Use of Risperidone in Children With Autism, Bipolar Disease, or Schizophrenia

Marcia L. Buck, Pharm.D., FCCP

Pediatr Pharm. 2008;14(1) 

In This Article

Pharmacokinetics

Risperidone is well absorbed after oral administration, with an absolute bioavailability of 70%. Administration with food does not affect the rate or extent of absorption. Peak concentrations occur 1 hour after an oral dose. Risperidone is rapidly distributed, with a volume of distribution of 1 to 2 L/kg, and is highly bound to plasma proteins. It is extensively metabolized via hydroxylation by CYP2D6 to 9-hydroxyrisperidone. This metabolite has similar pharmacologic activity to the parent compound, reaching a peak plasma concentration approximately 3 hours after the dose in extensive metabolizers and 17 hours post-dose in poor metabolizers. A minor metabolite is produced through N-dealkylation.[2,3]

In adults, the apparent half-life of risperidone is 3 hours in extensive metabolizers and 20 hours in poor metabolizers. The half-life of 9-hydroxyrisperidone is approximately 20 hours in extensive metabolizers and 30 hours in poor metabolizers. In a recent study of risperidone pharmacokinetics in 19 children (4-15 years of age), the average half-life for the parent compound was 3.0±2.3 hours.[8]

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