Antipsychotics Flashcards
Describe the clinical uses of antipsychotics
Common property of all is antagonising the actions of dopamine in the brain. They are mainly used in the treatment of schizophrenia/other psychotic illnesses but can also be used for emesis, Huntington’s disease and depression.
What are the clinical features of schizophrenia?
Positive symptoms - Delusions, hallucination or thought disorders.
Negative symptoms - withdrawal from social contact and flattening of emotional responses
Explain the dopamine theory for schizophrenia
Two changes seen in schizophrenic patients;
Increase of dopamine content in restricted area of the temporal lobe and increased dopamine synthesis and release in the striatum.
Further evidence to support the theory is D2 receptor agonists exacerbate symptoms in humans.
Explain the glutamate theory of schizophrenia
In schizophrenic patients brains there is a reduction of glutamate and receptor (NMDA) density.
Further evidence supported by NMDA receptor antagonists (KET) can produce psychotic symptoms.
Thought excess dopamine responsible for positive symptoms and reduced glutamate for negative symptoms
Name some examples of first generation (classical) antipsychotics
Chlorpromazine, haloperidol and flupentixol. They affect many different types of receptors
Name some second generation (Atypical) antipsychotics
Clozapine, Risperidone and Quetiapine
Describe features of 2nd gen antipsychotic drugs
Improve both negative and positive symptoms and show efficacy in treatment-resistant patients
What is the distinction between typical and atypical groups
- Receptor profice,
- Incidence of extrapyramidal side effects (less in atypical group),
- Efficacy in treatment-resistant group of patients,
- Efficacy against negative symptoms
Name some of the receptor types that antipsychotic drugs
Dopamine, Alpha-adrenoceptors, histamine, muscarinic acetylcholine receptors and serotonin
What are the behavioural effects of antipsychotics?
- Apathy and reduced initiative,
- Display few emotions and are drowsy,
- Inhibition of aggressive tendencies,
What are the common side effects of antipsychotics?
- Urinary retention,
- Weight gain,
- Seizure,
- Sedation,
- Extrapyramidal symptoms (shaking and tremors),
- Postural hypotension,
- Sexual dysfunction,
- Arrhythmias and sudden cardiac death,
- Dry mouth,
- Neuroleptic malignant syndrome (rare but life threatening, fever, muscle rigidity, altered mental status and autonomic dysfunction)
- Jaundice,
- Diabetes,
- Skin reactions
Name and describe the two motor disturbances
1) Acute, reversible Parkinson-like symptoms due to block of nigrostriatal dopamine receptors.
2) Slowly developing tardive dyskinesia - involuntary movements of face and limbs which can appear after months/years of treatment. It is associated with proliferation of dopamine receptors in the corpus striatum (severe problem with antipsychotics)
Describe other unwanted side effects and their related system
Endocrine actions - Increase in prolactin secretion by blocking D2 receptors in the pituitary.
Anti-muscarinic actions - Blurring of vision, dry mouth and eyes, constipation but can help reduce extrapyramidal actions.
Alpha-adrenoreceptor blocking actions - causes orthostatic hypotension.
H1 receptor blocking actions - sedative and anti-emetic actions
What side effect is associated with clozapine?
Leukopenia and agranulocytosis
What side effects are more associated with 1st generation antipsychotics?
- Prolactin elevation and extrapyramidal side effects
