Impact of Obesity on Brexpiprazole Pharmacokinetics: Proposal for Improved Initiation of Treatment.

Brexpiprazole is an oral antipsychotic agent indicated for use in patients with schizophrenia or as adjunctive treatment for major depressive disorder. As obesity (body mass index ≥35 kg/m2 ) has the potential to affect drug pharmacokinetics and is a common comorbidity of both schizophrenia and major depressive disorder, it is important to understand changes in brexpiprazole disposition in this population. This study uses a whole-body physiologically based pharmacokinetic model to compare the pharmacokinetics of brexpiprazole in obese and normal-weight (body mass index 18-25 kg/m2 ) individuals known to be cytochrome P450 2D6 extensive metabolizers (EMs) and poor metabolizers (PMs). The physiologically based pharmacokinetic simulations demonstrated significant differences in the time to effective concentrations between obese and normal-weight individuals within metabolizer groups according to the label-recommended titration. Simulations using an alternative dosing strategy of 1 week of twice-daily dosing in obese EMs or 2 weeks of twice-daily dosing in obese poor metabolizers, followed by a return to once-daily dosing, yielded more consistent plasma concentrations between normal-weight and obese patients without exceeding the area under the plasma concentration-time curve observed in the normal-weight EMs. These alternative dosing strategies reduce the time to effective concentrations in obese patients and may improve clinical response to brexpiprazole.

Review of maintenance trials for major depressive disorder: a 25-year perspective from the US Food and Drug Administration.

OBJECTIVE: The maintenance efficacy of antidepressants is usually assessed in postmarketing studies with a randomized withdrawal design. This report explores differences in relapse rates, trial characteristics, and success rates in maintenance efficacy studies submitted to the US Food and Drug Administration (FDA) over a 25-year period. DATA SOURCES: Clinical data from all maintenance trials with antidepressants submitted to FDA between 1987 and 2012. STUDY SELECTION: Efficacy data were compiled from 15 maintenance clinical trials in adults diagnosed with major depressive disorder according to DSM-III or DSM-IV criteria. DATA EXTRACTION: Trial characteristics, relapse rates, and time to relapse in each study were examined. RESULTS: Relapse rates were significantly lower (P < .05) in the drug arm than in the placebo arm in every study, with a mean relapse rate difference of 18% and an average percent reduction in relapse rate of 52% compared to placebo. Only 6% of the relapse events occurred in the first 2 weeks of the double-blind phase. The separation between treatment arms continued to increase throughout the double-blind phase only in the trial with longest response stabilization period. CONCLUSIONS: Antidepressant maintenance trials have a high rate of success, indicating a benefit of continuing drug treatment after initial response to an antidepressant. This benefit appears to result mainly from a decreased rate of recurrent depression rather than from an effect of drug withdrawal in the placebo groups.

Defining a clinically meaningful effect for the design and interpretation of randomized controlled trials.

OBJECTIVE: This article captures the proceedings of a meeting aimed at defining clinically meaningful effects for use in randomized controlled trials for psychopharmacological agents. DESIGN: Experts from a variety of disciplines defined clinically meaningful effects from their perspectives along with viewpoints about how to design and interpret randomized controlled trials. SETTING: The article offers relevant, practical, and sometimes anecdotal information about clinically meaningful effects and how to interpret them. PARTICIPANTS: The concept for this session was the work of co-chairs Richard Keefe and the late Andy Leon. Faculty included Richard Keefe, PhD; James McNulty, AbScB; Robert S. Epstein, MD, MS; Shelby D. Reed, PhD; Juan Sanchez, MD; Ginger Haynes, PhD; Andrew C. Leon, PhD; Helena Chmura Kraemer, PhD; Ellen Frank, PhD, and Kenneth L. Davis, MD. RESULTS: The term clinically meaningful effect is an important aspect of designing and interpreting randomized controlled trials but can be particularly difficult in the setting of psychopharmacology where effect size may be modest, particularly over the short term, because of a strong response to placebo. Payers, regulators, patients, and clinicians have different concerns about clinically meaningful effects and may describe these terms differently. The use of moderators in success rate differences may help better delineate clinically meaningful effects. CONCLUSION: There is no clear consensus on a single definition for clinically meaningful differences in randomized controlled trials, and investigators must be sensitive to specific concerns of stakeholders in psychopharmacology in order to design and execute appropriate clinical trials.

