Anti-psychotics in Schizophrenia Flashcards
Do first or second generation anti-psychotics have greater efficacy?
Both first and second generation anti-psychotics are used to treat the positive symptoms of Schizophrenia (hallucinations, delusions etc) and for this they have the same efficacy aside from Clozapine.
However second generation anti-psychotics have been shown to be have superior efficacy for negative symptoms of Schizophrenia and therefore you may choose these if negative symptoms predominate.
List some of the first generation anti-psychotics.
Chlorpromazine
Haloperidol
Flupentixol
Levomepromazine
List some of the second generation anti-psychotics.
Clozapine
Quetiapine
Aripiprazole
Risperidone
Olanzapine
What does choice of anti-psychotics depend upon?
Past history of response
Has the patient been sensitive to a particular adverse effect/or have they got risk factors
Co-morbidities
Concurrent medication which would pre-dispose a particular side effect and interactions
Dosing profiles
Is a depot formulation of the anti-psychotic available to switch to - other formulations - swallowing difficulties
Patient preference
Likely risk vs benefits
Anti-psychotic side effect profile
Cost
What are the depot (long acting) anti-psychotic formulations?
Involves the administration the anti-psychotic by injection intramuscularly and then is released in the blood over a number of weeks
Which depots need a test dose beforehand?
To make this clear all anti-psychotics before being given as depots must have a trial period in the oral formulation to determine efficacy and side effect profile, however:
First generation depots are oil based and require a test dose for sensitivity to the oil base/test for EPSEs
Second generation no test dose is required due to having an aqueous base and lower incidence of EPSEs.
What are the main side effects associated with the first generation anti-psychotics?
Extra-pyramidal dose dependent side effects which includes:
Akathisia
Dystonia
Tardive dyskinesia
Parkinsonism
In addition to other side effects:
Anticholinergic
Cardiac
Hyperprolactinaemia
Sexual dysfunction
What are the general advantages of using depots?
Can quickly identify non-adherence - Doctor can be informed immediately when a patient has missed a dose
Good for patients who struggle with adherence
Good for patients who don’t want to take tablets every day
Ensures the patient is always receiving a therapeutic effect from their medication regardless of their state of mind
More consistent plasma levels - less side effects
Remains 1-2 weeks after a missed dose
Avoids first pass metabolism
What are the general disadvantages of using depots?
Can be painful, uncomfortable, produce injection site reactions
Oral to long acting injections can be complicated
Stigma
Preparations require mixing/refrigeration
Dosing titration may be more difficult than with oral
ADRs persist for longer
Poor injection technique
What are some of the general principles of prescribing anti-psychotics?
Use the lowest effective dose as possible and any dose increases should not occur within 1-2 weeks to see a full therapeutic effect
Use a single anti-psychotic when possible due to the increased risk of adverse effects
Only use combinations when a single anti-psychotic is inadequate
Antipsychotics should not be prescribed as when necessary for sedative effect
Assess response using rating scales and document outcome in patients records
Reduce dose gradually to prevent withdrawal and symptom rebound
How is high dose anti-psychotic classified?
As single dose therapy above the BNF maximum or two or more antipsychotics prescribed concurrently that, when expressed as a percentage of their maximum daily dose total more than 100%.
This includes PRN use.
Does using two anti-psychotics equate to greater effectiveness?
No there is nothing to suggest anti-psychotic polypharmacy leads to greater effectiveness.
If high dose anti-psychotic therapy is used what needs to be monitored?
Target symptoms
Therapeutic response
Side effects with close physical monitoring
When is rapid tranquiliser used?
It is used to:
Reduce patient suffering
Reduce risk of harm by others
To do harm by prescribing safe regimens and monitoring physical health
It can only be used once verbal de-escalation has failed and oral medication has been refused.
Which medications can be used for rapid tranquilisation?
IM Lorazepam, or IM Haloperidol with IM Promethazine
What is the monitoring required for rapid tranquilisation?
Bp
Temperature
Respiratory rate
Consciousness
Should be done hourly or every 15 minutes if the BNF maximum was exceeded or additional concerns were raised.
How is treatment resistant psychosis defined?
Lack of satisfactory improvement despite use of at least two different anti-psychotic drugs including a SGA prescribed for at least 4-6 week trial period.
This affects 1/3 of patients using anti-psychotics.
Which anti-psychotic is licensed for treatment resistant psychosis?
Clozapine
Explain how extra-pyramidal side effects occur with first generation anti-psychotics.
First generation anti-psychotics have a much greater affinity for the D2 receptor in comparison to second generation anti-psychotics. It is believed that Schizophrenia occurs due to dopamine hyperactivity at D2 receptors within the mesolimbic system causing the positive symptoms (responsible for the reward pathway).
First generation anti-psychotics were designed as D2 receptor antagonists with a clinical effect seen once 80% of D2 receptors within this pathway are occupied. However D2 antagonists are not specific to this one dopamine pathway, they also bind to D2 receptors within the other three pathways.
D2 antagonism within the nigrostriatal pathway leads to depleted dopamine leads to the extrapyramidal side effects as seen in the symptomatic presentation of Parkinson’s disease such as akathisia, dystonia, tardive dyskinesia.
What are the signs of dystonias?
Uncontrolled muscle spasms of the head and neck
Patients may also experience pain and stiffness
Eye rolling
What are the risk factors for developing dystonia?
Occurs in 10% of patients those at a higher risk are:
Young men, those taking anti-psychotics for the first time, higher potency anti-psychotics
When are dystonia likely to occur?
Acutely within hours and even faster with IM
Tardive dystonia after months or years after taking the anti-psychotic
What is the appropriate management of dystonia?
Anticholinergics such as Procyclidine which can allow the patient to continue at the effective dose
Switching to a SGA
Reducing the dose of anti-psychotic
What are some of the signs and symptoms of Parkinsonism?
Tremours
Rigidity
Bradykinesia - reduced facial expression, slow body movements, inability to initiate movement, speaking with a flat monotone voice
Which patients are more likely to experience Parkinsonism and when does it occur?
Elderly females, those with pre-existing neurological damage
Days to weeks of initiation or following a dose increase
What is the appropriate management of anti-psychotic induced Parkinsonism?
Using anticholinergics (Procyclidine again)
Dose reduction
Switching to one with less EPSEs such as SGA
How does Akathisia present?
As an inner restlessness including pacing or a shaking leg
Which patients are more likely to experience Akathisia and when does it occur?
25% of those taking FGAs will experience it acutely and it is common when starting Aripiprazole.
Can occur within hours or days of starting the anti-psychotic/increasing the dose and can persist for months.
What is the appropriate management of akathisia?
Reducing the dose
Using an alternative - SGA
Short course of Benzodiazepines such as Lorazepam when starting the anti-psychotic
What are some of the signs and symptoms of tardive dyskinesia?
Lip smacking, blinking, upper body movements and choreiform hand movements (such as playing the piano).
Which patients are more likely to experience tardive dyskinesia and when does it occur?
Older age, affective illness, Schizophrenia, high doses of anti-psychotics, acute EPSEs in early treatment.
Can take months to years to develop
What is the appropriate treatment for tardive dyskinesias?
Stop all anticholinergics
Reduce dose or switch, Quetiapine and Clozapine are good