Short-term safety and pharmacokinetic profile of asenapine in older patients with psychosis

Optimisation of pharmacotherapy in psychiatry through therapeutic drug monitoring, molecular brain imaging and pharmacogenetic tests: Focus on antipsychotics

BACKGROUND

For psychotic disorders (i.e. schizophrenia), pharmacotherapy plays a key role in controlling acute and long-term symptoms. To find the optimal individual dose and dosage strategy, specialised tools are used. Three tools have been proven useful to personalise drug treatments: therapeutic drug monitoring (TDM) of drug levels, pharmacogenetic testing (PG), and molecular neuroimaging.

METHODS

In these Guidelines, we provide an in-depth review of pharmacokinetics, pharmacodynamics, and pharmacogenetics for 45 antipsychotics. Over 30 international experts in psychiatry selected studies that have measured drug concentrations in the blood (TDM), gene polymorphisms of enzymes involved in drug metabolism, or receptor/transporter occupancies in the brain (positron emission tomography (PET)).

RESULTS

Study results strongly support the use of TDM and the cytochrome P450 (CYP) genotyping and/or phenotyping to guide drug therapies. Evidence-based target ranges are available for titrating drug doses that are often supported by PET findings.

CONCLUSION

All three tools discussed in these Guidelines are essential for drug treatment. TDM goes well beyond typical indications such as unclear compliance and polypharmacy. Despite its enormous potential to optimise treatment effects, minimise side effects and ultimately reduce the global burden of diseases, personalised drug treatment has not yet become the standard of care in psychiatry.

Asenapine pharmacokinetics and tolerability in a pediatric population

Purpose

This study aimed to characterize the pharmacokinetic (PK) properties, safety, and tolerability of asenapine, and to develop a population PK model in pediatric patients with schizophrenia, bipolar disorder, or other psychiatric disorders.

Methods

Two Phase I multiple ascending-dose studies were conducted to evaluate the PK, safety, and tolerability of sublingual asenapine in pediatric patients (age 10–17 years) with schizophrenia or bipolar I disorder. Patients received asenapine 1–10 mg twice daily for up to 12 days. PK parameters (maximum concentration [C_max], area under the curve from 0 to 12 hours [AUC_0–12], time to C_max [T_max], and half-life) were summarized for asenapine with descriptive statistics, and safety parameters were collected. A population PK model, which included the two Phase I studies and two additional Phase III efficacy studies (asenapine 2.5–10 mg twice daily for up to 8 weeks, age 10–17 years), was developed using nonlinear mixed-effect modeling based on a previously developed adult PK model. The final model was used in simulations to obtain asenapine-exposure estimates across pediatric subgroups and to determine if intrinsic covariates warrant dose adjustments.

Results

The PK of asenapine showed rapid absorption (T_max ~1 hour) with an apparent terminal half-life between 16 and 32 hours. Increases in mean C_max and AUC_0–12 appeared to be dose-proportional in one study and near dose-proportional in the second study. Steady state was attained within 8 days. The most frequently occurring treatment-emergent adverse events were dysgeusia, sedation, and oral hypoesthesia. Simulation-based estimates of C_max and AUC_0–12 were similar for pediatric and adult patients; age, body-mass index, race, and sex were not associated with changes in asenapine exposure.

Conclusion

Asenapine was generally safe and well tolerated in pediatric patients aged 10–17 years. PK and safety data were similar to that observed in the adult population. Intrinsic factors had no significant impact on asenapine exposure, indicating there is no need for dose adjustments in the pediatric population.

Rapid vs. slow antipsychotic initiation in schizophrenia: A systematic review and meta-analysis

BACKGROUND

How antipsychotics should be initiated/titrated in patients with acute schizophrenia as well as patients undergoing an antipsychotic switch remains a question.

METHODS

MEDLINE, Embase, and Cochrane Central Register of Controlled Trials were systematically searched. Randomized controlled trials examining rapid vs. slow antipsychotic initiation in patients with schizophrenia were selected. Data on study discontinuation, psychopathology, extrapyramidal symptoms (EPS), and treatment-emergent adverse events (TEAEs) were extracted and synthesized in studies including clinically different populations of acute patients and stable patients undergoing an antipsychotic switch.

RESULTS

Among 11 studies that met eligibility criteria, 8 and 3 studies involving 809 and 777 patients were identified as acute patient studies and stable patient switching studies, respectively. Rapid antipsychotic initiation was not significantly different from slow antipsychotic initiation in acute patient studies for all-cause study discontinuation, while the former was significantly inferior to the latter in stable patient switching studies (N=3, n=777, RR=1.45, 95% CI=1.05-2.00, P=0.02). In contrast, rapid initiation was significantly superior to slow initiation for all psychopathology outcomes including the PANSS/BPRS total score (N=3, n=336, SMD=-0.28, 95% CI=-0.51--0.05, P=0.02) in acute patient studies, but not different in stable patient switching studies. Any other outcomes except for nausea did not significantly differ between the 2 groups.

