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

Recent Advances in representative small-molecule DRD2 inhibitors: Synthetic Routes and clinical applications

The dopamine D2 receptor (DRD2) represents a pivotal target for therapeutic intervention in the treatment of neuropsychiatric disorders, including schizophrenia, bipolar disorder, and Parkinson's disease. The successful discovery of numerous effective DRD2 inhibitors has led to their clinical application and ongoing evaluation in various clinical trials. This review explores the synthetic approaches and clinical applications of prototypical small-molecule DRD2 inhibitors that have received approval or are currently undergoing clinical trials, highlighting their therapeutic potential and challenges. The synthesis of these inhibitors employs various chemical strategies, including modifications of phenothiazine and butyrophenone structures, which have yielded significant antipsychotic agents like chlorpromazine and haloperidol. Additionally, newer classes of inhibitors, such as aripiprazole, exhibit partial agonist activity at DRD2, offering a unique therapeutic profile. Clinically, DRD2 inhibitors demonstrate efficacy in managing positive symptoms of schizophrenia, manic episodes in bipolar disorder, and dopaminergic imbalance in Parkinson's disease. However, the emergence of adverse effects, including tardive dyskinesia, extrapyramidal symptoms and metabolic syndrome, presents substantial challenges. Advances in the development of second-generation antipsychotics aim to balance efficacy with a better side effect profile by targeting additional neurotransmitter receptors. This review aims to deliver an overview of the synthesis and clinical applications of representative small-molecule DRD2 inhibitors across various clinical phases, thereby offering strategic insights for the advancement of DRD2 inhibitor development.

Seventy Years of Antipsychotic Development: A Critical Review

Since the mid-1950s discovery of the first effective antipsychotic medications (APM), we have only been able to improve the tolerability but not the overall efficacy of currently available APMs, as reflected by effectiveness trials in Europe and the United States. This inability to develop more effective APMs is attributable to multiple factors, including failure to create and use assessment tools to assess core symptom domains in schizophrenia, move beyond the dopaminergic hypothesis and to develop "me too" drugs, imposing ill-defined research domain criteria, and lacking federal funding for clinical trials. The classification of APMs is also confusing, including second-generation, partial agonists, and multimodal APMs in the same class of APMs, despite significant differences in their mechanisms of action. Other factors stagnating drug development include inadequate sample sizes to address heterogeneity, lack of statistical measures correlating with clinical significance, using the atheoretical basis of psychiatric diagnoses, failure to control placebo response, and high cost of newer and perhaps more tolerable APMs. Furthermore, there has been a failure to develop early predictors of antipsychotic response and various tools to optimize an APM response. Finally, some mental health providers are also responsible for the suboptimal use of APMs, by using excessive maintenance doses, often with irrational polypharmacy, further compromising effectiveness and medication adherence. However, some bright spots in antipsychotic development include improved tolerability of APMs and long-acting injectables to address the high prevalence of medication nonadherence. This review critically reviews 70 years of antipsychotic development, the reasons behind the failure to develop more effective APMs, and suggestions for future direction.

Effects of iloperidone on hERG 1A/3.1 heterotetrameric channels

OBJECTIVES

Iloperidone is an atypical antipsychotic drug that is widely used for the treatment of schizophrenia. hERG 3.1, alternatively spliced form of hERG 1A, is considered a potential target for an antipsychotic drug. The present study was designed to study the effects of iloperidone on hERG 1A/3.1 heterotetrameric channels.

METHODS

The interactions of iloperidone with hERG 1A/3.1 heterotetrameric channels stably expressed in HEK cells were investigated using the whole-cell patch-clamp technique and western blot analysis.

RESULTS

Iloperidone inhibited the hERG 1A/3.1 tail currents at -50 mV in a concentration-dependent manner with an IC50 value of 0.44 μM. The block of hERG 1A/3.1 currents by iloperidone was voltage-dependent and increased over a range of voltage for channel activation. However, the block by iloperidone was voltage-independent at more depolarized potentials where the channels were fully activated. A fast application of iloperidone inhibited the hERG 1A/3.1 current elicited by a 5-s depolarizing pulse to +60 mV to fully inactivate the hERG 1A/3.1 currents. Iloperidone also induced a rapid and reversible inhibition of hERG 1A/3.1 tail currents during repolarization. However, iloperidone had no effect on either hERG 1A or hERG 1A/3.1 channel trafficking to the cell membrane.

