A Phase I, Randomized, SAD, MAD, and PK Study of Risvodetinib in Older Adults and Parkinson's Disease.

Background: Pre-clinical studies suggest that c-Abl activation may play an important role in the etiology of Parkinson's disease, making c-Abl an important target to evaluate for potential disease-modification. Objective: To assess safety, tolerability, and pharmacokinetics of the c-Abl inhibitor risvodetinib (IkT-148009) in healthy subjects and participants with Parkinson's disease. Methods: Part 1 (single ascending dose (SAD)) and Part 2 (7-day multiple ascending dose (MAD)) studies were in healthy volunteers. Participants were randomized 3 : 1 across 9 SAD doses and 3 MAD doses of risvodetinib (IkT-148009) or placebo. Part 3 was a MAD study conducted at two doses in 14 participants with mild-to-moderate PD (MAD-PD). Primary outcome measures were safety, tolerability and pharmacokinetics. Exploratory outcomes in PD participants included clinical measures of PD state, GI function, and cerebrospinal fluid (CSF) concentration. Results: 108 patients were treated with no dropouts. The SAD tested doses ranging from 12.5 to 325 mg, while the MAD tested 25 to 200 mg and MAD-PD tested 50 to 100 mg in Parkinson's participants. All active doses had a favorable safety profile with no clinically meaningful adverse events. Single dose pharmacokinetics were approximately linear between 12.5 mg and 200 mg for both Cmax and AUC0 - inf without distinction between healthy volunteers and participants with PD. Exposures at each dose were high relative to other drugs in the same kinase inhibitor class. Conclusions: Risvodetinib (IkT-148009) was well tolerated, had a favorable safety and pharmacology profile over 7-day dosing, did not induce serious adverse events and did not appear to induce deleterious side-effects in participants administered anti-PD medications.

Experimental Medicine Approaches in Early-Phase CNS Drug Development.

Traditionally, Phase 1 clinical trials were largely conducted in healthy normal volunteers and focused on collection of safety, tolerability, and pharmacokinetic data. However, in the CNS therapeutic area, with more drugs failing in later phase development, Phase 1 trials have undergone an evolution that includes incorporation of novel approaches involving novel study designs, inclusion of biomarkers, and early inclusion of patients to improve the pharmacologic understanding of novel CNS-active compounds early in clinical development with the hope of improving success in later phase pivotal trials. In this chapter, the authors will discuss the changing landscape of Phase 1 clinical trials in CNS, including novel trial methodology, inclusion of pharmacodynamic biomarkers, and experimental medicine approaches to inform early decision-making in clinical development.

Diagnostic criteria for apathy in neurocognitive disorders.

INTRODUCTION: Apathy is common in neurocognitive disorders (NCD) but NCD-specific diagnostic criteria are needed. METHODS: The International Society for CNS Clinical Trials Methodology Apathy Work Group convened an expert group and sought input from academia, health-care, industry, and regulatory bodies. A modified Delphi methodology was followed, and included an extensive literature review, two surveys, and two meetings at international conferences, culminating in a consensus meeting in 2019. RESULTS: The final criteria reached consensus with more than 80% agreement on all parts and included: limited to people with NCD; symptoms persistent or frequently recurrent over at least 4 weeks, a change from the patient's usual behavior, and including one of the following: diminished initiative, diminished interest, or diminished emotional expression/responsiveness; causing significant functional impairment and not exclusively explained by other etiologies. DISCUSSION: These criteria provide a framework for defining apathy as a unique clinical construct in NCD for diagnosis and further research.

Placebo response mitigation with a participant-focused psychoeducational procedure: a randomized, single-blind, all placebo study in major depressive and psychotic disorders.

