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Results from previous ex-vivo continuous renal replacement therapy (CRRT) models have successfully demonstrated similar extraction coefficients (EC) identified from in-vivo clinical trials. The objectives of this study are to develop an ex-vivo in-vivo correlation (EVIVC) model to predict drug clearance for commonly used antiepileptics and to evaluate similarity in drug extraction across different CRRT modalities to extrapolate dosing recommendations.Levetiracetam, lacosamide, and phenytoin CRRT clearance was evaluated using the Prismaflex CRRT system and M150 hemodiafilters using an albumin containing normal saline (ALB-NS) vehicle with 3 different albumin concentrations (2 g/dL, 3 g/dL, and 4 g/dL) and a human plasma vehicle at 3 different effluent flow rates (1 L/hr, 2 L/hr, and 3 L/hr). Blood and effluent/dialysate concentrations were collected after circuit priming. ECs were calculated for each drug, modality, vehicle, and experimental arm combination.The calculated average EC for levetiracetam and lacosamide was approximated to the fraction unbound from plasma protein. Human plasma and ALB-NS vehicles demonstrated adequate prediction of in-vivo CRRT clearance. Geometric mean ratios indicated similarity in extraction coefficients when comparing between hemofiltration and hemodiafiltration modalities and between filtration and dialysis modalities at effluent flow rates ≤ 2L/hr. Evaluation of phenytoin provided inconsistent findings with regards to extraction coefficient similarity across different CRRT modalities.The findings indicate that an ex-vivo study can be used as a surrogate to predict in-vivo levetiracetam and lacosamide clearance in patients receiving CRRT.

7 tables and 3 figure legends

Relationship between AUC and Cmax after single dose (A)

Relationship between veliparib exposure-% CFB in PAR levels in PBMC (A) and �B in PAR levels-ORR (B)

Purpose: A phase I trial of veliparib in combination with topotecan plus carboplatin (T+C) demonstrated a 33% objective response rate in patients with hematological malignancies. The objective is to perform exposure–response analysis to inform the phase II trial design.Experimental Design: Pharmacokinetic, efficacy, and safety data from 95 patients, who were administered 10 to 100 mg b.i.d. doses of veliparib for either 8, 14, or 21 days with T+C, were utilized for exposure–efficacy (objective response and overall survival) and exposure–safety (≥grade 3 mucositis) analysis. Multivariate cox proportional hazards and logistic regression analyses were conducted. The covariates evaluated were disease status, duration of treatment, and number of prior therapies.Results: The odds of having objective response were 1.08-fold with 1,000 ng/hr/mL increase in AUC, 1.8-fold with >8 days treatment, 2.8-fold in patients with myeloproliferative neoplasms (MPN), and 0.5-fold with ≥2 prior therapies. Based on analysis of overall survival, hazard of death decreased by 1.5% for 1,000 ng/hr/mL increase in AUC, 39% with >8 days treatment, 44% in patients with MPN, while increased by 19% with ≥2 prior therapies. The odds of having ≥grade 3 mucositis increased by 29% with 1,000 ng.h/mL increase in AUC.Conclusions: Despite shallow exposure–efficacy relationship, doses lower than 80 mg do not exceed veliparib single agent preclinical IC50. Shallow exposure–mucositis relationship also supports the 80-mg dose. Based on benefit/risk assessment, veliparib at a dose of 80 mg b.i.d. for at least 14 days in combination with T+C is recommended to be studied in MPN patients. Clin Cancer Res; 23(21); 6421–9. ©2017 AACR.

Correlation between objective response rate (ORR) and overall survival (OS)

Although 17α-ethinyl estradiol-3-sulfate (EES) reduces mortality in animal models of controlled hemorrhage, its role in a clinically relevant injury model is unknown. We assessed the impact of EES in a swine model of multiple injuries and hemorrhage.The study was performed under Good Laboratory Practice, with 30 male uncastrated swine (25-50 kg) subjected to tibial fracture, pulmonary contusion, and 30% controlled hemorrhage for an hour. Animals were randomized to one of five EES doses: 0 (control), 0.3, 1, 3, and 5 mg/kg, administered postinjury. Subjects received no resuscitation and were observed for 6 hours or until death. Survival data were analyzed using Cox-proportional hazard regression. Left ventricular pressure-volume loops were used to derive preload recruitable stroke work as a measure of cardiac inotropy. Immediate postinjury preload recruitable stroke work values were compared with values at 1 hour post-drug administration.Six-hour survival for the 0, 0.3, 1, 3, and 5 mg/kg groups was 0%, 50%, 33.3%, 16.7%, and 0%, respectively. Following Cox regression, the hazard (95% confidence interval) of death was significantly reduced in the 0.3 (0.22 [0.05-0.93]) and 1 (0.24 [0.06-0.89]) mg/kg groups but not the 3 (0.49 [0.15-1.64]) and 5 (0.46 [0.14-1.47]) mg/kg groups. Mean survival time was significantly extended in the 1 mg/kg group (246 minutes) versus the 0 mg/kg group (96 minutes) (p = 0.04, t test). At 1 hour post-drug administration, inotropy was significantly higher than postinjury values in the 0.3 and 1 mg/kg groups (p = 0.003 and p0.001, respectively). Inotropy was unchanged in the 3 and 5 mg/kg groups but significantly depressed in the control (p = 0.022).Administration of EES even in the absence of fluid resuscitation reduces mortality and improves cardiac inotropy in a clinically relevant swine model of multiple injuries and hemorrhage. These findings support the need for a clinical trial in human trauma patients.

