Neuroprotection of paliperidone on SH-SY5Y cells against β-amyloid peptide(25-35), N-methyl-4-phenylpyridinium ion, and hydrogen peroxide-induced cell death

RATIONALE

Antipsychotic drugs (APDs) were widely used in treating schizophrenia. Some APDs were reported to have neuroprotective effects against neurotoxicants in the cell level.

OBJECTIVES

Thus, one typical APD (haloperidol) and three atypical APDs (paliperidone, olanzapine, and risperidone) were tested whether they provide neuroprotection against stressor-induced cell death of SH-SY5Y.

METHODS

Hydrogen peroxide, N-methyl-4-phenylpyridinium ion, and β-amyloid peptide were used to treat cells with or without preconditioning by APDs; cell survival and indicators of oxidative stress were measured, respectively.

RESULTS

Paliperidone has the lowest baseline cytotoxicity compared with other APDs at 24 h; in addition, the paliperidone group showed a better survival than the other APD groups (P < 0.05). In stressor challenging, with a fixed concentration of stressors, olanzapine provided the best neuroprotection at 100 μM against Aβ(25-35) and MPP(+) (P < 0.05). In contrast, paliperidone works finely at low concentrations (10 and 50 μM) against Aβ(25-35) and MPP(+) and solely protected SH-SY5Y from hydrogen peroxide. At 100 μM, paliperidone completely diminished cell reduction induced by different stressors, regardless of their dosages. Paliperidone was demonstrated with a higher oxidative stress-scavenging properties than other APDs in several aspects, such as generated bulk glutathione, low HNE, and protein carbonyl productions. Contradictorily, olanzapine, at 24 h, also enhanced HNE and protein carbonyl productions, which may underlie its induced cytotoxicity.

CONCLUSIONS

Different APDs exhibit variations against different stressors. Paliperidone might be useful not only in alleviating oxidative stress induced by Aβ(25-35) and MPP(+) but also in providing neuroprotection against hydrogen peroxide.

Changes in schizophrenia-related hospitalization and ER use among patients receiving paliperidone palmitate: results from a clinical trial with a 52-week open-label extension (OLE)

BACKGROUND

Schizophrenia affects ∼1.1% of the United States population, resulting in substantial direct, indirect and societal costs.

OBJECTIVE

To evaluate hospitalization rates associated with use of paliperidone palmitate (PP).

METHODS

Data were from a variable-duration double-blind (DB), randomized, relapse-prevention comparison (NCT00111189) of PP vs. placebo (Pbo), followed by a 1-year open-label extension (OLE). Between-phase change in schizophrenia-related hospitalizations was evaluated using data from an investigator-completed questionnaire. Change in hospitalizations using patients before enrollment who participated in the OLE phase was also analyzed. Poisson regression was used to evaluate changes in incidence density within exposure category and by schizophrenia duration.

RESULTS

A total of 160 patients in the PP-PP group and 153 in the Pbo-PP group from the DB to the OLE phase were included. Mean age (standard deviation [SD]), gender, and duration of schizophrenia were similar at the start of the DB phase (Pbo: 38.5 years [10.6], 51.0% male, 68.0% ≥5 years' duration; PP: 37.3 years [11.4] (p = 0.342); 51.9% male (p = 0.874); 70.0% ≥5 years' duration (p = 0.698), respectively. From the DB to the end of the OLE phase, the number of hospitalizations per person-year for patients treated during the DB phase with Pbo significantly declined from 0.27 to 0.06 (78% reduction; p = 0.005). A statistically nonsignificant difference was observed for PP patients treated during the DB phase with PP (0.11-0.04; 63.6% reduction; p = 0.076), compared with the OLE phase. Change from before enrollment to the end of the OLE phase (n = 381) produced similar results (0.35-0.04; 88.6% reduction; p < 0.001). Patients who enroll in a clinical trial may be different from the general population and this may affect the generalizability of results.

CONCLUSION

From the double-blind to the open-label phase and from prior to the trial until the end of the open-label phase, hospitalizations significantly decreased for patients with schizophrenia treated with PP.

A 52-week open-label study of the safety and tolerability of paliperidone palmitate in patients with schizophrenia

The safety and tolerability of paliperidone palmitate, an injectable atypical antipsychotic agent, were assessed in a 1-year open-label extension of a double-blind study in patients with schizophrenia. Patients from the double-blind study who experienced a recurrence, remained recurrence free until study end, or who were in the transition, maintenance or double-blind phases and had received at least one injection of paliperidone palmitate when enrollment was stopped, were eligible for the open-label extension. Patients received gluteal injections of paliperidone palmitate once every 4 weeks: starting dose 50 mg eq. followed by 25, 50, 75, or 100 mg eq. flexible dosing. Of the 388 patients enrolled, 288 completed the open-label extension. During the open-label extension, the median (range) duration of exposure to paliperidone palmitate was 338 days (10; 390), and 74% of patients received all 12 open-label injections of paliperidone palmitate. The most frequent (≥ 5% in total group) adverse events were insomnia (7%); worsening of schizophrenia; nasopharyngitis; headache; and weight increase (6% each). Potentially prolactin-related adverse events occurred in 13 (3%) patients, mostly women, and none resulted in study discontinuation. Extrapyramidal treatment-emergent adverse events were reported in 25 (6%) patients; tremor was the most frequently reported (n = 8, 2%). At open-label extension endpoint, investigator-rated redness at the injection site was observed in ≤ 4% of patients in each group. Injection-site pain was rated by investigators as absent in 82-87% of patients. Schizophrenia symptoms measured by Positive and Negative Syndrome Scale and personal and social performance changes improved during the open-label extension.

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.

Change in employment status over 52 weeks in patients with schizophrenia: an observational study

BACKGROUND

The aim of this post-hoc analysis was to describe change in employment status over time in patients with schizophrenia.

METHODS

Data were from three 52-week open-label extensions of the double-blind pivotal trials of paliperidone extended-release (ER) (trial numbers NCT00650793, NCT00210769 and NCT00668837). Employment status prior to trial entry was recorded at baseline of the open-label phase and change was measured at 4-week intervals. Patients were included if they were in the open-label, intent-to-treat analysis set (i.e., received at least one dose of the study medication and had a baseline and at least one post-baseline efficacy measurement) and had valid dates in the productivity data. Employment categories included full-time, part-time, casual, sheltered work, unemployed but seeking work, unemployed and not seeking work, retired, not employed outside the home and student. Change in employment status from baseline to post-baseline (last visit) was assessed using McNemar's test.

RESULTS

Of the 1077 patients enrolled in the open-label extensions, 1012 (94.0%) met inclusion criteria. The average age was 37.7 years (SD 10.9) and 59.1% were male. At baseline, the largest percentage of patients was unemployed and not seeking work (56.8%), followed by retired (14.9%) and unemployed but seeking work (11.7%). Five different definitions of employment were created. Employment rates increased according to all five definitions (p < 0.0001), ranging from a 43% increase according to the definition most similar to that used by the US Bureau of Labor Statistics to an increase of 114% when only part-time and full-time employment were considered.

CONCLUSION

In this uncontrolled population of patients with schizophrenia who were treated with paliperidone ER, the percentage of patients who were employed increased over time. By using multiple measures of employment, researchers can identify the nature of the employment status change.

