Risperidone

Risperidone

[1 mg tablets 34 cents]

ADMINISTRATION ROUTES:

• PO, IM

ALTERNATIVE NAMES:

• Ridal, Risperidal

ICU INDICATIONS:

1. agitation and delirium
2. psychosis

PRESENTATION AND ADMINISTRATION:

• IM:
  Long-acting Depot ONLY (not for use in ICU)

• PO:
  Tablets:
  Ridal 0.5mg (red), 1mg (white), 2mg (orange), 3mg (yellow), 4mg (green)
  Risperidal 0.5mg (brownish / red), 1mg (white), 2mg (orange), 3mg (yellow), 4mg (green)
  Oral Disintegrating Tablets:
  Risperdal Quicklet 0.5mg (light coral), 1mg (light coral), 2mg (coral)
  Oral Solution: Risperdal Solution 1mg/ml

DOSAGE:

• PO:
  0.5-1mg 12 hourly; increase to a maximum of 8mg 12 hourly

DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:

• Dose in renal impairment [GFR (ml/min)]:
  <10: initial dose of 0.5mg, increase slowly to 1-2mg BD
  10-20: initial dose of 0.5mg, increase slowly to 1-2mg BD
  >20-50: initial dose of 0.5mg, increase slowly to 1-2mg BD
• Dose in renal replacement therapy:
  CAPD: initial dose of 0.5mg, increase slowly to 1-2mg BD
  HD: initial dose of 0.5mg, increase slowly to 1-2mg BD
  CVVHDF: initial dose of 0.5mg, increase slowly to 1-2mg BD

DOSAGE IN PAEDIATRICS:

• 0.02mg/kg 12 hourly; increase to 0.15mg/kg 12 hourly

CLINICAL PHARMACOLOGY:

• Risperidone is a compound which belongs to a new class of antipsychotic agents, the benzisoxazole derivatives. Risperidone is a selective monoaminergic antagonist having a high affinity for serotoninergic 5-HT2 and dopaminergic D2 receptors. Risperidone binds also to alpha1-adrenergic receptors and, with lower affinity, to H1-histamine and alpha2-adrenergic receptors.

CONTRAINDICATIONS:

1. sensitivity to risperidone

WARNINGS

• Increased risk of deaths in patients with dementia:
  Elderly patients with dementia-related psychosis treated with atypical antipsychotic drugs are at an increased risk of death compared to placebo.
• Hyperglycemia and Diabetes Mellitus:
  Hyperglycemia, in some cases extreme and associated with ketoacidosis or hyperosmolar coma or death, has been reported in patients treated with atypical antipsychotics including risperidone.
• Neuroleptic Malignant Syndrome (NMS):
  A potentially fatal symptom complex sometimes referred to as Neuroleptic Malignant Syndrome (NMS) has been reported in association with administration of antipsychotic drugs, including risperidone.
• Tardive Dyskinesia: A syndrome of potentially irreversible, involuntary, dyskinetic movements may develop in patients treated with antipsychotic drugs.

PRECAUTIONS

• General:
  Risperidone may induce hypotension.
  Classical neuroleptics are known to lower the seizure threshold. Caution is recommended when treating patients with epilepsy.
• Laboratory Tests: No tests additional to routine ICU tests are indicated
• Drug/Laboratory Test Interactions: None reported

IMPORTANT DRUG INTERACTIONS FOR THE ICU

• Given the primary CNS effects of risperidone, it should be used with caution in combination with other centrally-acting medicines. Carbamazepine has been shown to decrease the plasma levels of the active antipsychotic fraction of risperidone. On discontinuation of carbamazepine the dosage of risperidone should be re-evaluated and, if necessary, decreased.

ADVERSE REACTIONS

• Cardiovascular System: Hypotension, Tachycardia, Hypertension
• Digestive System: Dry mouth, Constipation, Dyspepsia, Vomiting
• Nervous System: Somnolence, Dizziness, Tremor, Hypertonia
• Haematological System: Decreased neutrophil count, decreased platelet count