Receptor profile of P88-8991 and P95-12113, metabolites of the novel antipsychotic iloperidone

Activity of GPCR-targeted drugs influenced by human gut microbiota metabolism

Microbiota-mediated drug metabolism can affect pharmacological efficacy. Here we conducted a systematic comparative metabolomics investigation of drug metabolism modes by evaluating the impacts of human gut commensal bacteria on 127 G-protein-coupled receptor (GPCR)-targeted drugs. For the most extensively metabolized drugs in our screen, we elucidated both conventional and unconventional drug transformations and the corresponding activities of generated metabolites. Comparisons of drug metabolism by a gut microbial community versus individual species revealed both taxon intrinsic and collaborative processes that influenced the activity of the metabolized drugs against target GPCRs. We also observed iloperidone inactivation by generating unconventional metabolites. The human gut commensal bacteria mixture incorporated sulfur in the form of a thiophene motif, whereas Morganella morganii used a cascade reaction to incorporate amino-acid-derived tricyclic systems into the drug metabolites. Our results reveal a broad impact of human gut commensal bacteria on GPCR-targeted drug structures and activities through diverse microbiota-mediated biotransformations.

New Allosteric Modulators of AMPA Receptors: Synthesis and Study of Their Functional Activity by Radioligand-Receptor Binding Analysis

The synthetic approaches to three new AMPA receptor modulators-derivatives of 1,11-dimethyl-3,6,9-triazatricyclo[7.3.1.1^3,11]tetradecane-4,8,12-trione-had been developed and all steps of synthesis were optimized. The structures of the compounds contain tricyclic cage and indane fragments necessary for binding with the target receptor. Their physiological activity was studied by radioligand-receptor binding analysis using [³H]PAM-43 as a reference ligand, which is a highly potent positive allosteric modulator of AMPA receptors. The results of radioligand-binding studies indicated the high potency of two synthesized compounds to bind with the same targets as positive allosteric modulator PAM-43 (at least on AMPA receptors). We suggest that the Glu-dependent specific binding site of [³H]PAM-43 or the receptor containing this site may be one of the targets of the new compounds. We also suggest that enhanced radioligand binding may indicate the existence of synergistic effects of compounds 11b and 11c with respect to PAM-43 binding to the targets. At the same time, these compounds may not compete directly with PAM-43 for its specific binding sites but bind to other specific sites of this biotarget, changing its conformation and thereby causing a synergistic effect of cooperative interaction. It can be expected that the newly synthesized compounds will also have pronounced effects on the glutamatergic system of the mammalian brain.

Repurposing of Iloperidone: Antihypertensive and ocular hypotensive activity in animals

PURPOSE

Iloperidone, second generation antipsychotic drug, reported in clinical trial to produce orthostatic hypotension as side effect. It was claimed to be antagonistic at alpha adrenergic receptor in central nervous system. We evaluated effect of Iloperidone on peripheral alpha 1 adrenoreceptor by in silico and in vitro methods while in vivo hypotensive, antihypertensive and ocular hypotensive activity was evaluated in animals.

METHODS

Pharmacological activity prediction of Iloperidone was done using PASSOnline and SwissTargetPrediction softwares and molecular docking with Alpha 1A adrenoreceptor using AutoDock Vina. Hypotensive activity in normotensive and antihypertensive activity against DOCA-salt induced hypertension in rats were evaluated at doses 0.03 mg/Kg and 0.1 mg/Kg, i.p of Iloperidone. Blood pressure was measured by invasive blood pressure measurement technique using PowerLab 4/30 and intraocular pressure was measured using digital tonometer.

RESULTS

Iloperidone (0.1 mg/Kg) showed significant decrease in blood pressure (38.96 ± 1.1%) in normotensive rats, while in DOCA salt induced hypertensive rats, systolic blood pressure was found to be decreased by 29.04 ± 1.45% and 31.43 ± 1.21% in 0.03 mg/Kg and 0.1 mg/Kg treated rats respectively. Iloperidone prevented rise in systolic BP with adrenaline. Intraocular pressure was found to be decreased by 36.66 ± 3.15% in rabbits after 1 h of instillation of 0.1% Iloperidone.

CONCLUSION

Iloperidone exerted hypotensive and/or anti-hypertensive activity in rats and ocular hypotensive activity in rabbits.

Supported liquid extraction and LC–MS-MS determination of iloperidone and olanzapine in rat plasma: Application to a pharmacokinetic study

A sensitive, selective rapid bioanalytical assay method was developed and quantification of iloperidone (ILP) and olanzapine (OLZ) in rat plasma was done by mass spectrometry. Systematic sample preparation and extraction procedure were carried out by supported liquid extraction using dichloromethane to extract both the eluents (ILP and OLZ) from rat plasma samples. The extorted samples were injected on a selective Waters XTerra® C18 reverse-phase bonded column (250 × 4.6 mm i.d., 5 μm) using acetonitrile and 15 mM ammonium formate containing 0.05% trifluoroacetic acid (60:40 v/v) for isocratic elution mode and detected by mass spectrometry. Calibration curves were drawn with the respective assay statistical data and showed linear regression coefficients greater than 0.9996 over the concentration ranges 2–5,000 ng/mL for ILP and OLZ, respectively. The absolute mean recoveries were found to be in the replicate range of 87.12–94.47%, respectively. The obtained results by the method revealed good intra and interday assay performance in terms of 1.70–5.90% precision and 0–5% accuracy. The validated bioassay method has been successfully applied to the pharmacokinetics in rats.