CONCLUSIONS

Our results indicated that iloperidone concentration-dependently inhibited hERG 1A/3.1 currents by preferentially interacting with the open states of channels, but not by the disruption of membrane trafficking or surface membrane expression of hERG 1A and hERG 1A/3.1 channel proteins.

Lithium and Atypical Antipsychotics: The Possible WNT/β Pathway Target in Glaucoma

Glaucoma is a progressive neurodegenerative disease that represents the major cause of irreversible blindness. Recent findings have shown which oxidative stress, inflammation, and glutamatergic pathway have main roles in the causes of glaucoma. Lithium is the major commonly used drug for the therapy of chronic mental illness. Lithium therapeutic mechanisms remain complex, including several pathways and gene expression, such as neurotransmitter and receptors, circadian modulation, ion transport, and signal transduction processes. Recent studies have shown that the benefits of lithium extend beyond just the therapy of mood. Neuroprotection against excitotoxicity or brain damages are other actions of lithium. Moreover, recent findings have investigated the role of lithium in glaucoma. The combination of lithium and atypical antipsychotics (AAPs) has been the main common choice for the treatment of bipolar disorder. Due to the possible side effects gradually introduced in therapy. Currently, no studies have focused on the possible actions of AAPs in glaucoma. Recent studies have shown a down regulation of the WNT/β-catenin pathway in glaucoma, associated with the overactivation of the GSK-3β signaling. The WNT/β-catenin pathway is mainly associated with oxidative stress, inflammation and glutamatergic pathway. Lithium is correlated with upregulation the WNT/β-catenin pathway and downregulation of the GSK-3β activity. Thus, this review focuses on the possible actions of lithium and AAPs, as possible therapeutic strategies, on glaucoma and some of the presumed mechanisms by which these drugs provide their possible benefit properties through the WNT/β-catenin pathway.

Pharmacokinetic and pharmacodynamic studies of iloperidone-loaded lipid nanoemulsions via oral route of administration

Iloperidone (IL) is practically insoluble in water and has significant first-pass metabolism, resulting in low oral bioavailability in humans (36%). IL lipid nanoemulsions (IL-LNEs) were prepared to improve oral bioavailability. IL-LNEs were formulated by hot homogenization and ultrasonication method. Soybean oil and egg lecithin in various concentrations as emulsifier were used in the preparation of LNEs. Dynamic light scattering technique was used for globule size analysis. All LNE formulations showed narrow size distribution and the average globule size and Poly Dispersity Index (PDI) were found to be in between 182.2 ± 2.8 to 222.3 ± 1.9 nm and 0.200 ± 0.004 to 0.274 ± 0.005 respectively. Zeta potential values varied from -20.0 ± 0.15 to -28.9 ± 0.30 mV which indicated stability of prepared LNEs. All formulations showed good entrapment efficiency ranging from 99.07 ± 0.01 to 99.28 ± 0.01% when separated using centrisart tubes and the drug content varied from 96.99 ± 0.94 to 99.06 ± 0.36%. Physical stability testing indicated the stability of all LNEs and optimized LNE-IL4 was found stable for 3 months at both refrigerated (4 °C) and room temperature (25 °C). During in vivo studies in wistar rats, the optimized LNE showed 2.47-fold improvement in the oral bioavailability and superior (1.22-fold) pharmacodynamic activity when compared to marketed tablet suspension (Ilosure-4^®) in suppressing the hyperlocomotor activity, being induced by MK-801 (Dizocilpine).

A Comprehensive Review on Importance and Quantitation of Atypical Antipsychotic Drugs and their Active Metabolites in Commercial Dosage Forms

Background:

Schizophrenia is a severe mental illness that affects more than twenty-one million people throughout the world. Schizophrenia also causes early death. Schizophrenia and other related psychotic ailments are controlled by the prescription of antipsychotic drugs, which act by blocking certain chemical receptors in the brain and thus relieves the symptoms of psychotic disorder. These drugs are present in the different dosage forms in the market and provided in a certain amount as per the need of the patients.

