Paliperidone extended release

Zein-maltodextrin nanocomplex based dissolving microneedle: A promising approach for Paliperidone palmitate delivery

Researchers are looking at microneedle devices as a possible solution to the problems with poor patient compliance and severe gastrointestinal side effects associated with conventional oral or injectable techniques for treating schizophrenia. Microneedles (MNs) may be an effective approach for transdermal drug delivery of antipsychotic drugs. We fabricated polyvinyl alcohol (PVA) microneedles loaded with paliperidone palmitate (PLDN) nanocomplex and studied their therapeutic potency for schizophrenia. We demonstrated that PLDN nanocomplex-loaded MNs had a pyramidal shape with high mechanical strength, which allowed us to successfully deliver PLDN into the skin and improve permeation behavior ex-vivo. Microneedling enhanced the concentration of PLDN in plasma and brain tissue as compared with the plain drug as observed. In addition, the therapeutic effectiveness was significantly improved by MNs with the capability of extended release. According to the findings of our study, the nanocomplex-loaded microneedle-mediated transdermal delivery of PLDN has the potential to be a novel treatment for schizophrenia.

Rats and rabbits as pharmacokinetic screening tools for long acting intramuscular depots: case study with paliperidone palmitate suspension

Development of prodrug of 9-hydroxyrisperidone (paliperidone) long-acting intramuscular injection has enabled delivery over four-week time period with improved compliance. The key aim of this work was to establish a reliable preclinical model which may potentially serve as a screening tool for judging the pharmacokinetics of paliperidone formulation(s) prior to human clinical work. Sparse sampling composite study was used in rats, (Wistar/Sprague-Dawley (SD; n = 10)) and a serial blood sampling study design was used in rabbits (n = 4). Animals received intramuscular injection of paliperidone palmitate in the thigh muscle at dose of 16 (rats) and 4.5 mg/kg (rabbits). Samples were drawn in rats (retro-orbital sinus) and rabbits (central ear artery) and were analysed for paliperidone using liquid chromatography-mass spectrometry/ mass spectrometry (LC-MS/MS) assay. The plasma data was subjected to pharmacokinetic analysis. Following intramuscular injection of depot formulation in Wistar/SD rats and rabbits, absorption of paliperidone was slow and gradual with median value of time to reach maximum concentration (T_max) occurring on day 7. The exposures (i.e. area under the curve (AUC; 0-28) days) were 18,597, 21,865 and 18,120 ng.h/mL, in Wistar, SD and rabbits, respectively. The clearance was slow and supported long half-life (8-10 days). Either one of the two models can serve as a research tool for establishing pharmacokinetics of paliperidone formulation(s).

Development and Evaluation of pH-Responsive Cyclodextrin-Based in situ Gel of Paliperidone for Intranasal Delivery

Paliperidone (PLPD) is approved for treatment and management of schizophrenia. The current study demonstrates the potential of in situ gel of PLPD for nasal delivery. The permeation of drug through sheep nasal mucosa was analyzed since the nose-to-brain pathway has been indicated for delivering drugs to the brain. The carbopol 934 (CP)- and hydroxypropyl methyl cellulose K4M (HPMC)-based in situ gels containing 0.2% CP and 0.4% w/v HPMC were optimized using experimental design software. The use of hydroxypropyl-β-cyclodextrin (HP-β-CD) in nasal permeation of drug was investigated. Transmucosal permeation of PLPD was examined using sheep nasal mucosa. The in situ gels of PLPD exhibited satisfactory mucoadhesion and showed sustained drug release. The mucocilliary toxicity and histopathological examination confirmed that the nasal mucosa architecture remains unaffected after treatment with PLPD in situ gel. The formulation containing HP-β-CD complex of PLPD exhibited higher rate of drug permeation through sheep nasal mucosa revealing the role of HP-β-CD as nasal absorption enhancer. Thus, CP- and HPMC-based pH-triggered in situ gel containing HP-β-CD-drug inclusion complex demonstrates a novel nasal delivery of PLPD.

The Effects of Fluvoxamine on the Steady-State Plasma Concentrations of Escitalopram and Desmethylescitalopram in Depressed Japanese Patients

BACKGROUND

The aim of this study was to determine the impact of fluvoxamine, an inhibitor of Cytochrome P450 (CYP) 2C19 (CYP2C19), on the pharmacokinetics of escitalopram, a substrate of CYP2C19.