[Case of schizophrenia in which depressive and negative symptoms relapsed on switching from oral risperidone to risperidone long-acting injection]

I report a case of schizophrenia in which depressive and negative symptoms relapsed on switching from oral risperidone to risperidone long-acting injection (RLAI). The patient, with a 31-year history of schizophrenia, did not fully understand his disease. Therefore, adherence to medication had been extremely poor. The discontinuation of medication led to the recurrence of the disease. After hospital treatment, he was discharged to a group home. From then, the disease had been kept in remission by risperidone at 4 mg/day, and RLAI was introduced for the purpose of further social reintegration and QOL improvement. After starting RLAI at 25 mg, however, a stiff expression and irritability appeared. Therefore, RLAI was increased up to 50 mg, but depressive and negative symptoms relapsed. Subsequently, RLAI was discontinued and oral risperidone was re-administered, and the above mental symptoms improved in a relatively rapid manner. The difference in the ratio of plasma and brain concentrations between each active moiety, risperidone and 9-OH risperidone (paliperidone), resulting from the difference in administration routes, was suggested to be involved as the main factor. In this case, it is likely that positive symptoms did not relapse because plasma concentrations of the active moiety itself were well maintained by introducing RLAI. However, depressive and negative symptoms relapsed possibly as a result of reduced affinity for the alpha2A receptor with relatively decreased plasma concentrations of 9-OH risperidone when compared to oral administration. Another possibility is that negative symptoms were secondary induced by excess administration of antipsychotics, but there has been no such report on RLAI so far. For the reason noted above, careful follow-up is considered necessary when switching from oral risperidone to RLAI because mental symptoms might get worse.

Gender differences in the relationship between the risperidone metabolism and the plasma prolactin levels in psychiatric patients

BACKGROUND

Risperidone (RIS) has the highest propensity to elevate plasma prolactin (PRL) levels. While the active metabolite 9-hydroxy-risperidone (9-OH-RIS) plays a predominant role in the efficacy and side effects of RIS, the mechanistic details are still poorly understood. The present study evaluated the gender differences in the relationship between plasma levels of RIS or 9-OH-RIS and PRL.

METHODS

Twenty-one male and 19 female subjects treated with RIS were enrolled in the present series. All patients had been receiving RIS for at least 4 weeks at an average dosage of 4.7 mg/day. Plasma RIS, 9-OH-RIS and PRL levels were measured.

RESULTS

In the male patients, there was no correlation between the RIS dosage and plasma PRL levels, between plasma RIS levels and PRL levels, or between the plasma 9-OH-RIS levels and PRL levels. In the female patients, there was a significant positive correlation between the plasma 9-OH-RIS levels and PRL levels (rs=0.456, p=0.049). There was a trend toward a significant positive correlation between the RIS dosage and plasma PRL levels. There was no correlation between the plasma RIS levels and PRL levels.

CONCLUSION

9-OH-RIS is considered to play a more important role in PRL elevation than RIS, and a gender difference exists in the effect of 9-OH-RIS on PRL level.

[9-hydroxy-risperidone (9OHRIS) prevents stress-induced β-actin overexpression in rat hippocampus]

Alzheimer's disease (AD) is the most frequent form of neurodegenerative dementias. The aetiology and the exact pathomechanism of AD is not known, but stress has been considered recently in the aetiology. Beside the abnormal metabolism of the amyloid protein precursor (APP), the hyperactivity of the mitogen-activated protein kinase 1 (MAPK1) involved in the hyperphosphorylation of the tau proteins, which are considered the major component of neurofibrillary tangles, in addition to β-actin, being involved in synaptogenesis and neuronal plasticity, are all considered important contributors to the development of AD specific neuropathological changes. The chief aim of our present investigation was to examine the effect of stress on the expression of APP, MAPK1 and β-actin mRNAs in the rat hippocampus and cortex. The effect of 9-hydroxy-risperidone (9OHRIS) on the transcription of these genes was also examined. Adult, male Wistar rats were exposed to chronic immobilization stress for 3 weeks. The 9OHRIS (4 mg/bwkg) was administred by gastric tube. Four groups were formed depending on the treatment: (1) control, (2) stress, (3) 9OHRIS, (4) stress and parallel 9OHRIS treatment (n=5-6). The expression of APP, MAPK1, β-actin mRNAs from the perfused brain samples was measured with real-time PCR technique. The β-actin mRNA was significantly overexpressed in the hippocampus after 3 weeks of stress treatment. On the other hand, the stress induced hippocampal β-actin mRNA overexpression was repressed by the 9OHRIS treatment. There were no changes in the cortical or hippocampal expression of APP and MAPK1 mRNAs after neither the stress nor the 9OHRIS treatments. These results emphasize the importance of the stress induced β-actin expression in rat hippocampus. The stress induced alterations in the β-actin RNA expression could be associated with neuronal plasticity and adaptional processes, which could be modified by the 9OHRIS treatment. Our findings indicate that a second generation antipsychotic drug could have a beneficial effect in the pathomechanism of stress and this may have relevance in the treatment of such devastating conditions like AD and psychotic disorders.

[Efficacy of paliperidone extended-release tablets in the improvement of social functions in schizophrenics: a randomized and controlled study]

OBJECTIVE

To explore the efficacy of paliperidone extended-release tablets in the improvement of social functions in schizophrenics.

METHODS

A total of 81 schizophrenics were randomly divided into study group with paliperidone extended-release tablets and control group with risperidone for a 12-week treatment. They were assessed and analyzed by positive and negative symptoms scales (PANSS), social disability screening schedule (SDSS) and treatment emergent symptom scale (TESS) at baseline, 6(th) weekend and 12(th) weekend.

RESULTS

In study group, the factors and total scores of PANSS in the 12(th) weekend of treatment [(12.0 ± 2.8), (12.1 ± 3.6), (26.2 ± 5.0), (50.2 ± 8.7)] were all significantly lower than those at baseline [(24.7 ± 5.3), (23.8 ± 3.6), (45.0 ± 2.9), (93.5 ± 6.8)] (t = 9.60-16.78, P < 0.05). In study group, the positive factor, negative factor and total scores of PANSS in the 12(th) weekend of treatment [(12.0 ± 2.8), (12.1 ± 3.6), (50.2 ± 8.7)] were all significantly lower than those in the 6(th) weekend of treatment [(14.2 ± 1.8), (14.6 ± 2.4), (56.5 ± 6.4)] (t = 2.58-4.26, P < 0.05). In the 12(th) weekend of treatment, the factors and total scores of PANSS in study group [(12.0 ± 2.8), (12.1 ± 3.6), (26.2 ± 5.0), (50.2 ± 8.7)] were all significantly lower than those in control group [(16.9 ± 4.9), (18.7 ± 5.3), (32.5 ± 5.1), (68.1 ± 13.0)] (t = -4.28--5.67, P < 0.05). In study group, the total scores of SDSS in the 12(th) weekend of treatment (5.93 ± 2.78) were significantly lower than those at baseline (13.9 ± 3.4) (t = 10.83, P < 0.05). In study group, the total scores of SDSS in the 12(th) weekend of treatment (5.9 ± 2.8) were significantly lower than those in the 6(th) weekend of treatment (7.6 ± 2.9) (t = 5.21, P < 0.05). But there was no significant improvement in control group (t = 1.88, P > 0.05). In the 12(th) weekend of treatment, the total scores of SDSS in study group (5.9 ± 2.8) were significantly lower than those in control group (8.8 ± 2.9) (t = -4.49, P < 0.05). No severe adverse effect was reported in either group.

CONCLUSION

Paliperidone extended-release tablets are effective to improve social functions and psychiatric symptoms of schizophrenics.