The remarkably high and growing placebo response rates in clinical trials for CNS indications, such as depression and schizophrenia, constitute a major challenge for the drug development enterprise. Despite extensive literature on participant expectancies and other potent psychosocial factors that perpetuate placebo response, no empirically validated participant-focused strategies to mitigate this phenomenon have been available. This study evaluated the efficacy of the Placebo-Control Reminder Script (PCRS), a brief interactive procedure that educates participants about factors known to cause placebo response, which was administered prior to the primary outcome assessments to subjects with major depressive or psychotic disorders who had at least moderate depression. Participants were informed they would participate in a 2-week randomized clinical trial with a 50% chance of receiving either an experimental antidepressant medication or placebo. In actuality, all participants received placebo. Participants randomly assigned to receive the PCRS (n = 70) reported significantly smaller reductions (i.e., less placebo response) in depression than those who did not receive the PCRS (n = 67). The magnitude of this effect was medium (Cohen's d = 0.40) and was not significantly impacted by diagnostic status. The number of adverse events (i.e., nocebo effect) was also lower in the PCRS group, particularly in the first week of the study. These findings suggest that briefly educating participants about placebo response factors can help mitigate the large placebo response rates that are increasingly seen in failed CNS drug development programs.

Cost-effectiveness of vortioxetine compared with levomilnacipran and vilazodone in patients with major depressive disorder switching from an initial antidepressant.

Introduction: Many patients with major depressive disorder (MDD) do not achieve remission with their first antidepressant (AD), resulting in a high burden due to treatment failure. Vortioxetine is a valid treatment option for patients with MDD only partially responding to their first AD. Characterization of vortioxetine's potential benefits versus other approved treatments is important. Areas covered: The cost-effectiveness of vortioxetine, including cognitive outcomes, was modeled in comparison with levomilnacipran and vilazodone for patients switched to these medications after inadequate responses to a first AD. Expert opinion: Vortioxetine was associated with incremental quality-adjusted life-year (QALY) gains versus levomilnacipran (0.008) or vilazodone (0.009). Vortioxetine was dominant versus levomilnacipran and cost-effective versus vilazodone (incremental cost-effectiveness ratio [ICER],33,829 USD/QALY). In sensitivity analyses using residual cognitive dysfunction rates (vortioxetine, 49%; levomilnacipran, 58%, and vilazodone, 64%), incremental QALY gains for vortioxetine versus levomilnacipran (0.0085) or vilazodone (0.0109) were found. Vortioxetine remained dominant versus levomilnacipran and cost-effective versus vilazodone (ICER, 27,633 USD/QALY). ICER reduction was found with cognition outcomes inclusion. This model provides additional support for considering vortioxetine for patients requiring a switch of MDD treatments, although its conclusions are limited by the data available for inclusion. Additional research and real-world trials are needed to confirm the findings.

Candidate inflammatory biomarkers display unique relationships with alpha-synuclein and correlate with measures of disease severity in subjects with Parkinson's disease.

BACKGROUND: Efforts to identify fluid biomarkers of Parkinson's disease (PD) have intensified in the last decade. As the role of inflammation in PD pathophysiology becomes increasingly recognized, investigators aim to define inflammatory signatures to help elucidate underlying mechanisms of disease pathogenesis and aid in identification of patients with inflammatory endophenotypes that could benefit from immunomodulatory interventions. However, discordant results in the literature and a lack of information regarding the stability of inflammatory factors over a 24-h period have hampered progress. METHODS: Here, we measured inflammatory proteins in serum and CSF of a small cohort of PD (n = 12) and age-matched healthy control (HC) subjects (n = 6) at 11 time points across 24 h to (1) identify potential diurnal variation, (2) reveal differences in PD vs HC, and (3) to correlate with CSF levels of amyloid ß (Aß) and α-synuclein in an effort to generate data-driven hypotheses regarding candidate biomarkers of PD. RESULTS: Despite significant variability in other factors, a repeated measures two-way analysis of variance by time and disease state for each analyte revealed that serum IFNγ, TNF, and neutrophil gelatinase-associated lipocalin (NGAL) were stable across 24 h and different between HC and PD. Regression analysis revealed that C-reactive protein (CRP) was the only factor with a strong linear relationship between CSF and serum. PD and HC subjects showed significantly different relationships between CSF Aß proteins and α-synuclein and specific inflammatory factors, and CSF IFNγ and serum IL-8 positively correlated with clinical measures of PD. Finally, linear discriminant analysis revealed that serum TNF and CSF α-synuclein discriminated between PD and HC with a minimum of 82% sensitivity and 83% specificity. CONCLUSIONS: Our findings identify a panel of inflammatory factors in serum and CSF that can be reliably measured, distinguish between PD and HC, and monitor inflammation as disease progresses or in response to interventional therapies. This panel may aid in generating hypotheses and feasible experimental designs towards identifying biomarkers of neurodegenerative disease by focusing on analytes that remain stable regardless of time of sample collection.

