Switching to iloperidone: An omnibus of clinically relevant observations from a 12-week, open-label, randomized clinical trial in 500 persons with schizophrenia

An update on the efficacy and safety of iloperidone as a schizophrenia therapy

INTRODUCTION

Schizophrenia has a prevalence of approximately 1% in the general population, with 15.2 per 100,000 persons affected. Iloperidone is a second-generation antipsychotic drug approved for the treatment of schizophrenia in adults. It acts primarily by D2/5HT2a receptor antagonism, with greater affinity for the 5HT2a receptor than for the D2 receptor.

AREAS COVERED

This article discusses iloperidone and aims to provide useful information for clinicians to determine which circumstances would best suit the use of iloperidone to treat schizophrenic patients. In this review, the authors briefly discuss schizophrenia and its treatment, before they discuss properties of iloperidone, its indications, approval process, and adverse effects. Finally, the authors review the specific strengths and weaknesses of the medication.

EXPERT OPINION

Iloperidone would be an attractive option in patients who are particularly prone to EPS, or who are showing prominent negative symptoms, as well as cognitive deficits. Its availability only in an oral formulation makes it a better option for patients with good medication adherence, and though it could be useful in patients prone to weight gain or hepatic dysfunction on other second generation antipsychotics, it should be used with caution in patients prone to side effects related to alpha adrenergic blockade.

Iloperidone in the treatment of schizophrenia: an evidence-based review of its place in therapy

Introduction

Schizophrenia is a chronic and debilitating mental disorder that affects the patient’s and their family’s quality of life, as well as financial costs and health care settings. Despite the variety of available antipsychotics, optimal treatment outcomes are not always achieved. Novel drugs, such as iloperidone, can provide more effective, tolerable and safer strategies.

Aim

To review the evidence for the clinical impact of iloperidone on the treatment of patients with schizophrenia.

Evidence review

Clinical trials, observational studies and meta-analyses reached a common consensus that iloperidone is as effective as haloperidol, risperidone and ziprasidone in reducing schizophrenia symptoms. Similar amounts of adverse events and discontinuations were observed with iloperidone compared to placebo and active treatments. Common adverse events are mild and include dizziness, hypotension, dry mouth and weight gain. Iloperidone can induce extension of QTc interval, and clinicians should be aware of its contraindications. In long-term trials, iloperidone also showed promising safety and tolerability profiles. The low propensity to cause akathisia, extrapyramidal symptoms (EPS), increased prolactin levels or changes to metabolic laboratory parameters support its use in practice. Results showed that iloperidone prevents relapse in stabilized patients, with a time to relapse superior to placebo and similar to haloperidol. Patients using a prior antipsychotic (eg, risperidone and aripiprazole) can easily switch to iloperidone with no serious impact on safety or efficacy. However, the acquisition costs of iloperidone may hamper its use. Further evidence comparing iloperidone with other antipsychotics, and pharmacoeconomic studies would be welcome.

Place in therapy

Considering just the clinical profile of iloperidone, it represents a promising drug for treating schizophrenia, particularly in patients who are intolerant to previous antipsychotics, as well as being suitable as first-line therapy. Cost-effectiveness comparisons are needed to justify its use in clinical practice.

Effects of iloperidone, combined with desipramine, on alcohol drinking in the Syrian golden hamster

Alcohol use disorder in patients with schizophrenia dramatically worsens their clinical course, and few treatment options are available. Clozapine appears to reduce alcohol use in these patients, but its toxicity limits its use. To create a safer clozapine-like drug, we tested whether the antipsychotic iloperidone, a drug that combines a weak dopamine D2 receptor blockade and a potent norepinephrine alpha-2 receptor blockade would reduce alcohol drinking, and whether its effect on alcohol drinking could be increased if combined with an agent to facilitate norepinephrine activity. Syrian golden hamsters (useful animal model for screening drugs that reduce alcohol drinking in patients with schizophrenia) were given free access to water and alcohol (15% v/v) until stable drinking was established. Animals (n = 6-7/group), matched according to alcohol intake, were treated daily with each drug (iloperidone; clozapine; haloperidol; desipramine [norepinephrine reuptake inhibitor]; with idazoxan [norepinephrine alpha-2 receptor antagonist]) or with a two-drug (iloperidone + desipramine; iloperidone + idazoxan) combination for 14 days. Moderate doses of iloperidone (1-5 mg/kg) significantly reduced alcohol drinking (p < 0.05) in the hamster, whereas higher doses (10-20 mg/kg) did not. In addition, 5 mg/kg of iloperidone reduced alcohol drinking to the same extent as clozapine (8 mg/kg), whereas haloperidol (0.2 mg/kg) did not. Moreover, iloperidone's effects were enhanced via the addition of desipramine (3 mg/kg), but not idazoxan (1.5/3 mg/kg). In this animal model, iloperidone decreases alcohol drinking as effectively as clozapine, and desipramine appears to amplify this effect. The data suggest that iloperidone, alone or in combination with desipramine, should be tested in patients with schizophrenia and alcohol use disorder.

A Randomized Trial of Iloperidone for Prevention of Relapse in Schizophrenia: The REPRIEVE Study

BACKGROUND

The purpose of this study was to evaluate the safety and effectiveness of iloperidone for the prevention of relapse in schizophrenia.

METHODS

Study subjects were adults with schizophrenia who started on oral open-label iloperidone titrated to an initial target dose of 12 mg/day (6 mg twice daily) and then stabilized on a flexible-dose iloperidone regimen (range 8-24 mg/day) for up to 24 weeks. Subjects meeting stabilization criteria then entered the relapse-prevention phase and were randomized 1:1 in a double-blind fashion to continue with iloperidone or placebo withdrawal for up to 26 weeks or until meeting relapse or other withdrawal criteria.

RESULTS

A total of 303 subjects were randomized to the relapse-prevention phase; 153 continued to receive iloperidone, and 150 were withdrawn to placebo. The modal total daily dose for iloperidone in all phases of the study was 12 mg/day. The pre-defined unblinded interim analysis upon reaching 68 relapse events confirmed the hypothesis that iloperidone (n = 97) was more effective than placebo (n = 96) in preventing relapse events, and the trial was stopped early. The estimated relapse rates were 63.4 % (Kaplan-Meier [KM] estimate) for placebo compared with 20.4 % (KM estimate) for those continuing to receive iloperidone (log rank test: p < 0.0001). The mean time to relapse was 71 days for placebo and 139 days for iloperidone (hazard ratio 4.7; 95 % confidence interval 2.7-8.3; p < 0.0001). The safety profile observed in previous short-term studies was also reaffirmed in this maintenance treatment setting. The most common treatment-emergent adverse events (TEAEs) in the stabilization phase were dizziness (11.6 %), somnolence (8.3 %), and dry mouth (6.8 %). Rates of reported extrapyramidal disorder or akathisia during stabilization were 2.5 and 3.7 %, respectively.

CONCLUSIONS

Flexible dosing of iloperidone for maintenance-phase therapy, with a modal dose of 12 mg/day was effective in preventing relapse in subjects previously stabilized on iloperidone. The adverse event profile for iloperidone was consistent with other studies, and the low extrapyramidal symptom and akathisia burden during stabilization was sustained during the course of the study. ClinicalTrials.gov identifier: NCT01291511.