METHODS

Thirteen depressed patients initially received a 20-mg/d dose of escitalopram alone. Subsequently, a 50-mg/d dose of fluvoxamine was administered because of the insufficient efficacy of escitalopram. Plasma concentrations of escitalopram and desmethylescitalopram were quantified using high-performance liquid chromatography before and after fluvoxamine coadministration. The QT and corrected QT (QTc) intervals were measured before and after fluvoxamine coadministration.

RESULTS

Fluvoxamine significantly increased the plasma concentrations of escitalopram (72.3 ± 36.9 ng/mL versus 135.2 ± 79.7 ng/mL, P < 0.01) but not those of desmethylescitalopram (21.5 ± 7.0 ng/mL versus 24.9 ± 12.0 ng/mL, no significance [ns]). The ratios of desmethylescitalopram to escitalopram were significantly decreased during fluvoxamine coadministration (0.37 ± 0.21 versus 0.21 ± 0.10, P < 0.01). The CYP2C19 genotype did not fully explain the degree of the change. Fluvoxamine coadministration did not change the QT or QTc intervals.

CONCLUSIONS

The results of this study suggest that adjunctive treatment with fluvoxamine increases the concentration of escitalopram. The QTc interval did not change in this condition.

An update of safety of clinically used atypical antipsychotics

INTRODUCTION

The atypical antipsychotic (APs) drugs have become the most widely used agents to treat a variety of psychoses because of their superiority with regard to safety and tolerability profile compared to conventional/'typical' APs.

AREAS COVERED

We aimed at providing a synthesis of most current evidence about the safety and tolerability profile of the most clinically used atypical APs so far marketed. Qualitative synthesis followed an electronic search made inquiring of the following databases: MEDLINE, Embase, PsycINFO and the Cochrane Library from inception until January 2016, combining free terms and MESH headings for the topics of psychiatric disorders and all atypical APs as following: ((safety OR adverse events OR side effects) AND (aripiprazole OR asenapine OR quetiapine OR olanzapine OR risperidone OR paliperidone OR ziprasidone OR lurasidone OR clozapine OR amisulpride OR iloperidone)).

EXPERT OPINION

A critical issue in the treatment with atypical APs is represented by their metabolic side effect profile (e.g. weight gain, lipid and glycaemic imbalance, risk of diabetes mellitus and diabetic ketoacidosis) which may limit their use in particular clinical samples. Electrolyte imbalance, ECG abnormalities and cardiovascular adverse effects may recommend a careful baseline and periodic assessments.

Paliperidone palmitate long-acting injection--prospective year-long follow-up of use in clinical practice

OBJECTIVE

To follow-up patients prescribed paliperidone palmitate long-acting injection (PP) over 1 year to determine factors predicting continuation with PP treatment.

METHOD

Naturalistic observation of patients registered as starting PP in a single healthcare unit in London, UK. Monovariate and multivariate (Cox regression) analysis of factors predicting continuation at 1 year.

RESULTS

Data were available for 210 patients consecutively prescribed PP of whom 10 were lost to follow-up. At 1 year, 65% of 200 patients (176 with a diagnosis of schizophrenia or schizoaffective disorder) started on PP were still receiving it. The main reason for discontinuation was perceived ineffectiveness (52% of discontinuers); only 10 subjects (5% of total) discontinued because of adverse effects. Initiation as an out-patient [hazard ratio (HR) 0.39, 95%CI, 0.20, 0.67, P = 0.001]; being switched from risperidone (HR 0.56, 95%CI 0.32, 0.94, P = 0.026) and correct initiation (HR 0.56, 95%CI 0.34, 0.93, P = 0.024) were significantly associated with a lower likelihood of discontinuation.

CONCLUSION

Paliperidone palmitate was effective and well tolerated in this naturalistic cohort. Optimising treatment by targeting PP for patients identified as having lower risk of discontinuation can give rise to continuation rates approaching 80% at 1 year.

Interaction between paliperidone and carbamazepine

BACKGROUND

This aim of this study was to determine the impact of carbamazepine on the pharmacokinetics of paliperidone.

METHODS

Six schizophrenic patients initially received a 6-12 mg/d dose of paliperidone alone. Subsequently, a 200 mg/d dose of carbamazepine was administered, and the carbamazepine dose was increased to 400 mg/d and then 600 mg/d. Plasma concentrations of paliperidone before and after carbamazepine coadministration were quantified using liquid chromatography tandem mass spectrometry (LC-MS/MS).