CONCLUSIONS

Rapid initiation of antipsychotics may represent a reasonable option for the treatment of acute schizophrenia, while slower initiation may be a safer strategy when switching antipsychotics in stable schizophrenia. Because of the low to very low quality of evidence, findings should be considered preliminary.

Asenapine: A Review in Schizophrenia

Asenapine (Saphris(®), Sycrest(®)) is an atypical antipsychotic that is administered sublingually twice daily and is approved for schizophrenia in the USA, Japan and other countries, but not in the EU. This article reviews the pharmacology, clinical efficacy and tolerability profile of asenapine in the treatment of adults with schizophrenia. Clinical trials with asenapine have demonstrated efficacy in terms of both positive and negative symptoms of schizophrenia, although findings have not always been consistent. Across three short-term (6-week) studies in acute schizophrenia (including one in Asian patients), asenapine was generally superior to placebo and had broadly similar efficacy to active controls in improving total scores on the Positive and Negative Syndrome Scale. A meta-analysis of four short-term trials with asenapine (that also included a negative study and a failed trial) also showed significant benefit with asenapine over placebo. In longer-term trials and extensions (up to ≈3 years' duration), asenapine was effective relative to placebo in preventing relapse in schizophrenia, but was less effective than olanzapine in patients with schizophrenia or schizoaffective disorder (according to intent-to-treat LOCF analysis). However, in two trials in patients with persistent negative symptoms of schizophrenia, asenapine and olanzapine were similarly effective in reducing negative symptoms at week 26, with asenapine providing better results than olanzapine at week 52 in one of the extensions. The most frequently reported adverse events with asenapine are somnolence, akathisia and oral hypoesthesia. Although potentially associated with more extrapyramidal symptoms, asenapine appears to have less weight gain and metabolic effects than some other antipsychotic agents, such as olanzapine.

Atypical antipsychotic-induced metabolic disturbances in the elderly

The metabolic side effects of atypical antipsychotics (AAPs) have been widely studied in younger populations, but research investigating these sequelae in the elderly is lacking. This article reviews the available literature examining the use of AAPs in the elderly, evaluating their association with weight gain and changes in blood glucose and lipid parameters. We find a relative paucity of studies in this area; while some data highlight significant, collective changes in metabolic parameters, the majority suggests an apparent low vulnerability to these side effects. We conclude that the risk and clinical implications of unfavorable metabolic changes in the elderly being treated with AAP medications remain largely undetermined, and we caution against drawing firm conclusions based on the available data. The conflicting evidence leaves us recommending that metabolic monitoring be implemented, with regular follow-up as advocated in other populations.

Weight gain and antipsychotics: a drug safety review

INTRODUCTION

Second-generation antipsychotics (SGAs) are widely used in several psychiatric disease entities and exert to a different extent a risk for antipsychotic-induced weight gain (AIWG). As AIWG is associated with an increase in metabolic syndrome or cardiovascular events, knowledge of these risks is crucial for further monitoring and the initiation of counteractive measures.

AREAS COVERED

We searched PubMed and Web of Sciences for randomized-controlled trials and naturalistic observational studies published between 2010 and 2014 with sample sizes exceeding 100, including all marketed SGAs apart from zotepine, and providing data on weight increase. We also summarized relevant systematic reviews and meta-analyses of head-to-head comparisons.

EXPERT OPINION

Recently published data still support the hierarchical ranking of SGAs already proposed in previous reviews ranking clozapine and olanzapine as having the highest risk, followed by amisulpride, asenapine, iloperidone, paliperidone, quetiapine, risperidone and sertindole in the middle, and aripiprazole, lurasidone and ziprasidone with the lowest risk. Number needed to harm varied considerably in our meta-analysis. Younger patients and patients with a lower baseline body mass index are most vulnerable. The greatest amount of weight gain occurs within the first weeks of treatment. AIWG occurs in all diagnostic groups and is also common in treatment with first-generation antipsychotics; therefore, awareness of this adverse event is essential for anyone prescribing antipsychotics.

Asenapine review, part I: chemistry, receptor affinity profile, pharmacokinetics and metabolism

INTRODUCTION

Asenapine is a second-generation (atypical) antipsychotic currently marketed for the treatment of schizophrenia and bipolar mania/mixed episodes.

AREAS COVERED

The purpose of this review is to describe the chemistry, pharmacodynamics, and pharmacokinetics of asenapine.