Objective:

Since such medications treat mental disorders, it is very important to have a perfect and accurate dose so that the risk factor is not affected by a higher or lower dose, which is not sufficient for the treatment. For accurate assay of these kinds of drugs, different analytical methods were developed ranging from older spectrophotometric techniques to latest hyphenated methods.

Results:

The current review highlights the role of different analytical techniques that were employed in the determination and identification of antipsychotic drugs and their metabolites. Techniques such as spectrophotometry, fluorimetry, liquid chromatography, liquid chromatography-mass spectrometry, gas chromatography, and gas chromatography-mass spectrometry employed in the method development of such antipsychotic drugs were reported in the review. Different metabolites, identified using the hyphenated techniques, were also mentioned in the review. The synthesis pathways of few of the metabolites were mentioned.

Conclusion:

The review summarizes the analyses of different antipsychotic drugs and their metabolites. A brief introduction of illnesses and their symptoms and possible medications were highlighted. Synthesis pathways of the associated metabolites were also mentioned.

The atypical neuroleptics iloperidone and lurasidone inhibit human cytochrome P450 enzymes in vitro. Evaluation of potential metabolic interactions

Background

The present study aimed at examining the inhibitory effect of two atypical neuroleptics iloperidone and lurasidone on the main human cytochrome P450 (CYP) enzymes in pooled human liver microsomes and cDNA-expressed CYP enzymes (supersomes).

Methods

The activity of these enzymes was determined by the following CYP-specific reactions: caffeine 3-N-demethylation/CYP1A2, diclofenac 4′-hydroxylation/CYP2C9, perazine N-demethylation/CYP2C19, bufuralol 1′-hydroxylation/CYP2D6 and testosterone 6β-hydroxylation/CYP3A4, respectively, using HPLC.

Results

Iloperidone inhibited the activity of CYP3A4 via a noncompetitive mechanism (K_i = 0.38 and 0.3 µM in liver microsomes and supersomes, respectively) and CYP2D6 via a competitive mechanism (K_i = 2.9 and 10 µM in microsomes and supersomes). Moreover, iloperidone attenuated the activity of CYP1A2 (K_i = 45 and 31 µM in microsomes and supersomes) and CYP2C19 via a mixed mechanism (K_i = 6.5 and 32 µM in microsomes and supersomes) but did not affect CYP2C9. Lurasidone moderately inhibited CYP1A2 (K_i = 12.6 and 15.5 µM in microsomes and supersomes), CYP2C9 (K_i = 18 and 3.5 µM in microsomes and supersomes) and CYP2C19 via a mixed mechanism (K_i = 18 and 18.4 µM in microsomes and supersomes), and CYP3A4 via a competitive mechanism (K_i = 29.4 and 9.1 µM in microsomes and supersomes). Moreover, lurasidone competitively, though weakly diminished the CYP2D6 activity (K_i = 37.5 and 85 µM in microsomes and supersomes).

Conclusion

The examined neuroleptics showed inhibitory effects on different CYP enzymes. The obtained results indicate that metabolic/pharmacokinetic interactions with iloperidone (involving mainly CYP3A4 and CYP2D6) and possibly with lurasidone (involving CYP1A2, CYP2C9 or CYP2C19) may occur during combined therapy.

Psychopharmacologic Treatment of Schizophrenia in Adolescents and Children

An increasing number of antipsychotic medications have demonstrated efficacy in randomized placebo-controlled trials in the treatment of children and adolescents with schizophrenia. This review summarizes and synthesizes relevant antipsychotic medication studies, with particular emphasis on second-generation agents, and discusses other clinical considerations that may influence medication selection. With the exception of clozapine demonstrating superior efficacy in the improvement of psychotic symptoms in treatment-resistant patients, many antipsychotic agents have been shown to be similarly efficacious, including first-generation medications. Consideration of the side-effect profile, which can differ substantially from medication to medication, is essential when choosing treatment options.

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.

