Janssen, market exclusivity expires 2008.
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.
D2 and 5HT 2 receptor antagonist.
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.
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
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.
Metabolized by CYP2D6 to an active metabolite, 9-hydroxyrisperidone.
Half-life is about 20 hours.