Oral paliperidone extended-release: chemistry, pharmacodynamics, pharmacokinetics and metabolism, clinical efficacy, safety and tolerability

In vivo deposition of poorly soluble drugs

Administered drug molecules, whether dissolved or solubilized, have the potential to precipitate and accumulate as solid forms in tissues and cells within the body. This phase transition can significantly impact the pharmacokinetics of treatment. It is thus crucial to gain an understanding of how drug solubility/permeability, drug formulations and routes of administration affect in vivo behaviors of drug deposition. This review examines literature reports on the drug deposition in tissues and cells of poorly water-soluble drugs, as well as underlying physical mechanisms that lead to precipitation. Our work particularly highlights drug deposition in macrophages and the subcellular fate of precipitated drugs. We also propose a tissue permeability-based classification framework to evaluate precipitation potentials of poorly soluble drugs in major organs and tissues. The impact on pharmacokinetics is further discussed and needs to be considered in developing drug delivery systems. Finally, bioimaging techniques that are used to examine aggregated states and the intracellular trafficking of absorbed drugs are summarized.

Assessing the Clinical Efficacy of Therapeutic Drug Monitoring for Risperidone and Paliperidone in Patients with Schizophrenia: Insights from a Clinical Data Warehouse

This study investigated the usage patterns and impact of therapeutic drug monitoring (TDM) for risperidone and paliperidone in patients diagnosed with schizophrenia, utilizing retrospective real-world data sourced from a single center's Clinical Data Warehouse. Our study cohort comprised patients diagnosed with schizophrenia undergoing treatment with either risperidone or paliperidone. Data on demographic characteristics, comorbidities, medication utilization, and clinical outcomes were collected. Patients were categorized into two groups: those undergoing TDM and those not undergoing TDM. Additionally, within the TDM group, patients were further stratified based on their risperidone and paliperidone concentrations relative to the reference range. The findings revealed that patients in the TDM group received higher risperidone and paliperidone doses (320 mg/day and 252 mg/day, p = 0.0045) compared to their non-TDM counterparts. Nevertheless, no significant disparities were observed in hospitalization rates, duration of hospital stays, or compliance between the two groups (p = 0.9082, 0.5861, 0.7516, respectively). Subgroup analysis within the TDM cohort exhibited no notable distinctions in clinical outcomes between patients with concentrations within or surpassing the reference range. Despite the possibility of a selection bias in assigning patients to the groups, this study provides a comprehensive analysis of TDM utilization and its ramifications on schizophrenia treatment outcomes.

Evidence for Therapeutic Drug Monitoring of Atypical Antipsychotics

Second-generation antipsychotics (SGAs), also known as atypical antipsychotics, are a newer class of antipsychotic drugs used to treat schizophrenia, bipolar disorder, and related psychiatric conditions. The plasma concentration of antipsychotic drugs is a valid measure of the drug at its primary target structure in the brain, and therefore determines the efficacy and safety of these drugs. However, despite the well-known high variability in pharmacokinetics of these substances, psychiatric medication is usually administered in uniform dosage schedules. Therapeutic drug monitoring (TDM), as the specific method that can help personalised medicine in dose adjustment according to the characteristics of the individual patient, minimizing the risk of toxicity, monitoring adherence, and increasing cost-effectiveness in the treatment, thus seems to be an elegant tool to solve this problem. Non-response to therapeutic doses, uncertain adherence to medication, suboptimal tolerability, or pharmacokinetic drug-drug interactions are typical indications for TDM of SGAs. This review aims to summarize an overview of the current knowledge and evidence of the possibilities to tailor the dosage of selected SGAs using TDM, including the necessary pharmacokinetic parameters for personalised pharmacotherapy.

Risperidone is not only a prodrug: psychosis induced by medication switch from risperidone to paliperidone - a case report

Once administered, risperidone is converted into its pharmacologically active form, paliperidone. Thus, their pharmacological effects are expected to be equivalent. We encountered a psychosis induced by the switch from risperidone to paliperidone.This is the case of a schizoaffective patient stabilised on risperidone long-acting injection (LAI) who consented to switch to paliperidone LAI. On day 0, he received his first dose of paliperidone. On day 86, he presented to the emergency department with an acute psychotic episode. On day 92, he committed a violent act. The patient was restarted on risperidone LAI and stabilised.Risperidone is extensively metabolised to paliperidone via CYP450 2D6. Interindividual and ethnic genetic polymorphism cause variability in CYP450 2D6 phenotypes. In this possible case of low-functioning alleles, the patient had a higher risperidone to paliperidone ratio at steady state. Although risperidone is paliperidone's prodrug, this case highlights the interindividual pharmacotherapeutic response to these two antipsychotics.

