Iloperidone for the treatment of schizophrenia

To review the pharmacology, pharmacokinetics, efficacy, and safety data of iloperidone for the treatment of schizophrenia.

Data were selected by searching Pre-MEDLINE, MEDLINE, and International Pharmaceutical Abstracts (1966-January 2010). Abstracts, scientific posters, and unpublished data provided by the manufacturer in the English language were also assessed.

All published data including pharmacologic, pharmacokinetic, pharmacodynamic, and clinical studies related to iloperidone were considered for inclusion. Selected studies included randomized controlled trials, abstracts, and posters presented at national scientific meetings providing pertinent data.

Iloperidone is a benzisoxazole phenylethanone with a higher affinity for serotonin-2a than dopamine-2 receptors. The recommended therapeutic total daily dose is 12-24 mg divided in 2 doses titrated over 1 week to avoid orthostasis. Acute, 6-week, randomized, placebo-controlled, and active-controlled studies demonstrated iloperidone's efficacy in reducing psychotic symptoms according to changes in the total positive and negative symptom scale (PANSS-T) score from baseline. A long-term maintenance trial demonstrated similar efficacy with haloperidol in preventing time to relapse. Pharmacogenomic studies reported possible single nucleotide polymorphisms related to QT interval prolongation and efficacy with iloperidone. Common adverse effects included dizziness, dry mouth, and sustained orthostasis occurring more frequently with higher doses. Weight gain is possible at any dose. Additionally, studies showed that QTc interval prolongation may be dose related. The incidence of extrapyramidal symptoms appears to be low across all dosage ranges; however, akathisia may be more frequent with higher doses.

Iloperidone demonstrated efficacy in acute exacerbations and long-term maintenance in adults with schizophrenia. Caution may be warranted in elderly patients and patients with cardiac disease, due to orthostasis. Further studies regarding pharmacogenomic testing related to the drug's efficacy and tolerability are needed to justify its routine use in practice.