Long-acting injectable risperidone and metabolic ratio: a possible index of clinical outcome in treatment-resistant schizophrenic patients

RATIONALE

It is still common to encounter a partial or no response to antipsychotic treatment in clinical practice, but only individual case reports are currently available concerning the efficacy of long-acting risperidone (RLAI) in treatment-resistant schizophrenia. The relationship between RSP and 9-OH-RSP plasma levels, and clinical response or tolerability has not yet been thoroughly assessed.

METHODS

This open-label, non-randomised study involved 30 outpatients with treatment-resistant schizophrenia, who were prescribed RLAI for 6 months, and clinically evaluated using the Brief Psychiatric Rating Scale (BPRS), the Positive and Negative Symptoms Scale (PANSS), the Clinical Global Impression-Improvement Scale (CGI-I), and the Simpson and Angus Scale for Extrapyramidal Side Effects (EPSE). Plasma RSP and 9-OH-RSP levels were determined at steady-state, and the metabolic ratio (MR) was calculated as plasma 9-OH-RSP/RSP levels.

RESULTS

At the end of the study, 60% of the patients responded to RLAI (a >or=20% reduction in the PANSS score). Linear regression analysis showed a significant positive relationship between the RSP dose and active moiety (RSP + 9-OH-RSP) (r = 0.4; p = 0.02). There was a significant positive relationship between active moiety and EPSE scores (r = 0.6; p = 0.00). The BPRS responders had a significantly higher mean MR than the non-responders (3.41 +/- 1.87 SD vs 1.60 +/- 0.98 SD) (p = 0.00).

CONCLUSIONS

Therapeutic drug monitoring seems to be useful in optimising the dose of RLAI, especially in the case of tolerability problems. MR might be a better index of clinical response to RLAI than the value of the active moiety, although this needs to be confirmed by further data.

Efficacy and safety of atypical antipsychotic drugs (quetiapine, risperidone, aripiprazole and paliperidone) compared with placebo or typical antipsychotic drugs for treating refractory schizophrenia: overview of systematic reviews

CONTEXT AND OBJECTIVE

According to some cohort studies, the prevalence of refractory schizophrenia (RS) is 20-40%. Our aim was to evaluate the effectiveness and safety of aripiprazole, paliperidone, quetiapine and risperidone for treating RS.

METHODS

This was a critical appraisal of Cochrane reviews published in the Cochrane Library, supplemented with reference to more recent randomized controlled trials (RCTs) on RS. The following databases were searched: Medical Literature Analysis and Retrieval System Online (Medline) (1966-2009), Controlled Trials of the Cochrane Collaboration (2009, Issue 2), Embase (Excerpta Medica) (1980-2009), Literatura Latino-Americana e do Caribe em Ciências da Saúde (Lilacs) (1982-2009). There was no language restriction. Randomized controlled trials, systematic reviews and meta-analyses evaluating atypical antipsychotics for treating RS were included.

RESULTS

Seven Cochrane systematic reviews and 10 additional RCTs were included in this review. The data generally showed minor differences between the atypical antipsychotics evaluated and typical antipsychotics, regarding improvement in disease symptoms, despite better adherence to treatment with atypical antipsychotics. Risperidone was specifically evaluated in patients with RS in one of the systematic reviews included, with favorable outcomes, but without definitive superiority compared with other drugs of proven efficacy, like amisulpride, clozapine and olanzapine.

CONCLUSIONS

The findings underscore the difficulty in treating these patients, with high dropout rates and treatment patterns of modest improvement in assessments of effectiveness. Atypical antipsychotics have advantages over typical antipsychotics mainly through their better safety profile, which leads to better adherence to treatment. A combination of antipsychotics may also be an option for some refractory patients.

Effect of CYP2D6, CYP3A5, and MDR1 genetic polymorphisms on the pharmacokinetics of risperidone and its active moiety

Clinical studies suggest that plasma levels of risperidone and its active moiety (risperidone + 9-hydroxyrisperidone) correlate with adverse drug effects. The aim of this study is to evaluate the pharmacogenetic variability in the disposition of risperidone and the active moiety in healthy Chinese subjects. A 2-mg single dose of risperidone is orally administered to 23 healthy Chinese subjects. The risperidone and 9-hydroxyrisperidone serum concentrations are measured. The polymorphic alleles of CYP2D6*10, CYP3A5*3, MDR1 C1236T, G2677T/A, and C3435T are determined in each subject. The mean maximum plasma concentration and area under the time-concentration curve extrapolated to infinity for risperidone are significantly higher in subjects possessing the CYP2D6*10 allele than in those with the CYP2D6*1/*1 and *1/*10 genotype. For active moiety, the subjects who carry both homozygous CYP2D6*10 and homozygous CYP3A5*3 have 98% higher area under the time-concentration curve extrapolated to infinity and 59% higher maximum plasma concentration compared with other CYP2D6 EM subjects. The MDR1 2677GA genotype may also play a role in risperidone pharmacokinetics. Further studies are needed to explore the impact of MDR1 2677GA and CYP3A5 polymorphisms on risperidone therapy.

Practical guidance for dosing and switching paliperidone palmitate treatment in patients with schizophrenia

OBJECTIVE

This article overviews the recommended dosing strategies for the treatment of schizophrenia patients using the recently FDA-approved once-monthly long-acting injectable atypical antipsychotic, paliperidone palmitate.

METHODS

Using pharmacokinetic (PK), efficacy and safety data from clinical trials and a comprehensive population PK simulation model, dosing recommendations for paliperidone palmitate have been generated.

RESULTS

The recommended initiation regimen is 150 mg eq. paliperidone palmitate (234 mg) on Day 1 followed by 100 mg eq. paliperidone palmitate (156 mg) on Day 8, each administered into the deltoid muscle, using a 1-inch 23 gauge (G) needle in those <90 kg and a 1.5-inch 22 G needle in those > or =90 kg. No oral supplementation is required. Monthly maintenance doses of paliperidone palmitate range from 25-150 mg eq. (39-234 mg; recommended dose of 75 mg eq. [117 mg]) injected into the deltoid (using weight-adjusted needle) or gluteal (using 1.5 inch 22 G needle) muscle. The Day 8 dose may be administered +/-2 days and monthly doses +/-7 days, without a clinically significant impact on plasma concentrations. In patients with mild renal impairment (creatinine clearance [CrCL]: 50-80 mL/min), dosage should be adjusted. No dose adjustment is required in patients with mild or moderate hepatic impairment; no data currently exist regarding severe hepatic impairment. Elderly patients with normal renal function should receive the same dosage as younger adult patients with normal renal function. In the event of an age-related decline in CrCL, dosage should be adjusted accordingly. Paliperidone palmitate treatment can be initiated the day after discontinuing previous oral antipsychotic treatment. Paliperidone palmitate should be initiated at the next scheduled injection, and monthly thereafter, in patients switching from other long-acting injectable antipsychotics, including long-acting risperidone.

CONCLUSIONS

These data provide practical guidance to clinicians on how to use paliperidone palmitate in adult patients with schizophrenia.

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.

Exploratory analysis of psychiatric-related utilization and costs associated with paliperidone ER compared with other oral atypical antipsychotics using pharmacy claims from an administrative database

OBJECTIVE

To compare psychiatric-related healthcare resource utilization (inpatient facility admissions, emergency room visits and ambulatory visits) and costs (medical, pharmacy and total healthcare costs) in patients initiated on paliperidone extended release (ER), risperidone, aripiprazole, olanzapine, ziprasidone or quetiapine.

