A population pharmacokinetic-pharmacodynamic model evaluating efficacy of nalbuphine extended-release in patients with prurigo nodularis.

AIMS: Population pharmacokinetic (PK) and pharmacokinetic-pharmacodynamic (PK-PD) models were used to describe the exposure-response (E-R) relationship between nalbuphine exposure and two widely used rating scales for itch: the Numerical Rating Scale for the subject's 'average'; itch experience (NRS-AV) and the Worst Itch (WI-NRS), with 24-h recall. Simulations based on the model E-R relationship were used to support dose selection for Phase 3 clinical trials and were evaluated with a target of reducing the 7-day average of the 24-h WI-NRS by at least 30% from baseline in most of the analysis population. METHODS: Data from two clinical trials (NCT02373215: 9 healthy subjects; NCT02174419: 62 subjects with PN), in patients with prurigo nodularis (PN) with moderate to severe itch who received treatment with either of two doses of nalbuphine extended release (ER) or placebo, were used for the analysis. A two-compartment PK model with serial zero and first-order oral absorption was used to describe drug exposure. A maximum effect ( E max ) model with a placebo effect was used to model the itch response endpoints (NRS-AV, WI-NRS). RESULTS: The PK-PD model predicted the exposure-related reduction in both NRS-AV and WI-NRS over time with approximately 63% and 27% of E max , respectively. Exposures associated with 80% of E max were achieved in about 78% of the patients at 162 mg, twice daily (BID), compared to 35% at 81 mg BID. CONCLUSION: Simulated dose response indicated that 108 and 162 mg BID doses result in the highest proportion of patients achieving at least a 30% reduction in NRS-AV and WI-NRS, respectively.

A pharmacometric case study regarding the sensitivity of structural model parameter estimation to error in patient reported dosing times.

Although there is a body of literature focused on minimizing the effect of dosing inaccuracies on pharmacokinetic (PK) parameter estimation, most of the work centers on missing doses. No attempt has been made to specifically characterize the effect of error in reported dosing times. Additionally, existing work has largely dealt with cases in which the compound of interest is dosed at an interval no less than its terminal half-life. This work provides a case study investigating how error in patient reported dosing times might affect the accuracy of structural model parameter estimation under sparse sampling conditions when the dosing interval is less than the terminal half-life of the compound, and the underlying kinetics are monoexponential. Additional effects due to noncompliance with dosing events are not explored and it is assumed that the structural model and reasonable initial estimates of the model parameters are known. Under the conditions of our simulations, with structural model CV % ranging from ~20 to 60 %, parameter estimation inaccuracy derived from error in reported dosing times was largely controlled around 10 % on average. Given that no observed dosing was included in the design and sparse sampling was utilized, we believe these error results represent a practical ceiling given the variability and parameter estimates for the one-compartment model. The findings suggest additional investigations may be of interest and are noteworthy given the inability of current PK software platforms to accommodate error in dosing times.

Development and application of an aggregate adherence metric derived from population pharmacokinetics to inform clinical trial enrichment.

Nonadherence to prescribed medication is a common barrier to effective treatment, and current options to determine adherence are limited. This study describes development of an aggregate adherence measure based on population pharmacokinetics (PK), and its comparison to a subjective questionnaire, the Morisky 8-item medication adherence scale (MMAS8), in a trial of psychiatric patients on stable doses of oral aripiprazole. A comprehensive model was first built using plasma drug concentration data from 24 clinical studies comprising 448 patients with over 13,500 observations. Application of this model to independent patient profiles for a given drug-dosing regimen were used to generate the primary aggregate adherence metric, a ratio of observed versus expected plasma exposures at steady-state. Although the metric is capable of comparing relative adherence across groups, simulations showed that the metric is not sufficiently sensitive as an individual diagnostic in all cases. There were no trends observed between results from calculated aggregate adherence metrics and total scores from MMAS8 in a single-visit clinical trial of 47 patients with bipolar 1 disorder or schizophrenia who were on stable doses of aripiprazole, although a strong association was observed for one MMAS8 question. The range of the metric calculated for patients was between 0.16 and 3.15. The described approach of a novel "reverse" application of population PK to quantify relative adherence with an aggregate measure may be influential for both clinical and pharmacometric communities.

