Risperidone

Brand names

• Risperdal

Usage

To treat psychotic conditions (severe mental disorders characterized by distorted thoughts, perceptions, and emotions), such as schizophrenia. Also used for behavioral disturbances in severe dementia.

How it works

While the exact mechanism of action of risperidone is unknown, it appears to alter the activity of certain chemicals in the central nervous system to produce a tranquilizing and antipsychotic effect.

Side effects

Serious

Rapid heartbeat, profuse sweating, seizures, difficulty breathing, neck stiffness, swelling of the tongue, difficulty swallowing. Also a rare condition can develop called neuroleptic malignant syndrome, characterized by stiffness or spasms of the muscles, high fever, and confusion or disorientation.

Common

Nausea, reduced perspiration, dry mouth, blurred vision, drowsiness, shaking of the hands, muscle stiffness, stooped posture, unexpected weight gain.

Less common

Difficult urination, menstrual irregularities, breast pain or swelling, uncontrolled movements of the tongue, fever, chills, sore throat, unusual bruising or bleeding, heart palpitations, skin rash, itching, increased sensitivity of the skin to sunlight.

Possible interactions

Other medicaments:

Risperidone may decrease the effects of:

• levodopa (Sinemet, others).

Risperidone taken concurrently with:

• carbamazepine (Tegretol) will decrease the medicament level and perhaps the therapeutic effects of risperidone.
• other centrally acting medicines may result in increased central effects.
• clozapine (Clozaril) may decrease the therapeutic effects of risperidone.
• lithium (Lithobid, others) may lead to increased adverse effects.
• methadone (various) may decrease methadone levels and lead to withdrawal symptoms.
• paroxetine (Paxil) and perhaps other SSRIs may lead to serotonin syndrome.
• phenytoin (Dilantin) or fosphenytoin (Cerebyx) may decrease risperidone blood levels and blunt risperidone therapeutic benefits.
• propafenone (Rythmol) may lead to propafenone toxicity.
• ritonavir (Norvir) and perhaps other protease inhibitors may lead to toxicity.
• tramadol (Ultram) may increase seizure risk.
• venlafaxine (Effexor) may increase risperidone toxicity risk.
• zotepine (Nipolept) may increase seizure risk.

Herbal medicines or minerals:

Since risperidone and St. John's wort may act to increase serotonin, the combination is not advised. St. John's wort may also worsen sensitivity to the sun. Ma huang and yohimbe are also best avoided while taking this medicine. Kava kava and valerian may worsen drowsiness. Because part of the way that ginseng works is as an MAO inhibitor, do not combine with risperidone.

Alcohol:

Patients should avoid alcohol while taking risperidone.

Marijuana smoking:

Smoking: increased somnolence.

Exposure to sun:

Use caution-this medicament may cause photosensitivity.

Discontinuation:

Consult your doctor before stopping this medication.

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