Antiepileptic dosing information used to manage neonatal patients receiving extracorporeal membrane oxygenation (ECMO) is limited. The objective of this study is to quantify the extent of sequestration of various antiepileptic drugs using an ex-vivo neonatal ECMO circuit. Two neonatal closed-loop ECMO circuits were prepared using a Rotaflow centrifugal pump, custom polyvinylchloride tubing and a Quadrox-i Neonatal membrane oxygenator. After 5 minutes of circuit priming and stabilization with normal saline/albumin or expired human whole blood, single boluses of levetiracetam (200 mg), lacosamide (20 mg), and phenytoin (200 mg) were injected into the circuit. To account for spontaneous drug degradation, two polyvinylchloride beakers were filled with normal saline/albumin or expired human whole blood and equivalent antiepileptic drug doses were prepared. Simultaneous pharmacokinetic samples were collected from the control solution and the pre-centrifugal pump, pre-oxygenator, and post-oxygenator sampling ports from each circuit. Similar drug recovery profiles were observed among the three sampling sites investigated. Percent drug sequestration after a 24-hour circuit flow period was relatively similar between the two different circuits and ranged between 5.5%–13.2% for levetiracetam, 18.4%–22.3% for lacosamide, and 24.5%–30.2% for phenytoin. A comparison at 12 and 24 hours demonstrated similar percent drug sequestration across all three drugs in each circuit. Percent drug sequestrations for levetiracetam and lacosamide were less than 20% and for phenytoin were as high as 30% based on the sampling following single bolus dose administration into a neonatal ECMO circuit. Careful consideration of patient clinical status should be taken in consideration when optimizing antiepileptic therapy in neonates receiving ECMO.

Pharmacogenetics (PGx) seeks to enable selection of the right dose of the right drug for each patient to optimize therapeutic outcomes. Most PGx focuses on pharmacokinetics (PKs), due to our relatively advanced understanding of the genes involved in PKs and the causative effects of variants in those genes. Genetic variants can also affect pharmacodynamics (PDs), but relatively few PGx-PD associations have been identified. This is partially due to a more limited understanding of the relevant genes and the consequences of genetic variation, but is also due in part to the potential confounding of PK variability in assessments of clinical outcomes that have a contribution from both PKs and PDs. For example, it is challenging to confirm the effect of mu opioid receptor (OPRM1) genetic variation on opioid response due to the contribution of CYP2D6 genotype to bioactivation of some opioid drugs (i.e., codeine and tramadol). The objectives of this mini-review are to describe several recent efforts to discover and validate PGx-PD that disentangle the influence of PK variability and propose potential approaches that could be used in future PGx-PD analyses. We use the effect of OPRM1 genetics on opioid response to illustrate how these analyses could be conducted and conclude by discussing how PGx-PD could be translated into clinical practice to improve therapeutic outcomes.

Negative clinical outcomes after switching from brand to generic antidepressants have raised concerns regarding therapeutic equivalency. This research aims to estimate the prevalence of switching and to identify predictors for generic to brand switching for various antidepressants. This retrospective cohort study utilized data from a 10% random sample of enrollees in the IQVIA PharMetrics Plus claims database from 2007-2015. The base cohort consisted of commercially insured patients who were prescribed escitalopram, duloxetine, or venlafaxine extended release (ER) anytime from the year prior to the generic launch through December 2014. The primary outcome was defined as a switch from generic to a brand within 14 days of sustained generic use in a 1-year follow-up period. Adjusted logistic regression and generalized estimating equations for repeated measures estimated the drug specific and overall odds of switch-to-brand among brand initiators relative to generic initiators, respectively. A total of 102,831 unique patients across 3 drug products contributed to the final analytic sample. The overall prevalence of switch from generic to brand was 0.74%. Across all three antidepressants, brands initiators were more likely to experience a switch-to-brand: escitalopram (odds ratio (OR): 14.41, 95% confidence interval (CI): 11.14-18.64), duloxetine (OR: 8.08, 95% CI: 4.85-13.41) and venlafaxine ER (OR: 16.46, 95% CI: 11.56-23.46). The pooled odds of a switch-to-brand in brand vs. generic initiators was 13.77 (95% CI: 11.35-16.71). This study suggests a low overall switch-to-brand prevalence and may support therapeutic equivalence between brand and generic antidepressants. Initiating with a brand product was the strongest predictor for switching back to brand and suggests that patient experience may play a role in drug utilization.

Background and objectives Currently, no dosing information exists for ceftaroline fosamil in patients undergoing continuous renal replacement therapy (CRRT). The objectives of this study are to characterize the pharmacokinetics of ceftaroline in critically ill patients undergoing CRRT modalities and to derive individualized dosing recommendations. Methods This pharmacokinetic study aimed to enroll critically ill patients receiving ceftaroline fosamil and any CRRT modality from adult intensive care units. Selection of the specific CRRT modality and dosing regimen was based on clinical discretion. Pre-filter, post-filter, and ultrafiltrate samples were obtained before the administration of the fourth dose, after the completion of the infusion, and up to five additional time points post-infusion. Plasma concentrations were measured using a validated ultra-high performance liquid chromatography assay. Individual pharmacokinetic parameters were calculated using non-compartmental analysis. Results Four patients were enrolled to investigate the need for dosing adjustments. The average sieving coefficient for ceftaroline was 0.81 ± 0.1, indicating high filter efficiency. The average volume of distribution was 41.8 L (0.48 L/kg) and is within the previously reported range in patients with normal renal function. Non-renal clearance accounted for more than 50% of the total clearance observed in patients. The observed pharmacokinetic profiles suggest that the pharmacodynamic target for 2-log10 CFU reduction from baseline (%fT >1 mg/L of 50%) was met for each patient. Due to the impact of CRRT and non-renal clearance, dosing recommendations were derived for different ranges of effluent flow rates and adjusted body weights. For a patient with an adjusted body weight of 70 kg and receiving CRRT at an effluent flow rate of 3 L/h, a ceftaroline fosamil dosing regimen of 400 mg every 12 h is proposed. Conclusion Ceftaroline is cleared extensively in critically ill patients receiving CRRT and may impact pharmacodynamic target achievement. Dose adjustments should be based on the intensity of the CRRT regimen, patient weight, and the clinical status of the patient.

At least 60% of the neonates with opioid withdrawal syndrome (NOWS) require morphine to control withdrawal symptoms. Currently, the morphine dosing strategies are empiric, not optimal and associated with longer hospital stay. The aim of the study was to develop a quantitative, model-based, real-world data-driven approach to morphine dosing to improve clinical outcomes, such as reducing time on treatment. Longitudinal morphine dose, clinical response (Modified Finnegan Score (MFS)), and baseline risk factors were collected using a retrospective cohort design from the electronic medical records of neonates with NOWS (N = 177) admitted to the University of Maryland Medical Center. A dynamic linear mixed effects model was developed to describe the relationship between MFS and morphine dose adjusting for baseline risk factors using a split-sample data approach (70% training: 30% test). The training model was evaluated in the test dataset using a simulation based approach. Maternal methadone and benzodiazepine use, and race were significant predictors of the MFS response. Positive autocorrelations of 0.56 and 0.12 were estimated between consecutive MFS responses. On an average, for a 1,000 μg increase in the morphine dose, the MFS decreased by 0.3 units. The model evaluation showed that observed and predicted median time on treatment were similar (13.0 vs. 13.8 days). A model-based framework was developed to describe the MFS-morphine dose relationship using real-world data that could potentially be used to develop an adaptive, individualized morphine dosing strategy to improve clinical outcomes in infants with NOWS.