Use of an exposure-response model to aid early drug development of an oral sphingosine 1-phosphate receptor modulator.

Pharmacokinetic (PK) and exposure-response modeling of a selective sphingosine 1-phosphate receptor-1 modulator (CS-0777) was conducted in an iterative process to guide early clinical development decisions. A model based on preclinical data from monkeys was extrapolated to humans to support a single ascending dose (SAD) study. The model was updated after each cohort, providing guidance on both maximal inhibition and time to recovery for lymphocyte counts. A 2-compartment PK model with first-order absorption and elimination was found to describe the monkey and human datasets. The relationship between lymphocyte counts and active metabolite (M-1) concentrations was modeled via an indirect response model, whereby M-1 inhibited the reentry of lymphocytes to the circulation. The indirect-response model based on SAD data had an Imax of approximately 85% and an IC50 of 0.24 ng/mL. Additionally, based on SAD data, similar models were developed for lymphocyte subsets, including CD4 cells. Subsequently, simulations were utilized to design a multiple ascending dose study with adaptive dosing regimens that would meet targeted pharmacodynamic (PD) response thresholds (eg, minimum 40% reduction in lymphocytes) while maintaining CD4 counts above a reasonable safety threshold. In conclusion, model-based development and use of adaptive designs for dose optimization can reduce the time and number of subjects needed in early clinical development.

Population pharmacokinetic analyses to evaluate the influence of intrinsic and extrinsic factors on exposure of prasugrel active metabolite in TRITON-TIMI 38.

Serial pharmacokinetic (PK) sampling in 1159 patients from TRITON-TIMI 38 was undertaken. A multilinear regression model was used to quantitatively predict prasugrel's active metabolite (Pras-AM) concentrations from its 2 downstream inactive metabolites. Population-based methods were then applied to Pras-AM concentration data to characterize the PK. The potential influence of body weight, body mass index, age, sex, renal function, diabetes, tobacco use, and other disease status on Bayesian estimates of Pras-AM exposures was assessed. The PK of Pras-AM was adequately described by a multicompartmental model and consistent with results from previous studies. The systemic exposure of prasugrel was not appreciably affected by body mass index, gender, diabetes, smoking, and renal impairment. Pras-AM mean exposure in patients weighing <60 kg (4.1%) was 30% (90% confidence interval [CI] 1.16-1.45) higher than exposure in patients > or =60 kg. Mean Pras-AM exposures for patients > or =75 years (10.5%) were 19% (90% CI: 1.11-1.28) higher compared with patients <75 years.

Inhibition of platelet aggregation with prasugrel and clopidogrel: an integrated analysis in 846 subjects.

This integrated analysis compared speed of onset, level of platelet inhibition, and response variability to prasugrel and clopidogrel in healthy subjects and in patients with stable coronary artery disease with data pooled from 24 clinical pharmacology studies. Data from subjects (N = 846) were categorized into the following treatment groups: prasugrel 60 mg loading dose (LD)/10 mg maintenance dose (MD), clopidogrel 300 mg LD/75 mg MD, or clopidogrel 600 mg LD/75 mg MDs. Maximum platelet aggregation (MPA) and inhibition of platelet aggregation (IPA) to 5 and 20 muM ADP were assessed by turbidimetric aggregometry. A linear mixed-effect model compared the MPA and IPA between treatments over time points evaluated in the integrated database, and covariates affecting platelet inhibition were identified. Prasugrel 60 mg LD resulted in faster onset, greater magnitude, and more consistent levels of inhibition of platelet function compared to either clopidogrel 300 mg or 600 mg LDs. Greater and more consistent levels of platelet inhibition were observed with the prasugrel 10 mg MD compared to the clopidogrel 75 mg MD. This integrated analysis confirms the findings of earlier individual studies, that prasugrel achieves faster onset of greater extent and more consistent platelet inhibition compared to the approved and higher loading doses of clopidogrel. Gender, race, body weight, and age were identified as statistically significant covariates impacting platelet inhibition.

Evaluation of population pharmacokinetics and exposure-response relationship with coadministration of amlodipine besylate and olmesartan medoxomil.