METHODS

This exploratory, retrospective administrative claims analysis database compared patients from a large US commercial health plan who were initiated on their index oral atypical antipsychotics between January 1, 2007, and June 30, 2007. Cohorts were assigned by first antipsychotic claim and propensity score-matched by age, gender, US census division, race, household income, baseline antipsychotic use, co-morbid conditions and psychiatric-related utilization. Psychiatric-related healthcare resource utilization and costs were measured for 6 months post-initiation. Descriptive analyses compared paliperidone ER with the other cohorts.

RESULTS

There were 562 patients in matched paliperidone ER (n = 95), risperidone (n = 94), aripiprazole (n = 94), olanzapine (n = 89), ziprasidone (n = 95) or quetiapine (n = 95) cohorts. The paliperidone ER cohort had fewer mean psychiatric-related ambulatory visits than the risperidone cohort (p = 0.05). The paliperidone ER cohort had significantly lower mean psychiatric-related medical costs than the olanzapine, quetiapine and ziprasidone cohorts (p < 0.05) and lower total costs than the ziprasidone and olanzapine cohorts (p = 0.02). No other outcomes were significantly different.

LIMITATIONS

Small sample sizes and short post-index observation times due to the launch of paliperidone ER in January 2007, coupled with the inherent lag time with medical claims data, limit the generalizability of the study findings.

CONCLUSION

Patients treated with paliperidone ER may have psychiatric-related utilization costs that are comparable to those of patients who initiated treatment with other oral atypical antipsychotics.

[Non-fatal paliperidone overdose: a case report]

Paliperidone, a novel serotonin and dopamine antagonist, is one of the newest atypical antipsychotics on the market. It is an orally administered drug that is indicated for the treatment of schizophrenia, and is considered to be safe and well tolerated. A 37-year-old female with a long-standing history of schizophrenia had been taking paliperidone 12 mg d-1 for about 1.5 years. She overdosed on a total of 756 mg of paliperidone in response to auditory command hallucinations. She was promptly hospitalized, and fortunately did not suffer any major adverse clinical events, adverse laboratory parameters, or long lasting sequelae. Herein we discuss the inherent characteristics of paliperidone that limit the danger associated with overdosing.

[Successful quetiapine therapy in psychotic patients with mood elevation]

Antipsychotics have been used in the therapy of schizophrenia and bipolar disorder and several second generation antipsychotics (SGA) are already available in Hungary. The clinical trials' results are confusing in regarding the differences in the efficacy of the SGA's, but the differences in their side-effects are clear. Considering its most important side-effects, such as extrapyramidal symptoms, weight gain, metabolic syndrome and prolactin level elevation, quetiapine has a fairly good side effect profile, and can therefore be recommended especially in case of bipolar patients who are highly sensitive towards side effects.. In our case-report, we present four patients who were successfully treated with quetiapine for their psychotic mood elevation.

Impact of psychotic relapse definitions in assessing drug efficacy and costs: comparison of quetiapine XR, olanzapine and paliperidone ER

OBJECTIVE

The objective of this study was to illustrate the implications of using standardised psychotic relapse definitions by comparing published clinical trial relapse and drop-out rates for patients with schizophrenia.

METHODS

Relapse definitions from three published placebo-controlled clinical trials were standardised to facilitate pair-wise retrospective comparison of relapse outcomes in patients with schizophrenia receiving extended-release quetiapine fumarate (quetiapine XR), paliperidone extended release (paliperidone ER) and olanzapine. Relapse definitions were based on changes in the Positive and Negative Syndrome Scale score, Clinical Global Impression-Severity score and predefined Brief Psychiatric Rating Scale positive items. Economic implications of relapse outcomes were also calculated. A limitation of this study is that this was not a head-to-head comparison. In addition, patient-level data were lacking for the paliperidone ER and olanzapine studies.

RESULTS

When the relapse definition from the paliperidone study was applied to the quetiapine XR clinical trial data, 14 quetiapine XR patients (15%) relapsed compared with 23 (22%) in the paliperidone ER study. According to the olanzapine relapse definition, three quetiapine XR patients (3.2%) experienced a relapse compared with nine patients (4.0%) in the olanzapine study. An illustrative calculation of potential economic impact associated with these standardised relapse rates implied incremental expenditures ranging from 74.8 million pound sterling to 373.9 million pound sterling (2006 pound sterling) for paliperidone ER versus quetiapine XR treatment and no material difference with olanzapine.

CONCLUSION

The results show that the definition of relapse has a significant impact on relapse outcomes, and associated economic implications, and that relative drug efficacy can only be considered when results are based on standardised relapse criteria.

[Treatment with paliperidone extended-release tablets in a case of resistant undifferentiated schizophrenia: clinical improvement with 12 mg and evaluation through 3TRE scale]

The purpose of the study is to investigate the action of one antipsychotic molecule of recent introduction on the market. Paliperidone, in this occasion used in the formulation extended-release tablets, is an oral antipsychotic who takes advantage of the OROS system. Studies about are up to now focused on the effectiveness of paliperidone ER in the acute phase of the schizophrenia. In our job we have, instead, intention to show one possible application in a case of a chronic patient with undifferentiated schizophrenia resistant to the other antipsychotic treatments. Moreover 3TRE scale has been associated to establish the effects of the new therapy. The entrance prescription has been with paliperidone ER in a dosage of 6mg once a day. Clinical effects of paliperidone ER 6 mg became obvious and meaningful, online with other jobs, already in the first days of treatment. But the improvement of the partials and totals scale's scores have been had mainly with the dosage to 12 mg, that the patient has assumed autonomously unknown to the care provider.

Reliability, validity and ability to detect change of the clinician-rated Personal and Social Performance scale in patients with acute symptoms of schizophrenia

OBJECTIVE

To describe the measurement properties of the Personal and Social Performance scale (PSP), a clinician-reported measure of severity of personal and social dysfunction, in subjects with acute symptoms of schizophrenia.

METHODS

Pooled data from three paliperidone extended-release clinical studies (n = 1665) and data from a separate noninterventional, cross-sectional, validation study (n = 299) were analyzed.

RESULTS

The PSP showed good interrater (intraclass correlation coefficient [ICC] = 0.87) and test-retest (ICCs > 0.90) reliability. Pearson correlation coefficient for association between baseline PSP and Positive and Negative Syndrome Scale (PANSS) total scores was -0.32 for subjects assessed by the same rater and -0.29 for subjects assessed by different raters, suggesting low overlap in measurement constructs between the PANSS and PSP. Spearman Rank correlation coefficient for association between baseline PSP and Clinical Global Impression-Severity (CGI-S) scores was -0.51 with the same rater and -0.15 with different raters. Hypothesized relationships between the PSP and the PANSS or CGI-S based on levels of disease severity were prospectively defined. These hypotheses were confirmed by analyses showing statistically significant differences between baseline mean PSP scores in subjects grouped by severity rating on the CGI-S (mild or less vs. at least moderate) (p < 0.001) and the PANSS ('low symptom severity' vs. 'high symptom severity') (p = 0.005). The PSP was sensitive to change based on statistically significant correlations between change in the PSP and change in the CGI-S (p < 0.001) and the PANSS (p < 0.001). Limitations of analyses include pooling data across studies, interrater reliability assessment in the validation study only, post hoc assessment of test-retest reliability in the paliperidone ER studies, different raters for the PSP and PANSS not specified in the paliperidone ER studies, PSP validity assessment based on the PANSS and the CGI-S as comparators rather than another social function instrument.