Background BUP-XR (a.k.a. RBP-6000 or SUBLOCADE™) is an extended-release subcutaneous buprenorphine formulation for the treatment of opioid use disorder. BUP-XR was designed to provide sustained buprenorphine exposure throughout the monthly dosing interval, at concentrations sufficient to control all aspects of the disease (withdrawal, craving, and blockade of opioid subjective effects). Objectives To characterize the population pharmacokinetics of BUP-XR based on phase II and phase III data and to evaluate whether target therapeutic concentrations were reached with the dosing regimens evaluated in the phase III program. Methods The population pharmacokinetic analysis included 570 subjects with opioid use disorder who received up to 12 monthly BUP-XR injections following induction with sublingual buprenorphine. Results In phase III studies, target therapeutic concentrations of buprenorphine were achieved from the first injection and maintained over the entire treatment duration. Buprenorphine plasma concentration–time profiles were well described by a two-compartment model, with first-order absorption for sublingual buprenorphine and a dual absorption submodel for BUP-XR. A covariate analysis evaluated the effects of subjects’ demographic characteristics, laboratory data, and genetic status regarding buprenorphine-metabolizing enzymes. Only two covariates, body mass index and body weight, were retained in the final model. Overall, their effects were not of sufficient magnitude to justify a dose adjustment. Finally, pharmacokinetic simulations showed that buprenorphine plasma concentrations decreased slowly after discontinuation of treatment and that a 2-week occasional delay in dosing would not impact efficacy, which translated into labeling claims. Discussion In conclusion, the present analysis led to the development of a robust population pharmacokinetic model and confirms the ability of BUP-XR to deliver and maintain therapeutic plasma concentrations over the entire treatment duration. Electronic supplementary material The online version of this article (10.1007/s40262-020-00957-0) contains supplementary material, which is available to authorized users.

Limited data exist on the effect of continuous renal replacement therapy (CRRT) methods on anti‐epileptic drug pharmacokinetics (PK). This prospective practice‐based PK study aims to assess the impact of continuous venovenous hemofiltration (CVVH), a modality of CRRT, on levetiracetam PK in critically ill patients and to derive individualized dosing recommendations. Eleven patients receiving oral or intravenous levetiracetam and CVVH in various intensive care units at a large academic medical center were enrolled to investigate the need for dosing adjustments. Prefilter, postfilter, and ultrafiltrate samples were obtained before dosing, after the completion of the infusion or 1‐hour postoral dose, and up to 6 additional time points postinfusion or postoral administration. Patient‐specific blood and ultrafiltrate flow rates and laboratory values were also collected at the time of sampling. The average sieving coefficient (SC) for levetiracetam was 0.89 ± 0.1, indicating high filter efficiency. Six of the 11 patients experienced concentrations outside the reported therapeutic range (12–46 mg/L). The average volume of distribution was 0.73 L/kg. CVVH clearance contributes a major fraction of the total levetiracetam clearance (36–73%) in neurocritically ill patients. The average bias and precision of the estimated vs. observed total clearance value was ~ 10.6% and 21.5%. Major dose determinants were identified to be SC and effluent flow rate. Patients with higher ultrafiltrate rates will have increased drug clearance and, therefore, will require higher doses in order to match exposures seen in patients with normal renal function.

This study aimed to characterize the relationship between cannabis use, ACE score, and pregnancy outcomes. Pregnant patients in Baltimore, MD, completed the 17-point ACE checklist. Charts of the birth parent and neonate were reviewed for urine toxicology testing at initiation of care and delivery, prenatal care metrics, and birth statistics. Multivariable logistic regression analysis was performed to assess the relationship between ACE score, cannabis use, and pregnancy outcomes. Of 256 birth parents, 87 (34.0%) tested positive for cannabis at initial visit and 39 (15.2%) tested positive for cannabis at delivery. Testing positive for cannabis at initial visit or delivery was associated with higher ACE score (15.1 vs 13.7, p = 0.04; 16.2 vs 13.8, p = 0.01). Of those who tested positive for cannabis at initial visit, 39/87 (45.0%) tested positive at delivery. Continued cannabis use at delivery was associated with lower maternal weight gain (7.9 kg vs 13.3 kg, p = 0.003), fewer prenatal visits (7 vs 8, p = 0.010), and numerically higher mean ACE score. Cannabis use at delivery was associated with 10% lower birthweight (2665 g vs 3014 g p 0.05) but not with pre-term birth. Total ACE score was not significantly associated with any birth outcome. Worse pregnancy outcomes were associated with cannabis use throughout pregnancy but not with cannabis use at prenatal care initiation. The interplay of ACE and continued cannabis use during pregnancy warrants further research on the physiologic effects of cannabis and interventions to decrease substance use during pregnancy.

As with other psychiatric disorders, development of drugs to treat binge-eating disorder (BED) has been hampered by high placebo response and dropout rates in randomized controlled trials (RCTs). Although not approved for use in BED, several RCTs have suggested that topiramate is efficacious for BED in obese individuals. Using data from a positive investigator-initiated RCT of topiramate in 61 obese individuals with BED, the objective of the present study is (i) to develop a quantitative disease-drug-trial framework to inform future BED clinical trial designs, and (ii) to determine the optimal topiramate dose to achieve therapeutic efficacy. Disease-drug-trial models were developed separately for the two efficacy measures, namely, longitudinal normalized weekly binge-eating episode frequency (BEF) and binge day frequency (BDF). Model building consisted of (i) developing a placebo effect model that describes response from the placebo group, (ii) adding a drug effect to the placebo model to describe dose-response relationships, and (iii) developing a parametric time to event model to characterize patient dropout patterns. The placebo effect on normalized BEF and BDF over time demonstrated a maximum decrease of ~ 57% by 5 weeks. Participants had a higher dropout probability if no weight loss occurred during the trial period. The identified dose-response relationship demonstrated a daily dose of 125 mg was needed to exhibit a marked reduction in weekly BEF. The developed comprehensive disease-drug-trial model will be utilized to simulate different clinical trial designs to increase the success for future BED drug development programs.

Optimal pediatric dosing of unfractionated heparin (UFH) is challenging because of the paucity of clinical outcome and pharmacokinetic-pharmacodynamic (PK/PD) studies in pediatrics. This study aimed to: (i) develop a PK/PD model for UFH, quantified by anti-factor Xa assay, and the UFH effect, measured by activated partial thromboplastin time (aPTT); and (ii) use simulations to evaluate pediatric UFH infusions for achieving the anti-factor Xa (0.3-0.7 IU/mL) therapeutic target. Electronic health record data were retrospectively collected from 633 patients aged19 years admitted to Texas Children's Hospital. The PK/PD model was developed using a 70% (training)/30% (testing) split-sample approach. A 1-compartment PK model with linear elimination adequately described the UFH PK. An allometrically scaled body weight on clearance (CL) and volume of distribution (Vd) with an age-dependent maturation function of extracellular water on Vd were the covariates identified. Comparable with literature, the typical values for CL and Vd were 3.28 L/(h·50 kg) and 8.83 L/50 kg, respectively. A linear model adequately described the UFH-aPTT relationship with an estimated slope of 150 seconds/(IU/mL). Simulations of the currently recommended starting infusions (28 IU/h/kg for pediatrics1 year old or 20 IU/h/kg for pediatrics1 year old) showed that the anti-factor Xa therapeutic target was achieved only in 15.3%, 14.6%, 36.9%, and 45.11% of subjects in the age groups of1 year, 1-6 years, 6-12 years, and 12-19 years, respectively. In conclusion, the UFH anti-factor Xa target is not achieved initially, especially in young pediatrics, suggesting the need to optimize UFH dosing to achieve higher therapeutic success.

Antiepileptic dosing information used to manage neonatal patients receiving extracorporeal membrane oxygenation (ECMO) is limited. The objective of this study is to quantify the extent of sequestration of various antiepileptic drugs using an

BIO 300, a suspension of synthetic genistein nanoparticles, is being developed for mitigating the delayed effects of acute radiation exposure (DEARE). The purpose of the current study was to characterize the pharmacokinetic (PK) profile of BIO 300 administered as an oral or parenteral formulation 24 h after sham-irradiation, total-body irradiation (TBI) with 2.5-5.0% bone marrow sparing (TBI/BMx), or in nonirradiated sex-matched C57BL/6J mice and non-human primates (NHP). C57BL/6J mice were randomized to the following arms in two consecutive studies: sham-TBI [400 mg/kg, oral gavage (OG)], TBI/BM2.5 (400 mg/kg, OG), sham-TBI [200 mg/kg, subcutaneous (SC) injection], TBI/BM2.5 (200 mg/kg, SC), sham-TBI (100 mg/kg, SC), or nonirradiated [200 mg/kg, intramuscular (IM) injection]. The PK profile was also established in NHP exposed to TBI/BM5.0 (100 mg/kg, BID, OG). Genistein-aglycone serum concentrations were measured in all groups using a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay. The PK profile demonstrates 11% and 19% reductions in Cmax and AUC0-inf, respectively, among mice administered 400 mg/kg, OG, after TBI/BM2.5 compared to the sham-TBI control arm. Administration of 200 mg/kg SC in mice exposed to TBI/BM2.5 showed a 53% increase in AUC0-inf but a 28% reduction in Cmax compared to the sham-TBI mice. The relative bioavailability of the OG route compared to the SC and IM routes in mice was 9% and 7%, respectively. After the OG route, the dose-normalized AUC0-inf was 13.37 (ng.h/mL)/(mg/kg) in TBI/BM2.5 mice compared to 6.95 (ng.h/mL)/(mg/kg) in TBI/BM5.0 NHPs. Linear regression of apparent clearances and weights of mice and NHPs yielded an allometric coefficient of 1.06. Based on these data, the effect of TBI/BMx on BIO 300 PK is considered minimal. Future studies should use SC and IM routes to maximize drug exposure when administered postirradiation. The allometric coefficient is useful in predicting therapeutic drug dose regimens across species for drug approval under the FDA animal rule.

AIMS Although the use of continuous renal replacement therapy (CRRT) has increased, limited dosing information exists on the effect of CRRT on antiepileptic drug pharmacokinetics. The objectives of this practice-based study are to evaluate the pharmacokinetics of lacosamide and recommend individualized dosing recommendations in critically ill patients receiving continuous venovenous haemofiltration (CVVH). METHODS Seven patients receiving lacosamide and CVVH in a neurocritical care unit were enrolled. Pre-filter, post-filter and ultrafiltrate samples were obtained at baseline, right after the completion of the infusion, and up to six additional sampling time points post-administration. Patient-specific flow rates and clinical measures were also collected simultaneously at the time of sampling. Plasma concentrations were measured using a validated high-performance liquid chromatography with ultraviolet radiation detection (HPLC-UV) bioanalytical method. Non-compartmental analysis was utilized to characterize the pharmacokinetics of lacosamide. RESULTS The observed mean sieving coefficient for lacosamide was 0.80 ± 0.10, suggesting high removal of lacosamide. Concentrations measured in six out of seven patients were observed to be outside the therapeutic range (5-12 mg/L). The estimated average volume of distribution was found to be similar to healthy patients (0.58 L/kg). The mean bias and precision of the estimated total clearance was -2.53% and 14.9%, respectively. Simulations of various doses suggest that effluent flow rate-based dosing regimens could be used to individualize lacosamide therapeutics. CONCLUSIONS CVVH clearance contributed a major fraction of the total lacosamide clearance in neurocritically ill patients. Given that drug clearance increases with higher effluent flow rates, lacosamide dosing regimens should be increased to match exposures observed in patients with normal renal function.

The percentage of the time that the free drug concentration remains above a concentration threshold (%fT > concentration threshold) has frequently been identified to be the optimal pharmacokinetic (PK)-pharmacodynamic (PD) target of interest for tazobactam using in vitro infection models. Similar in vitro models suggested that an 85% fT > concentration threshold of 2 μg/ml for tazobactam is required to demonstrate a 2-log(10)-unit decrease in the number of CFU per milliliter from that at the baseline at 24 h for high-level β-lactamase-producing Escherichia coli strains. The objective of this study was to characterize the tazobactam concentrations in a cohort of critically ill patients with Gram-negative bacterial infections, determine if traditional dosing regimens achieve a prespecified PK/PD target of an 80% fT > concentration threshold of 2 μg/ml, and propose alternative dosing regimens. Hospitalized critically ill adult patients receiving piperacillin-tazobactam (TZP) for a culture-positive Gram-negative bacterial infection were eligible to consent for study inclusion. Two blood samples were drawn, one during the midpoint of the dosing interval and one at the time of the trough concentration once the patient achieved PK steady state. A population PK model was developed using Phoenix NLME (v8.1) software to characterize the observed concentration-time profile of tazobactam, explore potential covariates to explain the variability in the clearance and volume parameters, and to simulate potential dosing regimens that would achieve the PK/PD target. The PK of tazobactam were adequately described by a one-compartment model with first-order elimination in 18 patients who provided consent. The final model incorporated creatinine clearance as a covariate on clearance. Simulations demonstrated target attainments of less than 50% for tazobactam using traditional dosing regimens (4/0.5 g over 30 min every 6 h). Target attainments of greater than 75% were achieved when using extended infusion times of 4 to 6 h or when administering TZP as a continuous infusion (16/2 g over 24 h). Traditional tazobactam dosing regimens fail to achieve conservative PK/PD targets in critically ill patients. Increases in the tazobactam dose or prolongation of the infusion rate may be warranted to achieve activity against β-lactamase-producing Gram-negative bacteria.

Linezolid standard dosing is fixed at 600 mg every 12 h (q12h) for adults. Literature suggests critically ill, obese patients require higher doses. The study aim is 2-fold: (i) to describe linezolid pharmacokinetics (PK), and (ii) to evaluate if PK/pharmacodynamic (PD) target attainment is achieved with standard dosing in critically ill, obese patients with severe skin and soft tissue infections (SSTIs). Adult patients with a body mass index (BMI) of ≥30 kg/m(2) and receiving intravenous (i.v.) linezolid from August 2018 to April 2019 were eligible for consent in this prospective study. Severe SSTIs were defined as necrotizing fasciitis, myonecrosis, or SSTI with sepsis syndrome. Four blood samples were collected at steady state at 1, 3, 5 h postinfusion and as a trough. Target attainment was defined as achieving area under the concentration-time curve from 0 to 24 h to MIC (AUC(0–24h)/MIC) of ≥100 h*mg/liter. Monte Carlo simulations were used to determine the probability of target attainment (PTA). Eleven patients were included in the study. The median BMI was 45.7 kg/m(2), and median total body weight (TBW) was 136.0 kg. Seven patients received standard linezolid doses, and four received 600 mg q8h. A one-compartment model described linezolid PK. Based on AUC(0–24h)/MIC targets, for noncirrhotic patients at 140 kg, the PTA with standard linezolid doses was 100%, 98.8%, 34.1%, and 0% for MICs of 0.5, 1, 2, and 4 mg/liter, respectively. In conclusion, target attainment of ≥90% is not achieved with standard linezolid doses for noncirrhotic patients ≥140 kg with MICs of ≥2 mg/liter. This study adds to accumulating evidence that standard linezolid doses may not be adequate for all patients.

Importance Facilitating the development of safe and effective medications for schizophrenia is a public health imperative. Objectives To evaluate the association of shortening randomized clinical trial (RCT) duration with the modification of the Positive and Negative Syndrome Scale (PANSS) for the design of RCTs of medications for schizophrenia and to offer perspective on an alternative regulatory pathway to the historically accepted trial duration and response assessment. Data Sources A database was created consisting of clinical trial data from 32 placebo-controlled RCTs of 8 atypical antipsychotic drugs approved by the US Food and Drug Administration (FDA) between January 1, 2001, and December 31, 2015. The database included information on total and individual PANSS item ratings, demographic characteristics, disposition, and adverse events (AEs). Study Selection All clinical trials submitted to 8 new drug applications of atypical antipsychotic drugs were selected. Data Extraction and Synthesis Quality control checks were performed to ensure that the collected data were consistent with the reported results of each trial. Data were collected from March 15, 2015, to September 30, 2015. Data analysis was conducted from October 1, 2015, to June 20, 2016. Main Outcomes and Measures The following analyses were performed: (1) longitudinal assessment of mean change from baseline in total PANSS score, (2) correlation analyses between change from baseline in total PANSS score at week 6 and earlier time points, (3) concordance analyses of outcomes across trials between week 6 and earlier time points using total PANSS and modified PANSS, and (4) analyses of time course of treatment–emergent AEs. Results The final database contained data from 14 219 participants enrolled in 32 drug trials; 9805 of 14 219 participants (69.0%) were male and were either white (7183 [50.5%]) or black (4346 [30.6%]) individuals. The mean (SD) age during treatment was 38.9 (10.9) years, and the mean (SD) age at schizophrenia diagnosis was 25 (8.5) years. Statistically significant separation between treatment response and placebo response was observed after 1 week of treatment. The overall concordance rate across treatment groups steadily increased from week 1 to week 4 (68.0% for week 1, 74.0% for week 2, 83.0% for week 3, and 93.0% for week 4). Trends in AE occurrence were evident by week 1 and percentage of AEs were similar across weeks 3, 4, and 6. The overall concordance rate between change from baseline in the modified PANSS score and change from baseline in the total PANSS score was 93.0% (80 of 86 treatment groups) at week 4 and 97.7% (84 of 86 treatment groups) at week 6. Shortening the trial duration to 4 weeks increased the required sample size to 502 participants. Using the modified PANSS as the end point, the sample size for a 4-week trial was 402 participants and 296 participants for a 6-week trial. Conclusions and Relevance Findings from this analysis suggest that there is the potential to streamline the design of schizophrenia drug clinical trials. Trial sponsors may consider incorporating these strategies and are encouraged to consult with the FDA early in the drug development process.