Population pharmacokinetic models for amlodipine and olmesartan were developed using data collected from 4 phase I studies in healthy volunteers and 1 phase III study in subjects with mild to severe hypertension. A 2-compartment and a 1-compartment model best described the pharmacokinetics of olmesartan and amlodipine, respectively; both agents were characterized by first-order elimination/absorption and an absorption time lag. The analysis shows that neither agent had a clinically significant impact on the clearance of the other. The impact of covariates on the clearance of olmesartan and amlodipine was similar after coadministration of amlodipine besylate and olmesartan medoxomil as separate entities or as a fixed-dose combination compared with monotherapy. The effect of exposure to amlodipine and olmesartan on the change in trough seated diastolic blood pressure was best described by linear and maximum effect (E(max)) models, respectively. Black race was the most important covariate in the exposure-response model, decreasing the maximal possible effect of olmesartan on blood pressure while increasing the effect of amlodipine, without influencing pharmacokinetic parameters. The drug effect of combination therapy was defined on the basis of exposure to both compounds and was greater than the effect of monotherapy with either agent.

Population exposure-response modeling of metformin in patients with type 2 diabetes mellitus.

The exposure-response properties of metformin were characterized in 12 subjects with type 2 diabetes mellitus. The time course of drug concentration and effects on fasting plasma glucose and lactic acid concentrations were used from a study in which subjects received 500 mg of metformin twice daily for 5 days followed by 850 mg twice daily for 5 days. Pharmacokinetic sampling included morning trough concentrations obtained on days 7 to 9 and rich sampling (15 time points) on day 10. Fasting plasma glucose and lactic acid concentrations were measured on days 0 to 10 and served as biomarkers of therapeutic effect and tolerability, respectively. A population pharmacokinetic/pharmacodynamic analysis was conducted using nonlinear mixed effects modeling. Metformin pharmacokinetics were described using a 1-compartment model with first-order absorption. Population mean estimates (relative standard error [RSE]) of clearance (CL/F) and volume of distribution were 79.0 L.h(-1) (6.8%) and 648 L (13.8%), respectively. Covariate analyses revealed that creatinine clearance (CL(CR)) significantly influenced metformin CL/F [CL/F = 79.0.(CL(CR)/80)(0.822)]. An indirect response model was applied to describe the antihyperglycemic effect of metformin. Population mean estimates (RSE) of baseline fasting plasma glucose and the drug concentration producing half-maximal effect were 241 mg.dL(-1) (4.6%) and 4.23 mg.L(-1) (31.0%). An empirical linear model was used to describe a slight progressive increase in fasting lactic acid during metformin treatment with an estimated slope coefficient (RSE) of 0.0005 mM.mL.ng(-1) (38.1%). Model evaluation by predictive check and nonparametric bootstrap analysis suggested that the proposed model is robust, and parameter values were estimated with good precision. Simulations suggested that the clinical utility of metformin was maintained over the dose range evaluated with respect to fasting plasma glucose and lactic acid response.

Model-based development of a PPARgamma agonist, rivoglitazone, to aid dose selection and optimize clinical trial designs.

A model-based approach was implemented for the development of the proliferator-activated receptor gamma (PPARgamma) agonist rivoglitazone. Population pharmacokinetic and pharmacodynamic models were developed using data collected from 2 phase I and 2 phase II studies in healthy volunteers and participants with type 2 diabetes mellitus. A 2-compartment model with first-order absorption and elimination and an absorption time lag best described rivoglitazone pharmacokinetics. Modified indirect-response models were used to characterize changes in fasting plasma glucose, HbA(1c), and hemodilution as a function of rivoglitazone plasma concentrations. In addition, differences in hemodilution among participants correlated with the incidence of edema. Current use of oral antidiabetic medication was a significant covariate for the fasting plasma glucose-HbA(1c) exposure-response model. Using a learn-and-confirm process, models developed prior to the second phase II study were able to make valid predictions for exposures and response variables in that study. In future studies, seamless designs can be supported by models such as those developed here.

Pharmacokinetics of amlodipine and olmesartan after administration of amlodipine besylate and olmesartan medoxomil in separate dosage forms and as a fixed-dose combination.

