Risperdal Oral Solution

Generic Name: Risperidone
Product Name: Risperdal Oral Solution

Indication

Risperdal is a drug that belongs to a class known as ‘atypical antipsychotics’. Antipsychotic drugs are medications used to control disordered thinking by correcting the chemical imbalances that occur in disorders such as:

• Treatment of schizophrenia and related psychoses
• Acute Bipolar Type 1 mania (short-term)
• Behavioural disturbances in dementia
• Conduct and other disruptive behaviour disorders in adults and children >5 years old, with subaverage intellectual functioning or mental retardation in whom destructive behaviours are prominent
• Behavioural disorders associated with autism (children and adolescents)

It is a newer class of drug than the original (older antipsychotic agents), and has a lower risk of certain side effects. Many doctors see Risperdal as being safer and as such more suitable for elderly people.

Action

Risperidal acts on numerous different chemical signals within the brain. Within the brain are millions and millions of neurons (the cells that make up the brain), as well as tiny nerve fibres that connect them all. The way these cells communicate with each other is through the use of chemicals that are released by one nerve cell called neurotransmitters (or chemical messengers), and recognised by sites on another nerve cell called ‘receptors’.

While no one is fully sure what brain chemistry alterations result in schizophrenia and other psychiatric conditions, drugs such as Risperdal work to change the chemical balance around these receptors, and thus lessen the symptoms. In schizophrenia, one chemical that is thought to play a major role is called dopamine. Risperdal acts to lessen the amount of dopamine that can link into the receptors lessening dopamine’s effect and reducing symptoms.

Other than dopamine though, Risperdal also has effects on chemicals such as serotonin, histamine and adrenergic receptors. This combined effect makes it particularly useful for combating the psychiatric conditions described above. Your doctor will adjuct the dose of Respiral carefully to get control of unwanted symptoms without making you too sedated.

Dose advice

Risperidal oral solution comes as a clear, colourless liquid in a dose of 1mg/mL. Doses should be taken in a non-alcoholic drink (except for tea) The following doses are recommended:

Schizophrenia

Most dosing of Risperdal starts at 1mg taken twice a day, with an increase to 2mg on the second day slowing building up the dose to whatever is necessary. This dose is usually between 4 and 6mg per day either as one dose or two. In patients with severe liver problems, doses usually start at 0.5mg twice daily, possibly increasing to 1-2mg twice daily. If switching from other antipsychotics then gradual discontinuation therapy, where one drug is slowly stopped, is recommended while Risperdal is initiated.

Bipolar mania

Dosages usually start at 2mg once daily, with a possible increase of 1mg/day with a usual final range between 2-6mg/day.

Dementia

Doses usually start at 0.25mg twice daily, with a possible increase to 0.5-1mg twice daily in a divided dose made not more than once every second day. Once the target daily dose has been reached, the dose may be given as once daily dose.

Conduct disorder in patients > 50 kg

Initially start at 0.5mg once daily with a possible increase of 0.5mg per day made not more frequently than once every second day, to an optimum dose of 1mg once daily.

Conduct disorder in patients < 50 kg

Initially start at 0.25mg once daily with a possible increase of 0.25mg per day made not more frequently than once every second day, to an optimum dose of 0.5mg once daily.

Autism

Doses of Risperdal can be given once or twice daily and should be administered according to body weight. The dose will also change with time, as it will be gradually introduced over a period of a few days. The information below is a guide, but the information provided by your doctor will be more tailored and suited to individual patient needs.

• < 20kg:
  • Days 1-3: 0.25mg
  • Days 4-14+: 0.5mg
  • Increments: +0.25mg at greater than or equal to 2 week intervals
  • Dose Range: 0.5mg-1.5mg
• > 20kg:
  • Days 1-3: 0.5mg
  • Days 4-14+: 1.0mg
  • Increments: +0.5mg at greater than or equal to 2 week intervals
  • Dose Range: 1.0mg-2.5mg
• All:
  • Days 1-3: 0.01 mg/kg/day
  • Days 4-14+: 0.02mg/kg/day
  • Increments: +0.01mg at greater than or equal to 2 week intervals
  • Dose Range: 0.02mg/kg/day-0.06mg/kg/day

Schedule

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Common side effects

Due to the nature of Risperdal, it has sometime been very difficult to work out what are the side-effects of the drug, and what symptoms of the disease it is trying to treat.

Generally, adverse reactions are very much outweighed by the advantages of the medication, and only about 7% of patients will stop the medication because of them. However, some of the more common adverse effects associated with Risperdal include:

• Insomnia (difficulty sleeping)
• Agitation
• Anxiety
• Headache
• Weight gain (around 2.6kg after 1 year of treatment)
• Raised prolactin levels

Uncommon side effects

The following is a list of other adverse effects that, while possible, are actually very rarely seen:

• Tiredness/drowsiness
• Fatigue
• Dizziness
• Impaired concentration
• Constipation
• Pain on swallowing
• Nausea and vomiting
• Abdominal pain
• Blurred Vision
• Priapism
• Erectile dysfunction
• Ejaculatory dysfunction
• Urinary incontinence
• Angioedema
• Rhinitis
• Rash

There are some serious adverse reactions that, while rare, are important to consider before taking any antipsychotic such as Risperdal.

Tardive dyskinesia (TD)

Tardive dyskinesia is a syndrome in which there are potentially irreversible involuntary movements that may develop in patients who are treated with antipsychotic agents. It is impossible to predict which patients are likely to develop TD although it appears most prevalent in the elderly. It has been suggested that Risperdal has a lower chance of causing tardive dyskinesia than other, older antipsychotic medications. The symptoms often lessen or resolve completely once the medication is stopped.

Neuroleptic malignant syndrome (NMS)

NMS is a very rare but potentially fatal syndrome that has been associated with antipsychotic drugs, including Risperdal. The clinical manifestations of NMS are hyperthermia, muscle rigidity, altered mental status and evidence of autonomic instability (such as altered blood pressure, heart rhythm irregularities and diaphoresis – extreme sweating).

This very rare condition is more common when there has been previous damage to the brain (eg stroke or brain haemorrhage) and if combinations of multiple antipsychotic drugs are used together. Management is the discontinuation of all antipsychotic drugs and other drugs that are not essential to current management. Symptoms are intensively treated; however, there are no specific treatments available for NMS.

References

1. Australian Medicines Handbook. [online]. Risperidone. January, 2007. Available at URL: http://www.amh.net.au (last accessed 15/03/07)
2. Janssen-Cilag. (2006). Risperdal Product Information. North Ryde: Janssen-Cilag.
3. MIMS Australia. [online] Risperdal. 2007. Available at URL: http://www.mims.com.au (last accessed 15/03/07)
4. MIMS Australia. [online] Risperdal. 2007. Available at URL: http://www.mims.com.au (last accessed 2/05/08)

For further information talk to your doctor.