Development of a placebo effect model combined with a dropout model for bipolar disorder.

The aim of this study was to develop a placebo model for bipolar disorder to help optimize clinical trial designs for studies targeting manic episodes in bipolar disorder. A bipolar disease database was built based on individual longitudinal data collected from over 3,000 patients in 11 clinical trials for 5 approved bipolar drugs. An empirical placebo effect model with an exponential decay process plus a linear progression process was developed to quantify the time course of the Young Mania Rating Scale total score based on only placebo data from the database. In order to describe the dropout pattern during the trials, a parametric survival model was developed and the Weibull distribution was identified to be the best distribution to describe the data. Based on the likelihood ratio test, it was found that patients with higher baseline score, slower disease improvement and more rapid disease progression tended to dropout earlier, and the trial features such as trial starting year and trial site were also significant covariates for dropout. A combination of the placebo effect model and the dropout model was applied to simulate new clinical trials through Monte-Carlo simulation. Both the placebo effect model and dropout model described the observed data reasonably well based on various diagnostic plots. The joint placebo response and dropout models can serve as a tool to simulate the most likely level of placebo response with the expected dropout pattern to help design a new clinical trial.

An integrated approach for establishing dosing recommendations: paliperidone for the treatment of adolescent schizophrenia.

The Food and Drug Administration recently approved Invega for the treatment of schizophrenia in adolescents 12 to 17 years. If dosing recommendations for this population would have been based only on the results of the single efficacy trial included in this program, paliperidone dosing in adolescents might have been limited to 3 mg/d in adolescents less than 51 kg and to 6 mg/d in adolescents greater than or equal to 51 kg. This article provides an illustration of a more integrated approach to arrive at dosing recommendation that included practical considerations, modeling and simulation of data from the clinical trial, and the totality of evidence for both paliperidone and the parent drug, risperidone. On the basis of this integrated approach, the agency approved a starting dose of 3 mg/d in both adolescent weight groups and subsequent dosing in a range of 3 to 6 mg/d for adolescents less than 51 kg and 3 to 12 mg/d for adolescents greater than 51 kg, although the 3-mg dose was not evaluated in the greater than or equal to 51-kg group.

CYP2D6 genotype information to guide pimozide treatment in adult and pediatric patients: basis for the U.S. Food and Drug Administration's new dosing recommendations.

OBJECTIVE: The occurrence of pimozide-induced arrhythmias is concentration dependent. Hence, it is important for prescribers to consider causes of increased pimozide exposure. This article summarizes the U.S. Food and Drug Administration's (FDA's) review of drug interaction and pharmacogenomic studies and discusses pharmacokinetic simulations we performed to develop new cytochrome P450 2D6 (CYP2D6) genotype-guided dosing recommendations for pimozide. METHOD: Pharmacokinetic parameters by CYP2D6 genotype were derived from a published single-dose pharmacogenomic study of pimozide. We simulated what pimozide exposures would result from a multiple-dose scenario in different CYP2D6 genotype groups: extensive, intermediate, and poor metabolizers. The maximum dose for poor metabolizers was defined as the dose that would not exceed pimozide concentrations following 10 mg daily in extensive metabolizers and intermediate metabolizers (the current maximum dose in an unselected population). RESULTS: Dose-ranging analyses revealed that 4 mg daily in CYP2D6 poor metabolizers was the maximum dose that would not result in plasma concentrations in excess of those observed in extensive metabolizer and intermediate metabolizer patients receiving 10 mg daily. CYP2D6 genotyping is now consequently recommended in the pimozide product label before exceeding 4 mg of pimozide daily in adults or 0.05 mg/kg/d in children. Previously, dose adjustment was recommended every 3 days to achieve the desired clinical response for all patients. The label was modified to subsequently reflect that pimozide doses should not be increased earlier than 14 days in patients who are known CYP2D6 poor metabolizers. CONCLUSIONS: Given the risk of increased pimozide concentrations and longer time to steady state in CYP2D6 poor metabolizers, the FDA has revised the pimozide label to provide clinicians with clearer dosing, titration, and genotype testing recommendations. The new information is intended to enhance therapeutic individualization of pimozide in pediatric and adult patients.