RESULTS

Carbamazepine significantly reduced the plasma concentration of paliperidone. The plasma concentration of paliperidone at baseline and with coadministration of 200, 400, and 600 mg/d were 45.8 ± 11.7, 26.9 ± 13.7, 17.1 ± 8.2, and 15.9 ± 7.6 ng/mL, respectively. The concentration of paliperidone with carbamazepine coadministration at doses of 200, 400, and 600 mg/d were 55.7% ± 20.7%, 36.1% ± 12.2%, and 33.6% ± 10.4%, respectively, of baseline. This effect occurred even at the carbamazepine dose of 200 mg/d and reached a plateau at doses higher than 400 mg/d. However, carbamazepine coadministration exacerbated the psychotic symptoms in some patients.

CONCLUSIONS

The results of the present study suggest that adjunctive treatment with carbamazepine reduces the concentration of paliperidone in a dose-dependent manner, most likely because of the induction of several drug-metabolizing enzymes and several drug transporters.

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.

A review of paliperidone palmitate

Risperidone long-acting injection (RLAI) was the first second-generation antipsychotic available as a long-acting injection. Paliperidone (9-hydroxyrisperidone) is the active metabolite of risperidone, introduced initially as an extended release oral (ORal Osmotic System, OROS®, Alza Corporation) formulation (Invega®, Janssen). Paliperidone long-acting injection (PLAI) has now been developed as a suspension of paliperidone palmitate nanocrystals in an aqueous formulation (Invega Sustenna®, Xeplion®), administered monthly by intramuscular injection (deltoid or gluteal). Doses of PLAI can be expressed either in milligram equivalents (mg eq) of paliperidone palmitate or in milligrams of the active fraction of paliperidone. The recommended initiation regimen of 150 mg eq (234 mg) on day 1 and 100 mg eq (156 mg) on day 8 (both administered in the deltoid) achieves therapeutic blood levels rapidly and without the necessity of oral supplementation. No refrigeration or reconstitution prior to administration is required. PLAI has been shown in to be effective in controlling the acute symptoms of schizophrenia as well as delaying time to relapse. Safety and tolerability are comparable to RLAI with no new safety signals. Thus, PLAI may represent the rational development of RLAI with greater ease of use.

Interaction between paliperidone extended release and TS-1(®), an oral anticancer drug containing a 5-fluorouracil derivative, in a schizophrenic patient

Until now there has been no information available on drug interaction between paliperidone and TS-1(®), an oral anticancer drug containing a 5-fluorouracil derivative. The patient in the case presented here was a 39-year-old man with a 15-year history of schizophrenia. The patient's usual treatment of 2 mg/day of risperidone was changed to 3 mg/day of paliperidone extended release. He experienced worsening psychotic symptoms after switching from risperidone to paliperidone while he was also receiving TS-1. Retrospective analyses showed plasma concentration of paliperidone was consistently lower during the treatment with TS-1 than without TS-1. This case suggests there is drug interaction between paliperidone extended-release tablets and TS-1.

Relationship between inflammation and metabolic syndrome following treatment with paliperidone for schizophrenia

OBJECTIVE

Metabolic syndrome and antipsychotic medications are associated with inflammation. This study investigated the relationship between inflammation and metabolic syndrome in patients with schizophrenia. It also examined the effects of paliperidone extended release (ER) treatment on metabolic parameters.

METHODS

Data were analyzed from schizophrenic patients who participated in a multi-center, open-label, non-comparative clinical trial. Anthropomorphic measurements (i.e., weight, waist circumference, and blood pressure) were assessed along with fasting laboratory values, including white blood cell (WBC) count, glucose, high-density lipoprotein, and triglycerides.

RESULTS

Among the 225 patients at baseline, the group with the highest WBC count displayed a 5.9-fold risk for metabolic syndrome compared with that of the lowest group. An increase of 10(3)WBCs/μL was associated with a 1.4-fold increased risk for metabolic syndrome. After 24weeks of treatment with paliperidone ER, significant increases were observed in waist circumference and body weight. Changes in WBC count were positively correlated with changes in waist circumference.

CONCLUSIONS

Schizophrenic patients with high levels of inflammation should be carefully monitored for metabolic syndrome. Moreover, strategies to reduce inflammation and obesity may prevent metabolic syndrome in patients with schizophrenia who take atypical antipsychotic medication.