The pharmacokinetics of amlodipine and olmesartan in healthy volunteers after coadministration of amlodipine besylate and olmesartan medoxomil concomitantly as separate dosage forms and together in a fixed-dose combination tablet were characterized in 5 phase I, randomized, crossover studies. The mean steady-state pharmacokinetics of amlodipine and olmesartan were similar when olmesartan medoxomil 40 mg/day and amlodipine 10 mg/day were administered separately or concomitantly for 10 days. The total and maximum exposure to amlodipine and olmesartan after administration of fixed-dose combination amlodipine/olmesartan medoxomil 10 mg/40 mg was bioequivalent to amlodipine 10 mg plus olmesartan medoxomil 40 mg. The ratio of least squares mean and 90% confidence intervals for the area under the drug concentration-time curve from time zero to time t, from time zero to infinity, and the maximum observed plasma drug concentration of amlodipine and olmesartan fell within the prespecified range for bioequivalence (80.0% - 125.0%). The area under the drug concentration-time curve from time zero to time t, from time zero to infinity, and the maximum observed plasma drug concentration of both drugs also met the prespecified criterion for bioequivalence when the fixed-dose combination tablet was taken 30 minutes after a high-fat breakfast. Total exposure to amlodipine and olmesartan was dose-proportional after administration of olmesartan medoxomil 10 mg to 40 mg in the fixed-dose combination formulation with amlodipine 5 mg to 10 mg. From a pharmacokinetic perspective, the 2 drugs are well suited to coadministration in a fixed-dose combination.

Pain relief model for a COX-2 inhibitor in patients with postoperative dental pain.

AIM: To develop a pain relief model for a cyclooxygenase (COX)-2 inhibitor, CS-706, that permits prediction of doses for acute pain relief in Japanese and Western populations. METHODS: A categorical response model was developed to describe the probability of pain relief (PR) over time for a Phase 2a study. Models were also developed to describe patient's use of rescue medication and onset of pain relief. RESULTS: The placebo response was described by a first-order increase in PR that achieved a stable response after 4 h. The effect of CS-706 on PR was described using an E(max) model; the plasma concentration of CS-706 producing 50% of the maximum response was estimated to be 87 ng ml(-1), the median peak plasma concentration achieved after a 50-mg oral dose. The probability of rescue medication (REMD) decreased over time and was a function of the last observed PR score. This probability was < 16% for patients with a PR score > or =2. The probability of experiencing meaningful PR was 98% in patients who did not require REMD and 47% in those who required REMD. For patients who did not require REMD, the median onset time of meaningful pain relief (TMPR) decreased with increasing doses. In patients who required REMD, there was a saturable decline in TMPR, with the greatest improvement occurring from placebo to 50-mg doses. CONCLUSIONS: The set of models developed permitted compilation of multiple dose-response curves for dose selection of CS-706 in Westerners and facilitated scaling of doses to a Japanese population.

Pharmacokinetics of otamixaban, a direct factor Xa inhibitor, in healthy male subjects: pharmacokinetic model development for phase 2/3 simulation of exposure.

The pharmacokinetics of otamixaban was investigated in healthy male subjects over a wide range of intravenous doses, with duration of administration varying between 1-minute infusions (bolus dose) and 24-hour infusions, using noncompartmental and multicompartmental methods. A global compartmental analysis (2 and 3 compartments) generated a single set of pharmacokinetic parameters, regardless of infusion rate and duration, and took into account the 30% decrease in clearance and volume of distribution observed over the dose range. The 2-compartment model was retained to predict bolus plus 3-hour-infusion doses of otamixaban for future phase (2/3) studies. Otamixaban exhibited in healthy subjects several interesting pharmacokinetic features in view of its potential therapeutic use in coronary thrombosis: a rapid plasma distribution and elimination, a well-described dose-exposure relationship, a low intersubject variability in plasma exposure, and a mixed renal and biliary excretion with constant renal clearance.

Developing a Digital Medicine System in Psychiatry: Ingestion Detection Rate and Latency Period.