CONCLUSION

These initial reliability and validity assessments suggest the PSP has promise as a measure of social functioning in patients with acute symptoms of schizophrenia.

[Psychiatry]

In 2008 there is no major breakthrough in the field of psychopharmacology. Paliperidone, (Invega), or 9-hydroxyrisperidone, the main hydroxylated metabolite of risperidone, is now available in Switzerland. It has the same pharmacodynamic profile and a different pharmacokinetic profile, linked to an extended release preparation. Bupropion, an antidepressant with noradrenergic and dopaminergic activity, is now accepted on the Swiss market for the treatment of depression under the name of Wellbutrin. Until now, its indication was limited to tobacco withdrawal (under the name of Zyban). The article also includes new data issued from the STAR*D study (concerning the efficacy of cognitive behavioural therapy) and a few remarks about the recent debate in the media about the efficacy of antidepressants.

Paliperidon mediated modification of cortical inhibition

Transcranial magnetic stimulation is a neurophysiological method which enables direct quantitative in vivo assessment of cortical excitability and inhibition. The aim of the study was to assess the impact of paliperidone on the motor threshold and cortical silent period, in a drug-naive patient, with first episode schizophrenia using this technique. Paliperidone monotherapy caused a significant reduction of severity of schizophrenic symptomatology in the patient. At the same time, a significant prolongation of the cortical silent period, from 118.68 ms before to 185.13 ms after therapy, occurred. Because the cortical silent period is a function of GABA(B) receptors, we can assume that paliperidone may have the ability to enhance GABA(B) receptor-mediated neurotransmission.

[Paliperidone--a novel second-generation antipsychotic]

Paliperidone Depot (PAL ER) is a new second-generation antipsychotic with pharmacodynamics resembling those of risperidone. PAL ER is slowly and smoothly released in 24 hours. Its half-life is about 24 hours. PAL is primarily eliminated unchanged in urine. Three short-term studies and one relapse study found PAL ER to be significantly more effective than placebo in all doses (3-15 mg once a day). There are no head-to-head comparisons with other antipsychotics, including risperidone. On the existing evidence it is not possible to ascertain whether PAL ER is better than risperidone in terms of effects and tolerability.

Hospitalization rates before and after initiation of paliperidone ER in patients with schizophrenia: results from open-label extensions of the US double-blind trials

OBJECTIVE

To assess differences in the number of days hospitalized among schizophrenic patients receiving paliperidone extended-release (paliperidone ER) during the open-label extension (OLE) phases, compared to a similar time period prior to the screening for entry into the double-blind (DB) trials conducted in the United States.

METHODS

Mental health-related hospital days during the 52 weeks before entering the DB trials and during the OLE phases were compared. The mean number of hospital days per person per year in the pre- and post-periods was calculated and the statistical significance of pre-post differences was assessed using bootstrap resampling methods. Total person-years were also calculated for the pre- and post-periods to account for different lengths of observation.

RESULTS

Patients' (n=215) mean (+/-SD) age was 41.2 (+/-11.0) years; most were male (73.0%); and black (52.1 vs. 45.1% white). The mean (+/-SD) paliperidone ER treatment duration during the OLE phase was 167.0 (+/-145.0) days and the mean (+/-SD) daily dose was 10.5 (+/-2.0) mg. Overall, paliperidone ER patients spent an average (+/-SD) of 13.2 (+/-1.6) and 3.1 (+/-0.7) hospital days per person-year in the pre-and post-periods, respectively (mean +/-SD change 10.0+/-1.8, 95% CI 6.5, 13.4, p<0.001). Using the 2007 Federal Per Diem Base Rate (i.e., $595.09 per day), this reduction in hospital days would result in an average (+/-SD) cost savings of $5951 (+/-1071) per person per year.

CONCLUSIONS

Patients had significantly fewer hospital days in the OLE phase compared to the 1-year period prior to entering the DB trial. Paliperidone ER may play a role in reducing mental health-related hospital days and associated costs. Important study limitations include the lack of a control group, the pre-post design comparing historical data with data collected in the trials which could create a bias due to the mismatch in settings, and patients having more frequent contact with treating physicians and investigators during the trial period, which could favor the outcomes in the OLE phase. Further studies are needed to confirm these findings.

Paliperidone for treatment of schizophrenia

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.

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.

Pharmacodynamic consequences of P-glycoprotein-dependent pharmacokinetics of risperidone and haloperidol in mice

Efflux transporters, like P-glycoprotein (P-gp), may limit the access of drugs to the brain via the blood-brain barrier. The antipsychotic drug risperidone and its active metabolite 9-hydroxyrisperidone (paliperidone) are substrates of P-gp. Motor behavior of P-gp deficient mice (mdr1a/1b (-/-, -/-)) and wild type animals on a rotarod after acute doses of risperidone or haloperidol, a nonsubstrate of P-gp, were analysed aiming to show that P-gp substrate properties of an antipsychotic drug have functional consequences. Behavioral tests revealed dose-dependent effects of 0.3-3 mg/kg risperidone in wild type animals 0.5-12 h after i.p. injection of the drug. In knockout mice the 0.3 mg/kg dose of risperidone was as effective as the 3 mg/kg dose in wild type mice. A dose of 0.3 mg/kg haloperidol, however, exhibited similar pharmacodynamic effects in both genotypes. Brain concentrations of risperidone plus 9-hydroxyrisperidone were 10-fold higher in knockout than in wild type animals whereas brain concentrations of haloperidol did not differ between the two genotypes. P-gp-dependent brain distribution kinetics and behavioral effects of risperidone give evidence that the expression of P-gp has an impact on psychotropic drug actions when treating patients with drugs that are substrates of P-gp.

Relationship between prolactin secretion, and plasma risperidone and 9-hydroxyrisperidone concentrations in adolescents with schizophreniform disorder

BACKGROUND

Treatment with the atypical antipsychotic risperidone can result in elevated prolactin levels. To date, the relationships between plasma concentrations of prolactin, risperidone and its active 9-hydroxy-metabolite have been little investigated in adolescents with psychosis.

METHODS

Prolactin levels were determined at baseline in 16 hospitalized drug-naïve adolescents meeting DSM-IV criteria for schizophreniform disorder. Prolactin, risperidone, 9-hydroxyrisperidone levels were subsequently determined after 3 weeks of oral risperidone treatment.

RESULTS

Compared with pretreatment values, prolactin levels at endpoint were significantly increased (p<0.00001) and correlated with risperidone doses (r=0.58, N=16, p<0.02), and plasma levels of risperidone (r=0.60, N=16, p<0.02) and 9-hydroxyrisperidone (r=0.54, N=16, p=0.03).

CONCLUSIONS

These data suggest that risperidone's effect on prolactin release is dose-dependent in adolescents and is linked to both plasma risperidone and 9-hydroxyrisperidone concentrations.

Efficacy and safety of paliperidone extended-release tablets: results of a 6-week, randomized, placebo-controlled study

BACKGROUND

Paliperidone extended-release tablet (paliperidone ER; Invega, Janssen L.P., Titusville, New Jersey) is an oral psychotropic for schizophrenia treatment.

METHODS

Efficacy and safety of once-daily paliperidone ER (6 and 12 mg) were assessed versus placebo in 444 patients with acute schizophrenia in a 6-week, multicenter, double-blind, randomized, parallel-group study. An olanzapine (10 mg) treatment arm was included to confirm trial validity.

