schizophrenia: drug therapy Flashcards
(15 cards)
outline ways to take antipsychotics
- Antipsychotic drugs can be taken as tablets or in the form of syrup.
- For those who are at risk of failing to take their medication regularly some antipsychotics are available as injection given every 2 -4 weeks.
- Antipsychotics may be required in the short or long term.
when were typical and atypical antipsychotics developed
typical: 1950s
atypical: 1970s
how do typical and atypical antipsychotics work
typical: dopamine antagonists
atypical: target dopamine and serotonin
what is an example of a typical antipsychotic
chlorpromazine
what are examples of atypical antipsychotics
- clozapine
- risperidone
explain how typical antipsychotics work
- they target positive symptoms
- they act as antagonists > Antagonists are chemicals which reduce the action of a neurotransmitter.
- Dopamine antagonists work by blocking dopamine
receptors in the synapses of the brain, reducing the action of dopamine in key areas of the brain,
therefore reducing symptoms such as hallucinations - can be taken as tablets, syrup or injection
how are they used as sedatives
- chlorpromazine is a sedative > this is related to its effect on a histamine receptor
- this is useful for when patients are first admitted to the hospital and are very anxious
- normally given as a syrup as it is absorbed faster than tablets
what symptoms do atypical antipsychotics target and how do they differ from typical
- Atypical antipsychotic drugs target negative symptoms
- The aim in developing newer antipsychotics was to maintain or improve upon the effectiveness of drugs in suppressing the symptoms of psychosis and also minimise the side effects.
- There are a range of atypical antipsychotics and they do not all work in the same way
explain how clozapine works
Clozapine binds to dopamine receptors in the same way that chlorpromazine does, but in addition it acts on serotonin and glutamate receptors.
* This action helps improve mood and reduce depression and anxiety in patients and it may improve cognitive
functioning.
why is clozapine useful for suicidal patients
- it has mood-enhancing effects
- 30-50% of people suffering from schizophrenia attempts suicide at some point
explain issues with clozapine
- It was withdrawn in 1970s for a short while, following the death of some patients from a blood condition called agranulocytosis.
- However, in the 1980s when it was discovered it to be more effective than typical antipsychotic, Clozapine was
remarketed as a treatment for schizophrenia to be used when other treatments failed. - Today, people have to take regular blood tests to ensure they are not developing agranulocytosis
- Because of its fatal side effects, Clozapine is not available as an injection
explain risperidone
Risperone is a more recently developed atypical antipsychotic, having been around since the 1990s.
* It was developed in an attempt to produce a drug as effective as Clozapine but without its serious side effects.
* Taken as tablets, syrup and an injection that last for around two weeks.
* Risperone is believed to bind to dopamine and serotonin receptors, Risperone binds more strongly to dopamine receptors than clozapine and is therefore effective in much smaller doses than most antipsychotic.
* There is some evidence to suggest that this leads to fewer side effects than is typical for antipsychotics.
AO3: research to support
There is research to support the effectiveness of antipsychotic drugs
Thornley et al conducted a meta-analysis of 13 drug trials,totalling 1121 people, found chlorpromazine to be more effective than the placebo (+ lower rate of relapse).
However in more recent research Meltzer (2012)
found clozapine more effective than typical antipsychotics > treated 30-50% of previously treatment-resistant patients.
STRENGTH as this demonstrates the effectiveness of antipsychotic drugs in overcoming symptoms of schizophrenia, which suggests that the cause of schizophrenia must be due to abnormal levels of neurotransmitters.
AO3: side effects
Drug therapies can cause side effects
Less serious side effects involve nausea and headaches.
While more serious side effects can occur. Typical antipsychotics cause tardive dyskinesia which is uncontrollable facial movements and shaking and can also cause neuroleptic malignant syndrome (NMS) – caused by the drugs
blocking dopamine in the hypothalamus. This causes high temp, delirium (fever) and coma – it can be fatal. Effects 0.1-2%.
WEAKNESS because the patient may stop taking the drugs. If they don’t take the drug the symptoms of schizophrenia will return, meaning the patient will relapse. In less extreme cases, side effects may stop people taking them regularly/for as long as they’re supposed to, making them less effective.
AO3: unclear mechanism
Another limitation of antipsychotic drugs is that we do now know why they work
in the OG dopamine hypothesis there is a link between high levels of dopamine activity in the subcortex of the brain and the onset of schizophrenia symptoms
However, the updated version of the dopamine hypothesis also suggests that low levels of dopamine can also cause the onset of schizophrenia symptoms.
WEAKNESS because it suggests that most antipsychotic drugs should not work. So at least some antipsychotics may not be the best treatment to opt for and perhaps some other factor may be involved in their apparent success