BACKGROUND: A digital medicine system (DMS) has been developed to measure and report adherence to an atypical antipsychotic, aripiprazole, in psychiatric patients. The DMS consists of 3 components: ingestible sensor embedded in a medication tablet, wearable sensor, and secure mobile and cloud-based applications. An umbrella study protocol was designed to rapidly assess the technical performance and safety of the DMS in multiple substudies to guide the technology development. METHODS: Two sequential substudies enrolled 30 and 29 healthy volunteers between March-April 2014 and February-March 2015, respectively, to assess detection accuracy of the ingestible sensor by the DMS and the latency period between ingestion and detection of the ingestion by the wearable sensor or the cloud-based server. RESULTS: The first substudy identified areas for improvement using early versions of the wearable sensor and the mobile application. The second substudy tested updated versions of the components and showed an overall ingestion detection rate of 96.6%. Mean latency times for the signal transmission were 1.1-1.3 minutes (from ingestion to the wearable sensor detection) and 6.2-10.3 minutes (from the wearable sensor detection to the server detection). Half of transmissions were completed in < 2 minutes, and ~90% of ingestions were registered by the smartphone within 30 minutes of ingestion. No serious adverse events, discontinuations, or clinically significant laboratory/vital signs findings were reported. CONCLUSIONS: The DMS implementing modified versions of the smartphone application and the wearable sensor has the technical capability to detect and report tablet ingestion with high accuracy and acceptable latency time. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02091882.

Optimization of a Digital Medicine System in Psychiatry.

BACKGROUND: Nonadherence to medication compromises the effectiveness of psychiatric treatments in patients with serious mental illness (SMI). A newly developed digital medicine system (DMS) offers an opportunity to objectively assess and report patient medication adherence. DMS includes a wearable sensor that receives a data signal from a medication tablet with an embedded ingestible sensor after ingestion of the medication and transmits that data to the patient's mobile device to display health care information for the patient and treatment team. METHODS/RESULTS: Development of a DMS requires a program that investigates safety, tolerability, and usability of the system in patients with SMI. It necessitates rapid design adaptation of the individual components and the integrated system and human factors studies with the intended users. This article describes the program's methodology and shows results from 3 early studies, conducted in 2013 and 2014, to illustrate diversity of the programs' methodology. First, a standard 28-day study showed minimal skin irritation and demonstrated acceptable wearability of the wearable sensor. Second, a 16-week study provided usability feedback from patients with SMI and caregivers to improve the mobile application. Third, end-to-end bench-level integrated system testing led to multiple substudies of a master protocol (ClinicalTrials.gov identifier: NCT02091882) to investigate various aspects of the system (eg, ingestible sensor detection and latency). CONCLUSIONS: To develop a DMS in psychiatry, the system's multiple components must be considered simultaneously using various methodologies. A focus on usability, along with agile evaluation and feedback across studies, provides an optimal strategy for ensuring patient acceptance and successful regulatory review.

Usability of a novel digital medicine system in adults with schizophrenia treated with sensor-embedded tablets of aripiprazole.

OBJECTIVE: Digital medicine system (DMS) is a novel drug-device combination that objectively measures and reports medication ingestion. The DMS consists of medication embedded with an ingestible sensor (digital medicine), a wearable sensor, and software applications. This study evaluated usability of the DMS in adults with schizophrenia rated by both patients and their health care providers (HCPs) during 8-week treatment with prescribed doses of digital aripiprazole. METHODS: Six US sites enrolled outpatients into this Phase IIa, open-label study (NCT02219009). The study comprised a screening phase, a training phase (three weekly site visits), and a 5-week independent phase. Patients and HCPs independently rated usability of and satisfaction with the DMS. RESULTS: Sixty-seven patients were enrolled, and 49 (73.1%) patients completed the study. The mean age (SD) of the patients was 46.6 years (9.7 years); the majority of them were male (74.6%), black (76.1%), and rated mildly ill on the Clinical Global Impression - Severity scale (70.1%). By the end of week 8 or early termination, 82.1% (55/67) of patients had replaced the wearable sensor independently or with minimal assistance, based on HCP rating. The patients used the wearable sensor for a mean (SD) of 70.7% (24.7%) and a median of 77.8% of their time in the trial. The patients contacted a call center most frequently at week 1. At the last visit, 78% (47/60) of patients were somewhat satisfied/satisfied/extremely satisfied with the DMS. CONCLUSION: A high proportion of patients with schizophrenia were able to use the DMS and reported satisfaction with the DMS. These data support the potential utility of the DMS in clinical practice.

Ciclesonide, a novel inhaled steroid, does not affect hypothalamic-pituitary-adrenal axis function in patients with moderate-to-severe persistent asthma.

