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Risperdal Fact Sheet

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Medication Name (brand): 
Risperdal
Medication Name (clinical): 
risperidone
Manufacturer: 

Janssen, market exclusivity expires 2008.

Indications: 
  • Schizophrenia, both acute and maintenance treatment.

  • Bipolar disorder, including manic or mixed episodes, as both monotherapy and combination treatment with lithium or Depakote.
  • Common off-label use for augmentation for depression and anxiety.

Mechanism: 

D2 and 5HT 2 receptor antagonist.

Dosing: 
  • Supplied as:

  • Tablets in 0.25 mg, 0.5 mg, 1 mg, 2 mg, 3 mg, and 4 mg
  • Orally disintegrating “M-Tabs” in 0.5 mg, 1 mg, 2 mg, 3 mg, and 4 mg
  • Oral solution (1 mg/ml) in 30 ml bottles
  • Risperdal Consta is a long-acting injectable formulation which is dosed at 25 mg IM Q 2 weeks.
  • Dosing variable depending on population. Generally, start at 1-2 mg QD or QHS, advancing to 2 mg BID as needed. Increase to 6 mg QD only if necessary, since EPS is highly dose dependent.
  • Initial dose in elderly patients and those with severe renal or hepatic impairment is 0.5 mg BID.

Side Effects: 
  • BLACK BOX WARNING: All atypicals may increase mortality in elderly patients by 1.7 times greater than placebo.

  • Most common are EPS, somnolence, anxiety, constipation, nausea, and dyspepsia.
  • EPS: More frequent with Risperdal than any other atypical; occurs much less commonly at lower dosages.
  • Weight gain: Can be significant, 18% of patients receiving Risperdal in 8-week trials gained at least 7% of their baseline body weight, and the average gain for children in 12-month trials was over 16 pounds.
  • Glucose/Lipids: Causes diabetes infrequently, probably at a lower rate than Zyprexa.
  • EKG: No concerns.
  • Prolactin level: Causes the most hyperprolactinemia of all the atypicals. Symptoms in women are galactorrhea, amenorrhea, breast engorgement; in men, gynecomastia and lowered libido.
  • Pregnancy Category C

Drug-drug Interactions: 
  • Does not significantly affect the metabolism of other drugs.

  • Since Risperdal is metabolized by CYP2D6, Tegretol and other enzyme inducers decrease effective dose, Prozac and Paxil increase levels of Risperdal.

Pharmokinetics: 
  • Metabolized by CYP2D6 to an active metabolite, 9-hydroxyrisperidone.

  • Half-life is about 20 hours.

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