WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• There is marked variability among patients with Parkinson's disease (PD) in the rate of progression of status (severity) assessed with a global functional score (Unified Parkinson's Disease Rating Scale; UPDRS). It has been hypothesized that there are distinct PD subtypes with different rates of progression.• Previous studies attempted to quantify the rates of progression for tremor-dominant and postural instability and gait disorder (PIGD)-dominant subtypes using only baseline clinical features. WHAT THIS STUDY ADDS• We used a nonlinear mixed effects modelling approach to describe the time course of the four cardinal features of PD before and during anti-parkinsonian treatment.• Tremor-dominant and PIGD-dominant subtypes appear to be different stages of the disease rather than persistent attributes in individual patients and do not explain variability in progression among patients. Tremor progresses more slowly than other cardinal features with and without drug treatment. Postural instability and gait disorder is much less sensitive to the symptomatic effects of levodopa than the other cardinal features.• We have extended the finding that anti-parkinsonian treatments have symptomatic and disease-modifying effects on overall function and demonstrate similar effects on each of the four cardinal features of PD. AIMS(i) To describe the progression of the cardinal features of Parkinson's disease (PD); (ii) to investigate whether baseline PD subtypes explain disease progression; and (iii) to quantify the symptomatic and disease-modifying effects of anti-parkinsonian treatments. METHODSData were available for 795 PD subjects, initially untreated, followed for up to 8 years. Cardinal features [tremor, rigidity, bradykinesia, and postural instability and gait disorder (PIGD)] were derived from the total unified Parkinson's disease rating scale (total UPDRS), cognitive status from the mini-mental status exam score (MMSE) and depression status from the Hamilton depression scale (HAM-D). Analysis was performed using a nonlinear mixed effects approach with an asymptotic model for natural disease progression. Treatment effects (i.e. symptomatic and disease modifying) were evaluated by describing changes in the natural history model parameters. RESULTSTremor progressed more slowly (half-time of 3.9 years) than all other motor features (half-time 2-3 years). The MMSE progression was negligible, while HAM-D progressed with a half-time of 5 years. Levodopa had marked symptomatic effects on all features, but low potency for effect on PIGD (ED50 of 1237 mg day -1 compared with 7-24 mg day -1 for other motor and nonmotor features). Other anti-parkinsonian treatments had much smaller symptomatic effects. All treatments had disease-modifying effects on the cardinal features of PD. Baseline PD subtypes only explained small differences in disease progression. CONCLUSIONSThis analysis indicates that tremor progresses more slowly than other cardinal features and that PIGD is less treatment respon...

PurposeCapsaicin-induced dermal blood flow (CIDBF) is a validated biomarker used to evaluate the target engagement of potential calcitonin gene-related peptide-blocking therapeutics for migraine. To characterize the pharmacokinetics (PK) and quantify the inhibitory effects of erenumab (AMG 334) on CIDBF, CIDBF data were pooled from a single- and a multiple-dose study in healthy and migraine subjects.MethodsRepeated capsaicin challenges and DBF measurements were performed and serum erenumab concentrations determined. A population analysis was conducted using a nonlinear mixed-effects modeling approach. Effects of body weight, gender, and age on model parameters were evaluated.ResultsTwo-compartment target-mediated drug disposition (TMDD) model assuming binding of erenumab in the central compartment best described the nonlinear PK of erenumab. Subcutaneous absorption half-life was 1.6 days and bioavailability was 74%. Erenumab produced a maximum inhibition of 89% (95% confidence interval: 87–91%). Erenumab concentrations required for 50% and 99% of maximum inhibition were 255 ng/mL and 1134 ng/mL, respectively. Increased body weight was associated with increased erenumab clearance but had no effect on the inhibitory effect on CIDBF.ConclusionsOur results show that erenumab pharmacokinetics was best characterized by a TMDD model and resulted in potent inhibition of CIDBF.Electronic supplementary materialThe online version of this article (doi:10.1007/s11095-017-2183-6) contains supplementary material, which is available to authorized users.

Monoclonal antibodies (mAbs) targeting calcitonin gene-related peptide (CGRP) signaling are being explored as prophylactic treatments for migraine. Erenumab (AMG 334) is the first potent, selective, and competitive human mAb antagonist of the CGRP receptor. We report the data from two phase I studies assessing the safety, pharmacokinetics (PK), and pharmacodynamics of single and multiple administrations of erenumab in healthy subjects and patients with migraine. The results indicate that the PK profile of erenumab is nonlinear from 1 mg to 70 mg and the linear portion of the clearance from 70 mg to 210 mg is consistent with other human immunoglobulin G2 antibodies. Single doses of erenumab resulted in >75% inhibition of capsaicin-induced dermal blood flow, with no apparent dose-dependency for erenumab ≥21 mg. Erenumab was generally well tolerated, with an acceptable safety profile, supporting further clinical development of erenumab for migraine prevention.

BackgroundSubcutaneous erenumab reduced monthly migraine days and increased the likelihood of achieving a ≥ 50% reduction at all monthly assessment points tested in 2 pivotal trials in episodic migraine (EM) and chronic migraine (CM). Early efficacy of migraine preventive medications is an important treatment characteristic to patients. Delays in achievement of efficacy can result in failed adherence. The objective of these post-hoc analyses were to evaluate efficacy in the first 4 weeks after initial subcutaneous administration of erenumab 70 mg, erenumab 140 mg, or placebo.MethodsThere is no generally accepted methodology to measure onset of action for migraine preventive medications. We used a comprehensive approach with data from both studies to evaluate change from baseline in weekly migraine days (WMD), achievement of ≥ 50% reduction in WMD, and proportion of patients experiencing migraine measured on a daily basis. The 7-day moving averages were overlaid with observed data.ResultsIn both studies (EM: N = 955; CM: N = 667), there was evidence of onset of efficacy of erenumab vs. placebo during the first week of treatment, which in some cases reached nominal significance. For EM the changes in WMD were (least squares mean [LSM] [95% CI]): placebo, − 0.1 (− 0.3, 0.0); erenumab 70 mg, − 0.3 (− 0.5, − 0.2) p = 0.130; erenumab 140 mg, − 0.6 (− 0.7, − 0.4) p < 0.001. For CM the changes were: placebo, − 0.5 (− 0.8, − 0.3); erenumab 70 mg, − 0.9 (− 1.2, − 0.7) p = 0.047; erenumab 140 mg, − 0.8 (− 1.1, − 0.5) p = 0.18. Achievement of ≥ 50% reduction in WMD was observed as early as Week 1 (adjusted OR [95% CI] erenumab vs placebo) in EM: erenumab 70 mg, 1.3 (1.0, 1.9) p = 0.097; erenumab 140 mg, 2.0 (1.4, 2.7) p < 0.001. A similar outcome was observed for CM: erenumab 70 mg, 1.8 (1.1, 2.8) p = 0.011; erenumab 140 mg, 1.9 (1.2, 2.9) p = 0.009. Seven-day moving averages of observed data showed each treatment arm differed from placebo by Week 1 (OR [95% CI]): in EM Day 3 for erenumab 140 mg, 0.7 (0.5, 1.0) p = 0.031 and at Day 7 for 70 mg, 0.6 (0.4, 0.8) p = 0.002; in CM: Day 6 for erenumab 70 mg, 0.6 (0.4, 0.9) p = 0.022 and at Day 7 for 140 mg, 0.7 (0.4, 1.0); p = 0.038.ConclusionErenumab showed early onset of efficacy with separation from placebo within the first week of treatment in both chronic and episodic migraine patients.

The population pharmacokinetics of subcutaneously administered golimumab (50 mg or 100 mg every 4 weeks) were characterized in patients with active psoriatic arthritis (PsA) in GO-REVEAL, a randomized, double-blind, placebo-controlled, phase 3 study. A total of 2029 serum golimumab concentrations from 337 patients were analyzed using NONMEM. A 1-compartment pharmacokinetic model with first-order absorption and elimination was chosen to describe the observed concentration-time data. For a patient of standard weight (70 kg), the population estimates (typical value +/- standard error) for golimumab pharmacokinetic parameters were as follows: apparent clearance = 1.38 +/- 0.04 L/d, apparent volume of distribution = 24.9 +/- 1.04 L, and absorption rate constant = 0.908 +/- 0.121 per day. The between-subject variability was 37.6% in apparent clearance and 37.9% in apparent volume of distribution. Body weight, antibody-to-golimumab status, baseline C-reactive protein level, and smoking status were identified as significant covariates on apparent clearance. Body weight was also a significant covariate on apparent volume of distribution. None of the concomitant medications examined (methotrexate, corticosteroids, and nonsteroidal anti-inflammatory drugs) were significant covariates on apparent clearance, although the median trough golimumab concentration in patients receiving methotrexate was higher than for those not receiving methotrexate. These significant covariates account for part of the variability in systemic exposure to golimumab observed in patients with PsA.

