Antipsychotics Flashcards
Describe Schizophrenia
Chronic disease
onset in late adolescence / early adulthood
highly disabling to social and vocationaly functioning
Causes of Negative symptoms
- Depression
- EPS
- Environmental deprivation
- Positive symptoms
Differentiate positive and negative symptoms
Positive - abnormal behaviours added
Negative - normal behaviours subtracted
Symptoms of Schizophrenia
- Periods of acute presentation with positive symptoms are interspersed with periods during which the negative symptoms predominate
- Negative symptoms become more dominant
- Cognitive dysfunction
Aetiology of Schizophrenia
Genetic factors
- incomplete hereditary tendency
Environmental factors
- Neurodevelopmental abnormalities
Examples of Negative behaviours
- Withdrawal from social contact
- Flattening of emotional responses
Patients are aware of these changes and are distressed
Examples of positive behaviours
- Delusions - e.g.paranoia
- Hallucinations - e.g. exhortatory voices
- Thought disorder - feel as though thoughts are controlled by an outside agency
- Abnormal behaviours - aggressive
Patients are usually unaware
Neurochemical theories
- Dopamine theory - all antipsychotics have D2 antagonism
- 5-HT theory - Atypical antipsychotics have 5-HT2 antagonism
- Glutamate theory
Name 4 Typical antipsychotics
- Chlorpromazine
- Fluphenazine
- Haloperidol
- Trifluoperazine
Effects of Typical antipsychotics
- Controls positive symptoms of Schizophrenia
- Extrapyramidal side effects
List the Extrapyramidal Side effects (EPS)
- Acute dystonia - reversible
- Parkinsonism-like syndrome -> cogwheel rigidity and tremor at rest
- due to D2 antagonism in the nigrostriatal pathway - Tardive dyskinesia and Akathisia - IRREVERSIBLE
Tardive - develops slowly over months or years of treatment
Dyskinesia - repetitive and involuntary movements of face, tongue and limbs
Akathisia - involuntary movement and compulsion to act associated with restlessness, anxiety and agitation
- Akathisia but not dyskinesia correlates directly with duration on medication
- Due to Upregulation or supersensitivity of dopamine receptors in the nigrostriatal system
Define Atypical Antipsychotics
control positive symptoms of schizophrenia with lesser Extrapyramidal side effects
Main difference between Typical and Atypical antipsychotics
Mixed antagonism
- alpha-adrenoreceptors
- H1 histamine receptors
- muscuranic acetycholine receptors
- 5-HT2 receptors
Name 5 key Atypical antipsychotics
- Amisulpride
- Clozapine
- Olanzapine
- Risperidone
- Aripiprazole - partial agonist which acts as an antagonist in the presence of a complete agonist
Unique adverse effect of Amisulpride
- Increased prolactin secretion due to block of dopamine receptors in anterior pituitary gland
- Breast swelling, pain and lactation
- gynaecomastia in males
Unique adverse effect of Clozapine
- Clozapine-induced agranulocytosis
- Agranulocytosis develops in approximately 1% of patients - can be fatal
Regular blood counts required
Adverse effects of Atypical Antipsychotics
- Parasympatholytic effects - due to muscuranic receptor antagonism:
- dry mouth, constipation, blurred vision - Sympatholytic effects - alpha-adrenoreceptor antagonism:
- postural hypotension, reflex tachycardia - Sedation - histamine receptor antagonism
Reason for lesser EPS
D2 receptors have an inhibitory signalling pathway - blocking D2 autoreceptors -> increases dopamine release just enough to prevent EPS
Adverse effects by Risperidone, Clozapine and Olanzapine
- Drug-induced weight gain
- Drug-induced hyperglycaemia