AZD3293: Pharmacokinetic and Pharmacodynamic Effects in Healthy Subjects and Patients with Alzheimer's Disease.

AZD3293 (LY3314814) is a promising new potentially disease-modifying BACE1 (ß-secretase) inhibitor in Phase III clinical development for the treatment of Alzheimer's disease. Reported here are the first two Phase I studies: (1) a single ascending dose study evaluating doses of 1-750 mg with a food-effect component (n = 72), and (2) a 2-week multiple ascending dose study evaluating doses of 15 or 50 mg once daily (QD) or 70 mg once weekly (QW) in elderly subjects (Part 1, n = 31), and 15, 50, or 150 mg QD in patients with mild to moderate Alzheimer's disease (Part 2, n = 16). AZD3293 was generally well tolerated up to the highest doses given. No notable food effects were observed. PK following multiple doses (Part 2) were tmax of 1 to 3 h and mean t1/2 of 16 to 21 h across the 15 to 150 mg dose range. For single doses of ≥5 mg, a ≥70% reduction was observed in mean plasma Aß40 and Aß42 concentrations, with prolonged suppression for up to 3 weeks at the highest dose level studied. Following multiple doses, robust reductions in plasma (≥64% at 15 mg and ≥78% at ≥50 mg) and cerebrospinal fluid (≥51% at 15 mg and ≥76% at ≥50 mg) Aß peptides were seen, including prolonged suppression even with a QW dosing regimen. AZD3293 is the only BACE1 inhibitor for which prolonged suppression of plasma Aß with a QW dosing schedule has been reported. Two Phase III studies of AZD3293 (AMARANTH, NCT02245737; and DAYBREAK-ALZ, NCT02783573) are now ongoing.

The BACE1 inhibitor verubecestat (MK-8931) reduces CNS ß-amyloid in animal models and in Alzheimer's disease patients.

ß-Amyloid (Aß) peptides are thought to be critically involved in the etiology of Alzheimer's disease (AD). The aspartyl protease ß-site amyloid precursor protein cleaving enzyme 1 (BACE1) is required for the production of Aß, and BACE1 inhibition is thus an attractive target for the treatment of AD. We show that verubecestat (MK-8931) is a potent, selective, structurally unique BACE1 inhibitor that reduced plasma, cerebrospinal fluid (CSF), and brain concentrations of Aß40, Aß42, and sAPPß (a direct product of BACE1 enzymatic activity) after acute and chronic administration to rats and monkeys. Chronic treatment of rats and monkeys with verubecestat achieved exposures >40-fold higher than those being tested in clinical trials in AD patients yet did not elicit many of the adverse effects previously attributed to BACE inhibition, such as reduced nerve myelination, neurodegeneration, altered glucose homeostasis, or hepatotoxicity. Fur hypopigmentation was observed in rabbits and mice but not in monkeys. Single and multiple doses were generally well tolerated and produced reductions in Aß40, Aß42, and sAPPß in the CSF of both healthy human subjects and AD patients. The human data were fit to an amyloid pathway model that provided insight into the Aß pools affected by BACE1 inhibition and guided the choice of doses for subsequent clinical trials.

Effects of the glycine reuptake inhibitors bitopertin and RG7118 on glycine in cerebrospinal fluid: results of two proofs of mechanism studies in healthy volunteers.