RESULTS

Both doses of paliperidone ER demonstrated significant improvement in Positive and Negative Syndrome Scale (PANSS) total score (p < or = .006) and certain PANSS Marder factor scores compared with placebo (p < or = .025); PANSS total score also improved in the olanzapine treatment arm. Paliperidone ER 6 mg (p < or = .008), but not 12 mg, was associated with significant improvements in personal and social performance. The incidence of treatment-emergent adverse events (AEs) for paliperidone ER 6 mg was comparable with placebo and slightly greater with paliperidone ER 12 mg. Changes in blood glucose and lipid levels with paliperidone ER were comparable with placebo. Two patients treated with paliperidone ER experienced glucose-related AEs. Body-weight increases of 1-2 kg were observed with paliperidone ER. Although there were increases in plasma prolactin levels with paliperidone ER treatment, the incidence of prolactin-related AEs was < or =1%.

CONCLUSIONS

In this study, paliperidone ER, particularly the 6-mg dose, was effective and well tolerated, and provides a valuable new treatment option for schizophrenia.

Enantioselective analysis of the antipsychotic 9-hydroxyrisperidone, main metabolite of risperidone, by chiral capillary EKC using dual CDs

An analytical method for the enantioseparation of the 9-hydroxyrisperidone, main metabolite of the antipsychotic risperidone (Risp), was developed by CD-EKC in the dual CDs mode using anionic and neutral CDs at acidic pH 2.5. Preliminary experiments allowed us to select the more suitable couple of CDs composed of sulfated-alpha-CD and hydroxypropylated-beta-CD. The optimization of the main experimental parameters (concentrations of both CDs and concentration of the phosphate buffer) was based on a central composite design through the response surface methodology. Then, the influence of the voltage and the temperature on the enantioseparation was studied using the classical univariate approach. The final method permits to resolve the enantiomers of the 9-hydroxyrisperidone with a resolution of 3.13 and an analysis time of about 13 min. Finally, this method was successfully applied for the simultaneous determination of Risp and the enantiomers of 9-hydroxyrisperidone (9-OHRisp).

Serum prolactin levels, plasma risperidone levels, polymorphism of cytochrome P450 2D6 and clinical response in patients with schizophrenia

The object of this study is to assess 1) the relationship between plasma antipsychotic drug concentration, serum prolactin levels and the clinical efficacy of risperidone, 2) the relationship between the CYP2D6 polymorphisms and metabolizing of risperidone and 3) the role of 9-hydroxyrisperidone in elevating prolactin levels. One-hundred and eighteen Chinese schizophrenia patients (40 males, 78 females, age 15-60 years) were given risperidone at dosages ranging from 2-8 mg/day for 8 weeks. Clinical efficacy was determined using the Brief Psychiatric Rating Scores (BPRS). Serum prolactin levels were assayed before and after the 8 week treatment and plasma risperidone and 9-hydroxyrisperidone levels were also measured at the end of the 8-week treatment. The results showed there was no significant correlation between the concentration of active moiety and clinical response. Risperidone treatment significantly increased serum prolactin levels. Furthermore, changes of prolactin levels were not correlated with the clinical response. For the risperidone/ 9-hydroxyrisperidone ratio, there was a statistically significant difference among the CYP2D6*1/*1, *1/*10, *10/*10 genotypes (Kruskal-Wallis test, p = 0.012). No significant differences were found in the concentration of 9-hydroxyrisperidone and active moiety among the genotypes. In addition, the concentration of 9-hydroxyrisperidone was not significantly correlated with the increase of serum prolactin. In conclusion, our study has, for the first time, produced evidence that in Chinese schizophrenic patients, the metabolism of risperidone is dependent on CYP2D6. Neither changes in serum prolactin levels nor plasma concentration of active moiety were significantly correlated with clinical efficacy of risperidone. 9-hydroxyrisperidone may not play a predominant role in elevating serum prolactin level.

Sensitive liquid chromatography/tandem mass spectrometry method for the simultaneous determination of olanzapine, risperidone, 9-hydroxyrisperidone, clozapine, haloperidol and ziprasidone in rat brain tissue

One prerequisite for therapeutic effects of psychiatric drugs is the ability to pass the blood brain barrier. Hence, it is important to know the concentration of antipsychotic drugs in brain tissue. In general, determinations of lipophilic compounds from lipophilic matricies such as the brain are a challenge. Here we have adapted a plasma assay for antipsychotics for the target organ the brain. Using modified sample preparation and chromatographic strategies, the analytes were extracted from rat brain homogenate and analyzed by LC-MS/MS. The method used a Waters Atlantis dC-18 (30 mm x 2.1 mm i.d., 3 microm) column with a mobile phase of acetonitrile/5 mM ammonium formate (pH 6.1 adjusted with formic acid) and gradient elution. All analytes were detected in positive ion mode using multiple-reaction monitoring. The method was validated and the linearity, lower limit of quantitation, precision, accuracy, recoveries, specificity and stability were determined. This method was then successfully used to quantify the rat brain tissue concentration of the analytes after chronic treatment with these antipsychotic drugs.

Plasma pharmacokinetic characteristics of risperidone and their relationship to saliva concentrations in children with psychiatric or neurodevelopmental disorders

BACKGROUND

Risperidone is a second-generation antipsychotic agent widely used in the treatment of schizophrenia and other psychotic disorders in adults. Risperidone is probably the most frequently used atypical antipsychotic in the pediatric population.

OBJECTIVES

The goals of this study were to estimate the pharmacokinetic parameters of risperidone and its enantiomers in a pediatric population and explore relationships between saliva and plasma concentrations.

METHODS

Eligible patients, between 4 and 15 years of age, included those taking a stable dose of oral risperidone ranging from 0.01 to 0.07 mg/kg BID for > or =4 weeks to treat psychiatric or neurodevelopmental conditions. A trough blood level and predose saliva sample were collected at study initiation; the regular risperidone dose was administered; and paired samples of blood and saliva were collected at 1, 2, 4, and 7 hours postdose. Plasma/saliva concentrations of risperidone and enantiomers of its principal active metabolite, 9-hydroxyrisperidone (9-OH-risperidone), were measured using a chiral liquid chromatography-tandem mass spectrometry assay. Standard pharmacokinetic parameters were calculated. Cytochrome P450 2D6 genotypes of *3,*4,*5 deletion and duplication were determined.

RESULTS

The study included 19 patients (age range, 4 years 2 months to 15 years 11 months). Mean (SD) values for C(max), t(1/2), and AUC 0 to 12 hours for risperidone in plasma were 15.9 (22.2) ng/mL, 3.0 (2.3) h, and 92.1 (200.6) ng x h/mL, respectively. Corresponding values in saliva were 12.0 (21.0) ng/mL, 3.4 (3.2) h, and 27.8 (38.7) ng x h/mL, respectively. Mean (SD) plasma enantiomer values for C(max) and AUC calculated up to the last observation were: (+)-9-OH-risperidone, 13.6 (10.0) ng/mL and 73.6 (52.3) ng x h/mL; (-)-9-OH-risperidone, 4.9 (3.1) ng/mL and 29.3 (19.1) ng x h/mL. Corresponding enantiomer values in saliva were: (+)-9-OH-risperidone, 5.2 (8.8) ng/mL and 15.6 (8.9) ng x h/mL; (-)-9-OH-risperidone, 5.0 (7.9) ng/mL and 15.6 (9.1) ng x h/mL, respectively. Large interindividual variability in risperidone and enantiomer concentrations was noted. A highly significant relationship between predose plasma and predose saliva risperidone concentrations was observed. The logarithmic regression model indicated that the log risperidone saliva concentration = -0.100 + 0.594 x log plasma concentration (R(2) = 0.93 [Spearman]).