Paliperidone extended release: in adolescents with schizophrenia

Paliperidone, the major active metabolite of risperidone, is an atypical antipsychotic agent formulated as an extended-release (ER) tablet suitable for once-daily oral administration. Paliperidone ER is approved for the treatment of adolescents aged 12-17 years with schizophrenia in the US (the focus of this review). It is also approved for the treatment of adults with schizophrenia or schizoaffective disorder. Paliperidone ER has shown efficacy in the treatment of patients aged 12-17 years with acutely symptomatic schizophrenia in a randomized, double-blind, parallel-group, placebo-controlled, multicenter, 6-week trial. The primary endpoint was the change from baseline in Positive and Negative Syndrome Scale (PANSS) total score to day 43 or the final assessment point post-baseline. Patients with a PANSS total score of 60-120 received one of three weight-based, fixed once-daily doses of paliperidone ER (patients weighing 29 kg to <51 kg: 1.5 mg [low-dose], 3 mg [medium], or 6 mg [high]; patients weighing ≥51 kg: 1.5 mg [low], 6 mg [medium], or 12 mg [high]), or placebo. Compared with placebo, significant improvements in mean PANSS total scores were reported for the medium-dose (3-6 mg) paliperidone ER treatment groups. There were no significant differences in mean PANSS total scores between the recipients of low-dose or high-dose paliperidone ER versus placebo. Mean PANSS total scores in the actual dose treatment groups (regardless of weight) decreased from baseline (i.e. improved) and were significantly lower for the 3, 6, and 12 mg groups than for the placebo group. Treatment-emergent adverse events were dose related in adolescents with schizophrenia who received weight-based fixed doses of paliperidone ER.

Efficacy and metabolic influence of paliperidone ER, aripiprazole and ziprasidone to patients with first-episode schizophrenia through 52 weeks follow-up in China

BACKGROUND

There are no direct comparisons of paliperidone extended-release (ER), aripiprazole and ziprasidone in efficacy and metabolic influence in patients with first-episode schizophrenia.

OBJECTIVE

The present study examined the efficacy and metabolic influence of paliperidone ER, aripiprazole and ziprasidone in patients with first-episode schizophrenia in China.

METHODS

Subjects were recruited from outpatient and 254 patients entered the trial. These patients received treatment randomly with paliperidone ER, aripiprazole and ziprasidone and were assessed at baseline, 13, 26 and 52 weeks, respectively with Positive and Negative Syndrome Scale (PANSS), 7-item Clinical Global Impressions-Severity (CGI-S), anthropometric (weight, body mass index and waist circumference) and metabolic (fasting blood glucose, HbA1c, cholesterol, high density lipoproteins (HDL), low density lipoproteins and triglycerides) measures.

RESULTS

A total of 203 patients completed the trial. Paliperidone group had significant greater reduction in PANSS than aripiprazole group and ziprasidone group from 13 weeks, although the a reduction in PANSS of each group was more than 20%. There was no difference in CGI-S among the three groups, and all three groups had a significant reduction from baseline in CGI-S. Aripiprazole group increased in weight and body mass index despite no statistical change in waist circumference. Other two groups showed no changes in anthropometric measure. At the end of the study, two glucose metabolic indices (fasting blood glucose and HbA1c) of aripiprazole group were significantly higher than that of baseline. In lipid metabolism, aripiprazole group reduced triglycerides significantly and had no changes in other indices. Paliperidone group reduced HDL and increased triglycerides despite no changes in glucose metabolism. Ziprasidone group also had no significant changes in glucose metabolism, but reduced cholesterol, low density lipoproteins and increased HDL. Furthermore, 22 subjects in three groups reached the diagnostic criteria of metabolic syndrome.

CONCLUSIONS

Paliperidone ER, aripiprazole and ziprasidone are effective in treating first-episode schizophrenia, and the ranking of efficacy from high to low is paliperidone ER > aripiprazole > ziprasidone. Paliperidone ER can impair lipid metabolism potentially but had no influence on glucose metabolism. Aripiprazole can damage glucose metabolism and has little influence on lipid metabolism. Ziprasidone is considered an atypical antipsychotic with no evidence of harm to glucose and lipid metabolism.

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.

Paliperidone extended-release: does it have a place in antipsychotic therapy?

