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

Drug Interactions

Risperidone concentrations may be increased when administered with azole antifungals (fluconazole, itraconazole, ketoconazole), cimetidine, clozapine, lamotrigine, protease inhibitors (such as indinavir or ritonavir), ranitidine, selective serotonin reuptake inhibitors (such as fluoxetine or paroxetine), thioridazine, or verapamil. In the case of drugs that act as CYP2D6 inhibitors, concentrations of risperidone may initially increase, but the reduced production of 9-hydroxyrisperidone may offset the overall effect of the drug interaction.[2,3]

Co-administration of carbamazepine, phenobarbital, phenytoin, rifampin and other drugs that induce CYP2D6 may decrease serum risperidone concentrations. With carbamazepine, risperidone concentrations may be decreased by up to 50%. In cases where the interacting drug cannot be discontinued, the risperidone dose may need to be increased to produce optimal effect. Because of its antagonist activity at dopaminergic receptors, risperidone may antagonize the effects of levodopa or other dopamine agonists. Concomitant administration of risperidone and valproate may result in up to a 20% increase in serum valproate concentrations.[2,3]


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