Optimization of maintenance therapy of Risperidone with CYP2D6 genetic polymorphisms through an extended translational framework-based prediction of target occupancies/clinical outcomes

Risperidone, one of the second-generation antipsychotics, can efficiently target dopamine D₂ and serotonin 5-HT_2A receptors. There actually exists significant implication of CYP2D6 genetic polymorphisms on the metabolic kinetics of risperidone, little is known about the extent of CYP2D6 impacting human D2 and 5-HT2A receptor occupancies as well as the clinical efficacy and efficacy in schizophrenia treatment. Here we assessed the influences of CYP2D6 gene polymorphisms on human target occupancies/clinical outcomes and optimized the maintenance therapy of risperidone. A translational framework, previously developed using in vitro and in vivo information in rats, was used as the basis for integrating the effects of CYP2D6 genetic polymorphisms on target occupancies and clinical outcomes. D₂ occupancy as a biomarker was related to Positive and Negative Syndrome Scale (PANSS) response and Simpson-Angus Scale (SAS). The population approach was applied to characterize pharmacokinetic and pharmacodynamic (PK/PD) profiles of risperidone. Non-compartment analysis method was performed to calculate the steady state PK/PD parameters of both risperidone and 9-hydroxyrisperidone. The predictive power of this extended translational framework was determined by comparing the predictions of target occupancies and clinical outcomes with the reported human values of risperidone at clinically suggested dosage of 4.0 mg/day. This extended translational framework was adequately used to predict human target occupancies and clinical outcomes. At the steady state, D₂ ROs were 75.8%, 79.3% and 86.0% for CYP2D6 poor metabolizer (PM), intermediate metabolizer (IM) and extensive metabolizer (EM), respectively; 5-HT_2A ROs were 96.4%, 97.2% and 98.4% for CYP2D6 PM, IM and EM, respectively; PANSS changes from placebo were -5.3, -7.7 and -11.3 for CYP2D6 PM, IM and EM, respectively; SAS changes from placebo were 0.13, 0.15 and 0.18 for CYP2D6 PM, IM and EM, respectively. The predictions of human D₂, 5-HT_2A RO, PANSS and SAS changes for risperidone with CYP2D6 genetic polymorphisms were well in line with the reported values in clinic. 5.0, 4.0 and 2.5 mg/day were the equivalent dosages of risperidone for CYP2D6 PM, IM and EM, respectively. The optimized maintenance therapy of risperidone was provided through the Three-Step method and the dosage range was 2.5-5.0 mg/day for three CYP2D6 gene groups in the present study. Taken together, our findings demonstrate that this extended translational framework not only differentiates the effects of CYP2D6 genetic polymorphisms on target occupancies and clinical outcomes, but also constitutes a scientific basis to optimize the maintenance therapy of neuropsychiatric patients in clinic.

Tablets of paliperidone using compression-coated technology for controlled ascending release

The aim of this work was to prepare ascending release compression-coated (CC) tablets with paliperidone (PAL) using a simple manufacturing technique and short manufacturing process. The release behavior and mechanisms in vitro of the final tablets was investigated and evaluated. The PAL CC tablets were comprised of a core layer of high viscosity hydroxypropyl cellulose (HPC-H) and a coating layer of high viscosity hydroxypropyl methylcellulose (HPMC-K100M). Several factors such as materials and core tablet compositions were studied for their influence in the formulation procedure. The drug release mechanism was studied using gravimetric analysis. The data could be fitted to the Peppas model. The ascending drug release results were expressed in terms of the slope of the release curve at different time points. Results showed that the formulation could achieve a good ascending drug release when the weight ratio of PAL was 5:1 (core:layer). The fraction of HPC and HPMC was 33 %, and the combination of Eudragit RL-PO was 10%. The ascending release mechanism was due to solvent penetration into the PAL CC tablets, and subsequent drug dissolution from the gelatinous HPC and HPMC matrix erosion. The release mechanism was therefore a combination of diffusion and erosion. This work demonstrated that the compression-coated tablets could achieve controlled ascending release over 24 h for the oral administration systems.