Paliperidone (9-hydroxy-risperidone), the active metabolite of risperidone, was approved for treating schizophrenia worldwide in 2006 as paliperidone extended-release (PER), and became the first second-generation antipsychotic specifically licensed for treating schizoaffective disorder in 2009. However, at the same time, its comparatively high cost gave rise to concerns about the cost-effectiveness of PER as compared with its precursor, risperidone. This paper reviews the existing knowledge of the pharmacology, kinetics, efficacy, tolerability, and fields of application of PER, and compares PER with risperidone in order to determine whether it has a place in antipsychotic therapy. An independent assessment of all relevant publications on PER published until July 2010 was undertaken. PER has a unique pharmacological profile, including single dosing, predominantly renal excretion, low drug-drug interaction risk, and differs from risperidone in terms of mode of action and pharmacokinetics. High-level evidence suggests that PER is efficacious and safe in schizophrenia, schizoaffective disorder, and acute manic episodes. There is a striking lack of published head-to-head comparisons between PER and risperidone, irrespective of indication. Low-level evidence shows a lower risk for hyperprolactinemia and higher patient satisfaction with PER than with risperidone. PER adds to the still limited arsenal of second-generation antipsychotics. In the absence of direct comparisons with risperidone, it remains difficult to come to a final verdict on the potential additional therapeutic benefits of PER which would justify its substantially higher costs as compared with risperidone. However, in terms of pharmacology, the available evidence cautiously suggests a place for PER in modern antipsychotic therapy.

Safety and efficacy of paliperidone extended-release in acute and maintenance treatment of schizophrenia

Paliperidone, the major active metabolite of risperidone, is a second-generation antipsychotic that has been developed as an extended-release (ER) tablet formulation that minimizes peak-trough fluctuations in plasma concentrations, allowing once-daily administration and constant drug delivery. Paliperidone ER has demonstrated efficacy in the reduction of acute schizophrenia symptoms in 6-week, placebo-controlled, double-blind trials and clinical benefits were maintained in the longer-term according to extension studies of up to 52 weeks in duration. Compared with quetiapine, paliperidone ER was associated with a more rapid symptom improvement. In addition, it was more effective than placebo in the prevention of symptom recurrence. Paliperidone ER is generally well tolerated with a predictable adverse event profile. Like risperidone, it is associated with a dose-dependent risk of extrapyramidal symptoms and prolactin elevation. Short- and longer-term studies have indicated a low liability for paliperidone ER to cause metabolic (ie, weight gain, hyperglycaemia and lipid dysregulation) or cardiovascular adverse effects. Available safety data from elderly patients appear to be promising. Due to negligible hepatic biotransformation, paliperidone ER is unlikely to be involved in clinically significant metabolic drug-drug interactions. Additional active comparator trials evaluating efficacy, tolerability and cost-effectiveness are required to better define the role of paliperidone ER in the treatment of schizophrenia in relation to other currently available second-generation antipsychotics, particularly risperidone.

Tolerability of paliperidone: a meta-analysis of randomized, controlled trials

Balancing tolerability and efficacy of medications can be problematic for clinicians when assessing appropriate therapy for patients. For antipsychotic therapy, this can be especially challenging because of the hazardous movement and metabolic effects associated with them. Paliperidone is an atypical antipsychotic used for the treatment of schizophrenia and schizoaffective disorder. A systematic review of the literature for the tolerability of the drug, paliperidone, was performed. A total of 15 articles met the criteria for inclusion representing a total of 3779 patients. Data combination was conducted using the Mantel-Haenszel method, random effects model at 95% confidence. Adverse events with the greatest incidence in the paliperidone population were any treatment emergent adverse event (68%), extra-pyramidal symptoms (23%), headache (14%), insomnia (11%), somnolence (9%), tachycardia (9%) and weight gain (8%). Reported events most likely related to paliperidone [largest attributable risks (AR)] were extra-pyramidal symptoms (AR=10), reduction in acute psychosis (AR=8), any treatment emergent adverse event (AR=6), tachycardia (AR=4), and weight gain (AR=4). Events where incidence was entirely because of paliperidone (incidence equals AR) were hypersalivation (3), dysarthria (2), and sexual dysfunction (1). Reported events totally unrelated to paliperidone (AR=0) included anxiety, asthenia, constipation, depression, dyspepsia, glucose related events, and vomiting. Overall, a 50% reduction in treatment emergent psychosis was seen in schizophrenic patients treated with paliperidone, however the reduction of a psychotic event is about equal to the occurrence of an adverse event with paliperidone.

A population pharmacokinetic evaluation of the influence of CYP2D6 genotype on risperidone metabolism in patients with acute episode of schizophrenia