Novel Adverse Events of Iloperidone: A Disproportionality Analysis in US Food and Drug Administration Adverse Event Reporting System (FAERS) Database

Background:

The signal is defined as “reported information on a possible causal relationship between an adverse event and a drug, of which the relationship is unknown or incompletely documented previously”.

Objective:

To detect novel adverse events of iloperidone by disproportionality analysis in FDA database of Adverse Event Reporting System (FAERS) using Data Mining Algorithms (DMAs).

Methodology:

The US FAERS database consists of 1028 iloperidone associated Drug Event Combinations (DECs) which were reported from 2010 Q1 to 2016 Q3. We consider DECs for disproportionality analysis only if a minimum of ten reports are present in database for the given adverse event and which were not detected earlier (in clinical trials). Two data mining algorithms, namely, Reporting Odds Ratio (ROR) and Information Component (IC) were applied retrospectively in the aforementioned time period. A value of ROR-1.96SE>1 and IC- 2SD>0 were considered as the threshold for positive signal.

Results:

The mean age of the patients of iloperidone associated events was found to be 44years [95% CI: 36-51], nevertheless age was not mentioned in twenty-one reports. The data mining algorithms exhibited positive signal for akathisia (ROR-1.96SE=43.15, IC-2SD=2.99), dyskinesia (21.24, 3.06), peripheral oedema (6.67,1.08), priapism (425.7,9.09) and sexual dysfunction (26.6-1.5) upon analysis as those were well above the pre-set threshold.

Conclusion:

Iloperidone associated five potential signals were generated by data mining in the FDA AERS database. The result requires an integration of further clinical surveillance for the quantification and validation of possible risks for the adverse events reported of iloperidone.

A Focused Review on the Treatment of Pediatric Patients with Atypical Antipsychotics

OBJECTIVES

The use of atypical antipsychotic medications in pediatric patients has become more prevalent in recent years. The purpose of this review is to provide a clinically relevant update of recent selected key publications regarding the use of atypical antipsychotics in this population.

METHODS

Studies reviewed included randomized, double-blind, placebo-controlled medication trials conducted within the past 5 years. A PubMed search was conducted for each of the 11 second-generation antipsychotic medications currently approved by the Food and Drug Administration for use in the United States: clozapine, risperidone, olanzapine, quetiapine, aripiprazole, ziprasidone, paliperidone, asenapine, iloperidone, lurasidone, and cariprazine. Trials published in English with subjects 18 years of age and younger were included in this review. Additional studies, chosen for their significance to clinical practice, were also included at the discretion of the authors.

RESULTS

This review demonstrates that more empiric data are available regarding both the acute efficacy and, to a lesser extent, the longer-term efficacy and tolerability for several of the considered antipsychotic medications. The clinical conditions for which these medications have been studied include schizophrenia, bipolar disorder, Tourette's disorder, and autism spectrum disorder. They have also been used as an adjunctive treatment for disruptive behavior disorders with aggression, which have not responded to treatment with stimulants.

CONCLUSION

Evidence regarding the efficacy and tolerability of antipsychotic medications for mental health disorders in children and adolescents has expanded exponentially in recent years. However, more information is needed so that evidence-based comparisons between medications can be made. In the future, data enabling the selection of medications based upon individual patient characteristics could potentially lead to greater efficacy and efficiency in treating what are frequently debilitating medical conditions. Maladaptive aggression in children, often treated with antipsychotics, is one such area in which there is a dearth of actual information available to the clinician. It is to be hoped that additional, longer-term studies of these medications will further inform evidence-based practice in clinical settings.

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.

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

OBJECTIVE

To describe secondary analyses from a 12-week, randomized, open-label trial where adult schizophrenia outpatients receiving risperidone, olanzapine, or aripiprazole were switched to iloperidone.

METHODS

Patients were randomized into two groups: one where the antecedent antipsychotic dose was titrated downwards to zero over 2 weeks (n=240), and the other group where the antecedent antipsychotic was abruptly stopped (n=260). Adaptations of the Clinical Global Impression scale were used to evaluate clinical changes. Other assessments included the reporting of adverse events (AEs), study discontinuation, body weight, and metabolic variables.

