Risperidone belongs to group of medications known as antipsychotic agents. Other members of this group of drugs include olanzapine and quetiapine. These medicines are used to treat mental and emotional problems such as schizophrenia. Schizophrenia can cause symptoms such as hallucinations (e.g., hearing, seeing, or sensing things that are not there), delusions, unusual suspiciousness, and emotional withdrawal. People with this condition may also feel depressed, anxious or tense.

Risperidone is also used for the short-term treatment of behavior problems, such as verbal or physical aggression and suspiciousness and agitation, in people with severe dementia. Medicines like risperidone are thought to work by correcting the function of nerve pathways in certain areas of the brain. If you're unsure why you are taking this medication, contact your doctor.

The dose varies according to needs and the condition being treated.

For schizophrenia, the dose is usually started at 1 mg to 2 mg per day (given either once or twice per day) and increased slowly over several days to a usual dose of 4 mg to 6 mg per day. Lower doses are often used for the elderly and people with liver disease.

For behaviour problems in people with severe dementia, the usual starting dose is 0.5 mg per day (0.25 mg twice a day). This dose is slowly increased to a usual dose of 1 mg per day (0.5 mg twice a day). The safety of risperidone has not been established beyond a maximum dose of 16 mg/day (8 mg given twice daily).

Store risperidone at room temperature in a dry place (not the bathroom) and keep it out of the reach of children.

Risperdal® is supplied as tablets and an oral solution.

The tablets are oblong-shaped and available as 0.25 mg (yellow), 0.5 mg (brownish-red), 1 mg (white), 2 mg (orange), 3 mg (yellow), and 4 mg (green). Non-medicinal ingredients in the 1.0 mg tablets include colloidal anhydrous silica, hypromellose, lactose, magnesium stearate, maize starch, microcrystalline cellulose, propylene glycol, and sodium lauryl sulfate. The 0.5 mg tablets contain the same ingredients as the 1.0 mg tablets plus talc and titanium dioxide. The 0.25 mg tablets contain the same ingredients as the 1.0 mg tablets plus talc, titanium dioxide, and yellow ferric oxide. The 2.0 mg tablets contain the same ingredients as the 1.0 mg tablets plus talc, titanium dioxide, and sunset yellow aluminium lake. The 3.0 mg and 4.0 mg tablets contain the same ingredients as the 1.0 mg tablets plus talc, titanium dioxide, and quinoline yellow.

The oral solution contains 1 mg/mL risperidone. Non-medicinal ingredients include benzoic acid, purified water, sodium hydroxide, and tartaric acid.

Anyone with a known allergy to the drug or the ingredients of the product should not use it.

In patients with schizophrenia, the most common side effects are:

• sleeplessness/sleepiness
• anxiety
• tremors, decreased motor function or activity
• a feeling of restlessness
• dizziness
• stuffed nose
• constipation
• weight gain (average 2.3 kg)
• increased heart rate

In patients with severe dementia, the most common side effects are:

• sleepiness
• tremors, decreased motor function or activity
• a feeling of restlessness
• swelling of the ankles
• stuffed nose
• dizziness, lightheadedness
• difficulty breathing
• increased heart rate

Get emergency medical help immediately if the following side effects occur:

Rare

• seizures
• difficult or fast breathing
• fast heartbeat or irregular pulse
• high fever
• unusually high or low blood pressure
• increased sweating
• loss of bladder control
• severe muscle stiffness
• unusually pale skin
• severe, unusual tiredness or weakness

Contact your doctor as soon as possible if you experience the following side effects:

• muscle twitching or spasms (of face, neck, or body)
• high fever
• abnormal movements of the face or tongue
• a state of confusion, reduced consiousness, high fever, or pronounced muscle stiffness
• marked changes in body temperature
• convulsions
• fainting
• twisting movements of the body
• trouble speaking or swallowing
• difficulty moving eyes
• changes in vision
• decreased sexual desire
• loss of balance control
• mask-like face
• menstrual changes
• suicidal thoughts
• mood or mental changes

The side effects listed are not experienced by everyone who takes this medication. If you are concerned about the side effects, discuss the risks and benefits of the medication with your doctor.

In some patients, side effects other than those listed can occur. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Be sure to inform your physician of all your medical conditions before you begin taking a medication. Some conditions can affect how you should take this medication.

Parkinson's disease: Risperidone may cause a deterioration in the condition of people with Parkinson's disease and should therefore be used with caution.

Low blood pressure: Risperidone may cause lowering of blood pressure when moving from a sitting or lying to a standing position, and racing heart rate, especially during the few weeks of treatment. If you feel dizzy or lightheaded or feel your pulse is racing, call your doctor. Because this medication can cause dizziness or lightheadedness, do not get up too quickly after you have been sitting or lying for prolonged periods. You should not drive or operate machinery until you are reasonably certain that risperidone does not affect your ability to carry out these activities.

Tardive Dyskinesia (TD): A syndrome consisting of potentially irreversible, involuntary, dyskinetic movements may develop in people treated with conventional antipsychotic drugs. Although TD appears to be most prevalent in the elderly, especially elderly females, it is impossible to predict at the onset of treatment which people are likely to develop TD. The risk of developing TD increases with the dose used and the duration of treatment.

If signs and symptoms of TD (involuntary repetitive movements of the facial and tongue muscles) develop during treatment with risperidone, the doctor should be contacted. However, some people may require treatment with risperidone despite the presence of the syndrome.

Drowsiness/reduced alertness: Risperidone may interfere with activities requiring mental alertness. Those taking the drug are cautioned not to drive or operate machinery until they have determined that the drug does not effect them in this way.

Weight gain: With continued treatment, weight gain (average of about 2.3 kg ) has been seen.

Pregnancy: The safety of risperidone for use during pregnancy has not been established. Risperidone should not be used during pregnancy unless the expected benefits outweigh the potential risks.

Breastfeeding: It is not known whether risperidone is excreted in human milk. Nursing should not be undertaken while using risperidone.

Children and adolescents: The safety and efficacy of risperidone for children and adolescents under the age of 18 have not been established.

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, decongestants, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. In many cases, interactions are intended or are managed by close monitoring. Speak to your doctor about how any drug interactions are being managed or should be managed.