Exploratory analyses of efficacy data from schizophrenia trials in support of new drug applications submitted to the US Food and Drug Administration.

OBJECTIVE: There has been concern about a high rate of placebo response and a decline in treatment effect over time in schizophrenia trials as well as the implications of increasing conduct of such trials outside North America. This report explores differences in efficacy data over an 18-year period from randomized placebo-controlled trials submitted in support of new drug applications (NDAs) for the treatment of schizophrenia and differences in results between trials conducted in North America and elsewhere. DATA SOURCES: Clinical trial data that were submitted to the US Food and Drug Administration (FDA) as part of NDAs for the indication of schizophrenia between 1991 and 2009. STUDY SELECTION: Efficacy data were compiled from 32 clinical trials with 11,567 evaluable patients with schizophrenia. Data from completed, randomized, multicenter, double-blind, placebo-controlled, 4- to 8-week clinical trials in adult patients diagnosed with schizophrenia according to DSM-III or DSM-IV criteria were included. DATA EXTRACTION: Baseline demographic and disease characteristics, including mean Positive and Negative Syndrome Scale (PANSS) total scores, were summarized and compared between North American and multiregional trials. Mean change from baseline to endpoint in PANSS total scores was utilized as the primary outcome of interest. We explored differences in treatment effect and success rate of these trials based on when and where the studies were conducted, sample size, trial duration, and baseline patient characteristics. RESULTS: Twenty-one of the 32 trials were conducted solely in North America, and 11 were carried out in multiple regions. Of those 11 multiregional trials, 2 were conducted exclusively in foreign countries. Although the observed responses (change from baseline) in placebo and drug-treated groups in multiregional trials tended to be larger than in North American trials, the treatment effects (drug-placebo difference) were -9 and -8 PANSS units for North American and multiregional trials, respectively. When time of trial conduct was taken into account, an increasing placebo response and a diminishing treatment effect over time were observed in North American trials from -10.8 PANSS units for the first period (1991-1998) to -6.0 PANSS units for the later period (1999-2008). The overall trial success rate over the almost 2 decades was 78%, declining slightly in trials conducted after 1999, the time period during which multiregional trials were first conducted (74% for 1999-2008 vs 85% for 1991-1998), despite increasing sample sizes in the later period. The mean baseline PANSS total score was in the range of 87-100 for most of these trials. Trials in patients with higher mean baseline PANSS total scores tended to show larger treatment effects than those in patients with lower scores. The mean body weight and body mass index (BMI) were higher in patients in North American trials and North America-predominant multiregional trials compared to those in foreign-predominant multiregional trials (mean body weights of 85 kg and 81 kg vs 72 kg, and BMIs of 29 and 27 vs 25, respectively). Treatment effects decreased as body weights increased, especially in North American trials. In foreign-predominant multiregional trials, there were higher proportions of women than in North American trials and North America-predominant multiregional trials (40% vs 22% and 27%, respectively) and a relatively larger proportion of Asians (21% vs 1% and 8%, respectively). CONCLUSIONS: A high and increasing placebo response and a declining treatment effect are of great concern in schizophrenia trials conducted in North America. In this era of global clinical trials, close attention is needed to the design and conduct of these trials.