Influences of CYP2D6*10 polymorphisms on the pharmacokinetics of iloperidone and its metabolites in Chinese patients with schizophrenia: a population pharmacokinetic analysis

AIM

Iloperidone is an atypical antipsychotic drug that is mainly metabolized by CYP2D6, CYP3A4, and cytosolic enzymes. Previous studies show that extensive and poor metabolizers of CYP2D6 exhibit different plasma concentrations of iloperidone and its metabolites. The aim of this study was to develop a parent-metabolite population pharmacokinetic (PPK) model to quantify the effects of CYP2D6^*10 allele on the pharmacokinetics of iloperidone and its metabolites in Chinese schizophrenia patients.

METHODS

Seventy Chinese schizophrenia patients were enrolled, from whom limited blood samples were collected on d 15 (0 h) and d 28 (0, 4 and 12 h after drug administration). The plasma concentrations of iloperidone and its metabolites M₁ (P-88) and M₂ (P-95) were simultaneously detected using a validated HPLC-MS assay. CYP2D6^*10 (rs1065852) genotyping was performed. A PPK model was developed based on data from the patients using the NONMEM software (version 7.2). A one-compartment model with first-order absorption and elimination was used to describe the pharmacokinetic data related to iloperidone and its metabolites.

RESULTS

Patients with the CYP2D6^*10 T/T genotype had significantly higher concentrations of iloperidone and M₁, and lower concentrations of M₂ than the patients with C/C or C/T genotypes. The CYP2D6^*10 genotype affected the elimination constants for transformation of iloperidone to the metabolites M₁ (K₂₃) and M₂ (K₂₄). The K₂₃ value of the patients with T/T genotype was 1.34-fold as great as that of the patients with C/C or C/T genotype. The K₂₄ value of the patients with C/T and T/T genotypes was 0.693- and 0.492-fold, respectively, as low as that of the patients with C/C genotype.

CONCLUSION

CYP2D6^*10 mutations affect the pharmacokinetics of iloperidone and its metabolites in Chinese schizophrenia patients, suggesting that the clinical doses of iloperidone for patients with CYP2D6^*10 mutations need to be optimized.

Long-term efficacy and safety of iloperidone: an update

Schizophrenia is a devastating neuropsychiatric disease with a worldwide prevalence of approximately 0.5%-1%. Since many patients do not achieve adequate symptom relief from available agents, alternate pharmacotherapeutic approaches are needed. In this context, iloperidone was recently approved by the US Food and Drug Administration for the treatment of schizophrenia. This paper first reviews its pharmacodynamic and pharmacokinetic profiles, emphasizing their clinical relevance. Next, it summarizes the literature on its acute and maintenance efficacy, safety, and tolerability. It then considers pharmacogenetic data which may help to predict response and risk of cardiac arrhythmias with this agent. Finally, it critically positions iloperidone relative to other first- and second-generation antipsychotics.

Safety profile of iloperidone in the treatment of schizophrenia

INTRODUCTION

Iloperidone is a novel antipsychotic medication approved for the treatment of schizophrenia in adults with efficacy similar to its class counterparts. The purpose of this article is to describe the safety profile of iloperidone and its clinical implications.

AREAS COVERED

A PubMed search was undertaken on May 10, 2013, using the keyword iloperidone. Of the 121 articles that resulted, those with primary sources of information, along with secondary sources with an emphasis on drug safety, were included in this article. Iloperidone was found to have lower extrapyramidal symptom (EPS) and akathisia rates compared to haloperidol and risperidone. Twelve percent of patients experienced clinically significant weight gain, largely during initiation phase of treatment. No other clinically significant metabolic abnormalities were observed. QTc interval was increased by 10 ms, comparable to the effect observed with ziprasidone. QTc prolongation was heightened under inhibition of CYP2D6 and CYP3A4. Orthostatic hypotension was a common effect seen in the first week of treatment.

EXPERT OPINION

The favorable EPS and akathisia profile of iloperidone makes it an attractive choice for patients whose compliance is limited by these effects. However, the slow titration schedule adapted to reduce orthostasis may limit the use of this agent in an acute setting.

Pharmacological and clinical profile of recently approved second-generation antipsychotics: implications for treatment of schizophrenia in older patients

Antipsychotics are frequently used in elderly patients to treat a variety of conditions, including schizophrenia. While extensively studied for their impact in younger populations, there is comparatively limited evidence about the effectiveness of these agents in older patients. Further complicating this situation are the high comorbidity rates (both psychiatric and medical) in the elderly; age-related changes in pharmacokinetics that lead to a heightened proclivity for adverse effects; and the potential for multiple, clinically relevant drug interactions. With this background in mind, we review diagnostic and treatment-related issues specific to elderly patients suffering from schizophrenia. We then focus on the potential role of the most recently approved second-generation antipsychotics, paliperidone (both the extended-release oral formulation and the long-acting injectable formulation), iloperidone, asenapine and lurasidone, given the limited clinical experience with these agents in the elderly. While there is limited data to support their safety, tolerability and efficacy in older patients with schizophrenia, each has unique characteristics that should be considered when used in this population.