The objective of the study was to compare the pharmacokinetic (PK) and pharmacodynamic (PD) properties of an insulin glargine formulation, Glaritus® (test) with the innovator’s formulation Lantus® (reference) using the euglycemic clamp technique in a single-dose, double-blind, randomized, two sequences, four-period replicate crossover study in healthy volunteers (n = 40). Subjects received subcutaneous administration of the insulin glargine (0.4 IU/kg) formulation at two occasions for test and reference and a 20% glucose solution was infused at variable rate to maintain euglycemia for 24 h. Both PK [area under the plasma concentration time curve (AUC0–24 h) and maximum insulin concentration (Cmax)] and PD endpoints [area under glucose infusion rate time curve (AUCGIR0–24) and maximum glucose infusion rate (GIRmax)] demonstrated bioequivalence of Glaritus to Lantus with the 90% confidence interval of geometric mean ratio of test to reference entirely contained within 0.80–1.25. Both formulations showed equivalent geometric least-square mean LSM value (0.08 nmol/L) for Cmax. The geometric LSM AUC0–24 h value for Glaritus® (1.09 h nmol/L) was comparable to Lantus (1.05 h nmol/L). Median Tmax values were also identical (12 h for both), and median t1/2 values were also equal (18 h for both). For GIRTmax, the difference between the means for the two was not statistically significant. No AEs related to study formulations were reported, and both products were well tolerated. The test product (Glaritus) was found to be bioequivalent to the reference product (Lantus). CTRI/2015/06/005890; http://www.ctri.nic.in/ .

Background: Rintodestrant is an orally bioavailable, potent and selective estrogen receptor degrader (SERD) that competitively binds to the estrogen receptor (ER) and blocks ER signaling in tumors resistant to other endocrine therapies. Clinical trials have been conducted to evaluate the safety and efficacy of rintodestrant in healthy volunteers and patients with ER+/HER2- locally advanced or metastatic breast cancer (ABC). Population pharmacokinetic (PK) and exposure-response (Ex/Re) analyses were performed to further characterize the PK profile of rintodestrant and identify potential Ex/Re relationships. Methods: The present analyses include data from two studies: (1) G1T48-01, a Phase 1 first-in-human study of rintodestrant monotherapy (200-1000 mg once daily [QD]) in women with ER+/HER2- ABC after progression on endocrine therapy (NCT03455270), and (2) G1T48-10, a study in healthy volunteers investigating potential drug-drug interactions between rintodestrant (200 mg QD) and palbociclib (125 mg QD). A PK model was developed using nonlinear mixed effects methodology to estimate PK parameters for individual patients. A tumor dynamic model was built to characterize the relationship between rintodestrant concentrations and the longitudinal tumor sizes according to RECIST v1.1. Ex/Re for key pharmacodynamic markers, including ER target engagement (18F-fluoroestradiol positron emission tomography [FES-PET]), dynamics of cell-free DNA mutational burden, ER degradation and proliferation (Ki67) in tumors, and enumeration of circulating tumor cells are being evaluated. Relationships between model-predicted exposures and study endpoints (objective response rate, clinical benefit rate) are also being evaluated. Results: Rintodestrant PK was best described using a linear two-compartment model with a mixed absorption model. The predicted population mean trough concentration of rintodestrant at the recommended Phase 2 dose (800 mg QD) exceeded the IC90 value for ER degradation established in vitro. A positive Ex/Re relationship was identified between total exposure and target ER engagement as measured by FES-PET. A clear Ex/Re relationship was not identified between any PK parameters and ER degradation or proliferation, potentially due to confounding effects from covariates in the model (eg, prior SERD treatment, ESR1 mutations, etc). Additional exploration of these covariates is ongoing. The final PK, Ex/Re and PK/tumor dynamics model results will be presented. Conclusions: A population PK model was developed and Ex/Re relationship analyses were performed to support the development of rintodestrant for the treatment of patients with ER+ breast cancer. Initial results identified an Ex/Re relationship with target ER engagement via FES-PET analysis. Citation Format: Andrew P Beelen, Chao Li, Praneeth Jarugula, Mathangi Gopalakrishnan, Jessica A Sorrentino, Curt D Wolfgang, Sarika Jain, Wenli Tao. Population pharmacokinetic and exposure-response modeling of the oral selective estrogen receptor degrader, rintodestrant (G1T48), in patients with ER+/HER2- advanced breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS17-08.

COX-2 inhibitors can be effective for acute migraine, but none is supplied in a rapidly absorbed, ready-to-use oral liquid formulation. DFN-15, a novel oral liquid formulation of celecoxib, is being developed for the acute treatment of migraine with or without aura. Clinical studies with this formulation are ongoing. The objectives of the present study were to compare the bioavailability of DFN-15 with that of the commercial formulation of celecoxib 400-mg oral capsules (Celebrex®) and to determine the dose proportionality of DFN-15 in healthy fasted volunteers. This single-dose randomized crossover study in 16 healthy fasted volunteers evaluated the pharmacokinetics and relative bioavailability of DFN-15 at doses of 120, 180, and 240 mg against the commercial formulation of celecoxib 400-mg oral capsules and determined the dose proportionality of DFN-15. The maximum observed plasma concentrations (C max) of celecoxib after the administration of DFN-15 120, 180, and 240 mg (1062–1933 ng/ml) were higher than for the 400-mg oral capsules (611 ng/ml). The median time to peak concentration (T max) was within 1 h for DFN-15 and 2.5 h for the oral capsules. The pharmacokinetics of DFN-15 were dose proportional from 120 to 240 mg. Partial area under the plasma concentration–time curves (AUCs) from 15 min to 2 h for DFN-15 120 mg were at least threefold higher than for the oral capsules, and the relative bioavailability of DFN-15 was approximately 140% that of the oral capsules. DFN-15 was well tolerated, with no new or unexpected adverse events. Based on a faster rate of absorption and increased bioavailability, DFN-15 is being evaluated as an abortive medication for acute treatment in patients with migraine.

Children represent a large underserved population of "therapeutic orphans," as an estimated 80% of children are treated off-label. However, pediatric drug development often faces substantial challenges, including economic, logistical, technical, and ethical barriers, among others. Among many efforts trying to remove these barriers, increased recent attention has been paid to extrapolation; that is, the leveraging of available data from adults or older age groups to draw conclusions for the pediatric population. The Bayesian statistical paradigm is natural in this setting, as it permits the combining (or "borrowing") of information across disparate sources, such as the adult and pediatric data. In this paper, authored by the pediatric subteam of the Drug Information Association Bayesian Scientific Working Group and Adaptive Design Working Group, we develop, illustrate, and provide suggestions on Bayesian statistical methods that could be used to design improved pediatric development programs that use all available information in the most efficient manner. A variety of relevant Bayesian approaches are described, several of which are illustrated through 2 case studies: extrapolating adult efficacy data to expand the labeling for Remicade to include pediatric ulcerative colitis and extrapolating adult exposure-response information for antiepileptic drugs to pediatrics.

