Monday 5 June, 2006

How to start antipsychotics

Posted in Emergency Dept., May Su, Psychiatry, Wards at 17:38 by May Su

Original article by: May Su :: Printer friendly

Antipsychotics are the most appropriate medication to use when someone is suffering from a psychotic illness. This may be in the form of schizophrenia or a schizophrenia-like illness, or part of a psychotic depression or bipolar affective disorder. Antipsychotics are not particularly difficult to use and though they can have significant side-effects, are fantastic when they work well. The “first line” antipsychotics are any of the “atypical” antipsychotics with the exception of clozapine.

Assumptions:

  1. The patient is settled enough to tolerate regular oral medications (i.e., the patient doesn’t have a “behavioural emergency“);
  2. He or she actually has a psychotic disorder, rather than intoxication (e.g., with drugs and/or alcohol), withdrawal or delirium (e.g., from cerebral hypoxia post-operatively);
  3. The patient is of regular size and weight and does not have any specific comorbidity or contraindication to antipsychotics.
For the acutely psychotic but otherwise physically well adult:

Olanzapine

  • Starting: 5 mg daily
  • Week 2: 10 mg daily
  • Further: see below

Risperidone

  • Starting: 1 mg daily
  • Week 2: 2 mg daily
  • Further: see below

Step One: Work up

If at all possible, a thorough work up (organic screen) should be commenced before commencement of the antipsychotic. A completely history and physical examination is a must.

Tests to consider prior to starting antipsychotics

  • FBC (full blood count)
  • UEC (electrolytes, urea and creatinine)
  • LFT (liver function tests)
  • fasting BSL and lipid profile
  • BMI (body mass index)
  • CT brain
  • ECG (electrocardiogram)
  • and if indicated:
    • EEG (electroencephalogram)
    • neuropsychiatric testing

Step Two: Choose your poison

Choice of medication (principles)

  • In general, choose an atypical over a typical antipsychotic;
  • Choose a medication to which the patient has responded to in the past previously;
  • Avoid medications to which the patient has had significant side-effects in the past or where the side-effect profile will be particularly intolerable (e.g., weight gain or hyperprolactinaemia in young women).

In general, apart from clozapine (which is not a first line medication and is used with stringent monitoring due to toxicity), all the atypical antipsychotics are probably equally effective at appropriate doses. They do differ in their side-effect profiles.

The most commonly used antipsychotics in Australia as first line agents are olanzapine (Zyprexa) and risperidone (Risperdal).

Olanzpaine is more likely to cause weight gain, hyperprolactinaemia, dyslipidaemia, diabetes and sedation (compared to risperidone). Risperidone is more likely to cause extra pyramidal side-effects, postural hypotension and agitation (compared to olanzapine).

Step Three: How to start

Olanzapine:

  • start at 5 mg daily
  • increase to 10 mg daily in week two
  • increase the daily dose by 5 mg every 2 weeks if inadequate response (more rapidly if acutely unwell)
  • maximum daily dose of 20 mg daily
  • olanzapine can be given in twice daily divided doses

Risperidone

  • start at 1 mg daily
  • increase to 2 mg daily in week two
  • increase the daily dose by 1-2 mg every 2 weeks if inadequate response (more rapidly if acutely unwell)
  • maximum daily dose of 6 mg daily

Don’t be dogmatic

It is probably important to be aware that although atypical antipsychotics are great medications, are are not a panacea and have their own problems. Typical antipsychotics still have a role and it is important to be reminded that apart from the extremely expensive Risperdal Consta (the depot formulation of risperidone), the only depots availabe are all typical antipsychotics. Many patients still remain well controlled on typical antipsychotics.

The Australia Presciber (the publication from the independent National Prescribing Service) published a twin pair of articles in 2004:

Research articles

(1) Carr V. Are atypical antipsychotics advantageous? – the case against. Aust Prescr 2004;27:149-51 [download PDF :: 102 Kb]

(2) Keks N. Are atypical antipsychotics advantageous? – the case for. Aust Prescr 2004;27:146-9 [download PDF :: 150 Kb]

Edited by: Dr Michael Tam (19 June 2006) Resources: Therapeutic Guidelines: Psychotropic 5, 2003

Please read the disclaimer

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: