Risperidone in acutely exacerbated schizophrenia: dosing strategies and plasma levels

Racial/Ethnic Differences in the Pharmacokinetics of Antipsychotics: Focusing on East Asians

Empirical clinical studies have suggested that East Asian patients may require lower dosages of psychotropic drugs, such as antipsychotics, lithium, and antidepressants, than non-Asians. Both the pharmacokinetic and pharmacodynamic properties of a drug can affect the clinical response of an illness. The levels of antipsychotics used for the treatment of schizophrenia may affect patient clinical responses; several factors can affect these levels, including patient medication adherence, body weight (BW) or body mass index, smoking habits, and sex. The cytochrome P450 (CYP) system is a major factor affecting the blood levels of antipsychotics because many antipsychotics are metabolized by this system. There were notable genetic differences between people of different races. In this study, we determined the racial or ethnic differences in the metabolic patterns of some selected antipsychotics by reviewing therapeutic drug monitoring studies in East Asian populations. The plasma concentrations of haloperidol, clozapine, quetiapine, aripiprazole, and lurasidone, which are metabolized by specific CYP enzymes, were determined to be higher, under the same daily dose, in East Asian populations than in Western populations.

Therapeutic Drug Monitoring of Paliperidone in Patients With Schizophrenia in Taiwan

BACKGROUND

The blood level of antipsychotics affects clinical responses to the drug; it can be influenced by race and several individual factors. This study analyzed the therapeutic plasma concentrations (Cps) of paliperidone for both oral and long-acting injectable (LAI) formulations in clinical samples from Taiwanese patients.

METHODS

Patients diagnosed with schizophrenia and treated with either oral paliperidone for at least 4 weeks or LAI paliperidone for at least 6 months were enrolled. Blood samples were taken before the morning dose of oral paliperidone or the injection of LAI paliperidone to obtain the trough Cps.

RESULTS

Among the patients in this study, 51 were taking oral paliperidone, and 26 were receiving LAI paliperidone. In the oral group, the mean Cps were 40.2 ± 19.8 ng/mL in patients taking 9 mg/d and 44.2 ± 15.9 ng/mL in those taking 12 mg/d. In the LAI group, the mean Cps were 32.9 ± 12.7 ng/mL in patients receiving 100 mg per 28 days and 49.9 ± 25.9 ng/mL in those receiving 150 mg per 28 days. The mean Cps per daily dose (Cps/DD) were 4.11 ± 1.99 ng/mL/mg in the oral group and 9.24 ± 3.78 ng/mL/mg in the LAI group.

CONCLUSIONS

Under the suggested DD for oral and LAI paliperidone treatment, most Taiwanese patients with schizophrenia can reach the suggested therapeutic Cps range. Wide interindividual differences were observed in the Cps/DD for both the oral (7-fold) and LAI paliperidone (4-fold) groups. Compared with Western reports, no difference was observed in the body weight-adjusted Cps/DD.

Dose Adjustment Model of Paliperidone in Patients With Acute Schizophrenia: A post hoc Analysis of an Open-Label, Single-Arm Multicenter Study

This study aimed to investigate the factors that influenced the clinicians to adjust the paliperidone dose in the acute phase of schizophrenia. This was a post hoc study of an 8-week, open-label, single-arm multicenter trial which evaluated the efficacy, safety, and tolerability of flexible doses of paliperidone ER (3-12 mg/day) in patients with acutely exacerbated schizophrenia. Patients were divided into groups according to the dose at week 8 (3, 6, and 9-12 mg). The responder was defined as the reduction percentage in the Positive and Negative Syndrome Scale (PANSS) total score of ≥30%. According to the chi-squared automatic interaction detection algorithm, decision tree models predicting an increase in the dose of paliperidone ER were established. A decision tree, based on 4-week Marder positive factor, Clinical Global Impression (CGI), and BMI, was established to guide the dose adjustments of paliperidone ER in the acute phase of schizophrenia. The multivariable logistic regression analysis showed that lower age at onset, higher baseline PANSS positive subscale score, and lower baseline Personal and Social Performance Scale (PSP) score were significant predictors of increased dose in responders. Patients with young-onset age, severe baseline symptoms, and poor function are more likely to benefit from high dosage.

Dose reduction of risperidone and olanzapine can improve cognitive function and negative symptoms in stable schizophrenic patients: A single-blinded, 52-week, randomized controlled study

BACKGROUND

The long-term effects of dose reduction of atypical antipsychotics on cognitive function and symptomatology in stable patients with schizophrenia remain unclear. We sought to determine the change in cognitive function and symptomatology after reducing risperidone or olanzapine dosage in stable schizophrenic patients.

METHODS

Seventy-five stabilized schizophrenic patients prescribed risperidone (≥4 mg/day) or olanzapine (≥10 mg/day) were randomly divided into a dose-reduction group ( n=37) and a maintenance group ( n=38). For the dose-reduction group, the dose of antipsychotics was reduced by 50%; for the maintenance group, the dose remained unchanged throughout the whole study. The Positive and Negative Syndrome Scale, Negative Symptom Assessment-16, Rating Scale for Extrapyramidal Side Effects, and Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery were measured at baseline, 12, 28, and 52 weeks. Linear mixed models were performed to compare the Positive and Negative Syndrome Scale, Negative Symptom Assessment-16, Rating Scale for Extrapyramidal Side Effects and MATRICS Consensus Cognitive Battery scores between groups.

RESULTS

The linear mixed model showed significant time by group interactions on the Positive and Negative Syndrome Scale negative symptoms, Negative Symptom Assessment-16, Rating Scale for Extrapyramidal Side Effects, speed of processing, attention/vigilance, working memory and total score of MATRICS Consensus Cognitive Battery (all p<0.05). Post hoc analyses showed significant improvement in Positive and Negative Syndrome Scale negative subscale, Negative Symptom Assessment-16, Rating Scale for Extrapyramidal Side Effects, speed of processing, working memory and total score of MATRICS Consensus Cognitive Battery for the dose reduction group compared with those for the maintenance group (all p<0.05).

CONCLUSIONS

This study indicated that a risperidone or olanzapine dose reduction of 50% may not lead to more severe symptomatology but can improve speed of processing, working memory and negative symptoms in patients with stabilized schizophrenia.

Another triumph of hope over experience?

Schizophrenia continues to challenge services: recent advances in antipsychotic drug treatment and psychosocial interventions are hindered by non-adherence, disengagement and substance misuse. Furthermore, new side-effect concerns attach to atypical drugs, and psychosocial interventions may be underresourced or of unproven benefit. It is important to address all issues with which patients, families and carers need assistance, and to take a well-informed, creative approach to pharmacological treatment, using medication according to individual patient need rather than mechanistic adherence to guidelines. Psychiatrists should be realistic in their expectations of patient outcome, accepting outcomes that fall short of recovery and imply long-term supportive care, and insisting that this care be available to their patients. Psychiatrists should support early diagnosis and intervention as being possibly the only means to alleviate the burden of long-term schizophrenia for patients, families and services.

Optimal Dosing of Risperidone and Olanzapine in the Maintenance Treatment for Patients With Schizophrenia and Related Psychotic Disorders: A Retrospective Multicenter Study

OBJECTIVES

This study aims to determine the optimal tolerability dose ranges of risperidone (RIS) and olanzapine (OLZ) administered during schizophrenia maintenance phase.

METHODS

Two-year continuation rates of prescription at discharge were examined using a retrospective cohort study method. Adult patients with schizophrenia and related psychotic disorders, receiving antipsychotic monotherapy with RIS or OLZ at discharge, were included. The primary outcome measures were the time to treatment discontinuation and 2-year continuation rates at 4 modal dose ranges of each drug. We estimated the optimal tolerability dose ranges by comparing the continuation rates at various modal doses.

RESULTS

Of 648 patients, 344 received RIS and 304 received OLZ. The RIS 2-year continuation rates at 4 daily modal dose ranges were significantly different (0.5-2.5 mg: 46.0%, 3.0-5.0 mg: 40.0%, 5.5-7.5 mg: 30.0%, and 8.0-10.0 mg: 28.0%), with the difference favoring RIS at lower doses (0.5-5.0 mg) more than higher doses (5.5-10.0 mg). In contrast, there were no significant differences among OLZ 4 modal dose ranges (2.5-7.5 mg: 49.1%, 10.0-15.0 mg: 42.6%, 17.5-22.5 mg: 40.9%, and 25.0-30.0 mg: 39.0%). The time to treatment discontinuation significantly favored OLZ over RIS. However, it did not significantly differ between RIS and OLZ at lower doses.

CONCLUSIONS

It is suggested that the optimal tolerability dose range during maintenance treatment is 0.5 to 5.0 mg/d for RIS and 2.5 to 30 mg/d for OLZ, and that RIS at lower doses is comparable with OLZ at lower doses.

First demonstration that brain CYP2D-mediated opiate metabolic activation alters analgesia in vivo

The response to centrally acting drugs is highly variable between individuals and does not always correlate with plasma drug levels. Drug-metabolizing CYP enzymes in the brain may contribute to this variability by affecting local drug and metabolite concentrations. CYP2D metabolizes codeine to the active morphine metabolite. We investigated the effect of inhibiting brain, and not liver, CYP2D activity on codeine-induced analgesia. Rats received intracerebroventricular injections of CYP2D inhibitors (20 μg propranolol or 40 μg propafenone) or vehicle controls. Compared to vehicle-pretreated rats, inhibitor-pretreated rats had: (a) lower analgesia in the tail-flick test (p<0.05) and lower areas under the analgesia-time curve (p<0.02) within the first hour after 30 mg/kg subcutaneous codeine, (b) lower morphine concentrations and morphine to codeine ratios in the brain (p<0.02 and p<0.05, respectively), but not in plasma (p>0.6 and p>0.7, respectively), tested at 30 min after 30 mg/kg subcutaneous codeine, and (c) lower morphine formation from codeine ex vivo by brain membranes (p<0.04), but not by liver microsomes (p>0.9). Analgesia trended toward a correlation with brain morphine concentrations (p=0.07) and correlated with brain morphine to codeine ratios (p<0.005), but not with plasma morphine concentrations (p>0.8) or plasma morphine to codeine ratios (p>0.8). Our findings suggest that brain CYP2D affects brain morphine levels after peripheral codeine administration, and may thereby alter codeine's therapeutic efficacy, side-effect profile and abuse liability. Brain CYPs are highly variable due to genetics, environmental factors and age, and may therefore contribute to interindividual variation in the response to centrally acting drugs.

A comparison between augmentation with olanzapine and increased risperidone dose in acute schizophrenia patients showing early non-response to risperidone

We examined whether augmentation with olanzapine would be superior to increased risperidone dose among acute schizophrenia patients showing early non-response to risperidone. We performed a rater-blinded, randomized controlled trial at psychiatric emergency sites. Eligible patients were newly admitted patients with acute schizophrenia. Early response was defined as Clinical Global Impressions-Improvement Scale score ≤3 following 2 weeks of treatment. Early non-responders were allocated to receive either augmentation with olanzapine (RIS+OLZ group) or increased risperidone dose (RIS+RIS group). The 78 patients who completed 2 weeks of treatment were divided into 52 early responders to risperidone and 26 early non-responders to risperidone (RIS+OLZ group, n=13; RIS+RIS group, n=13). No difference in the achievement of ≥50% improvement in Positive and Negative Syndrome Scale total score was observed between RIS+OLZ and RIS+RIS groups. Although time to treatment discontinuation for any cause was significantly shorter in the RIS+RIS group (6.8 weeks [95% confidence interval, 5.2-8.4]) than in early responders to risperidone (8.6 weeks [7.9-9.3]; P=0.018), there was no significant difference between the RIS+OLZ group (7.9 weeks [6.3-9.5]) and early responders to risperidone. Secondary outcomes justify the inclusion of augmentation arms in additional, larger studies comparing strategies for early non-responders.

A randomized, double-blind comparison of risperidone versus low-dose risperidone plus low-dose haloperidol in treating schizophrenia

Monotherapy is recommended for schizophrenia treatment, but the risk-benefit issue of antipsychotic drug combination (except for clozapine) remains unclear. Risperidone, an atypical antipsychotic drug, has a lower incidence of extrapyramidal syndrome but higher risks of prolactinemia and metabolic syndrome than haloperidol, a typical agent. This study compared efficacy and safety of risperidone monotherapy versus low-dose risperidone plus low-dose haloperidol in schizophrenia. In this 6-week, double-blind study, patients were randomized to the combination group (2-mg/d risperidone plus 2-mg/d haloperidol, n = 46) or the monotherapy group (4-mg/d risperidone, n = 42). Efficacy assessments included Clinical Global Impression-Severity, Positive and Negative Syndrome Scale and subscales, Calgary Depression Scale, Global Assessment of Functioning, and Medical Outcomes Study Short-Form 36. Safety was rigorously monitored. Response was defined as 30% reduction in the Positive and Negative Syndrome Scale total score. The 2 treatment groups were similar in (1) demographic and clinical characteristics at baseline, (2) response rate, and (3) improvement in various psychopathological measures and quality of life at end point. The monotherapy group had a higher increase in prolactin levels (P = 0.04) and Simpson-Angus Scale scores (P = 0.04) and a higher percentage of biperiden use (P = 0.045). There were no significant between-group difference in changes in weight, vital signs, corrected QT interval, liver/renal function, fasting glucose level, and lipid profiles. The findings suggest that risperidone monotherapy may yield higher prolactin levels than a combination of low-dose risperidone plus low-dose haloperidol. The 2 treatment groups are similar in efficacy, life quality, and other safety profiles. Future long-term studies are warranted.

A randomized, double-blind, placebo-controlled comparison study of sarcosine (N-methylglycine) and D-serine add-on treatment for schizophrenia

Recent evidence indicates that enhancing N-methyl-D-aspartate (NMDA) neurotransmission with the treatment of NMDA/glycine site agonists, such as D-serine, or a glycine transporter-1 (GlyT-1) antagonist, N-methylglycine (sarcosine), can improve symptoms of schizophrenia. To compare these two novel approaches, 60 patients with chronic schizophrenia were enrolled into a 6-wk double-blind, placebo-controlled trial of add-on treatments at the reported effective dosages (2 g/d). Clinical assessments were conducted every other week. Treatment group x treatment duration interaction analysis by multiple linear regression showed that sarcosine was superior to placebo at all four outcome measures of Positive and Negative Syndrome Scale (PANSS) total (p=0.005), Scale for the Assessment of Negative Symptoms (SANS) (p=0.021), Quality of Life (QOL) (p=0.025), and Global Assessment of Functioning (GAF) (p=0.042). However, d-serine did not differ significantly from placebo in any measure. Sarcosine treatment was better than d-serine in effect sizes for all outcome measures. Sarcosine also surpassed placebo in most of the measures of five PANSS factors and five SANS subscales. All treatments were well tolerated. These findings suggest that the GlyT-1 inhibitor is more efficacious than the NMDA/glycine site agonist in treatment for schizophrenia, including life quality and global function, at the dosages tested.

Lack of association between AKT1 variances versus clinical manifestations and social function in patients with schizophrenia

The elucidation of genotype-phenotype relationships in psychiatric research is at an early stage. V-akt murine thymoma viral oncogene homolog 1 (AKT1) is a serine/threonine kinase known as protein kinase B. Emerging studies have implicated the role of AKT1 in pathogenesis of schizophrenia; however, the findings have not been consistent. This study aims to examine the association of AKT1 polymorphisms with drug-free and post-treatment symptomatology and social function in patients with schizophrenia. One hundred and twenty newly hospitalised patients with acutely exacerbated schizophrenia who had never been treated by atypical antipsychotics were recruited. They received optimal treatment of risperidone for up to 42 days in the inpatient research unit. Clinical manifestations were monitored by Positive and Negative Syndrome Scale (PANSS) and social function by Nurses' Observation Scale for Inpatients Evaluation (NOSIE). Patients were genotyped for eight AKT1 Single Nucleotide Polymorphism (SNPs), which have been previously investigated for association with schizophrenia. At drug-free status and after best possible treatment of risperidone, genotypes of each SNP did not influence performances in NOSIE, PANSS-total, -positive, -negative and -general psychopathology profiles. These results suggest that AKT1 does not play a significant role in clinical and functional manifestations in patients with schizophrenia who receive risperidone treatment. Future research should also focus on the relationships between genotypes of other susceptibility genes and phenotypes or functional outcomes of schizophrenia.

Relapse and long-acting injectable risperidone: a 1-year mirror image study with a national claims database in Taiwan

OBJECTIVES

The development of long-acting, injectable atypical antipsychotics has provided a new paradigm for schizophrenia treatment. The study was designed to assess whether a risperidone long-acting injection (RLAI) is associated with reduced relapses and service utilization in the real world.

METHODS

The Psychiatric Inpatients Medical Claims dataset was used for the analysis. It is a longitudinal dataset that includes the National Health Insurance claims of service uses by a cohort of mentally ill patients. The inclusion criteria for this analysis were patients who: 1) had available information for at least 12 months after the first dose of RLAI; 2) had a primary diagnosis of schizophrenia; and 3) were regularly treated with RLAI for at least 1 year. Patients who accumulatively received at least 75-mg RLAI per 3-month period were considered to be undergoing regular treatment. Wilcoxon signed rank tests were performed to compare differences in numbers of acute admissions, hospital days, emergency room visits, and relapses between the pre- and post-RLAI periods in this 1-year mirror-image study.

RESULTS

In total, 108 patients were eligible for analysis. Significant reductions in the total annual numbers of acute hospital admissions by 55% (80 vs. 36, P = 0.0003), hospital days by 48% (4106 vs. 2126, P = 0.0021), and relapses by 54% (115 vs. 53, P = 0.0005) were observed. A reduction of emergency room visits was also observed, but did not reach statistical significance (55 vs. 25, P = 0.1255).

CONCLUSIONS

This 1-year mirror-image analysis with claims-based data demonstrated that RLAI treatment was associated with reductions in relapses and hospital service utilization.

Pharmacokinetics and efficacy of a direct switch from conventional depot to risperidone long-acting injection in Chinese patients with schizophrenic and schizoaffective disorders

AIMS

This 12-week open-label study was designed to investigate the pharmacokinetics and efficacy of a direct switch from a conventional depot to long-acting injectable risperidone in patients with schizophrenia and schizoaffective disorder.

METHODS

Men or women from 18 to 65 years old with a diagnosis of schizophrenia or schizoaffective disorder were eligible for participation if they had been treated with conventional depot for at least 8 weeks before study entry. Intramuscular long-acting risperidone was administered starting from 25 mg, with the dose flexibly adjusted every two weeks for 12 weeks from week 4.

RESULTS

Of the 25 patients enrolled in this study, 21 completed at least one post-baseline assessment and were thus included in the analysis. The mean serum concentration of risperidone plus 9-hydroxyrisperidone was 29.1 ng/mL at the 12th week after switching, with an average injection dose of 31.25 mg long-acting risperidone every two weeks. The levels of active moiety of risperidone seemed to be higher in Chinese patients compared to those in Caucasian patients. Positive and Negative Syndrome Scale total scores (from 67.5 to 56.4; P = 0.002), scores for negative symptoms (P = 0.006) and general symptoms (P = 0.001) were improved significantly 12 weeks after the switch. Mean Extrapyramidal Symptom Rating Scale scores were improved significantly from 20.1 to 5.5 (P < 0.001). Significantly decreased levels of cholesterol and triglyceride were found at the 12th week. The levels of fasting glucose, low-density lipoprotein, high-density lipoprotein and bodyweight remained unchanged.

CONCLUSIONS

These findings suggest that switching from conventional depot to long-acting risperidone is feasible with the advantage of symptom reduction and side-effect profile decrement.

RGS4 polymorphisms predict clinical manifestations and responses to risperidone treatment in patients with schizophrenia

OBJECTIVE

Polymorphisms of the gene encoding the regulator of G-protein signaling subtype 4 (RGS4) are associated with schizophrenia. This study aims to investigate the association of 4 RGS4 polymorphisms (single nucleotide polymorphisms [SNPs] 1, 4, 7, and 18), implicated in previous studies, with baseline symptoms and treatment response to risperidone in patients with schizophrenia.

METHODS

One hundred twenty patients with acutely exacerbated schizophrenia who had never been treated by atypical antipsychotics were recruited. They received optimal treatment of risperidone for up to 42 days in the inpatient research unit. Patients' social functions were monitored by Nurses' Observation Scale for Inpatients Evaluation and clinical manifestations, by Positive and Negative Syndrome Scale.

RESULTS

At baseline status, the A/A genotype at SNP7 of RGS4 was associated with poorer social function when compared with the G/G genotype. After risperidone treatment, the A/A genotype at SNP1 was associated with greater improvement at social function, and the A/A genotype at SNP18 was associated with greater improvement at social function, Positive and Negative Syndrome Scale total score, and positive- and negative-symptom subscale.

CONCLUSIONS

These findings suggest that RGS4 variances influence clinical manifestations of schizophrenia as well as the treatment response to risperidone, suggesting that RGS4 plays a role in the fundamental process of disease pathophysiology.

Could HTR2A T102C and DRD3 Ser9Gly predict clinical improvement in patients with acutely exacerbated schizophrenia? Results from treatment responses to risperidone in a naturalistic setting

OBJECTIVE

This study seeks to replicate previous results indicating that T102C in the serotonin 2A receptor (HTR2A) and Ser9Gly in the dopamine D3 receptor (DRD3) were associated with a risperidone response to acutely exacerbated schizophrenia, and to determine whether possession of these alleles predicts clinical improvement in a naturalistic setting.

METHODS

We consecutively recruited 100 schizophrenia patients and assessed clinical improvement after 4 weeks of risperidone treatment.

RESULTS

The patients with T/T in the HTR2A gene showed less clinical improvement than did those with T/C or C/C (p = 0.044). In the case of the DRD3 gene, we did not find statically significant association with clinical improvement (p = 0.061). When patients were categorized into responders and nonresponders, the C allele was more frequent in responders (OR = 2.28, 95%CI = 1.06-4.91, p = 0.039). When combinations of the two polymorphisms were considered, patients who had T/T in the HTR2A gene and encoded Ser/Ser or Ser/Gly from DRD3 gene had a higher propensity to non-responsiveness compared to other subjects (OR = 3.57, 95%CI = 1.10-11.62, p = 0.039).

CONCLUSIONS

Our findings suggest that the HTR2A T102C could be a potential indicator of clinical improvement after risperidone treatment.

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.

Optimizing early prediction for antipsychotic response in schizophrenia

OBJECTIVE

Researchers, by studying first-generation antipsychotics, have established an early prediction model, which had a favorable specificity but a low sensitivity. This study aims to optimize early prediction of treatment response for schizophrenia using a novel statistic method that can be done even under the Microsoft Excel system of a personal computer.

METHODS

One hundred twenty-three inpatients with acutely exacerbated schizophrenia were given optimal therapy of risperidone, a commonly used second-generation antipsychotic agent. Response was defined as a reduction of 20% or more in the Positive and Negative Syndrome Scale total score. We applied the generalized estimating equation method's logistic regression to establish an early prediction model based on the treatment results of the first and the second weeks.

RESULTS

The proposed method correctly predicted nonresponse at 4 and 6 weeks in 80.8% and 81.8% of the patients, respectively. The method also identified responder at 4 and 6 weeks in 80.0% and 82.8%, respectively. The predictive powers (or correct prediction rates) at 4 and 6 weeks were 80.3% and 82.4%, respectively. In addition, the results based on the responses in Positive and Negative Syndrome Scale scores were slightly better than those in Brief Psychiatric Rating Scale scores.

CONCLUSIONS

Using the first 2 weeks' treatment results to predict the fourth or sixth week's treatment response is acceptable in terms of specificity, sensitivity, and predictive power. Further studies are needed. Moreover, whether this model could be applied to establish a prediction system for other psychotropics, such as antidepressants, also deserves research.

Plasma antipsychotic concentration and receptor occupancy, with special focus on risperidone long-acting injectable

Although effective plasma concentration ranges have been established for some antipsychotics, conventional and atypical, there is considerable inter-patient pharmacokinetic variation. Positron-emission tomography (PET) can be used to estimate D(2)-like receptor occupancy in the brain needed for an antipsychotic effect and the level above which extrapyramidal side effects (EPS) develop. For conventional antipsychotics, the window occupancy is approximately 70-80%. For the atypical antipsychotic risperidone, the antipsychotic effect starts at approximately 60% occupancy, with occupancy above 80% leading to EPS. The new formulation, risperidone long-acting injectable (RLAI), comprises risperidone in a biodegradable polymer. It is effective long-term at doses of 25 or 50 mg injected i.m. every 2 weeks. The constant and slow release of the long-acting formulation leads to less fluctuation in plasma levels and to a D(2)-like receptor occupancy which is below the threshold for EPS.

Risperidone-related weight gain: genetic and nongenetic predictors

OBJECTIVE

A serious side effect of atypical antipsychotics is increased body weight, which leads to further morbidity and nonadherence to medication. It has been suggested that both genetic and nongenetic variables may influence antipsychotics-related weight gain. This study aimed to simultaneously explore the effects of multiple candidate genes and environment factors on body weight of schizophrenia patients who received risperidone, a commonly used atypical antipsychotic agent.

METHODS

One hundred twenty-three ethnically Han Chinese inpatients with acutely exacerbated schizophrenia were given risperidone monotherapy for up to 42 days. Body weight and clinical manifestations were assessed biweekly. Drug efficacy was measured by the Positive and Negative Syndrome Scale (PANSS), and safety was evaluated by the Extrapyramidal Symptom Rating Scale (ESRS) and the UKU Side Effect Rating Scale. We collected body weight as the response value. Potential prognostic factors were baseline body weight, age, sex, diagnosis subtypes, risperidone dosage, PANSS total scores, treatment duration (weeks 0-6), and 15 genetic variants [across 10 candidate genes: 5-HT1A, 5-HT2A, 5-HT2C, 5-HT6, D1, D2, D3, and alpha1-adrenergic receptors, brain-derived neurotrophic factor (BDNF), and cytochrome P450 2D6 (CYP2D6)]. Because there were repeated assessments, multiple linear regression with the generalized estimating equation (GEE) method was used to adjust the within-subject dependence.

RESULTS

Of 15 genetic polymorphisms examined, 5-HT2A 102-T/C, 5-HT2C -759-C/T, 5-HT6 267-C/T, BDNF 66-Val/Met, and CYP2D6 188-C/T significantly influenced body weight, and so did baseline body weight, age, gender, schizophrenia subtype, and treatment duration and efficacy.

CONCLUSIONS

These results suggest that numerous genetic and nongenetic factors affect antipsychotics-related weight gain.

Adjunctive Treatment of Acute Mania with Risperidone versus Typical Antipsychotics: A Retrospective Study

Few studies have directly compared atypical antipsychotics (e.g. risperidone) with typical antipsychotics as adjunctive therapy in patients hospitalized for acute mania, especially during a lengthy hospital stay. Our retrospective, case-controlled study is a chart review of 64 patients with Diagnostic and Statistical Manual of Mental Disorders, 4th edition, defined bipolar I disorder (current episode, mania). Patients were divided into two groups according to the adjunctive medications used: the risperidone group (mood stabilizers plus risperidone) and the control group (mood stabilizers plus typical antipsychotics). Outcome at discharge, medications, adverse drug effects, and length of hospital stay were compared between groups, controlling for gender, age, number of prior admissions, and duration of illness. Results indicated no statistically significant differences between groups in the controlled factors, Global Assessment of Functioning and Clinical Global Impression-Improvement scores, and adverse drug events. Patients in the risperidone group used significantly lower doses of trihexyphenidyl than those in the control group (p < 0.05). Patients treated with risperidone had a shorter hospital stay than those treated with typical antipsychotics (p < 0.01). In conclusion, antipsychotics are effective as adjunctive agents in the treatment of acute mania. The use of risperidone, in particular, decreases the need for anticholinergics and may lead to a shorter hospital stay compared with typical antipsychotics.