RESULTS

Improvement was steady throughout the study for both gradual- and immediate-switch groups starting at Week 1 and continuing through Week 12. Discontinuations due to AEs in the first 2 weeks of treatment were higher for the immediate-switch group compared with the gradual-switch group (10.8% vs. 5.4%, NNT 19, 95% CI 10-151). Fewer patients in the gradual-switch group experienced dizziness as an AE, whereas a higher percentage of patients in the immediate-switch group exhibited earlier onset of a therapeutic response within the first 2 weeks; both groups were comparable thereafter with low rates of dizziness and similar efficacy outcomes.

CONCLUSIONS

Switching to iloperidone can be accomplished either with a gradual crossover or immediate discontinuation of the prior antipsychotic; however, the immediate-switch method is associated with greater proportion of initial dizziness. The observed outcomes are consistent with what has been previously reported regarding iloperidone's favorable akathisia/EPS profile and modest impact on somnolence/sedation, body weight, and metabolic variables.

Pharmacogenetics of second-generation antipsychotics

This review considers pharmacogenetics of the so called 'second-generation' antipsychotics. Findings for polymorphisms replicating in more than one study are emphasized and compared and contrasted with larger-scale candidate gene studies and genome-wide association study analyses. Variants in three types of genes are discussed: pharmacokinetic genes associated with drug metabolism and disposition, pharmacodynamic genes encoding drug targets, and pharmacotypic genes impacting disease presentation and subtype. Among pharmacokinetic markers, CYP2D6 metabolizer phenotype has clear clinical significance, as it impacts dosing considerations for aripiprazole, iloperidone and risperidone, and variants of the ABCB1 gene hold promise as biomarkers for dosing for olanzapine and clozapine. Among pharmacodynamic variants, the TaqIA1 allele of the DRD2 gene, the DRD3 (Ser9Gly) polymorphism, and the HTR2C -759C/T polymorphism have emerged as potential biomarkers for response and/or side effects. However, large-scale candidate gene studies and genome-wide association studies indicate that pharmacotypic genes may ultimately prove to be the richest source of biomarkers for response and side effect profiles for second-generation antipsychotics.

Priapism associated with iloperidone: a case report

Priapism is a known side effect of antipsychotics. The causal mechanism seems to be mediated through α1-adrenergic receptor blockade which many antipsychotics are known to possess. We present the first detailed case of iloperidone-induced priapism in a patient with bipolar disorder with psychotic features. His case highlights some of the important risk factors clinicians should consider when using iloperidone, as it may be the highest-risk antipsychotic for causing priapism given it is a very potent blocker of the alpha-adrenergic receptor.

The effects of novel and newly approved antipsychotics on serum prolactin levels: a comprehensive review

