schizophrenia- biological therapies Flashcards
what are antipsychotics
drugs used to reduce the intensity of symptoms, in particular the positive symptoms of psychotic conditions like schizophrenia
what are typical antipsychotics
the first generation of antipsychotics drugs having been used since the 1950s.
they work as dopamine antagonists
what is an example of a typical antipsychotics?
chlorpromazine
describe properties of chlorpromazine
taken as tablets
taken orally
administered daily up to a maximum of 1000mg
typical prescribed doses have decreased over years
what do typical antipsychotics act as like ?
antagonists (chemicals that reduce the action of a neurotransmitter) in the dopamine system.
how do dopamine antagonists work in the dopamine system ?
block dopamine dopamine receptors in the synapses of the brain,
reducing the action of dopamine
normalising neurotransmission in key areas - reducing symptoms like hallucinations
chlorpromazine is also an effective ——–
sedative
how is chloropromazine an effective sedative
effect on histamine receptors
used to calm people down with conditions other than schizophrenia as well
what are atypical antipsychotics ?
drugs for schizophrenia developed after typical antipsychotics.
typically target a range of neurotransmitters such as dopamine and serotonin
what are examples of atypical antipsychotics
clozapine and risperidone
what are the properties of clozapine ?
more effective than typical antipsychotics
side effect of agranulocytosis
300 to 400mg a day dose
how does clozapine work ?
binds to dopamine receptors but also acts on serotonin and glutamate receptors.
helps improve mood and reduce depression
why are the mood enhancing effects of clozapine important
prescribed to those high risk of suicide - 30% to 50% of people with schizophrenia attempt suicide at some point
what are properties of risperidone
quite new
in form of tablets, syrup or injection
4-8mg
how does risperidone work
binds more strongly to dopamine receptors than clozapine and therefore more effective in much smaller doses than most antipsychotics
what is a strength for typical antipsychotics
(evidence to support)
thornley et al (2003)
reviewed studies comparing the effects of chlorpromazine to control conditions
13 trials - 1121 participants showed chlorpromazine associated with better overall functioning - reduced symptom severity
typical antipsychotics likely to provide benefit
strength for atypical antipsychotics
support for benefit of atypical antipsychotics
meltzer (2012
clozapine more effective than typical antipsychotics
effective in 30%-50% of treatment resistant cases where typical antipsychotics have failed
- studies have compared the effectiveness of clozapine and other atypical AP → results inconclusive generally effective
limitation of typical antipsychotics (side efects)
likelihood of side affects
associated with range of side effects
most serious → neuroleptic malignant syndrome
drug blocks dopamine action in the hypothalmus - area of brain associated regulation of body systems
NMS - high temp, delirium and coma + fatal
shows that typical antipsychotics can possibly lead to serious or fatal outcomes
limitation + strength of atypical antipsychotics (side effects)
less side effects
ATp developed to reduce frequency of side effects and this has generally succeeded
however
clozapine - still have to take regular blood tests to detect agranulocytosis
side effects significant weakness of antipsychotic drugs
what is another limitation of antipsychotics (problems with evidence)
vigorous challenges to usefullness of evidence
healy → succesful trials have had their data published many times, exaggerating the evidence for positive effects.
in addition many studies show short term benefits rather than long term.
this lowers the effectiveness of antipsychotics as it questions their validity