The objective of this prospective study was to characterize the metabolism of risperidone to (+)- and (-)-9-hydroxyrisperidone in vivo and to evaluate the influence of CYP2D6 genotype. A population pharmacokinetic modeling approach was used to estimate the interindividual variability of the pharmacokinetic parameters in 50 hospitalized patients with acute episode of schizophrenia. CYP2D6 genotype remarkably influenced the formation clearances of the risperidone metabolites, while creatinine clearance was related to the plasma clearance of 9-hydroxyrisperidone. CYP2D6 genotype was also associated with the average plasma concentration of risperidone active moiety (a sum of all three active compounds). In comparison to the patients with CYP2D6*1/*1 genotype, average steady-state plasma concentration of risperidone active moiety was 3.3- and 1.6-fold higher in poor metabolizers (both alleles nonfunctional; CYP2D6*3 or *4) and intermediate metabolizers (one nonfunctional allele and one allele for diminished enzyme activity; CYP2D6*10 or *41), respectively. Additionally, average plasma concentration of risperidone active moiety was higher in the patients with dystonia (p=0.0066) and parkinsonism (p=0.046). The results of this study imply the potential role of CYP2D6 genotyping in personalizing risperidone therapy in patients with schizophrenia to reduce the incidence of adverse extrapyramidal symptoms.

Paliperidone palmitate - review of the efficacy, safety and cost of a new second-generation depot antipsychotic medication

OBJECTIVE

To describe the efficacy, safety and cost of paliperidone palmitate, a depot antipsychotic medication recently approved for the treatment of schizophrenia.

DATA SOURCES

A literature search was conducted by querying the websites http://www.pubmed.gov, http://www.fda.gov, http://www.accessdata.fda.gov/scripts/cder/drugsatfda and http://www.clinicaltrials.gov for the search term 'paliperidone palmitate'. Cost information was obtained from the pharmaceutical vendor servicing a local state-operated psychiatric facility.

STUDY SELECTION

All available reports of studies were identified. Product labelling provided additional information.

DATA EXTRACTION

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

DATA SYNTHESIS

Paliperidone palmitate is a newly available depot formulation of paliperidone (the 9-OH metabolite of risperidone). Upon injection into the deltoid or gluteal muscle, the release of the drug starts as early as day 1, reaches maximum plasma concentrations at 13 days and lasts for as long as 126 days. Maximum concentration following deltoid injection is approximately 28% higher compared with injection into the gluteal muscle, and thus paliperidone palmitate requires initiation by two initial deltoid injections spread 1 week apart to achieve therapeutic concentrations rapidly. Subsequent injections are at 4-week intervals. Acute efficacy was evidenced by four short-term double-blind, randomised, placebo-controlled, fixed-dose studies of acutely relapsed adult inpatients who met DSM-IV criteria for schizophrenia. NNT for a 30% or greater decrease in the Positive and Negative Syndrome Scale total score compared with placebo was consistently lower for the higher dose strengths of 156 and 234 mg, suggesting a therapeutic dose-response. Treatment with paliperidone palmitate at doses between 39 and 156 mg significantly delayed the time to recurrence of symptoms of schizophrenia after 24 weeks of maintained symptom stability. The NNT vs. placebo to avoid a recurrence of symptoms was 5 (95% CI 4-7). Overall, paliperidone palmitate was reasonably well tolerated, with low rates of extrapyramidal symptoms or body weight gain; however, these may be more common at higher doses. Injection site reactions occurred at a rate ranging from 4% to 10%, depending on the dose regimen, compared with 2% for the pooled placebo arms. The acquisition cost of a maintenance dose of paliperidone palmitate calculated on a per day basis is similar to that for risperidone microspheres, but about double the cost for oral paliperidone and approximately 19 times the cost of oral generic risperidone.

CONCLUSIONS

Paliperidone palmitate is efficacious for the acute and maintenance treatment of schizophrenia and is reasonably well tolerated. It offers several advantages over other available second-generation depot antipsychotics: it comes in prefilled syringes in a number of different dosage strengths; it does not require refrigeration; it does not require supplementation with oral antipsychotics; it can be administered once monthly; it can be administered with a very small bore needle; the injection volume is small; the injection site can be either the deltoid or gluteal muscles; it does not require an additional precautionary observation period after the injection. For patients for whom oral risperidone or paliperidone is otherwise effective, paliperidone palmitate offers a guaranteed delivery system that enhances adherence. However, the high acquisition cost of paliperidone palmitate will likely be an important obstacle to its routine use.

No pharmacokinetic interaction between paliperidone extended-release tablets and trimethoprim in healthy subjects

OBJECTIVE

The effect of trimethoprim, a potent organic cation transport inhibitor, on the pharmacokinetics (PK) of paliperidone extended-release tablets (paliperidone ER), an organic cation mainly eliminated via renal excretion, was assessed.

METHODS

Open-label, two-period, randomized, crossover study in 30 healthy males. Single dose of paliperidone ER 6 mg was administered either alone on day 1 or day 5 during an 8-day treatment period of trimethoprim 200 mg twice daily. Serial blood and urine samples were collected for PK and plasma protein binding of paliperidone and its enantiomers. The 90% confidence interval (CI) of ratios with/without trimethoprim for PK parameters of paliperidone and its enantiomers calculated.

