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Drugs

Risperdal Consta

Generic Name: Risperidone Intramuscular Injection
Product Name: Risperdal Consta

• Indication of Risperdal Consta
• Action of Risperdal Consta
• Dose advice of Risperdal Consta
• Schedule of Risperdal Consta
• Common side effects of Risperdal Consta
• Uncommon side effects of Risperdal Consta
• Reference

Indication of Risperdal Consta:

Risperdal Consta is a drug that belongs to a class known as 'atypical antipsychotics'. It is called this because it is a newer class of drugs than the older antipsychotic agents and has a lower risk of certain adverse effects. It is used for the treatment of schizophrenia and related psychoses.

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Action of Risperdal Consta:

Risperdal 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 cell, and recognised by sites on another 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 change the symptoms.

In schizophrenia, one chemical that is thought to play a major role is called dopamine, and 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 and this combined effect makes it particularly useful for combating the psychiatric conditions described above.

Risperdal Consta is a particularly clever form of Risperdal that is composed of lots of tiny 'microspheres' each containing some of the drug. When the spheres break, they release the drug. However, these microspheres take a while to break down, and so the effect of the drug can be prolonged over a period of time. In fact, when the drug is first injected, less than 1% of the dose is released into the blood stream. It takes 3 weeks for the main release of the drug to occur and so it is important that oral medication still be taken in this time. Release will continue in the 4th to 6th week after the initial injection and stop by 7 weeks. This means that by simply having an injection once every two weeks, the level of drug in the blood stream remains at a more stable level. It also means that there will still be some drug in the blood stream, 7 to 8 weeks after a final injection.

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Dose advice of Risperdal Consta:

Risperdal Consta is stored as a powder which contains either 25, 37.5 or 50mg of risperidone. It appears as a white to off-white free-flowing powder in a 5mL vial, and comes packaged with a prefilled syringe containing 2mL of liquid to suspend the powder in, as well as a device for reconstituting the powder in the liquid and a needle for injection.

For patients who have not previously had risperidone, it is recommended to establish a tolerance with immediate release oral formulations of risperidone (tablet, quicklet or oral solution) prior to initiating treatment with Risperdal Consta.

Risperdal Consta should be administered every two weeks by deep intramuscular injection into the gluteal (into the major muscles of the buttocks) or deltoid (into the muscle that forms the rounded contour of the shoulder) muscles  using the enclosed safety needle. Injections should alternate between left and right sides. It is for single use in one patient only.

In adults, the recommended dose is 25 mg intramuscularly every two weeks. Some patients may benefit from the higher doses of 37.5 or 50 mg. No additional benefit was observed with 75 mg in clinical trials. Doses higher than 50 mg every two weeks are not recommended.

Risperdal Consta may take up to three weeks to have its full effect, and so sufficient coverage with other antipsychotic agents should be used during that period. Upward dosage adjustment should not be made more frequently than every four weeks. The effect of this dose adjustment should not be anticipated earlier than three weeks after the first injection with the higher dose.

In elderly patients, the recommended dose is 25 mg intramuscularly every two weeks.

Risperdal Consta has not been sufficiently studied in patients who have severe trouble with their liver or kidneys. In case it is still necessary to treat these people with Risperdal Consta, a starting dose of oral risperidone 0.5 mg twice daily is recommended during the first week. The second week 1 mg b.i.d. or 2 mg daily can be given. If an oral dose of at least 2 mg is well tolerated, an injection of Risperdal Consta 25 mg can be administered every two weeks.

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Schedule of Risperdal Consta:

Risperdal Consta is a Schedule 4 medication.

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Common side effects of Risperdal Consta:

Some adverse events that occur in less than 1/20 but more than 1/100 include:

• Abnormal increase in muscle tone
• Drowsiness
• Fatigue
• Weight gain
• Tremor
• Saliva increase
• Depression
• Raised prolactin levels

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Uncommon side effects of Risperdal Consta:

These uncommon adverse effects occur in less than 1/100 people:

• Weight decrease
• Nervousness
• Sleep Disorder
• Apathy
• Impaired Concentration
• Abnormal Vision
• Hypotension
• Fainting
• Rash
• Itching
• Injection Site Reaction

There are also 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 irregular pulse or blood pressure, tachycardia, cardiac arrhythmias and diaphoresis). 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.

More information

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

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Reference:

1. Australian Medicines Handbook. Risperidone [online]. January 2007 [cited 15 March 2007]. Available at URL: http://www.amh.net.au
2. Janssen-Cilag. Risperdal Consta Product Information. North Ryde: Janssen-Cilag; 2007.
3. MIMS Australia. Risperdal [online]. 2007 [cited 2 May 2008]. Available at URL: http://www.mims.com.au

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Treatments associated with Risperdal Consta:

• Atypical Antipsychotics
  (Atypical Antipsychotics)

For further information talk to your doctor.

Article Dates:

Created: 10/5/2007

Modified: 22/3/2010