Withdrawal symptoms and rebound syndromes associated with switching and discontinuing atypical antipsychotics: theoretical background and practical recommendations

With the widespread use of atypical or second-generation antipsychotics, switching treatment has become current practice and more complicated, as the pharmacological profiles of these agents differ substantially despite their similarity in being 'atypical'. All share the ability to block dopamine D₂ receptors, and most of them also block serotonin 5-HT2A receptors. Apart from these common features, some atypical antipsychotics are also able to block or stimulate other dopamine or serotonin receptors, as well as histaminergic, muscarinergic or adrenergic receptors. As a result of the varying receptor affinities, in switching or discontinuing compounds several possible pitfalls have to be considered, including the occurrence of withdrawal and rebound syndromes. This article reviews the pharmacological background of functional blockade or stimulation of receptors of interest in regard to atypical antipsychotics and the implicated potential withdrawal and rebound phenomena. A MEDLINE search was carried out to identify information on withdrawal or rebound syndromes occurring after discontinuation of atypical antipsychotics. Using the resulting literature, we first discuss the theoretical background to the functional consequences of atypical antipsychotic-induced blockade or stimulation of neurotransmitter receptors and, secondly, we highlight the clinical consequences of this. We then review the available clinical literature on switching between atypical antipsychotics, with respect to the occurrence of withdrawal or rebound symptoms. Finally, we offer practical recommendations based on the reviewed findings. The systematic evaluation of withdrawal or rebound phenomena using randomized controlled trials is still understudied. Knowledge of pharmacological receptor-binding profiles may help clinicians in choosing adequate switching or discontinuation strategies for each agent. Results from large switching trials indicate that switching atypical antipsychotics can be performed in a safe manner. Treatment-emergent adverse events during or after switching are not always considered to be, at least in part, associated with the pre-switch antipsychotic. Further studies are needed to substantiate the evidence gained so far on different switching strategies. The use of concomitant medication, e.g., benzodiazepines or anticholinergic drugs, may help to minimize symptoms arising from the discontinuation or switching of antipsychotic treatment.

Asenapine, iloperidone and lurasidone: critical appraisal of the most recently approved pharmacotherapies for schizophrenia in adults

This article reviews the pharmacological profile and published efficacy and tolerability/safety data of iloperidone, asenapine and lurasidone, the most recent atypical antipsychotics to be approved in the USA for the treatment of schizophrenia. All three agents are similar in terms of overall efficacy and low propensity for clinically significant weight gain or adverse changes in glycemic or lipid profile. However, these agents differ from one another in terms of formulations, pharmacokinetics, and dosing and nonmetabolic adverse effect profile. For each drug, comparative and real-world effectiveness studies are lacking, as are effectiveness and safety data in elderly, young and pregnant/nursing patients. As such, the exact place of iloperidone, asenapine and lurasidone within the broader antipsychotic armamentarium is currently difficult to establish.

Newer antipsychotics and upcoming molecules for schizophrenia

BACKGROUND

The management of schizophrenia has seen significant strides over the last few decades, due to the increasing availability of a number of antipsychotics. Yet, the diminished efficacy in relation to the negative and cognitive symptoms of schizophrenia, and the disturbing adverse reactions associated with the current antipsychotics, reflect the need for better molecules targeting unexplored pathways.

PURPOSE

To review the salient features of the recently approved antipsychotics; namely, iloperidone, asenapine, lurasidone and blonanserin.

METHODS

We discuss the advantages, limitations and place in modern pharmacotherapy of each of these drugs. In addition, we briefly highlight the new targets that are being explored.

RESULTS

Promising strategies include modulation of the glutamatergic and GABAergic pathways, as well as cholinergic systems.

CONCLUSIONS

Although regulatory bodies have approved only a handful of antipsychotics in recent years, the wide spectrum of targets that are being explored could eventually bring out antipsychotics with improved efficacy and acceptability, as well as the potential to revolutionize psychiatric practice.

Stable-isotope dilution LC–MS/MS assay for determination of iloperidone and its two major metabolites, P 88 and P 95, in human plasma: application to a bioequivalence study

Background: Iloperidone is a novel antipsychotic drug with high affinity for serotonin and D2 dopamine receptors. A sensitive and rapid isotope dilution LC–MS/MS method has been developed for the simultaneous determination of iloperidone and its two major metabolites in human plasma. Results: The analytes and their deuterated analogs as internal standards were quantitatively extracted from 100-µl human plasma by SPE. The method was validated over the concentration range of 0.01–6 ng/ml for all the analytes. Baseline separation of analytes was possible within 3 min on ACE 5 C8 column. The accuracy and precision (%CV) of the method varied from 96.2 to 105%, and 1.17 to 4.75%, respectively. The extraction recovery was >84%, while the internal standard-normalized matrix factors ranged from 0.97–1.03 for all three analytes. Conclusion: The developed method was successfully applied to support a bioequivalence study in healthy volunteers.