BACKGROUND: Inhaled corticosteroids (ICSs) reduce local airway inflammation, which is an underlying cause of asthma symptoms. However, potential systemic side effects associated with ICS use are a major concern for asthmatic patients. METHODS: Adult patients (n = 60; > or = 18 years of age) with moderate-to-severe asthma were randomized to receive 4 weeks of treatment with ciclesonide (CIC), 320 microg bid (CIC 640), CIC, 640 microg bid (CIC 1280), fluticasone propionate (FP), 440 microg bid (FP 880), FP 880 microg bid (FP 1760), or placebo (PBO) [all doses expressed as ex-actuator; comparable to ex-valve doses of 800 and 1,600 microg/d for CIC and 1,000 and 2,000 microg/d for FP, respectively]. RESULTS: After 29 days of treatment, CIC 640, CIC 1280, and FP 880 had no significant effect on the mean serum cortisol area under the curve for 0 to 24 h (AUC0-24h). FP 1760 produced a statistically significant suppression in mean serum cortisol AUC0-24h compared to PBO (p = 0.0009; 95% confidence interval [CI] -117.5 [corrected] to -32.1). Results obtained with cosyntropin stimulation revealed no statistically significant differences among the groups. The CIC 640 group demonstrated a significant increase compared to the PBO group in 24-h urinary cortisol levels from baseline at week 4 (p = 0.0224; 95% CI, 0.0023 to 0.0283), while the other treatment groups revealed no change in this parameter. The incidence of treatment-emergent adverse events was similar in all groups, and all adverse events were mild or moderate in severity. CONCLUSION: Treatment with moderate and high doses of CIC does not result in hypothalamic-pituitary-adrenal-axis suppression as compared with PBO.

Are there lessons to be learned from drug development that will accelerate the use of molecular imaging probes in the clinic?

This special issue of the journal contains contributions from participants of the third La Jolla meeting (The Magic Bullet: A Century Later). The goal of this meeting was twofold: to review approaches to validating molecular imaging agents and to review the progress in advancing the use of molecular imaging from the bench to the bedside, with a special emphasis on how molecular imaging improves patient care and management. Drug development has changed its focus over the years. The original approach depended on direct measurements in patients, whereby, in many cases, the drug was advanced to an NDA based on physiological results (e.g., lowering blood pressure) without identifying a target. Over the past decade, the focus has been on validating a target and choosing the lead compound using combinatorial chemistry and high throughput screening, often at the expense of a focus on the biology of diseases. On the other hand, molecular imaging has been target based since its beginning because of the requirements dictated by external imaging (i.e., a target-to-nontarget ratio). This article explores the possible analogies between current targeted drug development and molecular imaging-targeted probe development with the goal of better defining the path to new molecular imaging probes for the clinic.

Effect of food on pharmacokinetics of an inhaled drug: a case study with a VLA-4 antagonist, HMR1031.

HMR1031 is a potent and specific antagonist of the integrin VLA-4 (alpha4beta1) binding to vascular cell adhesion molecule-1 (VCAM-1) and fibronectin. HMR1031 is an inhaled drug being developed for the treatment of asthma using an Ultrahaler dry-powder inhalation device. A pharmacoscintigraphic study of HMR1031 suggests a lung deposition of approximately 25% and gastrointestinal tract deposition of approximately 75%. Since oral absorption may be contributing to systemic plasma concentrations, the effect of food on HMR1031 was assessed. This was a single-dose (3 mg), open-label, randomized, two-way crossover (fasted vs. fed) study in 8 healthy male subjects. Blood samples were collected at predose and up to 24 hours postdose. Plasma concentrations were determined by the LC/MS/MS method. HMR1031 was rapidly absorbed, with median tmax values of 1.0 and 0.75 hours under fasted and fed conditions, respectively. Under fasted conditions, mean AUCinfinity and Cmax values were 16.4 ng x h/mL and 4.56 ng/mL, respectively. Under fed conditions, mean AUCinfinity and Cmax values decreased to 11.7 ng x h/mL and 2.81 ng/mL, respectively. The mean terminal elimination half-life (t1/2) for both treatment groups was similar (2.7 h). HMR1031 population estimates of the apparent clearance, apparent volume of distribution, and absorption rate were 225 L/h (4.1% coefficient of variation [CV]), 44.5 L (26% CV), and 0.340 h-1 (7.0% CV), respectively. Food is a significant covariate on clearance. These data suggest that food unexpectedly decreases the systemic exposure of inhaled HMR1031 by approximately 30%, probably due to increased liver blood flow and increased biliary excretion. This decrease in systemic exposure is unlikely to affect the topical effect of the drug but may result in increased variability in plasma pharmacokinetics. The disposition and food effect of HMR1031 can be described using mixed-effect modeling.