RESULTS

Creatinine clearance decreased from 119 to 102 mL min(-1) with trimethoprim. Addition of trimethoprim increased unbound fraction of paliperidone by 16%, renal clearance by 13%, AUC(infinity) by 9%, and t((1/2)) by 19%. The 90% CIs for ratios with/without trimethoprim were within the 80-125% range for C(max), AUC(last), and renal clearance. For AUC(infinity), 90% CI was 79.37-101.51, marginally below the lower bound of the acceptance range. Paliperidone did not affect steady-state plasma concentrations of trimethoprim.

CONCLUSIONS

No clinically important drug interactions are expected when paliperidone ER is administered with organic cation transport inhibitors.

Costs and effects of paliperidone extended release compared with alternative oral antipsychotic agents in patients with schizophrenia in Greece: a cost effectiveness study

BACKGROUND

To compare the costs and effects of paliperidone extended release (ER), a new pharmaceutical treatment for the management of schizophrenia, with the most frequently prescribed oral treatments in Greece (namely risperidone, olanzapine, quetiapine, aripiprazole and ziprasidone) over a 1-year time period.

METHODS

A decision tree was developed and tailored to the specific circumstances of the Greek healthcare system. Therapeutic effectiveness was defined as the annual number of stable days and the clinical data was collected from international clinical trials and published sources. The study population was patients who suffer from schizophrenia with acute exacerbation. During a consensus panel of 10 psychiatrists and 6 health economists, data were collected on the clinical practice and medical resource utilisation. Unit costs were derived from public sources and official reimbursement tariffs. For the comparators official retail prices were used. Since a price had not yet been granted for paliperidone ER at the time of the study, the conservative assumption of including the average of the highest targeted European prices was used, overestimating the price of paliperidone ER in Greece. The study was conducted from the perspective of the National Healthcare System.

RESULTS

The data indicate that paliperidone ER might offer an increased number of stable days (272.5 compared to 272.2 for olanzapine, 265.5 f risperidone, 260.7 for quetiapine, 260.5 for ziprasidone and 258.6 for aripiprazole) with a lower cost compared to the other therapies examined (euro 7,030 compared to euro 7,034 for olanzapine, euro 7,082 for risperidone, euro 8,321 for quetiapine, euro 7,713 for ziprasidone and euro 7,807 for aripiprazole). During the sensitivity analysis, a +/- 10% change in the duration and frequency of relapses and the economic parameters did not lead to significant changes in the results.

CONCLUSION

Treatment with paliperidone ER can lead to lower total cost and higher number of stable days in most of the cases examined.

Paliperidone for schizophrenia

BACKGROUND

Paliperidone, risperidone's active metabolite, is now available in an oral formulation for daily use, and an intramuscular formulation for monthly administration may follow shortly.

OBJECTIVES

To compare effects of oral paliperidone with any other treatment for people with schizophrenia and schizophrenia-like illnesses.

SEARCH STRATEGY

We searched the Cochrane Schizophrenia Group's Register (December 2006), and inspected references of identified studies for further trials. We contacted the manufacturers of paliperidone, the Food and Drug Administration, and authors of relevant trials for additional material.

SELECTION CRITERIA

We included all relevant randomised trials.

DATA COLLECTION AND ANALYSIS

We independently selected and critically appraised studies, extracted data and analysed on an intention-to-treat basis. Where possible and appropriate, we calculated risk ratios (RR) and their 95% confidence intervals (CI) with the number needed to treat (NNT). We calculated Weighted Mean Differences (WMD) for continuous data.