Iloperidone, asenapine and lurasidone: a primer on their current status

INTRODUCTION

Three newer atypical antipsychotic drugs were FDA-approved in 2009 and 2010 in the following order: iloperidone, asenapine and lurasidone. The three drugs are indicated for the treatment of acute schizophrenia. Asenapine is also approved for treatment of manic or mixed episodes associated with bipolar I disorder, for the maintenance treatment of schizophrenia and as an adjunctive therapy with lithium or valproate for the acute treatment of manic or mixed episodes associated with bipolar I disorder in adults.

AREAS COVERED

This review compares and contrasts the current preclinical, clinical, safety and tolerability profiles of the three newer drugs, as reported in published preclinical and clinical studies, product labels, poster presentations and press releases.

EXPERT OPINION

Preclinical studies have reported that the three drugs have variable affinities for a wide range of neurotransmitter receptors, and are active in animal models predictive of antipsychotic activity. Asenapine is the first antipsychotic to be administered sublingually, whereas iloperidone requires titration to minimize orthostatic hypotension. Asenapine and lurasidone are associated with dose-related akathisia, whereas iloperidone is not. The three drugs appear to have relatively benign metabolic profiles. The availability of the three novel antipsychotics should provide additional options for improved treatment of schizophrenia and other psychotic disorders.

Iloperidone (Fanapt®), a novel atypical antipsychotic, is a potent HERG blocker and delays cardiac ventricular repolarization at clinically relevant concentration

QT interval prolongation on the electrocardiogram (ECG) has extensively been reported with iloperidone, a novel antipsychotic drug. The objective of the present study was to evaluate the effects of iloperidone on cardiac ventricular repolarization at three different levels; in vitro, ex vivo and in vivo. (1) In vitro level: whole-cell patch-clamp experiments were performed on HERG-transfected HEK293 cells exposed to iloperidone 0.01-1 μmol/L (n = 35 cells, total) to assess drug effect on HERG current. (2) Ex vivo level: Langendorff retroperfusion experiments were performed on isolated hearts from male Hartley guinea pigs (n = 7) exposed to iloperidone 100 nmol/L with/without chromanol 293B 10 μmol/L to assess drug-induced prolongation of monophasic action potential duration measured at 90% repolarization (MAPD(90)). (3) In vivo level: ECG recordings using wireless cardiac telemetry were performed in guinea pigs (n = 5) implanted with radio transmitters and treated with a single oral gavage dose of iloperidone 3 mg/kg. (1) Patch-clamp experiments revealed an estimated IC50 for iloperidone on HERG current of 161 ± 20 nmol/L. (2) While pacing the hearts at stimulation cycle lengths of 200 or 250 ms, or during natural sinus rhythm (no external pacing), iloperidone 100 nmol/L prolonged MAPD(90) by respectively 9.2 ± 0.9, 11.2 ± 1.6 and 21.4 ± 2.3 ms. After adding chromanol 293B, MAPD(90) was further prolonged by 7.3 ± 3.3, 11.5 ± 2.3 and 29.2 ± 6.7 ms, respectively. (3) Iloperidone 3mg/kg p.o. caused a maximal 42.7 ± 10.2 ms prolongation of corrected QT interval (QTc(F)), 40 min after administration. Iloperidone prolongs the QT interval, the cardiac action potentials and is a potent HERG blocker. Patients are at increased risk of cardiac proarrhythmia during iloperidone treatment, as this drug possesses significant cardiac repolarization-delaying properties at clinically relevant concentration.

Iloperidone for the management of adults with schizophrenia

BACKGROUND

Iloperidone is a second-generation antipsychotic drug approved in May 2009 by the US Food and Drug Administration (FDA) for the acute treatment of schizophrenia in adults. It is a piperidinyl-benzisoxazole derivative with mixed serotonin (5HT2A) and D2 dopamine antagonist properties.

OBJECTIVE

The purpose of this article was to review the pharmacology, pharmacokinetics, efficacy, safety, and role in treatment for iloperidone in schizophrenia.

METHODS

Scientific and clinical data were collected through searches of PubMed, ClinicalTrials.gov, International Pharmaceutical Abstracts, and the FDA, using the search term iloperidone, and limited to English-language articles. Reference lists were reviewed for additional publications. Dates included the beginning of the database through 2010. No limits were placed on study design.

