Psychosis - Pharmacology Flashcards
Anti-psychotic drugs are most effective for treating what?
Acute, positive symptoms of psychosis
Anti-psychotic drugs can take up to how long to treat positive symptoms of psychosis?
3 months
What are some examples of typical anti-psychotics?
Chlorpromazine, thioridazine, haloperidol, zuclopenixol
Zuclopenixol is a typical anti-psychotic drug which is given how?
As a depot preparation
What is the mechanism of action of typical anti-psychotics?
D2 receptor blockade to increase cAMP
What group of side effects are typical anti-psychotics most likely to produce?
Extra-pyramidal side effects
What are the 4 main extra-pyramidal side effects?
Acute dystonic reaction, akathisia, Parkinsonism and tardive dyskinesia
Extra-pyramidal side effects occur due to D2 receptor blockade where?
In the nigrostriatal pathway
How soon after taking an anti-psychotic will an acute dystonic reaction occur?
Hours-days
What happens in an acute dystonic reaction?
Involuntary, sustained, painful muscle spasms
What can the muscle spasms which occur as a result of an acute dystonic reaction cause to happen?
Extensor spasm of the body, torticollis (abnormal neck posturing) and difficulty swallowing
How is an acute dystonic reaction treated? Give an example?
Anti-cholinergics e.g. Prochlorperazine
How soon after taking an anti-psychotic drug does akathisia present?
Within a few days
What is akathisia? What may patients with this complain of?
An internal restlessness - patients will complain of feeling like they need to move constantly and will feel mentally uneasy
Where does akathisia most commonly affect? What may you notice patients doing?
The legs / pacing, wriggling, fidgeting
Dysphonia (difficulty speaking) may occur as a result of which extra-pyramidal side effect?
Akathisia
How is akathisia treated?
By lowering the dose of anti-psychotic until it stops, or changing drug altogether
How soon after taking an anti-psychotic drug does Parkinsonism present?
Usually within a month
What are some features of Parkinsonism induced by anti-psychotic drugs?
Resting tremor, rigidity, postural instability and bradykinesia
Which anti-psychotic drug is most likely to result in Parkinsonism?
Haloperidol
How can Parkinsonism be treated?
Can be treated with anti-cholinergics or can stop the drug
How long after taking an anti-psychotic drug does tardive dyskinesia present?
Years later
Which extra-pyramidal side effect may persist even after stopping taking the anti-psychotic which was causing it?
Tardive dyskinesia
Tardive dyskinesia occurs as a result of what?
Long term anti-psychotic use
How will tardive dyskinesia present?
Repetitive, involuntary purposeless movements e.g. grimacing, lip smacking, pursing lips, sticking out tongue
Hypothalamic side effects are more likely to occur with which type of anti-psychotic drugs?
Typicals
What are some side effects of anti-psychotic drugs that result from D2 blockage in the tubulofundibular pathway in the hypothalamus?
Hyperprolactinaemia and galactorrhoea, gynaecomastia, sexual dysfunction
What are some side effects related to sexual dysfunction that anti-psychotics may cause?
Hypogonadism, decreased libido, amenorrhoea, infertility
Which ECG change can taking anti-psychotics predispose to? Which type of anti-psychotic is most likely to cause this?
QT prolongation - typicals
Dopamine blockade by anti-psychotic drugs can lead to low levels of which hormones? What can this lead to?
Oestrogen and testosterone / osteoporosis
What is the mechanism of action of atypical anti-psychotics?
Block many receptors, mostly 5-HT2A > D2
Which type of anti-psychotic drugs have a better efficacy against negative symptoms?
Atypicals
Name some examples of atypical anti-psychotics?
Olanzapine, quetiapine, risperidone, aripiprazole, clozapine
Why should olanzapine be avoided in people with diabetes?
High risk of destabilising blood sugars and causing weight gain
Atypical antipsychotics are first line in who?
People who have been newly diagnosed with schizophrenia and those experiencing side effects from typicals
What is the major side effect of atypical anti-psychotic drugs? This occurs due to blockade of what?
Metabolic syndrome / 5-HT2
What are the features of metabolic syndrome?
Dyslipidaemia, hypertension, weight gain and insulin resistance
What are some side effects of anti-psychotic drugs due to histamine blockade? What are the risks of these?
Sedation - risk of falls / increased appetite - risk of weight gain
What happens when antipsychotic drugs block alpha adrenergic receptors?
Decreases the alpha 1 adrenergic activity of blood vessels which interrupts the baroreceptor reflex and causes dizziness, lightheadedness and postural hypotension
Muscarinic receptors are the targets of what? Blockade of these receptors can cause what symptoms?
Parasympathetic nervous system / dry mouth, blurred vision, constipation, urinary retention
When should clozapine be used?
When 2 previous anti-psychotic drugs (one of which must have been an atypical) have failed i.e. 3rd line
Clozapine may be of especial benefit to who?
People with negative symptoms and those who are suicidal
What is the reason that clozapine is a 3rd line drug?
Agranulocytosis (neutropenia)
Describe the monitoring process for people taking clozapine?
Weekly FBCs for the first 6 months, fortnightly for the next 6 months and 4 weekly after that
If a patient who is taking clozapine presents with any signs of infection - what is the most important thing to do?
Check FBCs for neutropenia
If a patient taking clozapine stops smoking, what should be done? Why?
Decrease the dose since the drug can be metabolised faster
Why should patients getting started on clozapine always be in hospital when this is done?
Because it can be cardiotoxic and cause myocarditis
What are some reasons that clozapine may cause myocarditis?
IgE mediated hypersensitivity reaction, cytokine release, hypercatecholaminaemia
What should you monitor when starting a patient on clozapine? When should you interfere?
ECG, pulse, BP / if ECG shows non-specific ST segment changes this is positive for myocarditis
What are some other recognised side effects of clozapine?
Constipation, hyper-salivation, weight gain and seizures
Overall, which type of anti-psychotic drug is better? Which one specifically?
Atypical / clozapine
What is neuroleptic malignant syndrome? Who does it tend to occur in?
A rare but life-threatening reaction to anti-psychotic medication / most commonly young males
How long after starting an antipsychotic or increasing its dose will neuroleptic malignant syndrome occur?
Usually within 10 days
What will neuroleptic malignant syndrome present with? What are some signs?
Pyrexia, rigidity and tachycardia / Raised CK and maybe raised WCC
What is the management of neuroleptic malignant syndrome? How long should it take to resolve?
Stop antipsychotic drugs, supportive treatment / 1-2 weeks
