Antipsychotics Flashcards
What are the groups of antipsychotics?
- Typical
- Atypical
- Anxiolytics
What are examples Typical?
- Haloperidol (used for emergencies)
- Chlorpromazine
What is the main mechanism of action of Typical antipsychotics?
-Act as dopamine antagonists (D2 receptor)
What are some other mechanisms of action of Typical antipsychotics
- Dopamine receptor blockage
- Anticholinergic effects
- Alpha-adrenergic blockage
- Antihistamine effect
What are extrapyrimadial side of Typical antipsychotics?
- Dystonia = sustained muscle contraction resulting in abnormal fixed posture
- Akathisia = internal feeling of restlessness.(moving around a lot, can lead to suicide)
- Tardive dyskinesia = abnormal, involuntary, repetitive movements e.g. grimacing, sticking out the tongue or smacking of the lips
- Pseudo-parkinsonism = rigidity, tremor and increased tone
What are the side effects of Typical antipsychotics as a result of acting at other receptors?
- Anticholinergic: dry mouth, urinary retention, blurred
- Serotonergic: nausea, sexual dysfunction, insomnia (also due to anti-adrenergic)
- Metabolic syndrome: increased blood glucose, obesity, increased cardiovascular risk (most have significantly reduced life expectanc
- Antidopaminergic
- Endocrine changes
- Pigmentation
- Postural hypotension
- Neuroepileptic Malignant Syndrome
What is neuroepiletptic syndrome?
-Life threatening reaction within 2 weeks of initiating antipsychotics characterised by: fever, altered mental status, muscle rigidity, and autonomic dysfunction (tachycardia, labile BP, flushing), hyperthermia, increased CPK, autonomic lability
What are the uses of typical antipsychotics?
- Schizophrenia
- More sedating
What are examples of atypical antipsychotics?
- Clozapine (most effective but 3rd line due to side effects)
- Risperidone
- Quetiapine
- Aripiprazole
- Olanzapine (causes weight gain)
What is the mechanism of action of atypical antipsychotics?
-Act at serotonin (5HT2) receptors as agonists as well as dopamine antagonists so more effective in reducing negative symptoms of schizophrenia
What are side effects of atypical antipsychotics?
- Dystonia = sustained muscle contraction resulting in abnormal fixed posture
- Akathisia = internal feeling of restlessness
- Tardive dyskinesia = abnormal, involuntary, repetitive movements e.g. grimacing, sticking out the tongue or smacking of the lips
- Pseudo-parkinsonism = rigidity, tremor and increased tone
Neuroepileptic syndrome
What are the specific side effects of Clonazapine?
- Cause agranulocytosis resulting in neutropenia so requires FBC monitoring.
- Severe constipation
- Sedation
- Hyper salivation
- Weight gain.
How is Clonazapine prescriptions regulated?
If neutropenic no more clozapine given.
If FBC isn’t given clozapine isn’t used.
What are the advantages of Atypical antipsychotics?
- Different preparations e.g. dissolvable
- Some once daily dosage
- Differing side effect profiles can be matched to patient characteristics
- First line treatment in schizophrenia now as recommended by NICE
What are examples of Anxiolytics (Benzodiazepines)?
- Lorazepem
- Midazolam
- Diazepem
What is the mechanism of action of Benzodiazepines?
- Enhance the action of GABA (main inhibitory neurone)
- Increase opening of chloride channels – hyperpolarized membrane
- Increased depression of cortical transmission is a hypothesis
- Act as full agonists at these receptor sites
What are features of benzodiazepines?
- Highly addictive
- Develop tolerance to the drug in the short term
- Can only be used in the short term
- Can make patient more likely to act on suicidal impulses and are dangerous in overdose
What are side effects of benzodiazepines?
- Drowsiness
- Dizziness
- Psychomotor impairment
- Dry mouth
- Blurred vision
- Gastrointestinal upset
- Ataxia
- Headache
- Reduced blood pressure
- Rare (amnesia, restlessness, rash)
What are side effects of benzodiazepines being used in pregnancy?
- Cleft lip and palate if used in pregnancy
- If taken late in pregnancy may cause respiratory depression and feeding difficulties in baby
What is used to reverse benzodiazepines action?
-Flumazenil an antagonist/partial inverse agonist at benzodiazepines receptors may be useful in reversing effects of benzodiazepines
How are benzodiazepines used?
- Anxiolytic in the short term to treat anxiety (orally)
- Anticonvulsant in acute seizure (IM, IV, buccal)
- Sedative
What are the properties of benzodiazepines?
- Highly lipid soluble
- Renal excretion
- Long half life
- Bioavailability following oral admin. Almost complete
What is the action of all antipsychotics?
- Sedation within hours
- Tranquilisation within hours
- Antipsychotic – several days or weeks
- Activating effect within weeks – negative symptoms
- Production of extrapyramidal side effect – hour or days
What is the toxicity of antipsychotics?
- Central nervous system depression
- Cardiac toxicity
- Risk of sudden death with high dose