RATIONALE: Hypofunction of NMDA receptors has been implicated in neuropsychiatric disorders including schizophrenia. NMDA receptor neurotransmission can be enhanced through inhibition of glycine reuptake by the glycine transporter type 1 (GlyT1). OBJECTIVES: The primary objective of these studies was to explore the relationship between plasma exposure and glycine cerebrospinal fluid (CSF) concentrations following administration of bitopertin and RG7118 in healthy volunteers. METHODS: The bitopertin study comprised four dose levels (3, 10, 30 and 60 mg) administered once daily for 10 days. In the RG7118 study, placebo, 15 or 30 mg RG7118 was administered once daily for 28 days. CSF samples were taken on day -2 and day 10, and day -1 and day 26 for bitopertin and RG7118, respectively. RESULTS: Twenty-two and 24 subjects participated in the bitopertin and RG7118 study, respectively. In the bitopertin study, CSF glycine concentrations showed a dose-dependent increase from baseline to day 10. The geometric mean ratios (coefficient of variation) of AUC0-12 h on day 10 over baseline were 1.3 (17 %), 1.3 (49 %), 1.7 (18 %) and 2.3 (14 %) after 3, 10, 30 and 60 mg, respectively. In the RG7118 study, the geometric mean ratio of glycine concentration (CV) on day 26 at 6 h post-dose over time-matched baseline was approx. 1.9 (24 and 15 %) for 15 and 30 mg. CONCLUSIONS: The mechanism of action of bitopertin and RG7118, i.e. inhibition of glycine reuptake in the brain, was confirmed. The maximal increase observed in healthy volunteers was similar to the one observed in animals showing the good translatability of this biomarker.

The potent BACE1 inhibitor LY2886721 elicits robust central Aß pharmacodynamic responses in mice, dogs, and humans.

BACE1 is a key protease controlling the formation of amyloid ß, a peptide hypothesized to play a significant role in the pathogenesis of Alzheimer's disease (AD). Therefore, the development of potent and selective inhibitors of BACE1 has been a focus of many drug discovery efforts in academia and industry. Herein, we report the nonclinical and early clinical development of LY2886721, a BACE1 active site inhibitor that reached phase 2 clinical trials in AD. LY2886721 has high selectivity against key off-target proteases, which efficiently translates in vitro activity into robust in vivo amyloid ß lowering in nonclinical animal models. Similar potent and persistent amyloid ß lowering was observed in plasma and lumbar CSF when single and multiple doses of LY2886721 were administered to healthy human subjects. Collectively, these data add support for BACE1 inhibition as an effective means of amyloid lowering and as an attractive target for potential disease modification therapy in AD.

Relative efficacy and tolerability of vortioxetine versus selected antidepressants by indirect comparisons of similar clinical studies.

INTRODUCTION: Vortioxetine is an antidepressant with multimodal activity which has shown efficacy in major depressive disorder (MDD) patients in six of ten short-term, randomized, placebo-controlled trials (completed end 2012). METHODS: We performed meta-regression analyses to indirectly compare vortioxetine to seven marketed antidepressants with different mechanisms of action. To ensure study comparability, only experimental drug and placebo arms from placebo-controlled registration studies were included in primary analyses. The main outcomes were efficacy (standardized mean difference in change from baseline to 2 months on primary endpoint [MADRS/HAM-D]), and tolerability (withdrawal rate due to adverse events). RESULTS: For efficacy, estimates of treatment effect (negative estimates favor vortioxetine) for vortioxetine versus comparators were: agomelatine, -0.16 (p = 0.11); desvenlafaxine, 0.03 (p = 0.80); duloxetine, 0.09 (p = 0.42); escitalopram, -0.05 (p = 0.70); sertraline, -0.04 (p = 0.83); venlafaxine IR/XR, 0.12 (p = 0.33); and vilazodone, -0.25 (p = 0.11). For tolerability, all but one combination was numerically in favor of vortioxetine (odds ratio < 1), although not all differences were statistically significant: agomelatine, 1.77 (p = 0.03); desvenlafaxine, 0.58 (p = 0.04); duloxetine, 0.75 (p = 0.26); escitalopram, 0.67 (p = 0.28); sertraline, 0.30 (p = 0.01); venlafaxine, 0.47 (p = 0.01); and vilazodone, 0.64 (p = 0.18). Sensitivity analyses did not significantly alter antidepressant effect estimates or relative ranking. CONCLUSION: These meta-regression data show that vortioxetine offers a comparable or favorable combination of efficacy (measured by MADRS/HAM-D) and tolerability (measured by withdrawal rate due to adverse events) versus other antidepressants in registration studies in MDD. Alternative methods like mixed-treatment comparison and inclusion of all randomized studies and active reference arms may provide complementary information to this analysis (more evidence but also more heterogeneity). Key messages: Indirect comparisons based on registration studies allow a useful comparison between a recently approved antidepressant and an approved drug. Vortioxetine offers a comparable or favorable combination of efficacy (measured by MADRS/HAM-D assessments) and tolerability (measured by withdrawal rate due to adverse events) versus other antidepressants in registration studies in MDD.