CONCLUSIONS

In this preliminary pharmacokinetic study of parameters for risperidone and the enantiomers of 9-OH-risperidone in a pediatric population, mean C(max) and t(1/2) of risperidone were generally similar to those previously described in adults. The highly significant relationship between predose plasma and predose saliva risperidone concentrations suggests that saliva measurements may be a viable alternative to plasma sampling in children.

A double-blind, placebo-controlled, randomized study evaluating the effect of paliperidone extended-release tablets on sleep architecture in patients with schizophrenia

The effects of paliperidone extended-release on sleep architecture in patients with schizophrenia-related insomnia were evaluated in this multicenter, double-blind, randomized, placebo-controlled study. Patients received paliperidone extended-release 9 mg/day or matching placebo during the 14-day double-blind phase. Sleep architecture and sleep continuity were evaluated using polysomnograms. Subjective sleep measures were evaluated daily using the Leeds Sleep Evaluation Questionnaire. Efficacy and safety were also assessed. Thirty-six patients (17 on paliperidone extended-release, 19 on placebo; mean age 32.2 years) completed the study. Paliperidone extended-release treatment vs. placebo resulted in clinically and statistically significant differences in sleep measurements from baseline to endpoint including a reduction in: persistent sleep latency (41 min), sleep onset latency (35 min), number of awakenings after sleep onset (7), time awake in bed (50 min), and stage 1 sleep duration (12 min); prolongation in: total sleep time (53 min), sleep period time (42 min), stage 2 sleep duration (51 min), and rapid eye movement sleep duration (18 min); and an increase in sleep efficiency index (11%). Paliperidone extended-release, compared with placebo, did not exacerbate daytime somnolence and improved symptoms of schizophrenia. Paliperidone extended-release was well tolerated and improved sleep architecture and sleep continuity in patients diagnosed with schizophrenia and concomitant insomnia.

Analytical and semipreparative enantioseparation of 9-hydroxyrisperidone, the main metabolite of risperidone, using high-performance liquid chromatography and capillary electrophoresis

The HPLC semipreparative enantioseparation of 9-hydroxyrisperidone (9-OHRisp) was studied by optimizing various experimental conditions: the nature of the chiral stationary phase (CSP), mobile phase composition, temperature and analyte loading. This semipreparative enantioseparation was successfully completed using the polysaccharide Chiralcel OJ chiral stationary phase and a n-hexane/ethanol/methanol (50/35/15, v/v/v) ternary mobile phase. To assess the enantiomeric purity of both isolated isomers, three analytical methods using UV detection were developed and validated: one CE method using dual cyclodextrin mode and two HPLC methods using either the Chiralcel OJ CSP in normal-phase mode or the alpha-acid glycoprotein (alpha-AGP) CSP in reversed-phase mode. The three methods make it possible to obtain excellent enantioseparations (R(s) >3) with analysis times lower than 15 min, and the calculated limits of detection allow for the determination of minor enantiomeric impurities (0.1%). Enantiomeric purity obtained for dextrorotatory and levorotatory enantiomers was superior to 99.9% and equal to 98.9%, respectively, which proved the success of the semipreparative enantioseparation. A brief comparison of the performances of the analytical methods completes this work.

Distinct electrophysiological effects of paliperidone and risperidone on the firing activity of rat serotonin and norepinephrine neurons

RATIONALE

Paliperidone (9-OH-risperidone) is the main metabolite of the atypical antipsychotic risperidone. While both drugs are potent dopamine (D)2 antagonists, they have quantitative differential affinities for serotonin (5-HT) and norepinephrine (NE) receptor binding sites.

OBJECTIVES

The present study aimed to determine if paliperidone exerts distinct effects on 5-HT and NE neuronal activity from those of risperidone.

MATERIALS AND METHODS

Risperidone and paliperidone were administered to Sprague-Dawley rats. Neuronal activity of 5-HT and NE neurons was assessed using in vivo electrophysiology.

RESULTS

Acute administration of risperidone but not paliperidone inhibited the firing of 5-HT neurons, as previously reported. This inhibition was partially antagonized by the NE reuptake inhibitor desipramine, by the 5-HT(1A) receptor antagonist WAY 100635, and completely reversed when both drugs were given consecutively. Risperidone inhibited the firing of 5-HT neurons after 2 and 14 days of administration, with or without escitalopram. Paliperidone did not alter the firing rate of NE neurons by itself, but it reversed the suppression of NE neurons induced by escitalopram, as it was previously reported for risperidone.

CONCLUSION

These results indicate that although risperidone and paliperidone share a qualitatively similar receptor binding profile in vitro, they differentially alter the firing of 5-HT and NE neurons in vivo. The capacity of paliperidone to reverse the selective serotonin reuptake inhibitor (SSRI)-induced inhibition of NE neuronal firing, without interfering with the effect of SSRIs of 5-HT neuronal activity, suggests that paliperidone may be a very effective adjunct in SSRI-resistant depression.

A study of genetic (CYP2D6 and ABCB1) and environmental (drug inhibitors and inducers) variables that may influence plasma risperidone levels

Risperidone (R) is metabolized to 9-hydroxyrisperidone (9-OHR) by cytochrome P450 2D6 (CYP2D6). The main objective of this naturalistic study was to investigate the variables associated with two plasma ratios: the plasma R:9-OHR concentration ratio and the total concentration-to-dose (C:D) ratio. These ratios were studied as continuous measures by linear regression analyses and as three dichotomous variables in logistic regression analyses: R:9-OHR ratio >1 (indicative of lack of CYP2D6 activity), C:D ratio >14 (indicative of diminished R elimination), and C:D ratio <3.5 (indicative of increased R elimination). Plasma R levels; genotypes for CYP2D6, CYP3A5; and ABCB1 genes, and co-medication, including CYP inhibitors and CYP3A inducers, were studied in 277 patients. Almost all CYP2D6 poor metabolizers (PMs) had an inverted R:9-OHR ratio (>1). Having a CYP2D6 PM phenotype was strongly associated with a C:D ratio >14 (OR=8.2; 95% confidence interval [CI]=2.0-32.7), indicating diminished R elimination. CYP2D6 ultrarapid metabolizers (UMs) did not exhibit an increased R elimination. Some ABCB1 (or MDR1) variants were significantly associated with increased R:9-OHR ratios and decreased C:D ratios, but the results were neither consistent nor robust. Taking CYP inhibitors was significantly associated with a C:D ratio >14 (OR=3.8; CI=1.7-8.7) and with an inverted R:9-OHR ratio. Taking CYP3A inducers was significantly associated with a C:D ratio <3.5 (OR=41.8; CI=12.7-138), indicating increased R elimination. Female gender and old age appeared to be associated with a lower R elimination. Our study indicated that the CYP2D6 PM phenotype may have a major role in personalizing R doses, whereas the CYP3A5 PM phenotype probably has no role. CYP inducers and inhibitors appear to be relevant to R dosing. New studies are needed, particularly to further assess the role of the CYP2D6 UM phenotype and ABCB1 variants in R pharmacokinetics.