The percentage of the time that the free drug concentration remains above a concentration threshold (%fT > concentration threshold) has frequently been identified to be the optimal pharmacokinetic (PK)-pharmacodynamic (PD) target of interest for tazobactam using in vitro infection models. Similar in vitro models suggested that an 85% fT > concentration threshold of 2 μg/ml for tazobactam is required to demonstrate a 2-log10-unit decrease in the number of CFU per milliliter from that at the baseline at 24 h for high-level β-lactamase-producing Escherichia coli strains. The objective of this study was to characterize the tazobactam concentrations in a cohort of critically ill patients with Gram-negative bacterial infections, determine if traditional dosing regimens achieve a prespecified PK/PD target of an 80% fT > concentration threshold of 2 μg/ml, and propose alternative dosing regimens. Hospitalized critically ill adult patients receiving piperacillin-tazobactam (TZP) for a culture-positive Gram-negative bacterial infection were eligible to consent for study inclusion. Two blood samples were drawn, one during the midpoint of the dosing interval and one at the time of the trough concentration once the patient achieved PK steady state. A population PK model was developed using Phoenix NLME (v8.1) software to characterize the observed concentration-time profile of tazobactam, explore potential covariates to explain the variability in the clearance and volume parameters, and to simulate potential dosing regimens that would achieve the PK/PD target. The PK of tazobactam were adequately described by a one-compartment model with first-order elimination in 18 patients who provided consent. The final model incorporated creatinine clearance as a covariate on clearance. Simulations demonstrated target attainments of less than 50% for tazobactam using traditional dosing regimens (4/0.5 g over 30 min every 6 h). Target attainments of greater than 75% were achieved when using extended infusion times of 4 to 6 h or when administering TZP as a continuous infusion (16/2 g over 24 h). Traditional tazobactam dosing regimens fail to achieve conservative PK/PD targets in critically ill patients. Increases in the tazobactam dose or prolongation of the infusion rate may be warranted to achieve activity against β-lactamase-producing Gram-negative bacteria.

Protein therapeutics, also known as biologics, are currently manufactured at centralized facilities according to rigorous protocols. The manufacturing process takes months and the delivery of the biological products needs a cold chain. This makes it less responsive to rapid changes in demand. Here, we report on technology application for on-demand biologics manufacturing (Bio-MOD) that can produce safe and effective biologics from cell-free systems at the point of care without the current challenges of long-term storage and cold-chain delivery. The objective of the current study is to establish proof-of-concept safety and efficacy of Bio-MOD-manufactured granulocyte colony-stimulating factor (G-CSF) in a mouse model of total body irradiation at a dose estimated to induce 30% lethality within the first 30 days postexposure. To illustrate on-demand Bio-MOD production feasibility, histidine-tagged G-CSF was manufactured daily under good manufacturing practice-like conditions prior to administration over a 16-day period. Bio-MOD-manufactured G-CSF improved 30-day survival when compared with saline alone (p = .073). In addition to accelerating recovery from neutropenia, the platelet and hemoglobin nadirs were significantly higher in G-CSF-treated animals compared with saline-treated animals (p < .05). The results of this study demonstrate the feasibility of consistently manufacturing safe and effective on-demand biologics suitable for real-time release.

Deep learning is the fastest growing field in artificial intelligence and has led to many transformative innovations in various domains. However, lack of interpretability sometimes hinders its application in hypothesis-driven domains such as biology and healthcare. In this paper, we propose a novel deep learning model with individual feature ranking. Several simulated datasets with the scenarios that contributing features are correlated and buried among non-contributing features were used to characterize the novel analysis approach. A publicly available clinical dataset was also applied. The performance of the individual level dropout feature ranking model was compared with commonly used artificial neural network model, random forest model, and population level dropout feature ranking model. The individual level dropout feature ranking model provides a reasonable prediction of the outcomes. Unlike the random forest model and population level dropout feature ranking model, which can only identify global-wise contributing features (i.e., at population level), the individual level dropout feature ranking model allows further identification of impactful features on response at individual level. Therefore, it provides a basis for clustering patients into subgroups. This may provide a new tool for enriching patients in clinical drug development and developing personalized or individualized medicine.

Study objectives Obese patients with sepsis or septic shock may have altered vancomycin pharmacokinetics compared with the general population that may result in improper dosing or inadequate drug concentrations. The objective of this study was to characterize vancomycin pharmacokinetics in obese patients with sepsis or septic shock, and to develop a novel pharmacokinetic dosing model based on pharmacokinetic-pharmacodynamic target requirements. Design Prospective observational pharmacokinetic study. Setting Large quaternary academic medical center. Patients Sixteen obese (body mass index [BMI] 30 kg/m2 or higher) adults with sepsis and either a gram-positive bacteremia or requiring vasopressor support (septic shock), who were receiving vancomycin between November 2016 and June 2018, were included. Patients were excluded if they were receiving renal replacement therapy or extracorporeal membrane oxygenation, treatment for central nervous system infections, pregnant, or receiving vancomycin for surgical prophylaxis. Intervention Four blood samples per patient were collected following a single dose of vancomycin: one peak serum vancomycin level (within 1-2 hrs of infusion completion), two random levels during the dosing interval, and one trough level (within 30-60 min of the next dose) were measured. Measurements and main results A population pharmacokinetic model was developed to describe vancomycin concentrations over time. Simulations to determine optimal dosing were performed using the pharmacokinetic model with different ranges of creatinine clearance (Clcr ) and different vancomycin daily doses. Median age of the patients was 62 years; median BMI was 36.1 kg/m2 , Acute Physiology and Chronic Health Evaluation II score was 26, and Sequential Organ Failure Assessment score was 11. Eleven patients (69%) had an acute kidney injury. Median initial vancomycin dose was 15 mg/kg; median vancomycin trough concentration was 17 mg/L. A one-compartment model best characterized the pharmacokinetics of vancomycin in obese patients with sepsis or septic shock. Volume of distribution was slightly increased in this population (0.8 L/kg) compared with the general population (0.7 L/kg). Only Clcr effect on drug clearance was found to be significant (decrease in the objective function value by 16.4 points), confirming that it is a strong predictor of vancomycin clearance. Conclusion To our knowledge, this study provides the first population-based pharmacokinetic model in obese patients with sepsis or septic shock. The nomograms generated from this pharmacokinetic model provide a simplified approach to vancomycin dosing in this patient population.

