Safety profile of iloperidone: a pooled analysis of 6-week acute-phase pivotal trials

Abstract

Iloperidone, a mixed D2/5-HT2 antagonist, is currently in clinical development for the treatment of schizophrenia. This article assesses the short-term safety of iloperidone using a pooled analysis of 3 phase 2, short-term acute schizophrenia studies conducted between 1998 and 2002 (N = 1943). Patients exposed to 3 dose ranges of iloperidone, another antipsychotic, or placebo were compared on rates of serious adverse events (SAEs), adverse events (AEs), extrapyramidal symptoms, akathisia, prolactin, weight and metabolic parameters, QTc, and other standard safety parameters. The most common treatment-related AEs observed with iloperidone were dizziness, headache, dry mouth, nausea, and insomnia. Discontinuation due to AEs was 4.8% for iloperidone, 7.6% for haloperidol, 6.2% for risperidone, and 4.8% for placebo. Iloperidone groups showed better overall performance on the Extrapyramidal Symptom Rating Scale and Barnes Akathisia Scale than risperidone or haloperidol groups. Patients taking iloperidone experienced a mild weight increase (range, 1.5-2.1 kg) similar to that of risperidone (1.5 kg), whereas those on haloperidol and placebo showed mean weight loss (-0.1 kg and -0.3 kg, respectively). QTc interval significantly increased across all iloperidone groups (least squares mean change from baseline to end point, 2.9-9.1 msec) and for haloperidol (5.0 msec). No significant QTc changes occurred in the risperidone or placebo groups. Iloperidone was associated with no change from baseline in total cholesterol, mild elevation in serum glucose, and slight decrease in triglycerides. Prolactin levels decreased with iloperidone and increased significantly with risperidone and haloperidol. These short-term trials suggest that iloperidone has a reassuring safety profile in many of the areas that are of potential concern, including relatively low dropout rates because of AEs, low extrapyramidal symptoms, akathisia, and prolactin elevation, and a modest short-term effect on weight gain.