Antipsychotic Medications Flashcards
Name some typical antipsychotics
Haloperidol
Chlorpromazine
Sulpiride
Thioridazine
What occurs at high doses of the typical antipsychotics?
Immobility, rigidity and sleep i.e. Neurolepsis
What occurs at low doses of typical antipsychotics?
An antipsychotic effects especially treating the postive symptoms. May even make negative symptoms worse
What is the mechanism of the typical antipsychotics?
They have 100 fold more potent as D2 receptors over D1 and act to antagonise them.
What is the clincal efficacy of an typical antipsychotic correlated to?
The affinity to D2 receptors over D1
What percentage of patients show no improvement on typical Aps?
25-30%
What percentage of patients show partial respite to typical antipsychotics?
25%
What are the ADRs to typical antipsychotics?
Extrapyramidal side effects Sedation Hypotension Tachycardia Neuroleptic malignancy syndrome (idiosyncratic reactions) Prolonged QT (haloperidol) Hyperprolactinaemia
Name the extrapyramidal side effects?
Akinesia
Acute dystonia
Tardative dyskinesia
Parkinsonism
What is akinesia and how many patients of typical APs get it?
~20%
Restlessness in mainly lower legs and drive to move
Slow onset
What is tardative dyskinesia and how many patients get it on typical aPs?
Involuntary movements of the Lower face muscles and tongue (80%) and limbs
It is irreversible and due to long term typical AP therapy
~50% get this
What is acute dystonia and how many patients get it?
Contraction of muscle group to maximum which is normally self limiting. Onset is within hours and reminds to anticholingeric medication (procyclidine)
~10% get this
What are the characteristic symtoms f Parkinson’s induced by typical APs how many patients get this?
Most common EPSE with onset in days/months
Tremor, bradykinesia, rigidity
~50% get severe but ~100% get mild
Why does Parkinsonism occur in typical AP treatment?
Decreasing dopamine within the brain also affects the nigrostriatal pathway. Thus, modulation of striatal outputs from the SNc is impaired.
What are the effects of typical APs in the tubuloinfundibular pathway?
Dopamine normally inhibits prolactin release. Therefore, typical APs = hyperprolactinaemia which causes sexual dysfunction, lactation and infertility.
What receptors do atypical APs act on?
Mainly D2 and 5-HT2A but can also act on cholinerigc, adrenergic, histaminergic receptors
Name some atypical APs
Clozapine Quitiapine Olanzipine Aripiprazole Risperidone
What antipsychotics is good for L-DOPA induced psychosis?
Quitiapine
Why are atypical APs better at treating schizophrenia?
Work better for negative symptoms (?due to to the dirty nature and lack of specificity of drugs). May also improve cognitive symptoms
Advantages of atypical APs?
Treat negative symptoms
Less EPSE
Less NMS
Disadvantage of atypical APs?
Do not work as quickly as typical
Variable effect from patient to patients
Weight gain (due to histamine receptor antagonism)
No as selective for D2
What atypical AP is particular bad for weight gain?
Olanzipine
Why does the dopamine theory nor provide the full story for the pathogenesis on schizophrenia?
- Ampethamine do not = negative symptoms
- D2 antags do not treat negative symptoms
- Time course of antipsychotic action different from dopamine antagonists (antagonists = 30 mins, APs = 2-3 weeks)
- Atycoals act on many receptors and are more effective for negative symptoms
What is the discontinuation rate for treatments of schizophrenia.Why?
10% per month
Mainly due to ADRs, would rather risk another psychotic episode
Therefore, medication with fewer ADRs are important
What are some other treatments for schizophrenia?
Psychological interventions (CBT, family therapy) these are labour intensive but cost effective in long term as reduced hospitalisation
Support, advice and education
Social therapy in aiding find work and accommodation
?ECT for severe catatonia
What is the treatment regime for schizophrenia
Atypical forest choice. Normally 2 tried before clozapine therapy
Typical used rarely in the treatment of acute uncooperative patients where rapid onset is needed
Depot injections of typical/atypical recombined in an attempt to improve adherence and reduce relapse
Define treatment resistant schizophrenia…what is recommended in this case?
Lack of satisfactory clinical improvement despite the sequential use of at least 2 antipsychotics (which should be atypical) for 6-8 weeks
?clozapine use in these patients
What percentage of patients who are treatment resistant respond to clozapine?
~60%
What are some main ADRs of clozapine?
Agranulocytosis (0.5-2%) Excess salivation Transient hyperthermia Myocarditis PE Weight gain Sedation Constipation GI upset
Since clozapine causes agranulocytosis what must occur?
Administration as inpatient initially
Blood samples taken every week for 18 weeks
Then every 2 weeks for a year
Monetary thereafter
This is inconvenient for patients and expensive
What are some characteristics of risperidone?
Low dose = atypical
High dose = Typical