RESULTS

In a 4-week Phase III trial, iloperidone 12 mg twice daily lowered the Positive and Negative Syndrome Scale (PANSS) total scores to a significantly greater extent than did placebo (-12 vs -7.1; P < 0.01). The ziprasidone active control also separated from placebo (-12.3 vs -7.1; P < 0.05). A pooled analysis of 3 Phase III trials compared iloperidone in divided doses to placebo. The primary outcome was reduction in PANSS scores. Study 1 included iloperidone 4, 8, or 12 mg/d, haloperidol as an active control, and placebo. The PANSS reduction in the 12 mg/d group was significantly greater at end point versus baseline when compared with placebo (-9.9 vs -4.6; P = 0.047). Study 2 included iloperidone 4 to 8 mg/d or 10 to 16 mg/d, risperidone 4 to 8 mg/d, or placebo. The primary efficacy measure was change from baseline to end point in the Brief Psychiatric Rating Scale (BPRS). Improvement from baseline on all iloperidone doses was significantly greater than with placebo (4-8 mg/d group: -6.2, P = 0.012; 10-16 mg/d group: -7.2, P = 0.001; placebo, -2.5). Study 3 included iloperidone 12 to 16 mg/d, risperidone 6 to 8 mg/d, and placebo. The results on the primary efficacy variable, reduction in the BPRS score, was not significant for the 12 to 16 mg/d group versus placebo (-7.1 vs -5.0; P = 0.09), but was significant for the 20 to 24 mg/d iloperidone group (-8.6 vs -5.0; P = 0.01) and for the risperidone group (-11.5 vs 5.0; P < 0.001). A 52-week maintenance trial included iloperidone versus haloperidol as an active control. The primary efficacy variable was time to relapse. Comparison of mean time to relapse of the 2 arms showed no significant difference. The most common adverse events (AEs) associated with iloperidone were dizziness (5.1%-23.2%), dry mouth (5.2%-10.4%), somnolence (4%-13%), and dyspepsia (4.8%-7.8%). AEs appeared dose related. Prescribing information recommends a starting dosage of 1 mg twice daily and then titrated over 7 days to reach a target dosage of 12 to 24 mg/d. The titration is necessary to reduce the risk of orthostatic hypotension-related dizziness.

CONCLUSIONS

Data support that when titrated slowly to a therapeutic dosage, iloperidone is generally well tolerated, has a favorable safety profile, and is an effective treatment option in patients with schizophrenia. Its place in therapy and performance in a typical patient population remain to be established. Slow initial titration and twice-daily dosing are potential disadvantages.

Iloperidone: A new drug for the treatment of schizophrenia

PURPOSE

The pharmacology, pharmacokinetics, pharmacogenomics, clinical efficacy, and safety and tolerability profile of iloperidone for the treatment of schizophrenia are reviewed.

SUMMARY

Iloperidone is an atypical antipsychotic that recently received marketing approval from the Food and Drug Administration for the acute treatment of schizophrenia. Iloperidone is a pure antagonist and the first antipsychotic to have pharmacogenomic studies indicate predictive response based on six identified polymorphisms. Pharmacokinetic studies have determined that iloperidone is well absorbed orally, with a bioavailability of 96%. Phase II and III clinical trials have shown iloperidone to improve symptoms of schizophrenia, based on the Positive and Negative Symptom Scale, Brief Psychiatric Rating Scale, and Clinical Global Impressions-Severity scores (p < 0.05). Iloperidone has established tolerability at recommended dosages of up to 24 mg daily; however, the dosage must be slowly increased over seven days, and twice-daily administration is required to avoid orthostatic hypotension. The most common adverse effects associated with iloperidone were dizziness, dry mouth, fatigue, nasal congestion, orthostatic hypotension, somnolence, tachycardia, and weight gain. Safety studies have also found that iloperidone increases the risk of Q-Tc interval prolongation, similar to that seen with ziprasidone. Minimal changes in glucose and lipid abnormalities were seen in short-term (4- and 6-week) and long-term (52-week) studies, indicating a low chance of metabolic disturbance with iloperidone.

CONCLUSION

Iloperidone may be a viable and safe option for the treatment of schizophrenia in adult patients, especially for patients who cannot tolerate other antipsychotic agents. However, iloperidone lacks a clear benefit over other antipsychotic agents.

Iloperidone: chemistry, pharmacodynamics, pharmacokinetics and metabolism, clinical efficacy, safety and tolerability, regulatory affairs, and an opinion

IMPORTANCE OF THE FIELD

Iloperidone is a newly commercialized second-generation (atypical) antipsychotic approved for the acute treatment of schizophrenia in adults.

AREAS COVERED IN THIS REVIEW

the purpose of this review is to describe the pharmacokinetic profile of iloperidone and its clinical implications in the treatment of schizophrenia. Background information is also provided regarding chemistry, pharmacodynamics, clinical efficacy and safety data, and regulatory affairs.

WHAT THE READER WILL GAIN

the reader will have an understanding of the pharmacokinetics and overall metabolism of iloperidone within the context of efficacy and safety.

TAKE HOME MESSAGE

time to peak plasma concentration occurs in 2 - 4 h but elimination half-life is 18 h for extensive CYP2D6 metabolizers and 33 h for poor CYP2D6 metabolizers, suggesting that once or twice daily dosing would be feasible. Dizziness and/or postural hypotension are the limiting factors for how fast iloperidone can be titrated, and is explained by iloperidone and its metabolites' norepinephrine alpha 1 antagonism. Efficacy of iloperidone appears similar to that for ziprasidone and haloperidol, but iloperidone may be inferior in efficacy to risperidone. Iloperidone can prolong the ECG QT interval. The tolerability profile of iloperidone is noteworthy in terms of modest weight gain, no medically important changes in lipid and glucose, little in the way of prolactin elevation, and an absence of extrapyramidal adverse effects, including akathisia.

