3. Drugs in health and disease Flashcards
What is chlorpromazine?
A member of the phenothiazines,
antipsychotic and anti-emetic
moderate autonomic effects, strong sedative, moderate EPS
agonists vs antagonist drugs
agonists do the thing and elicit a response
antagonists dont do the thing by blocking the receptor
chlorpromazine mechanism of action
blocks postsynaptic dopamine receptors in cortical and limbic areas of brain, preventing dopamine excess in brain
leads to reduction in psychotic symptoms e.g. hallucinations and delusions
anti-emetic because block dopamine receptors in chemical trigger zone (CTZ) in brain, relieving nausea and vomiting
licensed doses
Doses in BNF are licenses so any higher dose is unlicensed and cannot be prescribed.
IM doses considerations
Always give less than oral dose because no first pass metabolism
Give less dose if person v active (more blood flow to muscles = more absorption)
Antipsychotic use
short term - calm disturbed patients whatever underlying psychopathology e.g. schizophrenia, brain damage, mania, toxic delirium, agitated depression
alleviate anxiety short term
Schizophrenia treatment aims
alleviate suffering of pt/carer
improve social and cognitive functioning
many pts require life-long treatment w antipsych meds
What symptoms do antipsychotic drugs drugs relieve?
positive psychotic symptoms e.g. thought disorder, hallucinations, delusions
prevent relapse
less effective on negative symptoms such as apathy and withdrawal
Schizophrenia treatment response
neg symptoms persist between episodes of treated positive symptoms but if you treat earlier then can stop neg symptoms developing
acute schiz pts respond better than those w chronic symptoms
Long term treatment usually required after first episode of illness in order to prevent relapses
Doses effective in acute episodes should be prophylaxis
First generation antipsychotics
phenothiazine derivatives split into 3 main groups
Block dopamine d2 receptors in brain
not selective so can cause lots of side effects, especially EPS and elevated prolactin
Group 1 phenothiazine derivatives
chlorpromazine hydrochloride, levomepromazine, promazine hydrochloride
v sedative, moderate antimuscarinic and EPS
Group 2 phenothiazine derivatives
pericyazine
moderate sedative effect
fewer EPS than groups 1 and 3
Group 3 phenothiazine derivatives
Fluphenazine deconoate, perphenazine, prochlorperazine and trifluoperazine
fewer sedative and antimuscarinic effects
more EPS than groups 1 and 2
Butyrophenones
benperidol and haloperidol
resemble group 3 phenothiazines so fewer sedative and antimuscarinif effects but more EPS
Thioxanthenes
Flupentixol and zuclopenthixol
moderate sedative, antimuscarininc and EPS
diphenylbutylpiperidines
Pimozide
reduced sedative effect
reduced antimuscarinic effects
reduced EPS
Substituted benzamides
sulpiride
reduced sedative effect
reduced antimuscarinic effect
reduced EPS
Second gen drugs
AKA atypical antiphsycotic drugs
act on more range of receptors than first-generation antipsychotics
Prescribing antipsychotic drugs for elderly
risk-benefit balance
Antipsychotic drugs are associated w small increased risk of mortality and increased risk of stroke/TIA
susceptible to postural hypotension & to hyper/hypothermia in hot.cold weather
When should antipsychotic drugs be prescribed in elderly?
- should not be used in elderly patients to treat mild to moderate psychotic symptoms
- initial doses should be reduced (to half or less) taking into account weight, comorbidity, other medicaition
- treatment should be reviewed regularly
Prescribing in pts with learning disabilities
if patients are prescribed antipsychotic drugs who aren’t having psychotic symptoms:
1. dose should be reduced/discontinued long term
2. pt’s condition should be reviewed after dose reduction/discontinuation
3.
referral to psychiatrist experienced in pts w learning disabilites and mental health problems
4. annual documentation of re
chlorpromazine hydrochloride indications
- Schizophrenia and other psychoses
- mania
- short term adjunctive management of severe anxiety
- Psychomotor agitation, excitement and violent or dangerously impulsive behaviour
- intractable hiccup
- relief of acute symptoms of psychoses
- nausea and vomiting in palliative care
drugs most likely to cause extrapyramidal symptoms
antipsychotic side effects
occur mostly w piperazine phenothiazines (fluphenazine, perphenazine, prochlorperazine, trifluoperazine)
butyruphenones (benperidol and haloperidol) and first generation depot preperations
Extrapyramidal symptoms
parkinsonian symptoms inc tremor
dystonia - abnormal face/body movements and dyskinesia
akathisia - restlessness, occurs after large initial doses
tardive dyskinesia, usually on longterm therapy w high doses
