Iloperidone: A new drug for the treatment of schizophrenia

Construction of An Oral Bioavailability Prediction Model Based on Machine Learning for Evaluating Molecular Modifications

OBJECTIVE

This study aims to explore the impact of ADME on the Oral Bioavailability (OB) of drugs and to construct a machine learning model for OB prediction. The model is then applied to predict the OB of modified berberine and atenolol molecules to obtain structures with higher OB.

METHODS

Initially, a drug OB database was established, and corresponding ADME characteristics were obtained. The relationship between ADME and OB was analyzed using machine learning, with Morgan fingerprints serving as molecular descriptors. Compounds from the database were input into Random Forest, XGBoost, CatBoost, and LightGBM machine learning models to train the OB 7prediction model and evaluate its performance. Subsequently, berberine and atenolol were modified using Chemdraw software with ten different substituents for mono-substitution, and chlorine atoms for a full range of double substitutions. The modified molecular structures were converted into the same format as the training set for OB prediction. The predicted OB values of the modified structures of berberine and atenolol were compared.

RESULTS

An OB database of 386 drugs was obtained. It was found that smaller molecular weight and a higher number of rotatable bonds (ten or less) could potentially lead to higher OB. The four machine learning models were evaluated using MSE, R2 score, MAE, and MFE as metrics, with Random Forest performing the best. The models' predictions for the test set were particularly accurate when OB ranged from 30% to 90%. After mono-substitution and double substitution of berberine and atenolol, the OB of both drugs was significantly improved.

CONCLUSIONS

This study found that some ADME properties of molecules do not have an absolute impact on OB. The database played a decisive role in the process of the machine learning OB prediction model, and the performance of the model was evaluated based on predictions within a range of strong generalization ability. In most cases, mono-substitution and double substitution were beneficial for enhancing the OB of berberine and atenolol. In summary, this study successfully constructed a machine learning regression prediction model that can accurately predict drug OB, which can guide drug design to achieve higher OB to some extent.

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.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

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.

Long-term effects of iloperidone on cerebral dopamine receptor subtypes

The atypical antipsychotic drug iloperidone has high affinity for a wide range of neurotransmitter receptors, including dopaminergic (DA), serotonergic, and adrenergic receptors. We examined the long-term effects of multiple doses of iloperidone on DA D1 , D2 , D3 , and D4 receptor subtypes. Sprague-Dawley adult rats (n = 8/group) received daily intraperitoneal injections of iloperiodone (0.5, 1, or 5 mg/kg) or vehicle for 4 weeks. Receptor autoradiography quantified the levels of DA receptors in medial prefrontal cortex (MPC), dorsolateral frontal cortex (DFC), caudate putamen (CPu), nucleus accumbens (NAc), and hippocampus (HIP). Four weeks of iloperidone treatment at 5 mg/kg significantly increased D1 receptors in NAc (36%) and CPu (38%). Iloperidone (1.5 and 5 mg/kg) dose-dependently increased D2 receptors in MPC (37 and 47%) and HIP (32 and 40%). Only the high dose of iloperidone (5 mg/kg) increased D2 receptors in NAc (39%) and CPu (38%). Repeated treatment with iloperidone (1.5 and 5 mg/kg) increased D4 receptors in the NAc (39 and 78%), CPu (42 and 83%) and HIP (54 and 72%). The three doses of iloperidone failed to alter D3 receptors in the brain regions examined in this study. These results suggest that iloperidone exerts region- and dose-specific effects on forebrain DA receptor subtypes, which may contribute to its therapeutic benefits in improving the positive and negative symptoms of schizophrenia with minimal extrapyramidal side effects.

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.

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.

Second-generation and newly approved antipsychotics, serum prolactin levels and sexual dysfunctions: a critical literature review

INTRODUCTION

Using antipsychotic (AP) medication can increase prolactin (PRL) levels and place the patient at risk of sexual dysfunction (SD).

AREAS COVERED

The aim of this review is to describe the PRL propensity of the different second-generation and newly approved APs. It then considers the prevalence rates of SDs associated with these compounds in patients with schizophrenia and treatment strategies for the management of SDs and/or hyperprolactinemia (HPRL). Furthermore, we address the lingering question regarding the association between SDs and PRL.

EXPERT OPINION

SD (particularly long-term) data remain scarce for several APs. A wide variety of assessment techniques used in SD research make reliable comparisons between APs impossible. The majority of these reports do not equally allow us to distinguish between treatment (AP and co-medication)-emergent SDs and illness-related SDs. This makes it difficult to assess the degree to which these side effects are associated with 'PRL-raising' APs, and what part of this fraction is directly reducible to serum PRL levels. Also, few evidence-based treatment strategies for HPRL and associated side effects are available. Therefore, longer-term randomized controlled trials, using reliable and valid structured interviews or questionnaires, are necessary to establish the precise relationship between APs, PRL levels and SDs rates and develop valuable treatment options.