Atypical antipsychotic tolerability and switching strategies in bipolar disorder

IMPORTANCE TO THE FIELD

Atypical antipsychotics have unequivocally advanced the pharmacotherapy of bipolar disorders. These broad-spectrum treatments offer efficacy against core symptoms of acute mania, mixed state, depressed and maintenance phases of the disorder. Atypical antipsychotics are not, however, a panacea and are associated with several problematic tolerability and safety concerns. For example, emerging evidence militates against the original notion that atypical agents are without risk for extrapyramidal side effects and possibly tardive dyskinesia when compared to their therapeutic predecessors, the conventional antipsychotics. Although classified together, atypical antipsychotics are heterogeneous in their tolerability and safety profile, an issue relevant to individualizing treatment selection and switching antipsychotics for optimal clinical management.

AREAS COVERED IN THIS REVIEW

This article reviews relevant adverse events attributable to the use of atypical antipsychotics and strategies for switching these agents, with particular attention to the bipolar disorder population.

WHAT THE READER WILL GAIN

The reader will gain both a perspective of treatment-emergent adverse events associated with atypical agents in the treatment of bipolar disorder and a precise analysis of common adverse events that frequently lead to treatment discontinuation and/or switching to a separate agent.

TAKE HOME MESSAGE

Atypical antipsychotics provide for a different array of treatment-emergent adverse events than conventional agents. The therapeutic index of treatment is a ratio of the relative benefit divided by the probability of harm (i.e., side effects). Taken together, the atypical antipsychotics offer an improved therapeutic index when compared to conventional agents in bipolar disorder. Nevertheless, atypicals fall short of the ideal, necessitating frequent discontinuation and switching.

Iloperidone—A Second-Generation Antipsychotic for the Treatment of Acute Schizophrenia

Objective:

To review the pharmacology, efficacy, and tolerability of iloperidone, a second-generation antipsychotic, in the treatment of acute schizophrenia in adults.

Data Sources:

English-language articles were obtained via MEDLINE (1966-March 2010) and International Pharmaceutical Abstracts (1970-March 2010) searches using the key words iloperidone, acute schizophrenia, atypical antipsychotics, second-generation antipsychotics, HP 873, P88–8991, P95–12113, and Fanapt. Bibliographies of selected articles were used to identify additional sources.

Study Selection and Data Extraction:

Available published articles reporting the results of human studies of iloperidone were reviewed for inclusion in this article. Additional information regarding pharmacology, adverse events, contraindications, and precautions was obtained from the manufacturer's prescribing information.

Data Synthesis:

Iloperidone is a second-generation antipsychotic approved for the treatment of acute schizophrenia in adults. Iloperidone is well absorbed upon oral administration, highly protein bound, and metabolized primarily by CYP3A4 and 2D6. Phase 3 clinical trials evaluating the efficacy of iloperidone demonstrated significantly higher response rates with iloperidone compared with placebo in the treatment of positive, negative, and cognitive symptoms associated with acute schizophrenia when the drug was given in doses up to 24 mg daily. Dizziness, dry mouth, and nausea were the most commonly reported adverse events and appear to be dose related. Additional adverse events occurring in 5% or more of patients include orthostatic hypotension, somnolence, tachycardia, fatigue, nasal congestion, and weight increase. Iloperidone should be titrated slowly over a 7-day interval to avoid the potential for orthostatic hypotension. Product labeling includes a black box warning against the use of iloperidone in dementia-related psychosis and precautions regarding QT interval prolongation.

Conclusions:

Iloperidone is an effective treatment for the symptoms of acute schizophrenia in adults. Additional studies are needed to assess comparative effectiveness with other pharmacologic treatments of schizophrenia, long-term efficacy, and long-term safety.

Iloperidone for the treatment of schizophrenia

OBJECTIVE

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

DATA SOURCES

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.

STUDY SELECTION AND DATA EXTRACTION

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.

DATA SYNTHESIS

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.

CONCLUSIONS

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.

New atypical antipsychotics for schizophrenia: iloperidone

The optimal treatment of schizophrenia poses a challenge to develop more effective treatments and safer drugs, to overcome poor compliance, discontinuation and frequent switching with available antipsychotics. Iloperidone is a new dopamine type 2/serotonin type 2A (D(2)/5-HT(2A)) antagonist structurally related to risperidone, expected to give better efficacy with less extrapyramidal symptoms than D(2) receptor antagonist antipsychotics. In double-blind phase III trials iloperidone reduced the symptoms of schizophrenia at oral doses from 12 to 24 mg. It was more effective than placebo in reducing positive and negative syndrome total score and Brief Psychiatric Rating scale scores; it was as effective as haloperidol and risperidone in post-hoc analysis. Its long-term efficacy was equivalent to that of haloperidol. The most common adverse events were dizziness, dry mouth, dyspepsia and somnolence, with few extrapyramidal symptoms and metabolic changes in short- and long-term studies in adults. Akathisia was rare, but prolongation of the corrected QT (QTc) interval was comparable to haloperidol and ziprasidone, which is of particular concern. Further comparative studies are needed to clarify the benefit/risk profile of iloperidone and its role in the treatment of schizophrenia.