Pharmacogenetic studies of response to risperidone and other newer atypical antipsychotics

Risperidone and other newer atypical antipsychotics are becoming the mainstay for schizophrenia treatment. Recent studies suggest that the 5-hydroxytryptamine receptor 2A (5-HT2A) gene (HTR2A) T102C and G-1438A polymorphisms may influence treatment response of risperidone or olanzapine for schizophrenia's negative symptoms (e.g., blunted affect and social withdrawal). In addition, the HTR6 T267C polymorphism has been linked to risperidone response for positive symptoms (delusions and hallucinations). The dopamine D2 receptor (DRD2) Ser311Cys polymorphism may also play a role in determining risperidone efficacy for positive, negative and cognitive symptoms, the DRD2 Ins-A2/Del-A1 diplotype may predict better risperidone response, and the DRD3 Ser311Cys variant may affect general treatment response of several atypical agents. Although investigators have started to explore genetic effects on cognitions of schizophrenia patients receiving antipsychotics, future larger sized pharmacogenetic studies on both psychotic symptoms and cognitive functions are warranted.

Dopamine D3 receptor Ser9Gly polymorphism and risperidone response

Risperidone is an atypical antipsychotic agent with efficacy for both positive and negative symptoms of schizophrenia. Risperidone is a potent dopamine D3 antagonist and agonism at D3 sites induces behavioral suppression in rodents. We thus hypothesized that D3 antagonism may contribute to response to risperidone in negative symptoms. This study aimed to explore the influence of the Ser9Gly polymorphism of the dopamine D3 receptor (DRD3) gene on response to risperidone after controlling for nongenetic factors. One hundred twenty-three Han Chinese patients with acutely exacerbated schizophrenia were given risperidone monotherapy for up to 42 days. Clinical manifestations were measured biweekly with Positive and Negative Syndrome Scale and Nurses' Observation Scale for Inpatients Evaluation (for assessment of social functioning). For adjusting the within-subject dependence over repeated assessments, multiple linear regression with generalized estimating equation methods was used to analyze the effects of Ser9Gly polymorphism and other covariates on clinical performance. Compared with patients with the Gly9Gly genotype, those with either Ser9Ser or Ser9Gly had better performance on negative symptoms after control for other prognostic factors (P = 0.0002 and 0.0092, respectively). Patients with the Ser9Ser genotype had better social functioning than those with Gly9Gly (P = 0.0029). The Ser9Gly polymorphism, however, did not significantly affect positive symptoms. Male gender, fewer previous hospitalizations, and higher risperidone dose also predicted better treatment response. These data suggest that the DRD3 Ser9Gly polymorphism or, alternatively, another genetic variation that is in linkage disequilibrium, may influence response to risperidone in negative symptoms and social functioning.

Switching atypical antipsychotics: a review

BACKGROUND

Atypical antipsychotics are increasingly used in the treatment of diverse psychiatric disorders; however, there is little information on the 'why, when, and how' of switching between the different atypical antipsychotics currently available.

OBJECTIVE

To review the data on switching and atypical antipsychotics.

METHODS

A literature search was initially conducted using the key words followed by a search of relevant articles including conference abstracts; relevant pharmaceutical companies were also contacted.

RESULTS

Clinical trial data are limited in terms of parameters measured, and case reports describe specific problems. Few studies are based on real world populations of psychiatric patients over the long-term. Careful patient and drug selections matched to a carefully supervised and appropriate cross titration based upon the pharmacodynamic and pharmacokinetic properties of all of the drugs involved is important to avoid potential complications such as re-emergence or worsening of psychosis and withdrawal, rebound, and emergent phenomena including new or uncovered side-effects. Psychoeducation and involvement of patients and caregivers in the process are also necessary for a successful switch.

CONCLUSION

Despite the prevalence of switching in real world clinical practice, there is a paucity of data to guide clinicians with respect to effective and safe strategies. There are no criteria defining a successful switch. With the increasing range and formulations of atypical antipsychotics available, there is a rationale for their early use to avoid the practical problems associated with switching from conventional antipsychotics as well as the opportunity to maintain patients on an optimal atypical antipsychotic monotherapy.