Lurasidone drug-drug interaction studies: a comprehensive review.

BACKGROUND: To evaluate potential drug-drug interactions with the atypical antipsychotic lurasidone. METHODS: Seven phase I studies were conducted to investigate the effects of repeated dosing of ketoconazole, diltiazem, rifampin, or lithium on the pharmacokinetics (PK) of single oral doses of lurasidone, or the effects of repeated dosing of lurasidone on the PK of digoxin, midazolam, or the oral contraceptive norgestimate/ethinyl estradiol. Two 6-week, phase III studies included evaluation of the potential for interaction between lurasidone and lithium or valproate. Maximum serum or plasma concentration (Cmax) and area under the concentration-time curve (AUC) were calculated. RESULTS: Concomitant ketoconazole administration resulted in a 6.8-fold increase in lurasidone Cmax and a 9.3-fold increase in lurasidone AUC; concomitant diltiazem administration resulted in 2.1- and 2.2-fold increases, respectively. Rifampin decreased lurasidone Cmax and AUC (one-seventh and one-fifth of lurasidone alone, respectively). Steady-state dosing with lurasidone increased Cmax and AUC0-24 (AUC from time 0 to 24 h postdose) of digoxin by 9% and 13%, respectively, and of midazolam by 21% and 44%, respectively. There were no significant interactions between lurasidone and lithium, valproate, ethinyl estradiol, or norelgestromin (the major active metabolite of norgestimate). CONCLUSIONS: Lurasidone PK is altered by strong cytochrome P450 (CYP) 3A4 inhibitors or inducers, and coadministration is contraindicated; whereas moderate CYP3A4 inhibitors have less effect, and lurasidone dosage restrictions are recommended. No dose adjustment for lurasidone is needed when administered with lithium or valproate. Dose adjustment is not required for lithium, valproate, digoxin (a P-glycoprotein substrate), or midazolam or oral contraceptives (CYP3A4 substrates) when coadministered with lurasidone.

Use of translational pharmacodynamic biomarkers in early-phase clinical studies for schizophrenia.

Schizophrenia is a severe mental disorder characterized by cognitive deficits, and positive and negative symptoms. The development of effective pharmacological compounds for the treatment of schizophrenia has proven challenging and costly, with many compounds failing during clinical trials. Many failures occur due to disease heterogeneity and lack of predictive preclinical models and biomarkers that readily translate to humans during early characterization of novel antipsychotic compounds. Traditional early-phase trials consist of single- or multiple-dose designs aimed at determining the safety and tolerability of an investigational compound in healthy volunteers. However, by incorporating a translational approach employing methodologies derived from preclinical studies, such as EEG measures and imaging, into the traditional Phase I program, critical information regarding a compound's dose-response effects on pharmacodynamic biomarkers can be acquired. Furthermore, combined with the use of patients with stable schizophrenia in early-phase clinical trials, significant 'de-risking' and more confident 'go/no-go' decisions are possible.

Effect of food on the pharmacokinetics of lurasidone: results of two randomized, open-label, crossover studies.