Paliperidone for the treatment of schizophrenia and schizoaffective disorders - a drug safety evaluation

INTRODUCTION

Paliperidone, the major active metabolite of risperidone, is a second-generation antipsychotic that has been developed as an extended-release (ER) oral formulation and a long-acting injectable paliperidone palmitate (PP) formulation. Paliperidone has demonstrated efficacy in the reduction of acute schizophrenia symptoms and clinical benefits were maintained also in the long-term treatments. Paliperidone ER and PP are generally well tolerated with a predictable adverse event profile. Areas covered: Data from studies evaluating safety and tolerability in the acute and maintenance treatment of schizophrenia with paliperidone are reviewed. The reported treatment-emergent adverse events of these formulations are discussed. Expert opinion: In the treatment of schizophrenia and schizoaffective disorders the safety profile has a central role because it can enhance patient compliance. In fact treatment-emergent adverse events are one of the main causes of discontinuation in these patients. In particular the main limitation in the administration of paliperidone could be represented by the onset of hyperprolactinemia (especially in women) and of mild parkinsonism. Paliperidone has a high impact on current long-term drug strategies, especially given the new 3 month long-acting injectable formulation of PP.

Comparative Physicochemical and Pharmacokinetic Properties of Quetiapine and Its Active Metabolite Norquetiapine

Quetiapine (QTP) is an atypical antipsychotic drug commonly used to treat several psychiatric disorders and is metabolized into the active metabolite norquetiapine (NQTP). This study was designed to evaluate and compare the physicochemical properties, metabolic stability, brain distribution, and pharmacokinetics of QTP and NQTP. Compared to QTP, NQTP had a higher pK_a, solubility, and rat liver microsomal stability, optimal log D and similar log P values. For pharmacokinetic evaluation, QTP and NQTP were administered orally and intravenously to rats at various doses. The plasma QTP and NQTP concentrations in rats were determined by a fully-validated liquid-chromatography tandem mass spectrometry (LC-MS/MS). Over the investigated dosing range, both QTP and NQTP showed linear pharmacokinetics. Following oral administration of the same dose, the area under the concentration-time curve (AUC_0-∞) and maximum serum concentration (C_max) were larger after NQTP administration compared to QTP administration. In addition, NQTP had a greater absolute oral bioavailability compared to QTP (15.6% vs. 0.63%, respectively). The brain-to-plasma concentration ratio was greater after NQTP administration compared to the QTP and NQTP ratios after QTP administration. NQTP administration results in increased systemic exposure and brain distribution compared to QTP administration. Future studies are needed to evaluate the pharmacologic and toxicologic effects of increased NQTP exposures.

Early treatment response predicted subsequent clinical response in patients with schizophrenia taking paliperidone extended-release

This 6-week open-labeled study investigated whether early treatment response in patients receiving paliperidone extended-release (paliperidone ER) can facilitate prediction of responses at Week 6. Patients with schizophrenia or schizoaffective disorder were administered 9mg/day of paliperidone ER during the first 2 weeks, after which the dose was adjusted clinically. They were assessed on Days 0, 4, 7, 14, 28, and 42 by the Positive and Negative Syndrome Scale (PANSS). The serum concentrations of 9-hydroxyrisperidone were examined on Days 14 and 42. Among the 41 patients enrolled, 26 were classified as responders (≧50% improvement on total PANSS scores at Week 6). In the receiver-operator curves (ROC) analyses, the changes in total PANSS scores at Week 2 appeared to show more accurate predictability compared to Day 4 and Day 7. At Week 6, no significant correlation was observed between blood 9-hydroxyrisperidone concentration and the total score or changes of PANSS scores. The results suggest that early treatment response to paliperidone ER, particularly at Week 2, can serve as a suitable outcome predictor at Week 6. Using 9mg/day paliperidone ER as an initial dose for schizophrenia treatment exhibited relatively favorable tolerability and feasibility.

Efficacy and tolerability of paliperidone ER in patients with unsatisfactorily controlled schizophrenia by other antipsychotics: a flexible-dose approach

This study evaluates the effectiveness of paliperidone ER in patients with symptomatic but not highly acute schizophrenia in terms of efficacy, safety, and patients' perception of their social functioning and well-being. This is a multicenter, open-label prospective study with a flexible-dose approach; 133 patients were enrolled and followed for 13 weeks after switching to paliperidone ER. Outcome efficacy measures were as follows: the Positive and Negative Syndrome Scale (PANSS), the Clinical Global Impression-Severity (CGI-S) scale, and the Personal and Social Performance (PSP) scale; in addition, the Subjective Well-being under Neuroleptics (SWN-20) scale, the Drug Attitude Inventory (DAI-30), and the sleep evaluation scale were used. Symptom Rating Scale (ESRS), adverse events, and subjective side effects were recorded. 118/133(88.7%) patients completed the study. The mean PANSS score decreased (88.98 ± 10.09 to 66.52 ± 16.29; P < 0.001); 40.5% of the patients achieved improvement of at least 30%. PSP and CGI-S scores as well as DAI-30 and SWN-20 decreased (P < 0.001). ESRS (P < 0.001) decreased significantly from the baseline. Throughout the trial, no deaths occurred and only one serious adverse event was reported. Paliperidone ER has proved to be efficacious, safe, and well tolerated also with this approach more closely resembling actual clinical practice. Patient-relevant outcome parameters such as social functioning and quality of life improved, which is crucial for treatment adherence in clinical practice.