Vilazodone: clinical basis for the US Food and Drug Administration's approval of a new antidepressant.

OBJECTIVE: Vilazodone was recently approved by the US Food and Drug Administration (FDA) for the treatment of major depressive disorder (MDD). The purpose of this review is to summarize the FDA's approach to its review of the clinical pharmacology and the clinical efficacy and safety data for this new drug application, important issues in its decision-making, and its conclusions. DATA SOURCES: The data sources for this review were the original raw data sets for all clinical trials included in the development program for vilazodone, as well as the sponsor's original analyses of these data. STUDY SELECTION: Data were available from 24 human trials involving vilazodone, and included a total of 2,898 human subjects exposed to 1 or more doses of this drug. DATA EXTRACTION: The FDA had access to original raw data sets for these trials. RESULTS: Vilazodone is effective in treating MDD at a dose of 40 mg/d, but it needs to be incrementally adjusted to this dose to minimize gastrointestinal symptoms. It needs to be taken with food to ensure adequate plasma concentrations. Vilazodone's profile of adverse events is similar to that seen with selective serotonin reuptake inhibitors. No dose adjustment is needed based on age, gender, or renal or hepatic impairment. It is recommended that the vilazodone dose be reduced to 20 mg when it is taken with strong cytochrome P450 (CYP) 3A4 inhibitors, eg, ketoconazole. Vilazodone is not expected to have important effects on the clearance of other drugs that are cytochrome P450 substrates. CONCLUSIONS: Vilazodone is a new treatment for MDD, but it is unknown whether it has any advantages compared to other drugs in the antidepressant class.

Exploratory analyses of efficacy data from major depressive disorder trials submitted to the US Food and Drug Administration in support of new drug applications.

OBJECTIVE: There has been concern about a high rate of placebo response and a substantial failure rate in recent clinical trials in major depressive disorder (MDD). This report explores differences in efficacy data from placebo-controlled MDD trials submitted in support of new drug applications (NDAs) over a 25-year period. METHOD: We compiled efficacy data from 81 randomized, double-blind clinical trials, with 21,611 evaluable patients, that were submitted to the US Food and Drug Administration as part of NDAs for an antidepressant claim between 1983 and 2008. Trial data were limited to completed, randomized, multicenter, double-blind, placebo-controlled clinical trials in adult patients diagnosed with MDD according to DSM-III or DSM-IV criteria. The database was further limited to patients who were involved in clinical trials for drugs widely viewed as effective antidepressants and for doses of these drugs also viewed as effective doses. Trials were rated as successful if they showed statistical superiority vs placebo for the investigational drug on change in Hamilton Depression Rating Scale (HDRS) score (last-observation-carried-forward data). (Trials with multiple investigational drug groups were successful if there was superiority in at least 1 drug group after adjustment for multiplicity.) In particular, we explored differences in effect size and success rate of these trials, based on when the studies were conducted, geographic location of the study sites (US vs non-US), trial duration, dosing regimen, study size, and baseline disease characteristics. RESULTS: Eighty-one percent of MDD patients were enrolled in US sites. Although the observed placebo and drug responses at non-US sites tended to be larger than at US sites, the treatment effect (drug-placebo difference) was similar (mean change from baseline of about -2.5 units in HDRS total score) in US and non-US trials. In both US and non-US trials, the placebo response showed a modest increase over the observation period (1983-2008). Treatment effect clearly diminished over this same period, at a similar rate for both US and non-US trials despite a marked increase in the sample size of the trials. Our analysis showed that 53% of all MDD trials in the last 25 years were successful. US trials had a higher success rate than non-US trials (58% vs 33%). Before 1995, the overall success rate was 55%, compared to 50% for trials in 1995 or later, and, in general, 6-week trials had a higher success rate than 8-week trials (55% vs 42%). It should be noted that the earlier trials were mostly 6 weeks, and the 6-week trials had higher mean baseline HDRS scores than the 8-week trials. Study size did not seem to influence trial success rates. Mean baseline HDRS total scores declined over the 25-year observation period for patients in both US and non-US trials, as did treatment effect in these trials, again, regardless of region. Fixed-dose trials had a numerically slightly greater success rate than flexible-dose trials (57% vs 51%), although on average treatment effect was numerically larger in the flexible-dose trials than in fixed-dose trials (mean of -2.9 vs -2.0 on HDRS units). CONCLUSIONS: Treatment effect has declined over time in MDD trials, and there has been a high failure rate for these trials during the entire period, but the reasons for these findings remain elusive. Baseline disease severity seems to be a more important factor in study outcome than study duration, dosing regimen, sample size, time when studies were conducted, and regions where data were generated. Close attention is needed to a variety of factors in the design and conduct of these studies, including patient population, diagnostic considerations, patient assessment, and clinical practice differences. These considerations become increasingly important as globalization of clinical trials continues to increase.

