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Brands and Forms

  • Risperdal
    • tablet: 0.25mg, 0.5mg, 1mg, 2mg, 3mg, 4mg
    • oral solution: 1mg/ml
  • Risperdal M-Tab
    • orally disintegrating tablet: 0.5mg, 1mg, 2mg, 3mg, 4mg
  • Risperdal Consta
    • powder for long-acting injectible solution: 12.5mg, 25mg, 37.5mg, 50mg

Uses of Risperidone

Risperidone is used in the treatment of Psychotic Disorders, Bipolar Disorder, Depressive Disorders, PTSD, OCD, and Tic Disorder.

Risperidone can also be used in the management of behavioral disturbances, such as agitation and impulsivity, that can occur in various conditions like Impulse-Control Disorders, Disruptive Behavior Disorders, and Borderline Personality Disorder.

How Risperidone Works

Risperidone is an Atypical Antipsychotic. It is an antagonist at the dopamine D2 receptor, the serotonin 2a receptors, and the adrenergic alpha-2 receptor, but also has interactions with a myriad of other receptors.

Cautions when Using Risperidone

In elderly individuals with Dementia, use of Antipsychotics has been associated with increased rates of sudden death. It is unclear whether the antipsychotic use is a cause, or simply a marker, of deteriorating health in these individuals.

Weight gain and metabolic side-effects (elevated glucose, lipids and cholesterol) can be pronounced in some individuals.

Individuals with Parkinson disease or Lewy-Body Dementia may have increased sensitivity to Risperidone, which may manifest as confusion, obtundation, severe extrapyramidal symptoms, and neuroleptic malignant syndrome.

Use with caution in people at risk for seizures or aspiration pneumonia.

People using Risperidone should become familiar with its effects before driving or operating heavy machinery.

Dosing of Risperidone

The usual therapeutic range of Risperidone is 0.5-6mg daily, given either once at bedtime or twice a day in the morning and at night. In cases where the symptoms to be treated are mild, or where the risk of side-effects needs to be avoided, doses as low as 0.25mg/day can be used. On the other hand, for severe conditions, including treatment-resistant Schizophrenia, doses of up to 16mg/day can be used, though this usually comes at the cost of increased side-effects, especially extrapyramidal symptoms.

The usual starting dose of Risperidone is 0.5-1mg daily. For individuals with severe symptoms of Mania or Psychosis, or who have been tried on other antipsychotics, an initial dose of 2mg/day could be tried. It is recommended to wait 1-2 weeks at the starting dose for therapeutic effects to occur before increasing the dose further, which can be done in increments of 0.5-2mg/day every week.

Risperidal Consta, the long-acting injectible form, is given intramuscularly once every 2 weeks. A dose of 12.5mg of Consta is equivalent to 1mg/day of the oral form. The onset of action of Risperdal Consta can be delayed by up to 2 weeks after the injection is given, and steady-state blood concentrations are usually reached after 4 injections (8 weeks). It is thus recommended that individuals started on Risperdal Consta continue taking the oral form of Risperidone for the first 3 weeks after starting Consta. The effects of Consta can be maintained for 4-6 weeks after the last injection.

When wanting to stop Risperidone, the dose should be decreased gradually over a period of 6-8 weeks.

Onset of action

Symptoms of Mania and Psychosis can improve within 1 week of use, but full therapeutic effect may take several weeks. If there is no significant effect after 4-6 weeks, including a couple of weeks at doses above 4mg/day, then it may not work at all.

Acute agitation can improve after a single dose.

For other conditions, 4-6 weeks may be needed to see a therapeutic effect.

Kidney impairment

Use lower doses. Initial recommended dose is 0.5mg twice a day for the first week, then increase to 1mg twice a day. Risperdal Consta should not be given unless the individual has tolerated at least 2mg/day of the oral form.

Liver impairment

Use lower doses. Initial recommended dose is 0.5mg twice a day for the first week, then increase to 1mg twice a day. Risperdal Consta should not be given unless the individual has tolerated at least 2mg/day of the oral form.

Side-effects of Risperidone

Below is a list of most of the reported side-effects of Risperidone. Most of these side-effects occur in only a minority of individuals, and many also resolve with time while the medication is continued.

Cardiovascular: tachycardia; palpitations; orthostatic hypotension; hypertension; cardiac arrhythmias including bundle branch block, first-degree AV block, sinus arrhythmia, and QTc prolongation.

