Atypical Antipsychotics

• What are atypical antipsychotics?
• What are atypical antipsychotics used for?
• How do atypical antipsychotics work?
• Injectable antipsychotics
• Side effects of atypical antipsychotics
• Precautions

What are atypical antipsychotics?

Atypical antipsychotics are a class of drugs used primarily to treat psychotic disorders. Rationale for use includes relief from symptoms such as hallucinations, delusions or abnormal behaviour/thought, and sedative and tranquillising effects in very disturbed or aggressive patients. Atypical antipsychotics are thought to be better in treating the negative symptoms of schizophrenia although differences may also be due to fewer adverse effects and/or better patient compliance. Members of this class include amisulpride, aripiprazole, clozapine, olanzapine, quetiapine, risperidone and ziprasidone.

What are atypical antipsychotics used for?

Atypical antipsychotics are used for:

• Treatment of acute and chronic psychoses (e.g. schizophrenia)
• Acute mania (olanzapine, quetiapine, risperidone)
• Organic psychoses (e.g. dementia-associated agitation)
• Severe behavioural disorders in children (risperidone)

How do atypical antipsychotics work?

The exact mechanism of atypical antipsychotics is unknown. They are though to block certain chemical receptors in the brain and hence relieve the symptoms of psychotic disorders. Risperdal Oral (risperidone) works by blocking the receptors of chemical messengers called dopamine and serotonin. Invega (paliperidone) is the substance created when risperidone is ingested into the body and hence works in the same way. Clopine (clozapine), Zyprexa (olanazapine) and Seroquel (quetiapine) block a number of receptor types including dopaminergic, serotonergic, muscarinic, and histaminic and tries to restore the chemical imbalance in the brain. Excessive weight gain and high blood glucose may occur with Clopine (clozapine) and Zyprexa (olanzapine), leading to type 2 diabetes. Solian (amilsulpride) has a variant dose dependent action. At high doses it has an antipsychotic effect; however at low doses it’s more effective against the negative symptoms of schizophrenia. The mechanism of action of Abilify (asripiprazole), as well as other drugs having efficacy in schizophrenia, is unknown. Zeldox (ziprasidone) has a complex pharmacology which gives its effectiveness against both positive and negative symptoms of schizophrenia.

Your doctor will decide which treatment is the best for your condition.

Injectable antipsychotics

Antipsychotics can also be administered via injections that release the drug over a period of time. At first, oral medication will also need to be administered as it takes time for the medication to reach steady state levels. The main advantage with administering antipsychotics via a long-acting injectable formula is that it improves compliance with taking the medication and ensures it is taken regularly. Compliance to medication can be poor due to a range of factors such as substance abuse and poor social skills influencing treatment. As a consequence, whilst behavioural therapies would be the most suitable method to promote compliance with medication, this may not be as effective as using injectables.

By ensuring long-term compliance to medication you can prevent relapse by some patients and also reduce symptoms in those suffering from severe forms of the disease. For example, Risperdal Consta is risperidone in an injectable form, administered once a fortnight. Risperidone is used to treat schizophrenia. In summary, injectable antipsychotics ensure patient compliance with medication; this will enable long term treatment of psychosis.

 

 

Side effects of atypical antipsychotics

The side effects for each type of medication vary but the most common side effects that occur to less than 10% of patients are:

• Weight gain
• Hypotension
• Tachycardia
• Insomnia
• Agitation
• Anxiety
• Headache
• Akathisia
• Hyperprolactinaemia

Some of the rare serious side effects that can occur in less than 1% are:

• Hyperglycaemia
• Dystonia
• Akathisia
• Parkinsonism
• Tardive dyskinesia
• Neuroleptic malignant syndrome

These side effects may not occur, but if you have any concerns, see your doctor about them.

Precautions

Elderly

The doctor may use a lower starting dose and more gradual dose increases because of greater risk for adverse effects in older people.

Pregnancy

Amisulpride, aripiprazole, olanzapine, quetiapine, risperidone are ADEC category B3; paliperidone and clozapine are ADEC category C. Therapy with an atypical antipsychotic for a person planning to become or is pregnant should be conducted under the supervision of a specialist. Please see your doctor if you have any concerns about it.

For further information, see your doctor.

More information

For more information on schizophrenia and its treatments, and some useful tools, animations and videos, see Schizophrenia.

Related articles:

• Treatment – Conventional Antipsychotics
• Anatomy – Central Nervous System

References

1. Atypical antipsychotics [online]. Australian Medicines Handbook. January 2007 [cited 24 October 2007]. Available at: [URL Link]
2. Psychotropic: Atypical antipsychotics [online]. Therapeutic Guidelines. Version 5, 2003 [cited 24 October 2007]. Available at: [URL Link]
3. Pharmaceutical Benefits Schedule [online]. [last cited 24 October 2007] Available at: [URL Link]
4. Risperdal [online]. MIMS Australia. 2007 [cited 24 October 2007]. Available at: [URL Link]
5. Clopine [online]. MIMS Australia. 2007 [cited 19 October 2007]. Available at: [URL Link]
6. Zyprexa [online]. MIMS Australia. 2007 [cited 19 October 2007]. Available at: [URL Link]
7. Seroquel [online]. MIMS Australia. 2007 [cited 19 October 2007]. Available at: [URL Link]
8. Solian [online]. MIMS Australia. 2007 [cited 19 October 2007]. Available at: [URL Link]
9. Abilify [online]. MIMS Australia. 2007 [cited 19 October 2007]. Available at: [URL Link]
10. Zeldox [online]. MIMS Australia. 2007 [cited 19 October 2007]. Available at: [URL Link]
11. Keks NA, Hope J. Long-term management of people with psychotic disorders in the community. Aust Prescr. 2007; 30(2): 44-6.