Iloperidone: in schizophrenia

Iloperidone is an atypical antipsychotic that is approved for the treatment of adult patients with schizophrenia. In several large (n > 570 per trial), 4- or 6-week, double-blind, multinational, multicentre trials in adult patients with schizophrenia, recommended target dosages of oral iloperidone (6-12 mg twice daily) generally showed better efficacy than placebo, in terms of improvements in Positive and Negative Syndrome Scale (PANSS) total scores or Brief Psychiatric Rating Scale (BPRS) scores (primary endpoints) and also for most secondary endpoints, including PANSS subscale scores. In addition, pharmacogenomic studies identified single nucleotide polymorphisms (SNPs) that were associated with an enhanced response to iloperidone during acute treatment of schizophrenia. More limited data also support the role of these SNPs in enhancing responses to iloperidone during longer-term treatment. In a pooled analysis of three 52-week, double-blind, multinational, multicentre trials (n = 473), iloperidone treatment was shown to be equivalent to that with haloperidol, based on Kaplan-Meier estimates of the time to relapse (primary endpoint). Iloperidone was generally well tolerated and was associated with few extrapyramidal symptoms or changes in metabolic parameters in short- and longer-term clinical trials in adult patients with schizophrenia.

Iloperidone for schizophrenia: a review of the efficacy and safety profile for this newly commercialised second-generation antipsychotic

OBJECTIVE

The aim of the study was to describe the efficacy and safety of iloperidone for the treatment of schizophrenia.

DATA SOURCES

The pivotal registration trials were accessed by querying http://www.pubmed.gov, http://www.fda.gov and http://www.clinicaltrials.gov for the search term 'iloperidone'.

STUDY SELECTION

Four published primary reports of phase III studies were identified as well as preclinical animal and receptor affinity studies that describe potential mechanisms of action and pharmacogenomic studies that identify potential genetic biomarkers for efficacy and tolerability. Product labelling provided additional data.

DATA EXTRACTION

Descriptions of the principal results and calculation of number needed to treat (NNT) and number needed to harm (NNH) for relevant dichotomous outcomes were extracted from the study reports. Additional safety outcomes subject to NNH analysis were obtained from product labelling.

DATA SYNTHESIS

Iloperidone is a second-generation antipsychotic agent indicated for the acute treatment of schizophrenia in adults. Iloperidone has been evaluated in several double-blind placebo-controlled clinical trials. The oral formulation has demonstrated efficacy in reducing the symptoms of acute schizophrenia at fixed daily doses ranging from 12 to 24 mg. Data reported for categorical definitions of response using the Positive and Negative Syndrome Scale were limited to one study and specifically to rates of achieving a > or = 20% decrease in the positive subscale from baseline; significantly more patients receiving iloperidone 24 mg/day (72%) than placebo (52%) met this criterion, yielding a NNT of five. Iloperidone should be titrated slowly to avoid orthostatic hypotension, potentially delaying the achievement of a therapeutic dose level. There appears to be a dose relationship for adverse events such as dizziness, somnolence and dry mouth; for example NNH vs. placebo for somnolence was 25 for iloperidone 10-16 mg/day and 10 for 20-24 mg/day. There is a possibility of a therapeutic dose response as well. Iloperidone is essentially free of extra-pyramidal side effects. Iloperidone is associated with weight gain comparable with risperidone. Long-term double-blind maintenance studies have demonstrated iloperidone's non-inferiority to haloperidol for relapse prevention. Product labelling includes a warning about the potential for QT interval prolongation. At present there are no efficacy studies available that are powered to directly compare iloperidone with other second-generation antipsychotics. The development of a depot formulation of iloperidone as well as efforts to identify genetic biomarkers for prediction of both efficacy and tolerability are in progress.

CONCLUSIONS

Aside from paliperidone, iloperidone is the first new second-generation antipsychotic to be commercialised in the USA since 2002. From the limited registration data, iloperidone appears to be relatively well tolerated once titrated to a therapeutic level and can be a useful option to consider. The development of a depot formulation and potential for genetic biomarkers may make this agent compelling. Further comparisons with other available agents among patients with schizophrenia in the 'real world' are needed.

Clinical and pharmacogenetic studies of iloperidone

Antipsychotic drugs have become the mainstay treatment of schizophrenia. However, patients who receive antipsychotic treatment differ with respect to treatment response and adverse events. The problem of antipsychotic response variability has stimulated further search for agents with improved effectiveness and tolerability. Equally intense is the search for novel ways of using DNA information to personalize treatment with antipsychotic drugs. Iloperidone is an investigational, atypical antipsychotic drug of the serotonin/dopamine type. The US FDA is currently reviewing the new drug application for an oral formulation of iloperidone for the treatment of schizophrenia. Data from 35 clinical trials and approximately 3000 patients treated with iloperidone were included in the new drug application submission, as well as data from pharmacogenetic studies of iloperidone. Given the emerging role of pharmacogenetics, knowledge of genetic biomarkers of iloperidone response could lead to personalized medicine.

