Schizophrenia - Drug Therapy Flashcards
Why are antipsychotics used as a treatment for Sz
Psychosis is a defining characteristic of Sz. Psychosis is loss of contact with reality. Hallucinations and delusions.
How are antipsychotics used.
Short term or long term. Long term for those with risk of relapsing. Typical or atypical antipsychotics can be administered as syrups, injections or pills.
Discuss use of typical antipsychotics
Since 1950s. CHLORPROMAZINE. Dosage is gradually increased up to a max of 1000mg. Typical precribed doses have declined over past 50 years. Liu and de Haan.
Typical antipsychotics as dopamine antagonists
Strong association between atypical antipsychotics and dopamine hypothesis. Work as antagonists in the dopamine system. Reduce action of the neurotransmitter. Block dopamine receptors in the synapses. First dopamine levels build up because of this, then dopamine production decreases. Reduces hallucinations according to dopamine hypothesis.
Chlorpromazine as a sedative
Effective sedative. Probably due to effect on histamine receptors. Not fully understood. Can be used to calm individuals with Sz and other conditions. Used during early hospitalisation when patients are anxious. Syrup absorbed faster so administered when sedation is needed.
Discuss use of atypical antipsychotics
Since 1970s. Aim is to improve on typical psychotics’ effectiveness and reduce side effects. Atypicals do no work in the same way.
Clozapine
First trialled in 1970s. Causes blood condition of agranulocytosis. More effective than typicals. Marketed as last resort treatment. People now take regular blood tests to monitor for agranulocytosis. Not available as injection due to having fatal side effects. Dosage lower than chlorpromazine. Acts on serotonin and glutamate receptors as well as dopamine. Improves mood and reduces depression which can improve cognitive functioning. Prescribed when high risk of suicide due to mood improvement. 30% to 50% of people with Sz attempt suicide at some point.
Risperidone
Sonce 1990s. Attempt to meet clozapine’s effectiveness without side effects. Can be taken as syrup, pills and injections. Daily does is gradually built up to max of 12mg. Binds to dopamine and serotonin receptors. Bids more strongly than clozapine and so a much smaller dose is used. So leads to fewer side effects compared to chlorpromazine and clozapine.
Evidence for effectiveness
COUNTERPOINT
Thornley et al
Reviewed studies. Found that chlorpromazine was associated with better overall functioning and less severe symptoms compared to placebo.
Meltzer et al.
Clozapine is more effective than typicals and other atypicals. 30%-50% effective in treatment resistant cases where other antipsychotics have failed.
COUNTERPOINT
Healy
Issues with evidence base. Most studies are only looking at short term effects. Successful trials have findings published multiple times exaggerating size of evidence base. Antipsychotics have calming effects, this means that they can calm someone experiencing Sz symptoms rather than treating the psychosis itself.
Serious side effects
Dizziness, agitation, sleepiness, stiff jaw, weight gain, itchy skin. Long term use can cause condition tardive dyskinesia - dopamine sensitivity and involuntary facial movements. Most serious side effect is neuroleptic malignant syndrome. Causes high temperature, delirium and coma and eve death. 0.1%-2%
Not sure how it actually works (mechanism)
Understanding based heavily around dopamine hypothesis. Limitation of hypothesis is that it is not complete explanation for Sz. Dopamine levels are too low in some parts of the brain and too high in other parts so antipsychotics would not work on the whole brain. Only appear o be successful.
Other uses like calming
Moncrieff
Hospitals use antipsychotics o calm them. Help staff manage them rather than help patient.
This calming effect can make them more likely to engage in other treatment. CBTp. May not be useful as treatment but can help more useful treatments happen.
