Target Occupancy and Functional Inhibition of JAK3 and TEC Family Kinases by Ritlecitinib in Healthy Adults: An Open-Label, Phase 1 Study

Ritlecitinib is a small molecule in clinical development that covalently and irreversibly inhibits Janus kinase 3 (JAK3) and the TEC family of kinases (BTK, BMX, ITK, TXK, and TEC). This phase 1, open-label, parallel-group study assessed target occupancy and functional effects of ritlecitinib on JAK3 and TEC family kinases in healthy participants aged 18-60 years who received 50 or 200 mg single doses of ritlecitinib on day 1. Blood samples to assess ritlecitinib pharmacokinetics, target occupancy, and pharmacodynamics were collected over 48 hours. Target occupancy was assessed using mass spectroscopy. Functional inhibition of JAK3-dependent signaling was measured by the inhibition of the phosphorylation of its downstream target signal transducer and activator of transcription 5 (pSTAT5), following activation by interleukin 15 (IL-15). The functional inhibition of Bruton's tyrosine kinase (BTK)-dependent signaling was measured by the reduction in the upregulation of cluster of differentiation 69 (CD69), an early marker of B-cell activation, following treatment with anti-immunoglobulin D. Eight participants received one 50 mg ritlecitinib dose and 8 participants received one 200 mg dose. Ritlecitinib plasma exposure increased in an approximately dose-proportional manner from 50 to 200 mg. The maximal median JAK3 target occupancy was 72% for 50 mg and 64% for 200 mg. Ritlecitinib 50 mg had >94% maximal target occupancy of all TEC kinases, except BMX (87%), and 200 mg had >97% for all TEC kinases. For BTK and TEC, ritlecitinib maintained high target occupancy throughout a period of 48 hours. Ritlecitinib reduced pSTAT5 levels following IL-15- and BTK-dependent signaling in a dose-dependent manner. These target occupancy and functional assays demonstrate the dual inhibition of the JAK3- and BTK-dependent pathways by ritlecitinib. Further studies are needed to understand the contribution to clinical effects of inhibiting these pathways.

Empiric dosing strategies to predict lamotrigine concentrations during pregnancy

INTRODUCTION

Maintaining seizure control with lamotrigine is complicated by altered pharmacokinetics and existence of subpopulations in whom clearance increases or remains constant during pregnancy.

OBJECTIVE

Our objective was to characterize the potential for particular dosing scenarios to lead to increased seizure risk or toxicity.

METHODS

Lamotrigine pharmacokinetic parameters obtained from our previous study were applied to a one-compartment model structure with subpopulations (75:25%) exhibiting different clearance changes. A single-patient simulation was conducted with typical pharmacokinetic parameter values from each subpopulation. Population-level simulations (N = 48,000) included six dosing scenarios and considered four preconception doses using the R package mrgsolve (Metrum Research Group). Thresholds for efficacy and toxicity were selected as drug concentration that are 65% lower than preconception concentrations and doubling of preconception concentrations, respectively.

RESULTS

Individual simulation results demonstrated that without dose increases, concentrations fell below 0.65 at 6-8 weeks in the high clearance change (HC) subpopulation, depending on preconception clearance. While no simulated dosing regimen allowed all women in both subpopulations to maintain preconception concentrations, some regimens provided a more balanced risk profile than others. Predicted concentrations suggested potential increased seizure risk for 7%-100% of women in the HC group depending on preconception dose and subpopulation. Additionally, in 63% of dosing scenarios for women with low clearance change (LC), there was an increased risk of toxicity (34%-100% of women).

SIGNIFICANCE

A substantial percentage of simulated individuals had concentrations low enough to potentially increase seizure risk or high enough to create toxicity. Early clearance changes indicate possible subpopulation categorization if therapeutic drug monitoring is conducted in the first trimester. An arbitrary "one-size-fits-all" philosophy may not work well for lamotrigine dosing adjustments during pregnancy and reinforces the need for therapeutic drug monitoring until a patient is determined to be in the LC or HC group.

