Biologicla Therpay For Sz Flashcards
(12 cards)
Outline drug therapy for sz
-antipsychotics is most common treatment
‘Antipsychotic’ refers to psychosis , someone who experiences loss of contact with reality , eg hallucinations and delusions
-may be required short or long term
-some may take short course and then stop without return of symptoms but some may require them for life or face likelihood of Sz recurring
-divided into typical (traditional) and atypical (newer)
What are antipsychotics
-drugs used to reduce intensity of symptom
-in particular +ve symptoms of psychotic disorder like sz
Outline and describe typical antipsychotics
-been around since the 50s , incl chlorpromazine (taken as tablets, syrup, injection)
-if taken orally, administered daily up to max of 1000mg ,altho initially doses are smaller
-for most, dosage is increased to max 400-800mg gradually
-typical prescribed doses reduced over last 50 yrs
How do typical antipsychotics act as dopamine antagonists
-strong association between use of typical, chlorpromazine and dopamine hypothesis
-these typical work like antagonists in the dopamine system (antagonists are chemicals which decr action of neurotransmitter)
-they block dopamine receptors in synapses,reduces action of dopamine
-initially taking chlorpromazine , dopamine levels build up , but production is then reduced
-according to dopamine hypothesis of sz, this antagonist effect normalises neurotransmission in key areas , to reduce symptoms of hallucinations
Describe the sedation effect of typical antipsychotics
-chlorpromazine is an effective sedative too
-believed to be related to its effect on histamine receptors , but X fully understood how this leads to sedation
-often used to calm ppl w other conditions too, not just sz
-done when patients are first sent to hospital , v anxious
-syrup isn adsorbed faster than tablets , so is a given to use chlorpromazine
Outline and describe atypical antipsychotics
-used since the 70s
-aim in developing atypical was to maintain/improve on effectiveness of drugs suppressing psychosis symptoms + minimise side effects of drugs used
-there’s a range of atypical and they all work differently
Describe atypical clozapine and also how it works
-developed in 60s, trailed early 70s
-80s, discovered to be more effective than typical , used as treatment when other treatments failed
-people taking it have regular blood tests to ensure not developing agranulocytosis - blood condition
-due to potentially fatal side effects, not available as injection , daily dose bit Lower than for chloropromazine, typically 300-450mg a day
Works by:
-binds to dopamine receptors like atypical but also acts on serotonin + glutamate receptors
-believed to help improve mood , reduce anxiety in patients + also improve cognition function
-due to mood enhancing effects, may be prescribed if someone at high risk of suicide
-imp as 30-50% ppl w sz attempt suicide at 1 point
Describe atypical risperidone and how it works
-more recently developed , since 90s
-developed in attempt to be as effective as clozapine but w out serious side effects
-like chlorpromazine, risperidone can be taken as tablets ,syrup, injection , lasting around 2 wk
-small dosage initially like others, and built up to daily dose 4-8mg, max 12mg
Works by:
-believed to bind to dopamine + serotonin receptors like clozapine
-risperidone binds more strongly than clozapine so more effective in smaller doses than most antipsychotics
-could lead to less side effects than other antipsychotics according to evidence
What evidence is there to support effectiveness of antipsychotics
Large body to support atypical and typical for at least moderate effectiveness in tackling sz symptoms
Thornley et al. Reviewed studies comparing effects of chlorpromazine to control conditions
Data from 13 trials, 1121 ps showed chlorpromazine associated w better overall functioning , reduced symptom severity compared to placebo
-Meltzer review concluded clozapine = more effective than typical + other atypical , effective in 30-50% treatment-resistant cases where others failed
Whats the counterpoint to evidence fort effectiveness of antipsychotics
Healy suggested flaws w evidence fort effectiveness effectiveness
Eg most studies = short term effects only , some successful trials have had data published many times, so exaggerating size of evidence base for +ve effects
Because antipsychotics have powerful calming effects, easy to say they have positive effect on ppl experiencing sz symptoms, but this isn’t the same as saying they reduce severity pf psychosis
Means evidence base for antipsychotic effectiveness is less impressive than it appears
Whats a limitation of the antipsychotics
Side effects are very likely, including dizziness ,agitations, sleepiness, stiff jaw, weight gain, itchy sin
Long term use can result in tardive dyskinesia , caused by dopamine supersensitivity, causing involuntary facial movements like grimacing, blinking, lip smacking
Most serious side effects , usually for typical, is neuroleptic malignant syndrome NMS
Believed to be caused when drug blocks dopamine action in hypothalamus , area associated w regulation of number of body systems
NMS - > high tend , delirium, coma, can be fatal
Antipsychotics can do harm aswell as good , so ppl may avoid such treatments and makes them ineffective
Whats a further limitation of antipsychotics in that we dont know why they work
Our understanding of mechanisms by which antipsychotics work is strongly associated w dopamine hypothesis , idea that sz symptoms linked to high levels of dopamine activity
But we know now that og dopamine hypothesis X complete explanation of Sz, and actually dopamine levels in other parts of the brain = too low rather than too high , so then antipsychotics shouldn’t work
Adds to ineffectiveness Argument
Means at least some antipsychotics may X be best to opt for , and maybe some other factor is involved in their success