OBJECTIVE: This study aimed to investigate the effect of prandial status and caloric and fat composition of meals on the pharmacokinetics of lurasidone. METHODS: Two randomized, open-label, crossover studies were conducted in clinically stable adults with schizophrenia or schizoaffective disorder. Study 1 (n = 16) evaluated the effect of fasting and three meal types (100 kcal/medium fat, 200 kcal/medium fat, and 800-1000 kcal/high fat), and Study 2 (n = 26) evaluated the effect of fasting and five meal types (350 kcal/high fat, 500 kcal/low fat, 500 kcal/high fat, 800-1000 kcal/low fat, and 800-1000 kcal/high fat) on the bioavailability of lurasidone. Subjects received lurasidone 120 mg once daily. Maximum serum concentration (Cmax ) and area under the serum concentration-time curve over the dosing interval (AUC0-tau ) were determined on Day 5 for each meal type. RESULTS: In Study 1, the geometric mean Cmax in the fasted state was 56.7 ng/mL compared with 123.0 ng/mL for the 800- to 1000-kcal meal; mean AUC0-tau was 360.0 versus 752.4 ng·h/mL (both p < 0.001). Lurasidone exposure following meals containing 100 and 200 kcal was substantially lower than with meals containing 800-1000 kcal. In Study 2, the geometric mean Cmax was 52.9 ng/mL in the fasted state, 161 ng/mL for the 350-kcal/high-fat meal, 135 ng/mL for the 500-kcal/high-fat meal, and 131 ng/mL for the 800- to 1000-kcal/high-fat meal; mean AUC0-tau was 390, 743, 727, and 769 ng·h/mL, respectively. For all comparisons, the 90% confidence interval of the fed to fasted ratios indicated nonequivalence. Lurasidone exposure was similar following meals containing 350-1000 kcal and was independent of fat content. CONCLUSION: Lurasidone should be administered with food-at least 350 kcal-to ensure maximum exposure.

Pharmacokinetic Profile of Orally Administered Scyllo-Inositol (Elnd005) in Plasma, Cerebrospinal Fluid and Brain, and Corresponding Effect on Amyloid-Beta in Healthy Subjects.

ELND005 (scyllo-inositol), an endogenous inositol stereoisomer, is being investigated as an oral treatment for Alzheimer's disease (AD). Pharmacokinetics of ELND005 in plasma, cerebrospinal fluid (CSF), and brain was characterized in healthy young subjects. Eight men received 2000 mg ELND005 every 12 hours for 10 days. Plasma and CSF samples were collected at predetermined time points; ELND005 and amyloid-beta (Aß) fragments were measured by validated bioanalytical methods. Brain ELND005 levels, estimated by (1) H Magnetic Resonance Spectroscopy (MRS) scans were obtained from gray/white matter voxels at baseline and Day 8. ELND005 was well-tolerated during the study. During the apparent steady state, ELND005 plasma levels rapidly peaked at 39.8 µg/mL and decreased to an average trough concentration of 10.6 µg/mL at the end of the 12-hour dosing regimen. In contrast, CSF drug levels slowly peaked at 13.7 µg/mL and remained near the same level with average trough concentrations of 12.4 µg/mL. At Day 8, Brain ELND005 concentrations increased by 58-76% compared to baseline levels. The CSF concentrations achieved in this study were similar to those associated with efficacy in transgenic models of AD. No changes were detected in plasma and CSF levels of Aß fragments.

Examination of Org 26576, an AMPA receptor positive allosteric modulator, in patients diagnosed with major depressive disorder: an exploratory, randomized, double-blind, placebo-controlled trial.

Org 26576 acts by modulating ionotropic AMPA-type glutamate receptors to enhance glutamatergic neurotransmission. The aim of this Phase 1b study (N=54) was to explore safety, tolerability, pharmacokinetics, and pharmacodynamics of Org 26576 in depressed patients. Part I (N=24) evaluated the maximum tolerated dose (MTD) and optimal titration schedule in a multiple rising dose paradigm (range 100 mg BID to 600 mg BID); Part II (N=30) utilized a parallel groups design (100 mg BID, 400 mg BID, placebo) to examine all endpoints over a 28-day dosing period. Based on the number of moderate intensity adverse events reported at the 600 mg BID dose level, the MTD established in Part I was 450 mg BID. Symptomatic improvement as measured by the Montgomery-Asberg Depression Rating Scale was numerically greater in the Org 26576 groups than in the placebo group in both study parts. In Part II, the 400 mg BID dose was associated with improvements in executive functioning and speed of processing cognitive tests. Org 26576 was also associated with growth hormone increases and cortisol decreases at the end of treatment but did not influence prolactin or brain-derived neurotrophic factor. The quantitative electroencephalogram index Antidepressant Treatment Response at Week 1 was able to significantly predict symptomatic response at endpoint in the active treatment group, as was early improvement in social acuity. Overall, Org 26576 demonstrated good tolerability and pharmacokinetic properties in depressed patients, and pharmacodynamic endpoints suggested that it may show promise in future well-controlled, adequately powered proof of concept trials.