Clinically significant drug interactions with atypical antipsychotics

Atypical antipsychotics [also known as second-generation antipsychotics (SGAs)] have become a mainstay therapeutic treatment intervention for patients with schizophrenia, bipolar disorders and other psychotic conditions. These agents are commonly used with other medications--most notably, antidepressants and antiepileptic drugs. Drug interactions can take place by various pharmacokinetic, pharmacodynamic and pharmaceutical mechanisms. The pharmacokinetic profile of each SGA, especially with phase I and phase II metabolism, can allow for potentially significant drug interactions. Pharmacodynamic interactions arise when agents have comparable receptor site activity, which can lead to additive or competitive effects without alterations in measured plasma drug concentrations. Additionally, the role of drug transporters in drug interactions continues to evolve and may effect both pharmacokinetic and pharmacodynamic interactions. Pharmaceutical interactions occur when physical incompatibilities take place between agents prior to drug absorption. Approximate therapeutic plasma concentration ranges have been suggested for a number of SGAs. Drug interactions that markedly increase or decrease the concentrations of these agents beyond their ranges can lead to adverse events or diminished clinical efficacy. Most clinically significant drug interactions with SGAs occur via the cytochrome P450 (CYP) system. Many but not all drug interactions with SGAs are identified during drug discovery and pre-clinical development by employing a series of standardized in vitro and in vivo studies with known CYP inducers and inhibitors. Later therapeutic drug monitoring programmes, clinical studies and case reports offer methods to identify additional clinically significant drug interactions. Some commonly co-administered drugs with a significant potential for drug-drug interactions with selected SGAs include some SSRIs. Antiepileptic mood stabilizers such as carbamazepine and valproate, as well as other antiepileptic drugs such as phenobarbital and phenytoin, may decrease plasma SGA concentrations. Some anti-infective agents such as protease inhibitors and fluoroquinolones are of concern as well. Two additional important factors that influence drug interactions with SGAs are dose and time dependence. Smoking is very common among psychiatric patients and can induce CYP1A2 enzymes, thereby lowering expected plasma levels of certain SGAs. It is recommended that ziprasidone and lurasidone are taken with food to promote drug absorption, otherwise their bioavailability can be reduced. Clinicians must be aware of the variety of factors that can increase the likelihood of clinically significant drug interactions with SGAs, and must carefully monitor patients to maximize treatment efficacy while minimizing adverse events.

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.

Therapeutic drug monitoring of common antipsychotics

The aim of this review is to provide information for interpreting outcome results from monitoring of antipsychotics in biological samples. A brief overview of the working mechanisms, pharmacological effects, drug interactions, and analytical methods of classical and atypical antipsychotics is given. Nineteen antipsychotics were selected based on their importance in the worldwide market as follows: amisulpride, aripiprazole, asenapine, bromperidol, clozapine, flupenthixol, haloperidol, iloperidone, lurasidone, olanzapine, paliperidone, perphenazine, pimozide, pipamperone, quetiapine, risperidone, sertindole, sulpiride, and zuclopenthixol. A straightforward relationship between administered dose, plasma or serum concentration, clinical outcome, or adverse effects is often lacking. Nowadays, focus lies on therapeutic drug monitoring and individualized therapy to find adequate treatment, to explain treatment failure or nonresponse, and to check patient compliance. However, extensive research in this field is still mandatory.

Overdose of atypical antipsychotics: clinical presentation, mechanisms of toxicity and management

Historically, treatment for schizophrenia focused on sedation. The advent of the typical antipsychotics resulted in treatment aimed specifically at the underlying disease, but these agents were associated with numerous adverse effects, and were not particularly effective at treatment of the negative symptoms of schizophrenia. As a result, numerous atypical agents have been developed over the past 2 decades, including several agents within the past 5 years. Overdose of antipsychotics remains quite common in Western society. In 2010, poison control centres in the US received nearly 43,000 calls related to atypical antipsychotics alone. Due to underreporting, the true incidence of overdose with atypical antipsychotics is likely much greater. Following overdose of an atypical antipsychotic, the clinical effects observed, such as CNS depression, tachycardia and orthostasis are largely predictable based on the unique receptor binding profile of the agent. This article, which focuses on the atypical antipsychotics commonly used in the treatment of schizophrenia, discusses the features commonly encountered in overdose. Specifically, agents that result in QT prolongation and the corresponding potential for torsades de pointes, as well as unique features encountered with the various medications are discussed. The diagnosis of this overdose is largely based on history. Routine use of drug screens is unlikely to be beneficial. The primary goal of management is aggressive supportive care. Patients with significant CNS depression with associated loss of airway reflexes and respiratory failure need advanced airway management. Hypotension should be treated first with intravenous fluids, with the use of direct acting vasopressors reserved for persistent hypotension. Benzodiazepines should be used for seizures, with barbiturates used for refractory seizures. Intravenous magnesium can be administered for patients with a corrected QT interval exceeding 500 milliseconds.

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.

Atypical antipsychotic-induced weight gain: insights into mechanisms of action

Prescriptions for second-generation antipsychotics (SGAs) have surpassed those for first-generation agents in the treatment of schizophrenia and bipolar disorder. While SGAs have the benefit of a much reduced risk of causing movement disorders, they have been associated with weight gain and metabolic effects. These adverse reactions are not uncommon, and threaten to have a significant impact on the patient's health over the long-term treatment that the patient requires. Currently, the aetiology of these effects is not known. This article reviews the data exploring the weight gain phenomenon. The literature was reviewed from searches of PubMed and the references of major articles in the field. The SGAs present a heterogeneous risk for weight gain. In addition, different individuals receiving the same drug can exhibit substantially different weight changes. This pattern suggests that a group of factors are associated with the weight gain phenomenon rather than a single mechanism. Coupled with the genetic profile that the patient brings to the treatment, the risk for SGA-induced weight gain will be different for different drugs and different individuals. Targets for exploration of the weight gain phenomenon include receptor interactions involving serotonin, histamine, dopamine, adrenergic, cannabinoid and muscarinic receptors. The association of SGA-induced weight gain and the role of orexigenic and anorexigenic peptides are reviewed. Also, a brief discussion of genetic factors associated with SGA-induced weight gain is presented, including that of the serotonin 5-HT(2C) receptor gene (HTR2C) and the cannabinoid 1 receptor gene (CNR1). The most promising data associated with SGA-induced weight gain include investigations of the histamine H(1), 5-HT(2A), 5-HT(2C), muscarinic M(3) and adrenergic receptors. In addition, work in the genetic area promises to result in a better understanding of the variation in risk associated with different individuals.