Biological therapies for schizophrenia: drug therapy Flashcards
Biological therapies for schizophrenia: drug therapy
parts
Typical antipsychotics e.g. chlorpromazine
Atypical antipsychotics e.g. Clozapine, Risperidone
antipsychotics
definition
drugs used to reduce the intensity of symptoms of psychotic conditions like schizophrenia
└particularly positive symptoms
antipsychotics
drugs used to reduce the intensity of symptoms of psychotic conditions like schizophrenia
└particularly positive symptoms
└administered via tablets, syrup, injections (lasts 2 weeks)
└dose often starts small and is built up
└can be taken short or long term
└some may need them long term to prevent return of schizophrenic symptoms
Typical antipsychotics
time
└the first generation of antipsychotic drugs, used since 1950s
Typical antipsychotics
how they work
└work as dopamine antagonists
└antagonists= chemicals which reduce the action of a neurotransmitter
└block dopamine receptors in synapse of brain- reducing action of dopamine
└aims to normalise neurotransmission in key areas on the brain
└reduces symptoms like hallucinations
└also an effective sedative
└believed to be linked to its effect on histamine receptors but not fully understood how his leads to sedation
Typical antipsychotics
how they are taken
└include chlorpromazine
└can be taken by tablets , syrup or injection
└Liu and de Hann (2009)- typical prescribed doses have declined over last 50 years
└commonly used as a syrup for this reason as absorbed faster than tablets
Atypical antipsychotics
└ schizophrenia (psychotic) drug developed after typical antipsychotics, used since 1970s
└developed to improve effectiveness of supressing symptoms of psychosis and minimise side effects
└usually target a range of neurotransmitters
└e.g. dopamine, serotonin
└include clozapine and risperidone
└atypical antipsychotics work in different ways to each other
Atypical antipsychotics
Clozapine
└developed in 1960s, first trialled in 1970s
└withdrawn in 1970s following deaths of patients from agranulocytosis (a blood condition)
└1980s- was found that it was more effective than typical antipsychotics
└ it was remarketed and used as a treatment when others failed
└patients have to have regular blood tests/can’t have as an injection/ have lower doses as may be fatal
└clozapine binds to dopamine, serotonin and glutamate receptors
└helps improve mood and reduce depression/anxiety
└may improve cognitive functioning
└prescribed if patient is at high risk of suicide
└50% of people with schizophrenia attempt suicide
Atypical antipsychotics
Risperidone
└used since 1990s
└developed to be like clozapine with less serious side effects
└taken as tablets, syrups, injections
└binds to dopamine, serotonin receptors
└binds more strongly to dopamine receptors than clozapine
└=effective in smaller doses than most antipsychotics
└=may lead to fewer side effects
Biological therapies for schizophrenia: drug therapy
limitations
summary
Serious side effects - Meltzer (2012)
Antipsychotics and the dopamine hypothesis
Problems with evidence for effectiveness - David Healy (2012)
Chemical cosh argument - Moncrieff (2013)
Biological therapies for schizophrenia: drug therapy
limitations
Serious side effects
└antipsychotics
└side effects: mild- serious, fatal
Typical antipsychotics
└dizziness, agitation, sleepiness, stiff jaw, weight gain, itchy skin
└long term use: tardive dyskinesia
└dopamine super sensitivity- involuntary facial movements
└grimacing, blinking, lip smacking
└most serious side effect: neuroleptic malignant syndrome (NMS)
└caused because the drug blocks dopamine action in hypothalamus
└an area of the brain associated with regulation of multiple body systems
└results in high temperature, delirium and coma- can be fatal
└NMS rarer as typical doses of antipsychotics have declined
└0.1%-2%
Atypical antipsychotics
└Meltzer (2012)
└atypical antipsychotics developed to reduce frequency of side effects
└generally succeeded
└patients taking clozapine need regular blood tests
└to look for early signs of agranulocytosis
Biological therapies for schizophrenia: drug therapy
limitations
Antipsychotics and the dopamine hypothesis
└our understanding of the mechanism of antipsychotic drugs depends on the original dopamine hypothesis
└high levels of dopamine activity in subcortex of brain
└evidence shows original dopamine hypothesis is not a complete explanation of schizophrenia
└dopamine levels in subcortex too low not too high
└if true, it is not clear how antipsychotics help schizophrenia
└as they are dopamine antagonists which reduce dopamine activity
└modern understanding of dopamine suggests antipsychotics shouldn’t work
Biological therapies for schizophrenia: drug therapy
limitations
Problems with evidence for effectiveness
└although lots of evidence to support effectiveness of antipsychotics
└challenges to their usefulness
└David Healy (2012)
└some successful trials have had their data published multiple times
└exaggerates evidence for positive effects
└may just have calming effects and not actually reduce severity of psychosis
└most published studies asses short term benefits not long term benefits
└compare patients who keep taking antipsychotics with those suffering withdrawal having just stopped taking them
Biological therapies for schizophrenia: drug therapy
limitations
Chemical cosh argument
└believed that antipsychotics have been used in hospitals to calm patients and make them easy to work with, rather than for the benefits of the patients themselves
└short term use of antipsychotics to calm agitated patients is recommended by the National Institute for Health and Clinical Excellence (NICE)
└this practice is seen as human rights abuse by some
└Moncrieff (2013)