Antiseizure Medication Concentrations During Pregnancy: Results From the Maternal Outcomes and Neurodevelopmental Effects of Antiepileptic Drugs (MONEAD) Study

IMPORTANCE

During pregnancy in women with epilepsy, lower blood concentrations of antiseizure medications can have adverse clinical consequences.

OBJECTIVE

To characterize pregnancy-associated concentration changes for several antiseizure medications among women with epilepsy.

DESIGN, SETTING, AND PARTICIPANTS

Enrollment in this prospective, observational cohort study, Maternal Outcomes and Neurodevelopmental Effects of Antiepileptic Drugs (MONEAD), occurred from December 19, 2012, to February 11, 2016, at 20 US sites. Enrolled cohorts included pregnant women with epilepsy and nonpregnant control participants with epilepsy. Inclusion criteria were women aged 14 to 45 years, an intelligence quotient greater than 70 points, and, for the cohort of pregnant women, a fetal gestational age younger than 20 weeks. A total of 1087 women were assessed for eligibility; 397 were excluded and 230 declined. Data were analyzed from May 1, 2014, to June 30, 2021.

EXPOSURE

Medication plasma concentrations in women taking monotherapy or in combination with noninteracting medications. The cohort of pregnant women was monitored through 9 months post partum, with similar time points for control participants.

MAIN OUTCOMES AND MEASURES

Dose-normalized concentrations were calculated as total or unbound plasma medication concentrations divided by total daily dose. Phlebotomy was performed during 4 pregnancy study visits and 3 postpartum visits for the pregnant women and 7 visits over 18 months for control participants. The primary hypothesis was to test pregnancy changes of dose-normalized concentrations from nonpregnant postpartum samples compared with those of control participants.

RESULTS

Of the 351 pregnant women and 109 control participants enrolled in MONEAD, 326 pregnant women (median [range] age, 29 [19-43] years) and 104 control participants (median [range] age, 29 [16-43] years) met eligibility criteria for this analysis. Compared with postpartum values, dose-normalized concentrations during pregnancy were decreased by up to 56.1% for lamotrigine (15.60 μg/L/mg to 6.85 μg/L/mg; P < .001), 36.8% for levetiracetam (11.33 μg/L/mg to 7.16 μg/L/mg; P < .001), 17.3% for carbamazepine (11.56 μg/L/mg to 7.97 μg/L/mg; P = .03), 32.6% for oxcarbazepine (11.55 μg/L/mg to 7.79 μg/L/mg; P < .001), 30.6% for unbound oxcarbazepine (6.15 μg/L/mg to 4.27 μg/L/mg; P < .001), 39.9% for lacosamide (26.14 μg/L/mg to 15.71 μg/L/mg; P < .001), and 29.8% for zonisamide (40.12 μg/L/mg to 28.15 μg/L/mg; P < .001). No significant changes occurred for unbound carbamazepine, carbamazepine-10,11-epoxide, and topiramate, although a decrease was observed for topiramate (29.83 μg/L/mg to 13.77 μg/L/mg; P = .18). Additionally, compared with dose-normalized concentrations from control participants, pregnancy dose-normalized median (SE) concentrations decreased significantly by week of gestational age: carbamazepine, -0.14 (0.06) μg/L/mg (P = .02); carbamazepine unbound, -0.04 (0.01) μg/L/mg (P = .01); lacosamide, -0.23 (0.07) μg/L/mg (P < .001); lamotrigine, -0.20 (0.02) μg/L/mg (P < .001); levetiracetam, -0.06 (0.03) μg/L/mg (P = .01); oxcarbazepine, -0.14 (0.04) μg/L/mg (P < .001); oxcarbazepine unbound, -0.11 (0.03) μg/L/mg (P < .001); and zonisamide, -0.53 (0.14) μg/L/mg (P < .001) except for topiramate (-0.35 [0.20] μg/L/mg per week) and carbamazepine-10,11-epoxide (0.02 [0.01] μg/L/mg).