EXPERT OPINION

Asenapine has a complex pharmacodynamic profile with affinities at multiple dopamine, serotonin, histamine, and α-adrenergic receptors, all at which asenapine functions as an antagonist. Sublingual asenapine tablets are absorbed in the oral mucosa, with a Tmax occurring between 30 and 90 min. Terminal half-life is approximately 24 h. Asenapine has multiple inactive metabolites, produced via direct glucuronidation (primarily via UGT1A4), demethylation, and oxidative metabolism (primarily via CYP1A2). Hepatic and renal routes contribute approximately equally to the elimination of asenapine and its metabolites. Two notable drug-drug interactions are evident: asenapine (an inhibitor of CYP2D6) can increase plasma levels of paroxetine, and fluvoxamine (a CYP1A2 inhibitor) can increase plasma levels of asenapine. Caution is required when coadministering asenapine with drugs that are both substrates and inhibitors of CYP2D6.

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.

Metabolic side-effects of the novel second-generation antipsychotic drugs asenapine and iloperidone: a comparison with olanzapine

Background

The second generation antipsychotic (SGA) drugs are widely used in psychiatry due to their clinical efficacy and low incidence of neurological side-effects. However, many drugs in this class cause deleterious metabolic side-effects. Animal models accurately predict metabolic side-effects for SGAs with known clinical metabolic liability. We therefore used preclinical models to evaluate the metabolic side-effects of glucose intolerance and insulin resistance with the novel SGAs asenapine and iloperidone for the first time. Olanzapine was used as a comparator.

Methods

Adults female rats were treated with asenapine (0.01, 0.05, 0.1, 0.5, 1.0 mg/kg), iloperidone (0.03, 0.5, 1.0, 5.0, 10.0 mg/kg) or olanzapine (0.1, 0.5, 1.5, 5.0, 10.0 mg/kg) and subjected to the glucose tolerance test (GTT). Separate groups of rats were treated with asenapine (0.1 and 1.0 mg/kg), iloperidone (1.0 and 10 mg/kg) or olanzapine (1.5 and 15 mg/kg) and tested for insulin resistance with the hyperinsulinemic-euglycemic clamp (HIEC).

Results

Asenapine showed no metabolic effects at any dose in either test. Iloperidone caused large and significant glucose intolerance with the three highest doses in the GTT, and insulin resistance with both doses in the HIEC. Olanzapine caused significant glucose intolerance with the three highest doses in the GTT, and insulin resistance with the higher dose in the HIEC.

Conclusions

In preclinical models, asenapine shows negligible metabolic liability. By contrast, iloperidone exhibits substantial metabolic liability, comparable to olanzapine. These results emphasize the need for appropriate metabolic testing in patients treated with novel SGAs where current clinical data do not exist.

Antipsychotic drug treatment for elderly people with late-onset schizophrenia

BACKGROUND

Schizophrenia is usually considered an illness of young adulthood. However, onset after the age of 40 years is reported in 23% of patients hospitalised with schizophrenia. At least 0.1% of the world's elderly population have a diagnosis of late-onset schizophrenia which seems to differ from earlier onset schizophrenia on a variety of counts including response to antipsychotic drugs.

OBJECTIVES

To assess the effects of antipsychotic drugs for elderly people with late-onset schizophrenia.

SEARCH METHODS

We searched the Cochrane Schizophrenia Group Trials Register (January 2010) which is based on regular searches of CINAHL, EMBASE, MEDLINE and PsycINFO. We inspected references of all identified studies for further trials. We contacted relevant authors of trials for additional information.

SELECTION CRITERIA

All relevant randomised controlled trials that compared antipsychotic drugs with other treatments for elderly people (at least 80% older than 65 years) with a recent (within five years) diagnosis of schizophrenia or schizophrenia like illnesses.

DATA COLLECTION AND ANALYSIS

For the 2010 search, two new review authors (AE, AG) inspected all citations to ensure reliable selection. We assessed methodological quality of trials using the criteria recommended in the Cochrane Handbook for Systematic Reviews of Interventions. AE and AG also independently extracted data. For homogenous dichotomous data, we planned to calculate the relative risk (RR) and 95% confidence interval (CI).

MAIN RESULTS

There were no included studies in the original version of this review (2002 search). The 2010 search for the current update produced 211 references, among which we identified 88 studies. Only one study met the inclusion criteria and was of acceptable quality. This was an eight-week randomised trial of risperidone and olanzapine in 44 inpatients with late-onset schizophrenia. All participants completed the eight-week trial, indicating that both drugs were well tolerated. Unfortunately, this study provided little usable data. We excluded a total of 81 studies, 77 studies because they either studied interventions other than antipsychotic medication or because they involved elderly people with chronic - not late-onset - schizophrenia. We excluded a further four trials of antipsychotics in late-onset schizophrenia because of flawed design. Five studies are still awaiting classification, and one is on-going.

AUTHORS' CONCLUSIONS

There is no trial-based evidence upon which to base guidelines for the treatment of late-onset schizophrenia. There is a need for good quality-controlled clinical trials into the effects of antipsychotics for this group. Such trials are possible. Until they are undertaken, people with late-onset schizophrenia will be treated by doctors using clinical judgement and habit to guide prescribing.