What's next after 50 years of psychiatric drug development: an FDA perspective.

This article discusses changes in psychiatric drug development from a US Food and Drug Administration (FDA) standpoint. It first looks back at changes that have been influenced by regulatory process and then looks forward at FDA initiatives that are likely to affect psychiatric drug development in the future. FDA protects the public health by ensuring the safety and efficacy of drug products introduced into the US market. FDA works with drug sponsors during development, and, when applications are submitted, reviews the safety and efficacy data and the proposed labeling. Drug advertising and promotion and postmarketing surveillance also fall within FDA's responsibility. Among the many changes in psychiatric drug development over the past 50 years, several have been particularly influenced by FDA. Populations studied have expanded diagnostically and demographically, and approved psychiatric indications have become more focused on the clinical entities actually studied, including in some cases specific symptom domains of recognized syndromes. Trial designs have become increasingly complex and informative, and approaches to data analysis have evolved to better model the reality of clinical trials. This article addresses 2 general areas of innovation at FDA that will affect psychiatric drug development in years to come. Several programs falling under the general heading of the Critical Path Initiative, ie, biomarkers, adaptive design, end-of-phase 2A meetings, and data standards, are described. In addition, a number of important safety initiatives, including Safety First, the Sentinel Initiative, the Safe Use Initiative, and meta-analysis for safety, are discussed.

Trial design issues and treatment effect modeling in multi-regional schizophrenia trials.

In recent years, we have seen an increasing trend of foreign data as part of clinical trial data submitted in new drug applications (NDA) to US Food and Drug Administration (FDA). To understand the design and analysis characteristics, we studied schizophrenia multi-regional clinical trials (MRCTs). The schizophrenia data set consisted of a total of 12,585 patients collected from 33 clinical trials with 63.8% patients from North America, the largest region. The data set constituted 10 schizophrenia drug programs in support of NDAs submitted to FDA from December 1993 to December 2005. Two main objectives were pursued. First, we investigated some study design issues including potential heterogeneity of treatment effect via meta analysis and placebo response pattern over time. Second, we performed empirical modeling in two ways, supervised and unsupervised, to explain potential impact of baseline covariates on treatment effect in MRCTs. Based on our analysis results, placebo response appeared to increase over time and primarily attributed to US region. On average, the observed treatment effect in the US was generally smaller than non-US region. Both supervised and unsupervised empirical modeling selected baseline Positive and Negative Syndrome Scale total score as one of the most important covariates explaining a treatment effect. Region also played a role in explaining potential treatment effect heterogeneity. When baseline body weight was considered as a covariate in an empiric model, our results indicated that it alone did not seem to be an important factor in explaining regional difference.

Suicide rates in short-term randomized controlled trials of newer antidepressants.

