BMA Concise Guide to Medicine & Drugs

Risperidone

Brand names Risperdal, Risperdal Consta, Risperdal Quicklet

Used in the following combined preparations None

QUICK REFERENCE

Drug group Antipsychotic drug

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes

Available as generic Yes

GENERAL INFORMATION

Risperidone is used to treat patients with acute psychiatric disorders and long-term psychotic illnesses such as schizophrenia and mania. Although it does not cure the disorder, the drug helps to alleviate distressing symptoms. It relieves “positive” symptoms (such as hallucinations, thought disturbances, and hostility) and “negative” symptoms (such as emotional and social withdrawal). The drug may also help with other symptoms often associated with schizophrenia, such as depression and anxiety. Risperidone is an atypical antipsychotic and has less of a sedative effect and is less likely to cause movement disorders as a side effect than some other antipsychotics.

INFORMATION FOR USERS

Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets, dispersible tablets, liquid, injection.

Frequency and timing of doses 1–2 x daily (tablets, liquid).

Adult dosage range Tablets 2mg daily (starting dose) increasing to 4–6mg daily (usual maintenance dose); maximum 16mg daily. Injection 25mg every 2 weeks (starting dose) increasing to 50mg every two weeks (maximum maintenance dose).

Onset of effect Tablets Within 2–3 days, but may take up to 6 weeks before maximum effect is seen. Injection Up to 3 weeks before onset of effect.

Duration of action Approximately 2 days.

Diet advice None.

Storage Keep in original container at room temperature (tablets) or in a refrigerator (injection) out of the reach of children. Protect from light.

Missed dose Take as soon as you remember. If your next dose is due within 3 hours, take a single dose now and skip the next.

Stopping the drug Do not stop taking the drug without consulting your doctor; symptoms may recur.

Exceeding the dose An occasional unintentional extra dose is unlikely to cause problems. If larger doses have been taken, notify your doctor.

POSSIBLE ADVERSE EFFECTS

Risperidone is generally well tolerated and has a low incidence of movement disorders. It is also less sedating than some other antipsychotic drugs. Insomnia, anxiety, agitation, headache, difficulty in concentrating, and weight gain are common; discuss with your doctor if they are severe. Shakiness and tremor are also common and should be discussed with your doctor in all cases. Sexual dysfunction, dizziness, and drowsiness are rare; consult your doctor if sexual dysfunction is severe or if dizziness or drowsiness occur. If you develop a high fever and/or rigid muscles, stop taking the drug and contact your doctor immediately.

INTERACTIONS

Sedatives All drugs that have a sedative effect on the central nervous system are likely to increase any sedative effect of risperidone.

Lithium increases the risk of nerve toxicity when used with riseperidone.

Drugs for parkinsonism Risperidone may reduce the effect of these drugs.

Fluoxetine, paroxetine, and verapamil These drugs increase the blood levels of risperidone and the risk of side effects.

Carbamazepine This drug reduces the effects of risperidone. Other liver-enzyme inducing drugs (e.g. phenytoin) may have the same effect.

SPECIAL PRECAUTIONS

Be sure to tell your doctor if:

· You have liver or kidney problems.

· You have heart or circulation problems.

· You have diabetes.

· You have epilepsy.

· You have Parkinson’s disease.

· You have had a stroke.

· You are taking other medicines.

Pregnancy Short-term nervous system problems may occur in babies when the drug is taken in the third trimester. Discuss with your doctor.

Breast-feeding The drug probably passes into breast milk. Discuss with your doctor.

Infants and children Not recommended under 15 years.

Over 60 Reduced dose may be necessary.

Driving and hazardous work Avoid such activities until you have learned how risperidone affects you because the drug may cause difficulty in concentrating and slowed reactions.

Alcohol Avoid. Alcohol may increase the sedative effects of this drug.

PROLONGED USE

If used long term, permanent movement disorders (tardive dyskinesia) may occur, although they are less likely than with many other antipsychotic drugs.