A double-blind, placebo-controlled study of the efficacy and safety of ebastine 20 mg once daily given with and without food in the treatment of seasonal allergic rhinitis.

The efficacy and safety of ebastine 20 mg once daily given with and without food were compared in patients ages 12 to 70 years with seasonal allergic rhinitis (SAR) caused by mountain cedar allergen. This double-blind, placebo-controlled study was conducted at six centers in Texas. Efficacy and safety analyses were performed on the intent-to-treat population, which comprised 652 patients; 540 patients completed the study. Following 2 weeks' treatment, no significant differences (p > or = 0.91) were found between the ebastine with and without food groups in the percentage change from baseline of daily "reflective" total rhinitis symptom scores (i.e., patients' assessment of severity over the previous 12 h), but both ebastine groups exhibited significantly greater reductions versus patients receiving placebo (p < 0.0001). There were also no significant differences in the percentages of patients experiencing adverse events between the ebastine with and without food groups. Mean steady-state plasma concentrations of ebastine and its active metabolite carebastine were, respectively, 5.5% (ns) and 15.1% (p < 0.05) higher when ebastine was given with food versus its administration without food. Overall, these results indicate that in clinical practice, ebastine does not need to be administered with reference to food.

Estimating mass balance for inhaled drugs in humans: an example with a VLA-4 antagonist, IVL745.

IVL745 is an inhaled VLA-4 antagonist developed for the treatment of asthma. Following inhalation (Inh), a fraction of the drug is deposited in the oropharynx, and the rest is deposited in the lungs. For inhaled drugs, it is technically and ethically difficult to formulate and administer radiolabeled drugs. Hence, if the drug is metabolically stable in the lungs, mass balance and metabolism of inhaled drugs, such as IVL745, can be determined by administering radiolabeled intravenous (IV) and oral drugs and by comparing with the data following Inh administration. The study was a three-period crossover design in 6 healthy subjects to evaluate the absorption, distribution, metabolism, and elimination following IV and oral administration of (14)C-IVL745 (4 mg/50 microCi) and inhaled (10-mg) dose. Serial sampling of blood and excreta was performed maximally up to 168 hours postdose. Plasma IVL745 concentrations were determined using a liquid chromatography tandem mass spectrometry (LC/MS/MS) method with a minimum quantifiable limit of 10 pg/mL. Overall, the drug was safe and well tolerated. The recovery of the radioactive dose varied from 94.8% to 117% for both IV and oral administration. Following IV administration, 90.2% of the radioactive dose was recovered in the feces, suggesting extensive biliary excretion of the drug. After oral administration, 99.7% of the radioactivity was recovered in the feces, and no radioactivity was detected in plasma, suggesting lack of absorption of the drug. Negligible (14)C-radioactivity concentrations were observed in the red blood cell fractions. The mean t(1/2) values were 1.6, 1.5, and 4.4 hours following IV, oral, and Inh administration, respectively. The oral bioavailability of IVL745 was low (< 2%), and the inhaled bioavailability was 26%. The volume of distribution at steady state (V(ss)) was low (19.0 L). The predicted blood clearance of IVL745 was 86 L/h, which was comparable to the commonly used liver blood flow value of 90 L/h. Only a minor fraction of the dose was excreted in the urine with low to moderate renal clearance. The parent drug accounted for 77% to 89% of the dosed radioactivity in excreta. Two major metabolites observed in excreta were mono-o-desmethyl IVL745 and di-o-desmethyl IVL745. The data showed that the drug had negligible oral bioavailability, low oral absorption, 26% inhaled bioavailability, low extent of metabolism, high biliary excretion, and low renal clearance. This knowledge may aid in the prediction of potentially relevant drug-drug interactions and dosing adjustments in high-risk populations for IVL745.