Since the 1970s, clinicians have increasingly become more familiar with hyperprolactinemia (HPRL) as a common adverse effect of antipsychotic medication, which remains the cornerstone of pharmacological treatment for patients with schizophrenia. Although treatment with second-generation antipsychotics (SGAs) as a group is, compared with use of the first-generation antipsychotics, associated with lower prolactin (PRL) plasma levels, the detailed effects on plasma PRL levels for each of these compounds in reports often remain incomplete or inaccurate. Moreover, at this moment, no review has been published about the effect of the newly approved antipsychotics asenapine, iloperidone and lurasidone on PRL levels. The objective of this review is to describe PRL physiology; PRL measurement; diagnosis, causes, consequences and mechanisms of HPRL; incidence figures of (new-onset) HPRL with SGAs and newly approved antipsychotics in adolescent and adult patients; and revisit lingering questions regarding this hormone. A literature search, using the MEDLINE database (1966-December 2013), was conducted to identify relevant publications to report on the state of the art of HPRL and to summarize the available evidence with respect to the propensity of the SGAs and the newly approved antipsychotics to elevate PRL levels. Our review shows that although HPRL usually is defined as a sustained level of PRL above the laboratory upper limit of normal, limit values show some degree of variability in clinical reports, making the interpretation and comparison of data across studies difficult. Moreover, many reports do not provide much or any data detailing the measurement of PRL. Although the highest rates of HPRL are consistently reported in association with amisulpride, risperidone and paliperidone, while aripiprazole and quetiapine have the most favorable profile with respect to this outcome, all SGAs can induce PRL elevations, especially at the beginning of treatment, and have the potential to cause new-onset HPRL. Considering the PRL-elevating propensity of the newly approved antipsychotics, evidence seems to indicate these agents have a PRL profile comparable to that of clozapine (asenapine and iloperidone), ziprasidone and olanzapine (lurasidone). PRL elevations with antipsychotic medication generally are dose dependant. However, antipsychotics having a high potential for PRL elevation (amisulpride, risperidone and paliperidone) can have a profound impact on PRL levels even at relatively low doses, while PRL levels with antipsychotics having a minimal effect on PRL, in most cases, can remain unchanged (quetiapine) or reduce (aripiprazole) over all dosages. Although tolerance and decreases in PRL values after long-term administration of PRL-elevating antipsychotics can occur, the elevations, in most cases, remain above the upper limit of normal. PRL profiles of antipsychotics in children and adolescents seem to be the same as in adults. The hyperprolactinemic effects of antipsychotic medication are mostly correlated with their affinity for dopamine D2 receptors at the level of the anterior pituitary lactotrophs (and probably other neurotransmitter mechanisms) and their blood-brain barrier penetrating capability. Even though antipsychotics are the most common cause of pharmacologically induced HPRL, recent research has shown that HPRL can be pre-existing in a substantial portion of antipsychotic-naïve patients with first-episode psychosis or at-risk mental state.

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.

A review of the pharmacology, efficacy and tolerability of recently approved and upcoming oral antipsychotics: an evidence-based medicine approach

Evidence-based medicine (EBM) is a broad concept, but the key elements include the incorporation of clinical judgment (which requires clinical experience) together with relevant scientific evidence while remaining mindful of the individual patient's values and preferences. Using the framework and philosophy of EBM, this systematic review summarizes the pharmacology, efficacy, and tolerability of newly approved oral antipsychotics, including iloperidone, asenapine, and lurasidone, and outlines what is known about agents that are in late-stage clinical development, such as cariprazine, brexpiprazole, zicronapine, bitopertin, and EVP-6124. Potential advantages and disadvantages of these agents over existing antipsychotics are outlined, centered on clinically relevant issues such as the potential for weight gain and metabolic abnormalities, potential association with somnolence/sedation, extra-pyramidal side effects, akathisia, and prolongation of the electrocardiogram (ECG) QT interval, as well as practical issues regarding dosing instructions, titration requirements, and drug-drug interactions. Lurasidone appears to be best in class in terms of minimizing untoward alterations in body weight and metabolic variables. However, iloperidone, asenapine, lurasidone, and cariprazine differ among themselves in terms of on-label dosing frequency (once daily for lurasidone and, presumably, cariprazine versus twice daily for iloperidone and asenapine), the need for initial titration to a therapeutic dose for iloperidone and possibly cariprazine, requirement to be taken sublingually for asenapine, requirement for administration with food for lurasidone, lengthening of the ECG QT interval (greater for iloperidone than for asenapine and no effect observed with lurasidone), and adverse effects such as akathisia (seen with cariprazine, lurasidone, and asenapine but not with iloperidone) and sedation (most notable with asenapine).

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.

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.

Body weight and metabolic adverse effects of asenapine, iloperidone, lurasidone and paliperidone in the treatment of schizophrenia and bipolar disorder: a systematic review and exploratory meta-analysis

BACKGROUND

The introduction of second-generation antipsychotics (SGAs) over the past 2 decades generated considerable optimism that better antipsychotic treatments for schizophrenia and bipolar disorder were possible. SGAs offer several tolerability benefits over first-generation antipsychotics (FGAs), particularly with respect to extrapyramidal symptoms. However, SGAs can induce serious metabolic dysregulations, especially in drug-naive, first-episode, and child and adolescent populations, with olanzapine and clozapine having the highest propensity to cause these abnormalities. In this context, newer SGAs were developed to further improve the adverse effect burden of available agents. However, until now, the metabolic risk profile of the newly approved SGAs - asenapine, iloperidone, lurasidone and paliperidone (paliperidone extended release and paliperidone palmitate) - has not been compared.