Antipsychotic treatment in schizophrenia: atypical options and NICE guidance

Following the reintroduction of clozapine, several atypical antipsychotics have become available for the treatment of schizophrenia. These drugs are at least as effective as conventional treatment. Although each has an individual pattern of affinities, new work suggests that the hallmark of atypicality is fast dissociation at the dopamine-2 receptor. Numerous novel drugs are in development, but it is not clear how these conform to this theory of therapeutic effect. Atypical antipsychotics cause less extrapyramidal side effects than conventional treatment, but other effects such as hyperprolactinaemia, weight gain, glucose dysregulation and prolonged QTc interval remain problematic for some. Current antipsychotic prescribing practice is far from ideal: the NICE guidance stresses that atypical treatments should be considered unless symptoms are well controlled and side effects are acceptable, or depot formulation is indicated. There is a welcome emphasis on drug treatment as part of an integrated package of care negotiated with patients and their carers.

Design and reporting modifications in industry-sponsored comparative psychopharmacology trials

This review of recently published pharmaceutical industry-sponsored comparative psychotropic drug trials aims to classify apparent design and reporting modifications that favor the sponsor's product. The modifications have been grouped into 13 discrete categories, and representative examples of each are presented. Strong circumstantial evidence suggests that marketing goals led to these adjustments. The consequences of marketing influences on comparative psychopharmacology trials are discussed in terms of conflicts of interest, the integrity of the scientific literature, and costs to consumers, as well as their impact on physician practice.

Influences of patient-related variables on risperidone efficacy for acutely exacerbated schizophrenia: analyses with rigorous statistics

Response predictors of risperidone or other newer atypical antipsychotics for schizophrenia treatment remain unclear. This study aimed to investigate the influence of patient demographics on risperidone efficacy for schizophrenia. One hundred twenty-one newly hospitalized patients who had schizophrenia with acute exacerbation entered this prospective, 6-week risperidone trial. The target dose was 6 mg/day, or lower in case of side effects. Consequently, the mean +/- SD dose remained quite stable after week 2 and reached 4.4 +/- 1.3 mg/day at week 6. Efficacy and side effect assessments were conducted biweekly. The mean total score of the Positive and Negative Syndrome Scale (PANSS) declined during the trial, particularly within the first 4 weeks. Further, of the various efficacy scores (and their natural logarithm values) collected, only the logarithm of the PANSS total score was selected to serve as the response value, because it was normally distributed and thus suitable for regression analyses. After adjusting the effects of treatment duration (weeks 0-6) and other patient-related variables with the generalized estimating equation method, each 1-week increase in duration of prior hospitalizations raised the PANSS total by 0.04% (p = 0.002) and each 1-year increment in the education duration decreased the PANSS by 0.94% (p = 0.04). Gender, age, age at illness onset, duration of illness, diagnosis subtype, or number of prior hospitalizations, however, did not significantly impact the response value. These preliminary results suggest that longer hospitalization duration and shorter education predict higher symptomatology. Further studies with longer observation and larger samples in not only acutely ill patients but also other populations (e.g., first-episode patients) are warranted.

Shifting from haloperidol to risperidone for behavioral disturbances in dementia: safety, response predictors, and mood effects

For agitated dementia showing insufficient response to conventional antipsychotics, the feasibility of transition to atypical agents remains unknown. Sixty-two Chinese inpatients with dementia and disruptive behaviors were recruited into an 8-week screening trial of haloperidol. Thirty-five (56%) of them responded insufficiently. They then entered a prospective, 16-week, open-labeled study. Haloperidol was abruptly shifted to risperidone 0.5 mg/day at weeks 1 to 4 and then 1 mg/day at weeks 5 to 12. At weeks 13 to 16, the regimen was shifted back to haloperidol at previous doses, mostly 1 mg/day. Safety, efficacy, cognition, and moods were evaluated at least every 4 weeks. Generalized estimating equation methods were used for determining the effects of the prognostic variables on the outcome values. Risperidone, particularly at 0.5 mg/day, was generally tolerable. The Brief Psychiatric Rating Scale (BPRS) score decreased progressively under risperidone treatment; at week 12, 16 (46%) patients showed response (>or=25% reduction in the BPRS). Patients with vascular dementia were more likely to respond than those with Alzheimer's disease ( p = 0.02). Haloperidol reinstitution resulted in no further improvement, except trend increments in motor symptoms. Risperidone also tended to benefit the performance on the Behavioral Pathology in Alzheimer's Disease Rating Scale. Six (17%) patients improved on moods and self-care with risperidone. These preliminary results suggest that crossover from haloperidol to risperidone is generally safe and effective and may produce favorable moods in agitated dementia patients. Vascular dementia is a predictor of treatment response. In contrast to the dose (1 mg/day) recommended for most white individuals, 0.5 mg/day could be tried at first in Chinese patients. Because of the design's limitations, further controlled studies are warranted.