MAIN RESULTS

Five studies compared paliperidone with placebo. Fewer people left the studies early if they were randomized to paliperidone (n=1647, 5 RCTs, RR 0.68 CI 0.61 to 0.76, NNT 7 CI 6 to 9) and those receiving any dose of paliperidone were significantly more likely to have an improvement in global state (n=1420, 4RCTs, RR 0.69 CI 0.63 to 0.75, NNT 5 CI 4 to 6). People randomised to paliperidone were less likely to experience a recurrence of psychosis (n=1638, 5 RCTs, RR 0.45 CI 0.31 to 0.66, NNT 16 CI 13 to 26) than those allocated to placebo. Adverse effect data were not well reported but paliperidone does seem to produce a greater incidence of tachycardia than placebo (n=1638, 5 RCTs, RR1.88 CI 1.28 to 2.76, NNH 21 CI 11 to 90) and a consistent, significant elevation in serum prolactin was found for both men (n=413, 3 RCTs, WMD 27.68 CI 23.66 to 31.69) and women (n=252, 3 RCTs, WMD 87.39 CI 74.27 to 100.51). People receiving paliperidone were more likely to experience extrapyramidal disorders (n=1638, 5 RCTs, RR 2.21 CI 1.26 to 3.88, NNH 28 CI 12 to 129) and weight gain (n=769, 4 RCTs, WMD 1.07 CI 0.65 to 1.49, I-squared 78%) compared with those allocated to placebo. When compared with 10 mg/day olanzapine we found no differences between paliperidone and olanzapine for leaving in the short term (n=1332, 3 RCTs, RR 1.04 CI 0.89 to 1.21; 40% in both groups left by six weeks). Those receiving any dose of paliperidone were no more likely to have a recurrence of psychotic symptoms than those receiving 10 mg/day olanzapine (n=1327, 3 RCTs, RR 0.1.07 CI 0.64 to 1.76). Data from all three studies found paliperidone was less likely to produce a weight change than olanzapine (n=660, 3 RCTs, WMD -0.88 CI -1.38 to -0.37). Results for various movement disorders all favoured olanzapine. There are no clear data relating to social functioning, services use, quality of life, satisfaction and cost.

AUTHORS' CONCLUSIONS

In short-term studies, oral paliperidone is an antipsychotic that is more efficacious than placebo. We found its adverse effects to be similar to those of its parent compound, risperidone, with movement disorders, weight gain, and tachycardia all more common with paliperidone than placebo. In addition, paliperidone is associated with substantial increases in serum prolactin that may be associated with sexual dysfunction, although sexual functioning outcomes were not reported. At doses greater than 3 mg per day, oral paliperidone appears comparable in efficacy to oral olanzapine 10 mg per day. Regarding the critical comparison of oral paliperidone to risperidone, we have no information and are thus unable to determine if paliperidone has any advantages or disadvantages compared to its well-known parent compound.

Absorption, metabolism, and excretion of paliperidone, a new monoaminergic antagonist, in humans

Absorption, metabolism, and excretion of paliperidone, an atypical antipsychotic, was studied in five healthy male subjects after a single dose of 1 mg of [(14)C]paliperidone oral solution ( approximately 16 microCi/subject). One week after dosing, 88.4 to 93.8% (mean 91.1%) of the administered radioactivity was excreted: 77.1 to 87.1% (mean 79.6%) in urine and 6.8 to 14.4% (mean 11.4%) in the feces. Paliperidone was the major circulating compound (97% of the area under the plasma concentration-time curve at 24 h). No metabolites could be detected in plasma. Renal excretion was the major route of elimination with 59% of the dose excreted unchanged in urine. About half of the renal excretion occurred by active secretion. Unchanged drug was not detected in feces. Four metabolic pathways were identified as being involved in the elimination of paliperidone, each of which accounted for up to a maximum of 6.5% of the biotransformation of the total dose. Biotransformation of the drug occurred through oxidative N-dealkylation (formation of the acid metabolite M1), monohydroxylation of the alicyclic ring (M9), alcohol dehydrogenation (formation of the ketone metabolite M12), and benzisoxazole scission (formation of M11), the latter in combination with glucuronidation (M16) or alicyclic hydroxylation (M10). Unchanged drug, M1, M9, M12, and M16 were detected in urine; M10 and M11 were detected in feces. The monohydroxylated metabolite M9 was solely present in urine samples of extensive CYP2D6 metabolizers, whereas M10, another metabolite monohydroxylated at the alicyclic ring system, was present in feces of poor metabolizers as well. In conclusion, paliperidone is not metabolized extensively and is primarily renally excreted.

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

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

Pharmacokinetics in geriatric psychiatry

Safe, effective drug therapy in older adults requires an understanding of drug disposition and response in this population. Evidence suggests that physiologic changes during aging, including hepatic or renal function changes, contribute to pharmacokinetic differences. A major issue surrounding the study of older adults relates to the ability to study a large number of people in a minimally invasive way. Population pharmacokinetics provides a potential means of addressing this issue and a tool to evaluate drug exposure's magnitude and consistency. This article highlights examples of pharmacokinetic studies in psychiatry, in particular those conducted in older adults. It also reviews new drugs approved for treatment in psychiatry or neurology, many of which were developed as novel formulations (eg, extended-release transdermal film) with improved pharmacokinetic profiles or developed with regard to the actions of a specific enantiomer or metabolite.