Paliperidone Palmitate for Schizoaffective Disorder: A Review of the Clinical Evidence

INTRODUCTION

Despite being frequently diagnosed, there has been very limited study of efficacious treatments for schizoaffective disorder. Paliperidone had been approved for the treatment of schizoaffective disorder, and a recently completed relapse prevention study of the use of a once-monthly injectable paliperidone formulation has also led to an indication for that preparation to treat schizoaffective disorder.

METHODS

To review the efficacy and tolerability of paliperidone for schizoaffective disorder, we conducted a systematic literature search of studies of paliperidone in the treatment of schizoaffective disorder, and briefly reviewed evidence regarding the somewhat controversial nature of that diagnostic entity.

RESULTS

We located several studies of the use of paliperidone extended release in the treatment of schizoaffective disorder, but only one completed study of the use of paliperidone palmitate, which demonstrated efficacy in preventing relapse. Three other studies are currently recruiting participants. Efficacy and tolerability were similar to the profile of oral paliperidone in the treatment of individuals with schizophrenia. These results were similar for both individuals treated with paliperidone palmitate alone, and for those treated with paliperidone palmitate with adjunctive mood stabilizers and/or antidepressants. The use of paliperidone palmitate does not require initial co-administration of oral paliperidone, has relatively little risk of drug-drug interactions, and its pharmacokinetics are favorable for once-monthly administration, an important treatment option for individuals with psychotic disorders, who may often be non-adherent to effective medication regimens.

CONCLUSION

Paliperidone palmitate is an approved treatment for schizoaffective disorder, and can be efficacious with or without commonly employed adjunctive treatments.

Paliperidone extended-release in patients with non-acute schizophrenia previously unsuccessfully treated with other oral antipsychotics

OBJECTIVE

This study explores relevant outcomes with flexibly dosed paliperidone extended-release (ER) in a real-world design.

RESEARCH DESIGN AND METHODS

Patients were recruited from 23 countries. Adults with non-acute schizophrenia (n = 1812), previously unsuccessfully treated with other oral antipsychotics, were transitioned to paliperidone ER and prospectively treated for 6 months.

MAIN OUTCOME MEASURES

Primary efficacy outcome for patients switching for the main reason of lack of efficacy was ≥ 20% improvement in Positive and Negative Syndrome Scale (PANSS) total scores. For patients switching for main reasons other than lack of efficacy, primary outcome was non-inferiority in efficacy compared with the previous medication.

RESULTS

Among the lack-of-efficacy group, 61% achieved a ≥ 20% improvement in PANSS total scores from baseline to endpoint. For switchers from other than the lack-of-efficacy group, efficacy maintenance after switching to paliperidone ER was confirmed. Clinically relevant and statistically significant symptomatic improvements occurred for each patient group based on main reason for switching.

CONCLUSION

Paliperidone ER was well tolerated and associated with a meaningful clinical response in patients who switched from other oral antipsychotics, with insomnia and anxiety as most frequent side-effects.

Influencing Factors and Predictors of Early Response in Schizophrenia Patients Receiving the Paliperidone Extended-Release Tablets (Paliperidone ER)

OBJECTIVE

Paliperidone extended-release tablet (paliperidone ER) is a new oral psychotropic agent developed for schizophrenia treatment. There have been some studies about paliperidone's good efficacy and tolerability. Clinicians appear to change the antipsychotic medication to paliperidone ER. However, it is not known what patients are favorable responsive to paliperidone ER. The aim of this study was to evaluate the characteristics of early responders and investigate predictors of acute response when the medications changed to paliperidone ER.

METHODS

Data were analyzed from schizophrenic patients who participated in a multi-center, open-label, non-comparative clinical trial. Total 320 patients were examined in this study. Sociodemographic, psychopathology, social function and metabolic data were evaluated. Unpaired t-test for continuous and χ(2) for categorical data, respectively, were used to compare early responder and non-responders. Logistic regression analysis was used to establish a prediction model.

RESULTS

38.7% of study subjects (124 of 320) responded to paliperidone ER treatment. Logistic regression analysis showed that a good paliperidone ER response was more likely when patients were social drinkers, when patients had started medication at inpatient, when negative symptoms were less severe, and when patients' social relationship and self-care were better.

CONCLUSION

Early response to paliperidone ER treatment is associated with less negative symptoms and good social relationships and self-care. Strategies to reduce these symptoms may contribute to early response to paliperidone ER.