OBJECTIVE

The objective of this systematic review and exploratory meta-analysis was to assess the effects of asenapine, iloperidone, lurasidone and paliperidone on body weight and other metabolic parameters (cholesterol, triglycerides and glucose), as this information is relevant to guide clinical decision making.

METHOD

A systematic literature search (1966-March 2012), using the Cochrane Central Register of Controlled Trials and MEDLINE, CINAHL and EMBASE databases, was conducted for randomized, placebo-controlled and head-to-head clinical trials of asenapine, iloperidone, lurasidone and paliperidone. Published and unpublished data on changes in body weight and glucose and lipid metabolism parameters were extracted. For placebo-controlled, short-term (≤12 weeks) and longer-term (>12 weeks) trials with available data on ≥7% weight increase compared with pre-treatment weight, or mean weight change with standard deviation, a formal meta-analysis was performed, estimating the pooled effect size (represented as relative risk [RR], numbers-needed-to-harm [NNH] and weighted mean difference [WMD]). An exploratory meta-analysis was also performed for the other metabolic variables (cholesterol, triglycerides and glucose). Data from active- and placebo-controlled studies were used for a pooled comparison of simple mean changes in weight, cholesterol, triglyceride and glucose levels.

RESULTS

Fifty-six trials (n = 21 691) in schizophrenia (N = 49, n = 19 299) or bipolar disorder (N = 7, n = 2392) were identified (asenapine: N = 9, iloperidone: N = 11, lurasidone: N = 8, paliperidone: N = 28). Most of the trials (64.3%) were of ≤12 weeks' duration. In the short-term trials, compared with placebo, a ≥7% weight increase was statistically significantly (p < 0.05) most prevalent for asenapine (5 trials, n = 1360, RR = 4.09, 95% confidence interval [CI] 2.25, 7.43, NNH = 17), followed by iloperidone (4 trials, n = 1931, RR = 3.13, 95% CI 2.08, 4.70, NNH = 11) and paliperidone (12 trials, n = 4087, RR = 2.17, 95% CI 1.64, 2.86, NNH = 20). The effect of lurasidone on body weight (6 trials, n = 1793, RR = 1.42, 95% CI 0.87, 2.29) was not statistically significant. Short-term weight gain was statistically significantly (p < 0.001) greater than placebo with iloperidone (1 trial, n = 300, +2.50 kg, 95% CI 1.92, 3.08), paliperidone (15 trials, n = 3552, +1.24 kg, 95% CI 0.91, 1.57), asenapine (3 trials, n = 751, +1.16 kg, 95% CI 0.83, 1.49), as well as with lurasidone (5 trials, n = 999, +0.49 kg, 95% CI 0.17, 0.81, p < 0.01). Sufficient meta-analysable, longer-term, weight change data were only available for asenapine and paliperidone, showing statistically significantly (p < 0.001) greater weight gain versus placebo for both drugs (asenapine, 3 trials, n = 311, +1.30 kg, 95% CI 0.62, 1.98; paliperidone, 6 trials, n = 1174, +0.50 kg, 95% CI 0.22, 0.78). Although statistically significant, in general, no clinically meaningful differences were observed between the four newly approved SGAs and placebo regarding the mean change from baseline to endpoint in cholesterol levels in short-term trials, with the exception of iloperidone for total cholesterol (1 trial, n = 300, +11.60 mg/dL, 95% CI 4.98, 18.22, p ≤ 0.001), high-density cholesterol (1 trial, n = 300, +3.6 mg/dL, 95% CI 1.58, 5.62, p < 0.001) and low-density cholesterol (1 trial, n = 300, +10.30 mg/dL, 95% CI 4.94, 15.66, p < 0.001) and with the exception of lurasidone for high-density cholesterol (5 trials, n = 1004, +1.50 mg/dL, 95% CI 0.56, 2.44, p < 0.01). Asenapine increased total cholesterol statistically significantly (p < 0.05) during longer-term treatment (1 trial, n = 194, +6.53 mg/dL, 95% CI 1.17, 11.89). Regarding triglycerides, only short-term (3 trials, n = 1152, +1.78 mg/dL, 95% CI 0.40, 3.17, p < 0.01) and longer-term treatment with paliperidone (4 trials, n = 791, -0.20 mg/dL, 95% CI -0.40, -0.01, p < 0.05) had a statistically, but not clinically, significant effect. Statistically significant changes in glucose levels were noticed during short-term treatment with asenapine (2 trials, n = 379, -3.95 mg/dL, 95% CI -7.37, -0.53, p < 0.05) and iloperidone (1 trial, n = 300, +6.90 mg/dL, 95% CI 2.48, 11.32, p < 0.01), and during long-term treatment with paliperidone (6 trials, n = 1022, +3.39 mg/dL, 95% CI 0.42, 6.36, p < 0.05).