Efficacy of iloperidone in the treatment of schizophrenia: initial phase 3 studies

Iloperidone is an atypical antipsychotic in development for the treatment of schizophrenia. This report examines efficacy results from three 6-week, randomized, double-blind, placebo- and active comparator-controlled studies in patients with schizophrenia or schizoaffective disorder. Multiple doses of iloperidone were studied. Active comparators (haloperidol 15 mg/d, or risperidone 4-8 mg/d) were included to confirm trial validity. The primary protocol-defined efficacy variable in Study 1 was change from baseline to end point in Positive and Negative Syndrome Scale total scores; in Studies 2 and 3, it was change in the Positive and Negative Syndrome Scale-derived Brief Psychiatric Rating Scale scores. Results were assessed through analysis of covariance using last observation carried forward in the intent-to-treat population. In total, 1943 patients were randomized. At least 1 iloperidone dosing group in each study demonstrated significantly better efficacy than placebo (Study 1, iloperidone 12 mg/d [P = 0.047]; Study 2, 4-8 mg/d [P = 0.012] and 10-16 mg/d [P = 0.001]; and Study 3, 20-24 mg/d [P = 0.010]). Active controls were also significantly more effective than placebo in each trial, thus validating the trials. Additional analysis in patients who received active treatment for at least 2 weeks indicated comparable efficacy score reductions at 6 weeks for patients receiving iloperidone 20 to 24 mg/d versus those receiving haloperidol or risperidone. Risk for motor-related adverse events (eg, akathisia and extrapyramidal symptoms) was lower with iloperidone than with risperidone and haloperidol and was generally similar to placebo. These trials indicate that iloperidone is effective for the treatment of schizophrenia.

Long-term efficacy and safety of iloperidone: results from 3 clinical trials for the treatment of schizophrenia

This research compared the long-term efficacy and safety of iloperidone with those of haloperidol in individuals with schizophrenia. Data were pooled from 3 prospective multicenter studies, each with 6-week stabilization followed by 46-week double-blind maintenance phases. Patients were randomized to iloperidone 4 to 16 mg/d or haloperidol 5 to 20 mg/d. Patients included in this analysis completed the initial 6-week phase with at least 20% reduction in Positive and Negative Syndrome Scale (PANSS) total score at weeks 4 and 6, had 7-item Clinical Global Impressions of Change (CGI-C) scores less than 4, received 1 or more doses of long-term phase medication, and had 1 or more efficacy/safety assessments during the long-term phase. The primary efficacy variable was time to relapse, defined as a 25% or more increase in PANSS total score, including at least a 10-point change; discontinuation because of lack of efficacy; aggravated psychosis with hospitalization; or 2-point increase in the 7-item CGI-C after week 6. Of 1644 patients randomized and 1326 completing the 6-week phase, 473 (iloperidone, n = 359; haloperidol, n = 114) were included in the long-term efficacy analysis, and 489 (iloperidone, n = 371; haloperidol, n = 118) in the safety analysis. Iloperidone was equivalent to haloperidol in time to relapse. The most common adverse events were insomnia (18.1%), anxiety (10.8%), and schizophrenia aggravated (8.9%) with iloperidone, and insomnia (16.9%), akathisia (14.4%), tremor (12.7%), and muscle rigidity (12.7%) with haloperidol. The Extrapyramidal Symptoms Rating Scale scores improved with iloperidone and worsened with haloperidol. Metabolic changes were minimal for both groups. Mean changes in Fridericia's QT interval correction were 10.3 msec (iloperidone) and 9.4 msec (haloperidol) at end point. Iloperidone demonstrated long-term efficacy equivalent to haloperidol and a favorable long-term safety profile, potentially making this agent a suitable option as maintenance therapy for schizophrenia.

Iloperidone: a new benzisoxazole atypical antipsychotic drug. Is it novel enough to impact the crowded atypical antipsychotic market?

Iloperidone is a new-generation atypical antipsychotic agent, acting as a serotonin/dopamine (5-HT(2A)/D(2)) antagonist, under development by Vanda Pharmaceuticals for the treatment of schizophrenia, bipolar disorder and other psychiatric conditions. Chemically, iloperidone is a benzisoxazole, like risperidone, and shows a multiple receptor binding profile, sharing this feature with the other atypical antipsychotic agents. Administered orally, the drug is highly bound to plasma proteins and extensively metabolised. Several clinical trials have been carried out, to check efficacy, safety and side effects. In order to introduce iloperidone as an agent for the treatment of schizophrenia, a short overview of the disease and of the most important antipsychotic drugs available or under development will be reported. Iloperidone pharmacokinetics and pharmacodynamics are presented herein, together with an evaluation of clinical safety and efficacy results.