Maximum tolerated dose evaluation of the AMPA modulator Org 26576 in healthy volunteers and depressed patients: a summary and method analysis of bridging research in support of phase II dose selection.

BACKGROUND: A key challenge to dose selection in early central nervous system (CNS) clinical drug development is that patient tolerability profiles often differ from those of healthy volunteers (HVs), yet HVs are the modal population for determining doses to be investigated in phase II trials. Without clear tolerability data from the target patient population, first efficacy trials may include doses that are either too high or too low, creating undue risk for study participants and the development program overall. Bridging trials address this challenge by carefully investigating safety and tolerability in the target population prior to full-scale proof-of-concept trials. OBJECTIVE: Org 26576 is an alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor positive allosteric modulator that acts by modulating ionotropic AMPA-type glutamate receptors to enhance glutamatergic neurotransmission. In preparation for phase II efficacy trials in major depressive disorder (MDD), two separate phase I trials were conducted to evaluate safety, tolerability, and pharmacokinetics in HVs and in the target patient population. METHODS: Both trials were randomized and placebo controlled, and included multiple rising-dose cohorts (HV range 100-400 mg bid; MDD range 100-600 mg bid). HVs (n = 36) and patients with MDD (n = 54) were dosed under similarly controlled conditions in an inpatient facility, HVs for up to 14 days and MDD patients for up to 28 days. Safety, tolerability, and pharmacokinetics were assessed frequently. RESULTS: Despite comparable pharmacokinetic profiles, the maximum tolerated dose (MTD) in depressed patients was 450 mg bid, twice the MTD established in HVs. No clinically relevant safety issues associated with Org 26576 were noted. CONCLUSION: This article presents safety, tolerability, and pharmacokinetic data from two different populations examined under similar dosing conditions. The important implications of such bridging work in phase II dose selection are discussed, as are study design and data interpretation challenges.

Clinically significant psychotropic drug-drug interactions in the primary care setting.

In recent years, the growing numbers of patients seeking care for a wide range of psychiatric illnesses in the primary care setting has resulted in an increase in the number of psychotropic medications prescribed. Along with the increased utilization of psychotropic medications, considerable variability is noted in the prescribing patterns of primary care providers and psychiatrists. Because psychiatric patients also suffer from a number of additional medical comorbidities, the increased utilization of psychotropic medications presents an elevated risk of clinically significant drug interactions in these patients. While life-threatening drug interactions are rare, clinically significant drug interactions impacting drug response or appearance of serious adverse drug reactions have been documented and can impact long-term outcomes. Additionally, the impact of genetic variability on the psychotropic drug's pharmacodynamics and/or pharmacokinetics may further complicate drug therapy. Increased awareness of clinically relevant psychotropic drug interactions can aid clinicians to achieve optimal therapeutic outcomes in patients in the primary care setting.

Effect of human cerebrospinal fluid sampling frequency on amyloid-ß levels.

BACKGROUND: ß-amyloid peptide (Aß) is associated with neurodegeneration in Alzheimer's disease. Emerging evidence indicates that Aß levels in cerebrospinal fluid (CSF) may serve as an early clinical biomarker for evaluating pharmacological activity of new drug candidates targeting Aß production or Aß clearance. Therefore, it is critical to understand whether intrasubject levels of CSF Aß are consistent between sampling intervals to determine whether Aß can be used as a pharmacodynamic biomarker for drug candidates. Previous studies have produced seemingly conflicting observations for the intrasubject stability of CSF Aß levels; we attempt to reconcile these conflicting observations. METHODS: The current study examined the Aß levels in CSF collected with various sampling frequencies from three clinical studies conducted in healthy young or elderly subjects at the same investigative site for the purpose of designing future studies. RESULTS: The results suggest that CSF sampling frequency and/or sampling volume contributes to intrasubject variability in CSF Aß levels, and that lowering the CSF sampling frequency may help minimize this effect. CONCLUSION: These results will help guide clinical trial design for Alzheimer's disease therapy.