Central Nervous System: somnolence; extrapyramidal symptoms; headache; dizziness; tremor; weakness; fatigue; loss of libido; confusion; abnormal gait; vertigo; seizures (rare); stroke (rare).

Dermatologic: rash; acne; dry skin; hair loss (rare); erythema multiforme (rare).

Ears, Eyes, Nose and Throat: rhinitis; abnormal vision; pharyngitis; conjunctivitis; otitis media; earache.

Endocrine/Metabolic: Weight gain; metabolic syndrome (insulin resistance, elevated blood sugars, hyperlipidemia and hypercholesterolemia); elevated prolactin; breast pain, enlargement, or milk production in men and women; trouble conceiving; hyperthermia; SIADH.

Gastrointestinal: increased appetite; vomiting; increased salivation; constipation; abdominal pain; dyspepsia; nausea; dry mouth; appetite loss; diarrhea; flatulence; toothache; intestinal obstruction; elevated lived enzymes; pancreatitis (rare).

Genitourinary: urinary incontinence; amenorrhea; ejaculation failure; erectile dysfunction; impotence; urinary frequency; priapism.

Hematologic: granulocytopenia; leukopenia; easy bruising; nose bleed; anemia.

Musculoskeletal: muscle stiffness; muscle pains; muscle spasms; neuroleptic malignant syndrome (rare).

Psychiatric: emotional lability; anxiety; agitation; depressed mood; obsessive-compulsive symptoms; suicidality; psychosis (rare); mania (rare).

Respiratory: upper respiratory tract infection; coughing; shortness of breath; sinusitis; pulmonary embolism (rare); aspiration pneumonia (due to esophageal dysmotility; rare).

Common side-effects of Risperidone

Somnolence, headache, extrapyramidal symptoms, dizziness, increased appetite, weight gain, metabolic syndrome (elevated blood sugars, lipids and cholesterol), nausea, vomiting, increased salivation, constipation, abdominal pain, dyspepsia, dry mouth, elevated prolactin, erectile dysfunction.

Rare but serious side-effects of note of Risperidone

  • severe hypoglycemia with associated ketoacidosis
  • increased risk of sudden death in elderly individuals with Dementia.
  • neuroleptic malignant syndrome
  • cardiac arrhythmias including QTc prolongation
  • seizures
  • priapism (sustained erection)

Risperidone overdose

Drowsiness, extrapyramidal symptoms, hypokalemia, hyponatremia, hypotension, QTc prolongation, sedation, tachycardia, unsteady gait, seizures, neuroleptic malignant syndrome, cardiopulmonary arrest.

Risperidone and pregnancy

Category C: some animal studies show adverse effects at very high doses, but no controlled human studies have been done; should only be used in pregnancy if clearly needed and if benefits outweigh potential risks.

Risperidone, weight gain and metabolic syndrome

Nearly 20% of people taking Risperidone will gain about 7% of their total body weight within 8 weeks of starting the medication [ref, ref]. Metabolic side-effects, including elevated glucose and lipids can also occur, which in the long-term increase the risk for heart disease and vascular problem.

See here for further information on these side-effects, and how they can be managed.

Medical Monitoring for Risperidone

Monitoring for weight gain and a metabolic syndrome requires the following measures to be taken prior to starting the medication, then monthly for the first 3 months of use, and then every 3 months:

  • Body Mass Index (BMI)
  • waistline circumference at umbilicus
  • blood pressure
  • fasting blood glucose
  • fasting blood lipids and cholesterol

To monitor for elevated prolactin, prolactin levels should be measured prior to starting the medication, and then one month after starting and after every dose increase.

Drug Interactions with Risperidone

  • Risperidone oral solution is not compatible with cola or tea.
  • Risperidone may enhance the effects of some antihypertensives.
  • Avoid combining with medications that can prolong the QTc interval, including Gatifloxacin, Moxifloxacin, Chlorpromazine, Thioridazine, Ziprasidone, class IA antiarrhythmic agents (eg. Procainamide, Quinidine), class III antiarrhythmic agents (eg. Amiodarone, Sotalol).
  • Risperidone blood concentrations can be reduced by Carbamazepine, Phenobarbital, Phenytoin, and Rifampin.
  • Risperidone blood concentrations can be increased by Cimetidine, Ranitidine, Clozapine, Fluoxetine, Paroxetine, Sertraline, Thioridazine, Indinavir, Itraconazole, Ketoconazole, Ritonavir.
  • Risperidone can increase blood concentrations of Maprotiline, Valproic Acid.