Biological Oxidation of Fe(II)-Bearing Smectite by Microaerophilic Iron Oxidizer Sideroxydans lithotrophicus Using Dual Mto and Cyc2 Iron Oxidation Pathways.

Fe(II) clays are common across many environments, making them a potentially significant microbial substrate, yet clays are not well established as an electron donor. Therefore, we explored whether Fe(II)-smectite supports the growth of Sideroxydans lithotrophicus ES-1, a microaerophilic Fe(II)-oxidizing bacterium (FeOB), using synthesized trioctahedral Fe(II)-smectite and 2% oxygen. S. lithotrophicus grew substantially and can oxidize Fe(II)-smectite to a higher extent than abiotic oxidation, based on X-ray near-edge spectroscopy (XANES). Sequential extraction showed that edge-Fe(II) is oxidized before interior-Fe(II) in both biotic and abiotic experiments. The resulting Fe(III) remains in smectite, as secondary minerals were not detected in biotic and abiotic oxidation products by XANES and Mössbauer spectroscopy. To determine the genes involved, we compared S. lithotrophicus grown on smectite versus Fe(II)-citrate using reverse-transcription quantitative PCR and found that cyc2 genes were highly expressed on both substrates, while mtoA was upregulated on smectite. Proteomics confirmed that Mto proteins were only expressed on smectite, indicating that ES-1 uses the Mto pathway to access solid Fe(II). We integrate our results into a biochemical and mineralogical model of microbial smectite oxidation. This work increases the known substrates for FeOB growth and expands the mechanisms of Fe(II)-smectite alteration in the environment.

Randomized, Double-Blind, Placebo-Controlled, Flexible-Dose Titration Study of Methylphenidate Hydrochloride Extended-Release Capsules (Aptensio XR) in Preschool Children with Attention-Deficit/Hyperactivity Disorder.

Objectives: To assess the efficacy and safety of a methylphenidate hydrochloride extended-release capsule (MPH-MLR) formulation in treating attention-deficit/hyperactivity disorder (ADHD) in preschool children. Methods: Children aged 4 to <6 years with qualifying ADHD Rating Scale Fourth Edition (ADHD-RS-IV) Preschool Version scores (≥90th percentile for age/gender) participated in four behavior management training (BMT) sessions or immediately entered (based on investigator assessment of symptom severity or previous participation) into a 6-week, open-label, flexible MPH-MLR dose optimization phase. After BMT, children with <30% improvement in ADHD-RS-IV score and ≥3 score on the Clinical Global Impression-Improvement (CGI-I) scale also entered the open-label period. All children began the open-label period with MPH-MLR 10 mg once daily; weekly adjustments permitted once-daily maximum of up to 40 mg. Children with ≥30% improvement in ADHD-RS-IV total score and a CGI-I score of 1-2 at open-label completion were randomized to their optimized dose of MPH-MLR or placebo for 2 weeks (double blind [DB]). Safety measures included adverse events (AEs), vital signs, and electrocardiograms. Results: Open-label enrollment was 119 children. Mean (SD) ADHD-RS-IV total scores at open-label start and open-label end was 40.8 (10.4) and 19.5 (11.1), respectively. Ninety children were enrolled in the DB phase. Mean (SD) ADHD-RS-IV total scores for the MPH-MLR and placebo group were similar at DB beginning and was 25.8 (14.6) and 34.9 (14.1), respectively, at DB end. Mean change from baseline in ADHD-RS-IV total score during DB was significantly greater in children randomized to placebo compared with MPH-MLR; least squares mean change difference from baseline was -11.2, p = 0.002. During open-label dosing, the most common AEs (≥10%) were decreased appetite, decreased weight, insomnia, hypertension, emotional disorder, and affect lability. Conclusion: Results demonstrate MPH-MLR efficacy in preschool children and a safety profile consistent with known AEs of methylphenidate when used for ADHD.

Characteristics of ADHD Symptom Response/Remission in a Clinical Trial of Methylphenidate Extended Release.