Concerns have been raised about the appropriateness of placebo controls in clinical trials for major depressive disorder (MDD), given that there are approved treatments for this illness. Critics have argued that patients with untreated depression would be exposed to an unnecessary risk of suicide. There is also a competing concern that antidepressant drug treatment itself may induce suicidal behavior and thinking (suicidality). To examine this question, we have evaluated the rate of suicide in placebo- and active drug-treated groups of patients with MDD and various anxiety disorders participating in short-term randomized controlled trials (RCTs). We examined data from all manufacturer-sponsored short-term RCTs of 9 commonly used antidepressants in patients with MDD and various anxiety disorders. All short-term RCTs of antidepressants in patients with MDD and various anxiety disorders were included. Individual patients' data were available for all trials. Data were available for the 207 trials conducted in patients with MDD, including a total of 40,028 patients. There were 21 cases of suicide in these patients. Forty-four trials were conducted in patients with various anxiety disorders, including a total of 10,972 patients. There were 2 cases of suicide in these patients. Overall, at least 1 case of suicide occurred in 21 of the 251 trials. Sixteen of the suicides in MDD trials occurred in trials that had only an active control comparison group, and most of these (14 cases) were observed in the non-North American trials. In the placebo-controlled MDD trials, the rate ratios of suicide in the combined drug groups compared with placebo were 1.07 (0.1-63.4) and 0.5 (0.0-36.7) for the non-North American and North American trials, respectively. In the anxiety disorder studies, the overall rate ratio of suicide for the selective serotonin reuptake inhibitors compared with placebo was 0.9 (0.0-71.4). Neither use of placebo nor of antidepressants in short-term RCTs was associated with an increased risk of completed suicide among patients with MDD or various anxiety disorders. Nonetheless, because of the small numbers of suicides in these trials and the subsequent lack of statistical power, an increased risk of completed suicide in association with either drug or placebo treatment cannot be definitively excluded.

Mood disorders in the medically ill: scientific review and recommendations.

OBJECTIVE: The purpose of this review is to assess the relationship between mood disorders and development, course, and associated morbidity and mortality of selected medical illnesses, review evidence for treatment, and determine needs in clinical practice and research. DATA SOURCES: Data were culled from the 2002 Depression and Bipolar Support Alliance Conference proceedings and a literature review addressing prevalence, risk factors, diagnosis, and treatment. This review also considered the experience of primary and specialty care providers, policy analysts, and patient advocates. The review and recommendations reflect the expert opinion of the authors. STUDY SELECTION/DATA EXTRACTION: Reviews of epidemiology and mechanistic studies were included, as were open-label and randomized, controlled trials on treatment of depression in patients with medical comorbidities. Data on study design, population, and results were extracted for review of evidence that includes tables of prevalence and pharmacological treatment. The effect of depression and bipolar disorder on selected medical comorbidities was assessed, and recommendations for practice, research, and policy were developed. CONCLUSIONS: A growing body of evidence suggests that biological mechanisms underlie a bidirectional link between mood disorders and many medical illnesses. In addition, there is evidence to suggest that mood disorders affect the course of medical illnesses. Further prospective studies are warranted.

Developing novel treatments for mood disorders: accelerating discovery.

This review was generated from discussions by the Pharmacologic and Somatic Treatments Section of the National Institute of Mental Health Strategic Plan for Mood Disorders Committee on advancing novel pharmacologic and somatic treatments for mood disorders. The opening section of the article summarizes in broad strokes, current pharmacologic treatments, and new directions in the field. Thereafter the topics focus on specific research initiatives that could advance the current therapeutics for mood disorders including new basic and clinical research in vivo human imaging procedures, somatic therapeutics, and the vast new area of pharmacogenetics. New scientific and technical opportunities exist today based on advances in basic neuroscience, opportunities in clinical testing, industry interest in advancing central nervous system therapeutics, and on active consumer advocacy groups. The question of how to bring all of these positive forces together to accelerate discovery in mood disorder thera-peutics is the topic of this article.