Dexmedetomidine administered as a single bolus dose following cardiac surgery produces a biphasic effect on MAP. A plasma dexmedetomidine concentration of above 1.0 microg.l(-1) was associated with a 20% increase in MAP in this specific cohort. A dosage regimen involving a small bolus dose (0.5 microg.kg(-1)) followed by a continuous infusion should be used to avoid initial increases in MAP.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• The marked between variability in the rate of progression of Parkinson's disease severity assessed with a global functional score (Unified Parkinson' Disease Rating Scale, UPDRS) is recognized but its origin is uncertain and variously attributed to different subtypes of Parkinson's disease, life style, genetic variability and treatment. An increased risk of death in patients treated with selegiline has been reported but this is controversial. WHAT THIS STUDY ADDS• We used a hazard model approach to describe the time to clinical events (death, disability, depression and dementia). The time course of disease status changes was shown to be a key predictor of the risk of these events. Baseline motor subtype was not a predictor of outcome events. Selegiline was associated with an increased risk of death that was independent of its effect on disease status. AIMTo describe the time to clinical events (death, disability, cognitive impairment and depression) in Parkinson's disease using the time course of disease status and treatment as explanatory variables. METHODSDisease status based on the Unified Parkinson's Disease Rating Scale (UPDRS) and the time to clinical outcome events were obtained from 800 patients who initially had early Parkinson's disease. Parametric hazard models were used to describe the time to the events of interest. RESULTSTime course of disease status (severity) was an important predictor of clinical outcome events. There was an increased hazard ratio for death 1.4 (95% CI 1.31, 149), disability 2.75 (95% CI 2.30, 3.28), cognitive impairment 4.35 (95% CI 1.94, 9.74), and depressive state 1.43 (95% CI 1.26, 1.63) with each 10 unit increase of UPDRS. Age at study entry increased the hazard with hazard ratios of 49.1 (95% CI 8.7, 278) for death, 4.76 (95% CI 1.10, 20.6) for disability and 90.0 (95% CI 63.3-128) for cognitive impairment at age 60 years. Selegiline treatment had independent effects as a predictor of death at 8 year follow-up with a hazard ratio of 2.54 (95% CI 1.51, 4.25) but had beneficial effects on disability with a hazard ratio of 0.363 (95% CI 0.132, 0.533) and depression with a hazard ratio of 0.372 (95% CI 0.12, 0.552). CONCLUSIONSOur findings show that the time course of disease status based on UPDRS is a much better predictor of future clinical events than any baseline disease characteristic. Continued selegiline treatment appears to increase the hazard of death.

Purpose For AMG 317, a fully human monoclonal antibody to interleukin receptor IL-4Rα, we developed a population pharmacokinetic (PK) model by fitting data from four early phase clinical trials of intravenous and subcutaneous (SC) routes simultaneously, investigated important PK covariates, and explored the relationship between exposure and IgE response. Methods Data for 294 subjects and 2183 AMG 317 plasma concentrations from three Phase 1 and 1 Phase 2 studies were analyzed by nonlinear mixed effects modeling using first-order conditional estimation with interaction. The relationship of IgE response with post hoc estimates of exposure generated from the final PK model was explored based on data from asthmatic patients.Results The best structural model was a two-compartment quasi-steady-state target-mediated drug disposition model with linear and non-linear clearances. For a typical 80-kg, 40-year subject, linear clearance was 35.0 mL/hr, central and peripheral volumes of distribution were 1.78 and 5.03 L, respectively, and SC bioavailability was 24.3%. Body weight was an important covariate on linear clearance and central volume; age influenced absorption rate. A significant treatment effect was observable between the cumulative AUC and IgE response measured.Conclusion The population PK model adequately described AMG 317 PK from IV and SC routes over a 60-fold range of doses with two dosing strengths across multiple studies covering healthy volunteers and patients with mild to severe asthma. IgE response across a range of doses and over the sampling time points was found to be related to cumulative AMG 317 exposure.