 1951 what antipsychotic was discovered?
- Chlorpromazine (largactil and Thorazine)
- Antimedic effect— helps with nausea
Alternative terms for these types of drugs?(3)
- Antipsychotics
- Neuroleptics - causes rigidity and difficulty of movement seen in Parkinson’s
- Major Tranquilizers -sedating effect
Typical Antipsychotics?
- developed?
- blocks?
- effective in treating?
- side effects?
- ineffective in ?
- developed before 1975
- D2 blockers
- effective for positive symptoms
- produce diff degrees of EPS (extra pyramidal side effects)
- Ineffective in 1/3 of patients…no placebo effect as seen in depression
Atypical Antipsychotics?
- weak affinity for?
- low risk of ?
- high affinity for ? catch?
- Bind to what other receptor?
- first atypical?
- New atypical?
- weak affinity for D2 receptors
- low risk for EPS due to weak affinity in nigrostriatal system
- high affinity for D3 and D4 receptors in the motor system
- very few D3 and D4 in motor system
- Bind to 5-HT receptors (serotonin )
- First: Clozapine ( Clozapril)
L> 2% patients died = wiped out WBC - Aripiprazole ( Abilify)
L>3rd gen, take with antidepressants that are not working to enhance effect
Third gen antipsychotics ( Atypical)
- partial agonist to?
- how does it act in areas where DA is low /high
- What does this solve?
- partial agonist /antagonist to what other receptor?
- partial agonist to D2 D3 and D4
- high affinity for its receptors but activates the receptor to a lesser degree vs natural ligand
- where DA is decreased acts an agonist ( prefrontal cortex)
- Where DA is increased it acts as an antagonist by blocking DA and activating receptors to a lesser degree (nucleus accumbans)
- partial agonist or antagonist at 5-HT receptor subtypes.
How are they usually taken?
- orally but it can be given intramuscular or intravenous injections
L> rarely injected when needed for antipsychotic (usually only when needed as a tranq )