Despite agreement that early-onset schizophrenia is continuous with the adult-onset form, quantitative relationships between antipsychotic exposure and clinical response are relatively unexplored in adolescents, compared to adults. Clinical efficacy data from second-generation antipsychotic development programs (N = 5951 adults and N = 1035 adolescents ranging from 12 to 17 years old) were collected from available new drug applications submitted to the US Food and Drug Administration from 1993 to 2017. The developed disease-drug trial models adequately predicted the longitudinal trend in total positive and negative syndrome scale scores in both adults and adolescents using a Weibull placebo response, time-delayed drug effect, and a Weibull structural dropout model. Maximum drug effect was similar between the two populations and was estimated to be between a range of 5% to 11% in adults and 5% to 7% in adolescents. Half maximal effective concentration parameter estimates also indicated similar exposure-response relationships in adults and adolescents across all 4 antipsychotics. Simulated adolescent data using final model parameter estimates from the adult model were in agreement with adolescent observations. This analysis confirms similarity in exposure-response for efficacy and could expedite the development of second-generation antipsychotics for adolescents.

Purpose: The purpose if this study was to develop a rabbit model of total body irradiation (TBI) -induced thrombocytopenia and coagulopathy across the dose-range which induces the hematopoietic subsyndrome of the acute radiation syndrome (H-ARS). Methods: Twenty male New Zealand White rabbits were assigned to arms to receive 6-MV of TBI at a dose of 6.5, 7.5, 8.5 or 9.5 Gy. Animals were treated with moderate levels of supportive care including buprenorphine for pain management, antibiotics, antipyretics for rectal body temperature >104.8 ��F, and fluids for signs of dehydration. Animals were closelyfollowed for up to 45 days after TBI for signs of major morbidity/mortality. Hematology and serum chemistry parameters were routinely monitored. Hemostasis parameters were analyzed prior to TBI, 2 and 6 hours post-TBI, and at the time of euthanasia. Results: Animals developed the characteristic signs and symptoms of H-ARS during the first-week post TBI. Animals became thrombocytopenic with signs of severe acute anemia during the second week post TBI. Moribund animals presented with petechia and ecchymosis of the skin and generalized internal hemorrhage. Multiorgan dysfunction characterized by bone marrow failure, gastric ileus, acute renal toxicity, and liver abnormalities were common. Severe abnormalities in coagulation parameters were observed. Conclusions: The presentation of bone marrow failure and multiorogan injury associated with ARS in the New Zealand White rabbit model is consistent with that described in the canine, swine, non-human primate, and in humans. The hemorrhagic syndrome associated with the ARS in rabbits is characterized by thrombocytopenia and hemostasis dysfunction, which appear to underlie the development of multiorgan dysfunction following TBI to rabbits. Taken together, the rabbit recapitulates the pathogenesis of ARS in humans, and may present an alternative small animal model for medical countermeasure pilot efficacy screening, dose-finding and schedule optimization studies prior to moving into large animal models of TBI-induced ARS.

Objective Concerns of increasing placebo response and declining treatment effect in acute schizophrenia trials have been reported for new drug applications (NDAs) submitted to the US Food and Drug Administration (FDA) during an 18-year period from 1991 through January 2009 (ie, the pre-2009 period). Current exploratory analyses provide an update in the trends observed in placebo response, treatment effect, and dropout rates for NDAs submitted from February 2009 to 2015 (ie, the post-2009 period). Data sources Clinical trial data from all acute schizophrenia trials that were submitted as part of NDAs to the US FDA during a 24-year period from 1991 to 2015. Study selection Aggregate trial-level efficacy data from multicenter, multiregional, randomized, placebo-controlled, 4- to 8-week, fixed- and flexible-dose trials in adult schizophrenia patients were compiled. There were 12 NDAs pre-2009 (32 trials, N = 11,567) and 3 NDAs post-2009 (14 trials, N = 6,434). Data extraction Baseline demographic and disease variables and scores on the Positive and Negative Syndrome Scale (PANSS) were summarized and compared for the two time periods (pre-2009 and post-2009). The primary efficacy measure was mean change from baseline to endpoint in total PANSS score obtained by last-observation-carried-forward analysis. Regional differences in placebo response and treatment effect were explored for the two time periods based on baseline patient characteristics, sample size, and dropout rates. Results Trials were predominantly multiregional (10/14; 71%) during the post-2009 period compared to the pre-2009 period (11/32; 34%). The overall trial success rates were 57% (8/14) and 78% (25/32) during the post-2009 and pre-2009 periods, respectively. Comparing the pre-2009 and post-2009 periods, the mean placebo response (change from baseline in PANSS score) increased from -6.4 to -10.5 and the mean treatment effect (drug response - placebo response) declined from -8.6 to -5.8 , with substantial differences observed especially in North American trials. In North American trials, placebo response increased from -4.3 (pre-2009) to -8.5 (post-2009), and treatment effect decreased from -9.0 (pre-2009) to -3.4 (post-2009). The difference in placebo response (pre- and post-2009: -10.0 and -11.3 ) and treatment effect (pre and post-2009: -8.1 and -6.4 ) in multiregional trials for the two time periods remained minimal. Baseline disease severity remained similar in the pre- and post-2009 time periods, with PANSS scores ranging between 85 and 100. Trials with higher mean baseline PANSS scores tended to show higher treatment effect irrespective of the time period and region. Post-2009, dropout rates were higher (55%) in North American trials compared with 33% in multiregional trials, similar to the pre-2009 trend. Conclusions The continuing trend of increasing placebo responses and decreasing treatment effects in schizophrenia trials over the 24-year period does remain of great concern, especially with respect to North American trials. However, given the current global nature of drug development, close attention to trial conduct and reexamination of design elements for future trials may be warranted.