CONCLUSION

While preliminary data suggest the lowest weight gain potential with lurasidone and potentially relevant short-term metabolic effects for asenapine and iloperidone, data are still too sparse to comprehensively evaluate the metabolic safety of the newly approved SGAs. Therefore, there is a clear need for further controlled studies to evaluate whether these agents are less problematic regarding treatment-emergent weight gain and metabolic disturbances than other currently available antipsychotics.

Clinical Need and Rationale for Multi-Target Drugs in Psychiatry

High attrition in attempts to discover new pharmacological agents for the treatment of psychiatric disorders has triggered a decline in R&D investment in important disease categories such as schizophrenia and mood disorders. Poor knowledge about disease molecular pathology and molecular target validation coupled with notable costly failures involving clinical trials with highly novel and selective single target agents (STAs) have contributed to the development of this trend. One positive development arising from the current situation is the renewed interest in investigating approaches involving multi-target agents (MTAs), which have historically shown a strong track record of success and utility in the treatment of psychiatric disorders. However, it is clear that the traditional serendipity-dependent drug discovery approach for multi-target agents is suboptimal and has to evolve towards a new model of rationally designed and tailored MTAs. It is of course highly challenging to optimise compounds across several therapeutic targets whilst minimising potential broad receptor promiscuity as well as other properties to generate high quality drug candidates. Nevertheless, recent developments in medicinal chemistry approaches and pharmacological evaluation suggest that feasibility for tailored MTAs is not unrealistic. Appropriately designed MTAs, such as hybrids of validated and unprecedented novel molecular targets, offer a multi-functional pharmacology with the potential for multi-symptomatic efficacy and multi-indicational use. If successful this will help to address the compelling unmet medical need and the treatment requirements of schizophrenia and mood disorder patients as well as easing the burden of carers and the societal costs arising from these devastating illnesses.

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, asenapine, and lurasidone: a brief overview of 3 new second-generation antipsychotics

Three new second-generation antipsychotics were approved by the US Food and Drug Administration in 2009 and 2010: iloperidone, asenapine, and lurasidone. All 3 agents are approved for the treatment of acute schizophrenia in adults, and asenapine is also approved for the maintenance treatment of schizophrenia and as a monotherapy or as an adjunct to lithium or valproate for the treatment of bipolar manic or mixed episodes. The expectation is that these new agents will be less problematic regarding treatment-emergent weight gain and metabolic disturbances, which unfortunately can occur with several other second-generation antipsychotics. Asenapine is a sublingual preparation, in contrast to iloperidone and lurasidone, which are swallowed. Iloperidone and asenapine are dosed twice daily, in contrast to lurasidone, which is dosed once daily with food. Both asenapine and lurasidone can be initiated at a dose that is possibly therapeutic, but iloperidone requires 4 days of titration to reach its recommended target dose range. Although both asenapine and lurasidone can be associated with dose-related treatment-emergent akathisia, iloperidone is essentially free of extrapyramidal adverse effects or akathisia throughout its recommended dose range. Sedation and/or somnolence have been reported with each medication. They are the most common adverse events associated with asenapine treatment, and are clearly dose-related for lurasidone. In contrast, no therapeutic dose response for iloperidone, asenapine, or lurasidone is clearly evident from short-term clinical trials. Longer-term and naturalistic studies will be helpful in evaluating these agents and their role in the psychiatric armamentarium.