Clinical trials in attention-deficit/hyperactivity disorder (ADHD) have typically measured outcome using clinician ratings on the Attention-Deficit/Hyperactivity Disorder Rating Scale, Fourth Edition (ADHD-RS-IV) and the Clinical Global Impression-Improvement (CGI-I) scale. Remission has been defined as an endpoint score of less than or equal to 18 on the ADHD-RS-IV (or a mean score of 1). Responders have been defined as patients who achieve a CGI-I score of much or very much improved (1 or 2). There is a lack of agreement in the literature on what percent change in symptoms on the ADHD-RS-IV should be used to define improvement or remission. This study uses data from a clinical trial of a methylphenidate extended release (MPH-MLR; Aptensio XR®) phase III clinical trial to attempt to determine the percent change of symptoms that best corresponds with improvement and remission. Symptom remission at endpoint (ADHD-RS-IV total score ≤18) was most closely aligned with a ≥46% reduction in ADHD-RS-IV total score. Clinical improvement was most closely aligned with a ≥40% reduction in ADHD-RS-IV total score. The three different measures of outcome were strongly aligned during double blind and open label treatment, and were independent of subtype status. Our data suggest that at least 40% improvement in symptoms is needed to achieve a robust response at endpoint.

Relationship Between Symptomatic and Functional Improvement and Remission in a Treatment Response to Stimulant Trial.

OBJECTIVE: To evaluate the relationship between symptom and functional improvement and remission in children and adolescents with attention-deficit/hyperactivity disorder (ADHD) enrolled in an 11-week open-label dose-optimization phase of an methylphenidate extended release (MPH-MLR) pivotal study. METHODS: Assessments included the Weiss Functional Impairment Rating Scale-Parent (WFIRS-P) and ADHD Rating Scale, Fourth Edition (ADHD-RS-IV). Definitions included the following: symptom improvement (≥30% decrease in ADHD-RS-IV total score); symptom remission (ADHD-RS-IV total score ≤18); functional improvement (decrease in WFIRS-P total score ≥0.25 [minimally important difference]); and functional remission (WFIRS-P total score ≤0.65). RESULTS: Two hundred children completed the open-label phase. At initial assessment, functional impairment was evident across all WFIRS-P domains and similar between children and adolescents. Those who were treatment naive had more functional impairment (WFIRS-P total: 0.82 vs. 0.70, p = 0.02). Significant improvements in all WFIRS-P domains were noted at open-label end (p < 0.001), with the largest improvement in Learning. At open-label end, 94% of children and adolescents demonstrated symptom improvement, of which 57% also showed functional improvement, and 75% of children and adolescents showed symptom remission, of which 81% also showed functional remission. CONCLUSIONS: Children and adolescents treated with MPH-MLR showed moderate-to-large improvement in functioning during 3 months of treatment, both overall and in specific domains. However, a significant number of those who would be considered symptomatic responders failed to show improvement in functioning or continue to have significant functional impairment. Treatment with MPH-MLR showed that both symptomatic and functional remission are achievable goals. Identification of children and adolescents who have been successfully treated for their symptoms, but continue to suffer functional impairment, will allow us to offer additional targeted treatment interventions over and above medication to address residual difficulties.

Effect of Aptensio XR (Methylphenidate HCl Extended-Release) Capsules on Sleep in Children with Attention-Deficit/Hyperactivity Disorder.

OBJECTIVE: To evaluate measures of sleep (exploratory endpoints) in two pivotal studies of a multilayer bead extended-release methylphenidate (MPH-MLR) treatment of attention-deficit/hyperactivity disorder in children. METHODS: Study 1 evaluated the time course of response to MPH-MLR (n = 26) patients in an analog classroom setting through four phases: screening (≤28 days), open label (OL) dose optimization (4 weeks), double-blind (DB) crossover (2 weeks; placebo vs. optimized dose), and follow-up call. Study 2 was a forced-dose parallel evaluation of MPH-MLR (n = 230) in four phases: screening (≤28 days), DB (1 week; placebo or MPH-MLR 10, 15, 20, or 40 mg/day), OL dose optimization (11 weeks), and follow-up call. Sleep was evaluated by parents using the Children's or Adolescent Sleep Habits Questionnaire (CSHQ or ASHQ) during the DB and OL phases. DB analysis: Study 1 (crossover), analysis of variance; Study 2, analysis of covariance. OL analysis: paired t-test. RESULTS: DB: treatments were significantly different in Study 1 only for CSHQ Sleep Onset Delay (MPH-MLR, 1.90 vs. placebo, 1.34; p = 0.0046, placebo was better), and Study 2 for CSHQ Parasomnias (treatment, p = 0.0295), but no MPH-MLR treatment was different from placebo (pairwise MPH-MLR treatment to placebo, all p ≥ 0.170). OL: CSHQ total and Bedtime Resistance, Sleep Duration, Sleep Anxiety, Night Wakings, Parasomnias, and Sleep-disordered Breathing subscales decreased (improved, Study 1) significant only for CSHQ Night Wakings (p < 0.05); in Study 2 CSHQ total and Bedtime Resistance, Sleep Duration, Night Wakings, Parasomnias, and Daytime Sleepiness, and ASHQ total, Bedtime, Sleep Behavior, and Morning Waking all significantly improved (p < 0.05). CONCLUSIONS: In both studies, there was minimal negative impact of MPH-MLR on sleep during the brief DB phase and none during the longer duration OL phase. Some measures of sleep improved with optimized MPH-MLR dose.

Efficacy of Methylphenidate Hydrochloride Extended-Release Capsules (Aptensio XR™) in Children and Adolescents with Attention-Deficit/Hyperactivity Disorder: A Phase III, Randomized, Double-Blind Study.

BACKGROUND: Psychostimulants remain first-line treatment options for the management of attention-deficit/hyperactivity disorder (ADHD). A multilayer extended-release bead methylphenidate capsule (provisional name Aptensio XR™, MPH-MLR) with unique release properties is being investigated for the treatment of ADHD. OBJECTIVE: The aim of this study was to assess the efficacy (primary) and safety and tolerability (secondary) of MPH-MLR compared with placebo in children and adolescents aged 6-18 years with ADHD. METHODS: This study was a parallel, double-blind, multicenter, placebo-controlled, forced-dose, phase III study in which patients were randomized to placebo or MPH-MLR 10, 15, 20, or 40 mg given once daily. There were four study phases: (1) 4-week screening/baseline; (2) 1-week, double-blind treatment (DBP); (3) 11-week, open-label, dose-optimization period; and (4) 30-day follow-up call. During the open-label dose-optimization period all patients started with MPH-MLR 10 mg, unless the investigator deemed it necessary to begin at a higher dose, and were titrated to an optimized dose (10, 15, 20, 30, 40, 50, 60 mg; all given once daily) based on response and adverse events (AEs). The primary endpoint was the change from baseline to end of DBP in ADHD Rating Scale, 4th Edition (ADHD-RS-IV) total score. Secondary endpoints included changes in ADHD-RS-IV subscales and Clinical Global Impression-Improvement Scale (CGI-I) at the end of the DBP. The primary analysis was an analysis of covariance including terms for treatment, site, and baseline ADHD-RS-IV total score. RESULTS: A total of 221 patients completed the DBP. The primary endpoint had a statistically significant difference among treatments (p = 0.0046) and sites (p = 0.0018), and baseline covariate made a significant contribution (p < 0.0001). As the MPH-MLR dose increased, the ADHD-RS-IV total score improved; the 20 and 40 mg doses were statistically different (p = 0.0145 and p = 0.0011, respectively) from placebo. Females responded differently than did males (p = 0.0238); there was a significant difference among treatments for males but not for females, partly because only one-third of subjects were female and partly because some females who received placebo had considerable improvement during the DBP. Similarly, the ADHD-RS-IV subscales and CGI-I scores at the end of the DBP also showed more improvement as the dose of MPH-MLR increased. During the open-label phase, ADHD-RS-IV total scores improved (mean change from baseline -22.5) and correlated as the dose of MPH-MLR increased; CGI-I scores also improved. No unexpected AEs were noted. CONCLUSIONS: Dose-related improvements in ADHD-RS-IV scores that exceeded those of placebo were observed in patients treated with MPH-MLR. No new safety signals were noted.

Population pharmacokinetics of methylphenidate hydrochloride extended-release multiple-layer beads in pediatric subjects with attention deficit hyperactivity disorder.

A new multilayer-bead formulation of extended-release methylphenidate hydrochloride (MPH-MLR) has been evaluated in pharmacokinetic studies in healthy adults and in Phase III efficacy/safety studies in children and adolescents with attention deficit hyperactivity disorder (ADHD). Using available data in healthy adults, a two-input, one-compartment, first-order elimination population pharmacokinetic model was developed using nonlinear mixed-effect modeling. The model was then extended to pediatric subjects, and was found to adequately describe plasma concentration-time data for this population. A pharmacokinetic/pharmacodynamic model was also developed using change from baseline in the ADHD Rating Scale (ADHD-RS)-IV total scores from a pediatric Phase III trial and simulated plasma concentration-time data. During simulations for each MPH-MLR dose level (10-80 mg), increased body weight resulted in decreased maximum concentration. Additionally, as maximum concentration increased, ADHD-RS-IV total score improved (decreased). Knowledge of the relationship between dose, body weight, and clinical response following the administration of MPH-MLR in children and adolescents may be useful for clinicians selecting initial dosing of MPH-MLR. Additional study is needed to confirm these results.

A randomized placebo-controlled double-blind study evaluating the time course of response to methylphenidate hydrochloride extended-release capsules in children with attention-deficit/hyperactivity disorder.

OBJECTIVE: The purpose of this study was to assess the time of onset and time course of efficacy over 12.0 hours of extended-release multilayer bead formulation of methylphenidate (MPH-MLR) compared with placebo in children 6-12 years of age with attention-deficit/hyperactivity disorder (ADHD) in a laboratory school setting. METHODS: This randomized double-blind placebo-controlled study included children 6-12 years of age with ADHD. Enrolled children went through four study phases: 1) Screening period (≤4 weeks) and a 2 day medication washout period; 2) open-label period with dose initiation of MPH-MLR 15 mg daily and individual dose optimization treatment period (2-4 weeks); 3) double-blind crossover period in which participants were randomized to sequences (1 week each) of placebo and the optimized MPH-MLR dose given daily; and 4) follow-up safety call. Analog classroom time course evaluations were performed at the end of each double-blind week. The primary efficacy end-point was the mean of the on-treatment/postdose Swanson, Kotkin, Agler, M-Flynn, and Pelham (SKAMP)-Total scores over time points collected 1.0-12.0 hours after dosing. End-points were evaluated using a mixed-effects analysis of covariance. RESULTS: The evaluable population included 20 participants. The least-squares mean postdose SKAMP-Total score was higher for placebo than for MPH-MLR (2.18 vs. 1.32, respectively; p=0.0001), indicating fewer symptoms with MPH-MLR therapy than with placebo. No difference in SKAMP-Total score between participants who received sequence 1 or sequence 2 was noted. From each of hours 1.0-12.0, least-squares mean SKAMP-Total score was significantly lower for those receiving MPH-MLR than for those receiving placebo (p≤0.0261). Neither serious adverse events nor new or unexpected safety findings were noted during the study. CONCLUSIONS: MPH-MLR showed a significant decrease in SKAMP scores compared with placebo in children with ADHD 6-12 years of age, indicating a decrease in ADHD symptoms. The estimated onset was observed within 1.0 hour, and duration was measured to 12.0 hours postdose. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01269463.

Steady-state bioavailability of extended-release methylphenidate (MPH-MLR) capsule vs. immediate-release methylphenidate tablets in healthy adult volunteers.

