Risperidone Itraconazole

Itraconazole increases the plasma levels of both risperidone and its active metabolite, 9-hydroxyrisperidone. 

A study in 19 patients who were taking risperidone 2 to 8 mg daily found that the addition of itraeonazole 200 mg daily for a week inereased the plasma levels of risperidone and its active metabolite, 9-hydroxyrisperidone, by 82% and 70%, respectively. The levels returned to pre-treatment values one week after the itraconazole was stopped. There was a small difference in the increase in the levels of risperidone between CYP2D6 extensive and poor metabolisers of risperidone, with extensive metabolisers showing a rise of 67% and poor metabolisers a rise of 70%. 

Risperidone levels are expected to increase if itraconazole is given concurrently. Be aware for any signs of increased adverse effects, and consider reducing the dosage as necessary. 

Jung SM, Kim KA, Cho HK, Jung IG, Park PW, Byun WT, Park JY. Cytochrome P450 3A inhibitor itraconazole affects plasma concentrations of risperidone and 9-hydro risperidone in schizophrenic patients. Clin Pharmacol Ther (2005) 78, 520-8. 

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