Paliperidone extended release

Paliperidone extended release (ER) is an atypical antipsychotic that is administered orally once daily to provide consistent plasma drug concentrations over 24 hours in adult patients with schizophrenia. In four well controlled trials, once-daily administration of paliperidone ER 3-12 mg over 6 weeks was more effective than placebo in reducing the positive and negative symptoms experienced by adult patients with schizophrenia, including elderly individuals aged > or =65 years. Patients with schizophrenia treated with paliperidone ER achieved greater improvement in clinically relevant measures of personal and social functioning and disease severity than those who received placebo. In another well controlled trial, paliperidone ER demonstrated superior efficacy to placebo in preventing the recurrence of schizophrenia symptoms. In patients who experienced a recurrence, time to recurrence was delayed with paliperidone ER compared with placebo administration.black triangle Paliperidone ER 3-12 mg/day for 6 weeks was generally well tolerated by patients with schizophrenia in clinical trials.

Efficacy, safety and early response of paliperidone extended-release tablets (paliperidone ER): results of a 6-week, randomized, placebo-controlled study

BACKGROUND

Paliperidone extended-release tablet (paliperidone ER) is an oral psychotropic agent developed for schizophrenia treatment. Paliperidone (9-OH-risperidone, metabolite of risperidone), when used with OROS technology has a unique pharmacokinetic profile undergoing limited hepatic metabolism.

METHODS

The efficacy and safety of once-daily paliperidone ER (3 mg, 9 mg and 15 mg) were compared with placebo in 618 patients with acute schizophrenia in a 6-week, multicenter, double-blind, randomized, parallel-group study. An assay sensitivity group with known efficacy was included to confirm trial validity (olanzapine 10 mg).

RESULTS

All doses of paliperidone ER demonstrated significant improvements in PANSS total and PANSS factors scores (p<0.05) and in personal and social functioning (p<0.001) compared with placebo. Symptom improvement has been observed at the first observation assessment (Day 4) (p<0.001) compared with placebo, suggesting a rapid onset of action for paliperidone ER. Paliperidone ER was associated with a low incidence of treatment-emergent adverse events. The incidence of movement disorder-related adverse events and rating scale scores were similar in the paliperidone ER 3 mg and placebo groups and increased with dose. Increases in prolactin plasma levels and dose-related increases in body weight (<2 kg) were observed; there were no significant changes in serum lipid or glucose levels.

CONCLUSION

In this study, all doses of paliperidone ER were effective in significantly improving the symptoms of schizophrenia and personal and social functioning and were generally well tolerated. As such, paliperidone ER may provide a valuable new treatment option for patients with schizophrenia.

Treatment with risperidone for 4 weeks increased plasma 3-methoxy-4-hydroxypnenylglycol (MHPG) levels, but did not alter plasma brain-derived neurotrophic factor (BDNF) levels in schizophrenic patients

In the present study, we investigated the effects of risperidone treatment for 4 weeks on plasma levels of 3-methoxy-4-hydroxyphenylglycol (MHPG) and brain-derived neurotrophic factor (BDNF) in 89 schizophrenic patients. We also compared the plasma levels of BDNF and MHPG between the schizophrenic group and 103 sex-and age-matched normal controls. In addition, we investigated the effects of two SNPs of the noradrenaline transporter (NAT) gene on plasma levels of MHPG, BDNF, and clinical improvement. The mean dose of risperidone was 3.8+/-1.4 mg/day. We demonstrated that treatment with risperidone increased plasma MHPG levels, and this increase was associated with an improvement of the negative symptoms of schizophrenia. In contrast, plasma BDNF did not change after 4 weeks of risperidone treatment, and the two SNPs in NAT did not influence the response to risperidone treatment or plasma MHPG and BDNF levels. These results suggest that the enhancement of noradrenergic neurons by risperidone, which occurs independently of the two SNPs of NAT, plays a role in the clinical efficacy of the drug.

[Development and identifiability analysis of parent-metabolite pharmacokinetic model for risperidone and its main active metabolite 9-hydroxyrisperidone]

To develop a parent-metabolite pharmacokinetic model for risperidone (RIP) and its major active metabolite (9-hydroxyrisperidone) and investigate their pharmacokinetics characteristics in healthy male volunteers, twenty-two healthy volunteers were orally given a single dose of 2 mg RIP. Plasma samples were collected in the period of 96 hours and concentrations of RIP and 9-hydroxyrisperidone were measured by a validated HPLC/MS method. CYP2D6 phenotypes were identified by the T1/2 of RIP and 9-hydroxyrisperidone according to the literature. Model structure identifiability analysis was performed by the similarity transformation approach to investigate whether the unknown parameters of the proposed model could be estimated from the designed experiment. Pharmacokinetics parameters were estimated using weighted least squares method, and the final pharmacokinetics model were tested and evaluated by Monte Carlo simulation. Eighteen volunteers were phenotyped as extensive metabolizers (EM) and four volunteers were identified as intermediate metabolizers (IM). The final model included central and peripheral compartment for both parent (RIP) and metabolite (9-hydroxyrisperidone) respectively. Model structure identifiability analysis indicated that the proposed model was local identifiable. However, if the ratio of RIP converted to 9-hydroxyrisperidone was assumed to be 32% in EM, and 22% in IM, the model could be globally identifiable. The predicted time-concentration curve and AUC(0-t), C(max), T(max) of RIP and 9-hydroxyrisperidone estimated by the established model were in agreement with the observations and noncompartment analysis. Rate constant of RIP conversion to 9-hydroxyrisperidone was (0.12 +/- 0.08) h(-1) and (0.014 +/- 0.007) h(-1) for EM and IM, respectively. Elimination rate constants of RIP were (0.25 +/- 0.18) and (0.05 +/- 0.23) h(-1) for EM and IM, respectively. Model validation result showed that all parameters derived from the concentration data fitted well with the theoretical value, with mean prediction error of most PK parameter within +/- 15%. The established model well defined the disposition of RIP and 9-hydroxyrisperidone simultaneously and showed large inter-individual pharmacokinetics variation in different CYP2D6 phenotype. The model also provide a useful approach to characterize pharmacokinetics of other parent-metabolite drugs.

Paliperidone Extended-Release Tablets: A New Atypical Antipsychotic

This article reviews the use of the new atypical antipsychotic drug paliperidone extended-release (Pal-ER). Pal-ER is a delayed-release formulation that provides continual drug delivery over 24 hours and reduces fluctuations in serum drug concentrations. This delayed release minimizes side effects related to high serum levels that occur with immediate-release formulations. Pal-ER is effective, safe, and relatively well tolerated. Although Pal-ER does not have any major advantages or disadvantages compared with other antipsychotic drugs, it has unique pharmacological properties and may be a beneficial alternative medication for some patients.

Lack of bioequivalence between generic risperidone oral solution and originator risperidone tablets

Risperidone is an atypical anti-psychotic, available in various formulations.

OBJECTIVE

The objective of the study was to compare the bioavailability of a generic oral solution of risperidone (Test formulation) and Risperdal tablets (Reference formulation). Both formulations contained 1 mg risperidone per dosing unit.

METHODS

The study was carried out in 32 healthy volunteers under fasting conditions. Risperidone and 9-hydroxyrisperidone concentrations in plasma were determined using HPLC/MS/MS.

RESULTS

The results show that the 90% confidence intervals for the geometric mean ratios of the solution and the tablet formulations were not within the acceptance range of 80 125% for risperidone, whereas the confidence intervals for 9-hydroxyrisperidone were within the acceptance range of 80 - 125%.

CONCLUSION

Bioequivalence between the generic 1 mg/ml risperidone solution and the originator tablet formulation was not proven in this study.