OBJECTIVES: The objective of the study was to determine the relative bioavailability of an extended-release multilayer bead formulation of methylphenidate hydrochloride (MPH-MLR) 80 mg vs. methylphenidate immediate-release (IR; Ritalin(®)) tablets as single and multiple doses in the fed state. METHODS: A single-center, multiple-dose, randomized, open-label, two-period crossover study conducted in 26 healthy adults assigned to 4 days of once-daily MPH-MLR 80 mg or IR methylphenidate 25 mg three times daily. RESULTS: MPH-MLR 80 mg produced reproducible biphasic profiles of plasma methylphenidate concentrations characterized by a rapid initial peak, followed by a moderate decline reaching a plateau ~5 h post dose, then a gradual increase culminating in an attenuated second peak ~7 h post dose. Maximum concentration was lower for MPH-MLR 80 mg than IR methylphenidate 25 mg three times daily on day 1 (23.70 vs. 31.47 ng/mL); exposure was similar. The geometric mean ratios (MPH-MLR/IR methylphenidate [90 % CI]) of log-transformed area under the plasma drug concentration-time curve to the last measurable observation (day 1: 0.88 [84.75-91.80]; day 4: 0.84 [81.16-86.94]), and area under the plasma drug concentration extrapolated to infinity (day 1: 0.93 [88.57-97.28]; day 4: 0.88 [84.48-91.17]) were within the 80-125 % bioequivalence range. The mean ± SD MPH-MLR 80-mg capsule day 4 area under the plasma drug concentration vs. time curve from 0 to 4 h (74.5 ± 15.2 ng·h/mL) was greater than IR methylphenidate 25 mg three times daily (66.0 ± 17.4 ng·h/mL), confirming steady-state levels during the study period. All treatment regimens were safe and well tolerated. CONCLUSION: MPH-MLR 80-mg capsule once daily or IR methylphenidate 25 mg three times daily provides comparable maximum methylphenidate concentrations and systemic exposure in the fed state.

Single-dose pharmacokinetics of methylphenidate extended-release multiple layer beads administered as intact capsule or sprinkles versus methylphenidate immediate-release tablets (Ritalin(®)) in healthy adult volunteers.

OBJECTIVES: The purpose of this study was to evaluate the relative bioavailability and safety of a multilayer extended-release bead methylphenidate (MPH) hydrochloride 80 mg (MPH-MLR) capsule or sprinkles (37% immediate-release [IR]) versus MPH hydrochloride IR(Ritalin(®)) tablets, and to develop a pharmacokinetic (PK) model simulating MPH concentration-time data for different MPH-MLR dosage strengths. METHODS: This was a single-center, randomized, open-label, three-period crossover study conducted in 26 fasted healthy adults (mean weight±standard deviation, 70.4±11.7 kg) assigned to single-dose oral MPH-MLR 80 mg capsule or sprinkles with applesauce, or Ritalin IR 25 mg (1×5 mg and 1×20 mg tablet) administered at 0, 4, and 8 hours. RESULTS: MPH-MLR 80 mg capsule and sprinkles were bioequivalent; ratios for maximum concentration (Cmax), area under plasma drug concentration versus time curve (AUC)0-t, and AUC0-inf were 1.04 (95% confidence interval [CI], 96.3-112.4), 0.99 (95% CI, 95.3-102.8), and 0.99 (95% CI, 95.4-103.0), respectively. MPH-MLR capsule/sprinkles produced highly comparable, biphasic profiles of plasma MPH concentrations characterized by rapid initial peak, followed by moderate decline until 5 hours postdose, and gradual increase until 7 hours postdose, culminating in an attenuated second peak. Based on 90% CIs, total systemic exposure to MPH-MLR 80 mg capsule/sprinkles was similar to that for Ritalin IR 25 mg three times daily, but marked differences in Cmax values indicated that MPH-MLR regimens were not bioequivalent to Ritalin. MPH Cmax and total systemic exposure over the first 4 hours postdose with MPH-MLR capsule/sprinkles was markedly higher than that associated with the first dose of Ritalin. All study drugs were safe and well tolerated. The PK modeling in adults suggested that differences in MPH pharmacokinetics between MPH-MLR and Ritalin are the result of dosage form design attributes and the associated absorption profiles of MPH. CONCLUSIONS: MPH-MLR 80 mg provides a long-acting biphasic pattern of plasma MPH concentrations with one less peak and trough than Ritalin IR.