CONCLUSIONS AND RELEVANCE

Study results suggest that therapeutic drug monitoring should begin early in pregnancy and that increasing doses of these anticonvulsants may be needed throughout the course of pregnancy.

Effect of body mass index on pharmacokinetics of paclitaxel in patients with early breast cancer

Background

Paclitaxel is dosed according to body surface area (BSA) but there is scant information on actual drug exposure in overweight and obese patients.

Methods

Early breast cancer patients receiving paclitaxel at 175 mg/m² every 3 weeks, in two BMI groups (normal, 18–24.9 kg/m² and overweight/obese, ≥25 kg/m², respectively), matched for age, serum albumin and bilirubin levels using minimization technique, were included. Sparse pharmacokinetic (PK) sampling was performed at 7 time points from 0 h until 24 h of starting paclitaxel in cycle 1. Paclitaxel concentration was measured using a validated LCMS/MS method. Covariate effect on paclitaxel PK was evaluated by population PK analysis using NONMEM software.

Results

Eighteen female patients each were enrolled in normal and overweight groups with mean BMI of 21.62 ± 2.06 and 28.16 ± 2.31 kg/m², mean BSA of 1.44 ± 0.11 and 1.69 ± 0.14 m² and mean paclitaxel dose of 250 ± 18 and 293 ± 21 mg, respectively. Model predicted AUC and dose normalized AUC (mean ±SD) in the normal BMI versus overweight obese groups were 23 ± 11.0 µmol*h/L versus 25.7 ± 13.7 µmol*h/L (two‐sample t‐test p > 0.05) and 0.08 ± 0.04 (µmol*h/L)/ µmol versus 0.08 ± 0.04 (µmol*h/L)/ µmol (2‐sample t‐test p > 0.05), respectively. No significant correlation was observed between BMI and standardized dose normalized AUC (Pearson's correlation coefficient, −0.009; p > 0.05).

Conclusion

When dosed according to BSA calculated using actual body weight there is no significant difference in paclitaxel exposure between normal and overweight women. Using alternative descriptors of weight to calculate BSA could lead to under‐dosing of this drug.

Trial registration

This study is registered in the Clinical Trials Registry of India CTRI/2015/09/006193.

Bupivacaine Pharmacokinetics and Breast Milk Excretion of Liposomal Bupivacaine Administered After Cesarean Birth

Very little plasma bupivacaine was transferred into breast milk after liposomal bupivacaine wound infiltration in patients who had undergone cesarean delivery.

To evaluate bupivacaine concentrations in maternal plasma and transfer into breast milk in women undergoing liposomal bupivacaine infiltration in the transversus abdominis plane after cesarean birth.

Antiepileptic Drug Exposure in Infants of Breastfeeding Mothers With Epilepsy

Importance

There is limited information on infant drug exposure via breastfeeding by mothers who are receiving antiepileptic drug therapy.

Objective

To provide direct, objective information on antiepileptic drug exposure through breast milk.

Design, Setting, and Participants

This prospective cohort study was conducted between December 2012 to October 2016, with follow-up in children until 6 years of age at 20 sites across the United States. Data were collected via an observational multicenter investigation (Maternal Outcomes and Neurodevelopmental Effects of Antiepileptic Drugs [MONEAD]) of outcomes in pregnant mothers with epilepsy and their children. Pregnant women with epilepsy who were aged 14 to 45 years, had pregnancies that had progressed to less than 20 weeks' gestational age, and had measured IQ scores of more than 70 points were enrolled and followed up through pregnancy and 9 postpartum months. Their infants were enrolled at birth. Data were analyzed from May 2014 to August 2019.

Exposures

Antiepileptic drug exposure in infants who were breastfed.

Main Outcomes and Measures

The percentage of infant-to-mother concentration of antiepileptic drugs. Antiepileptic drug concentrations were quantified from blood samples collected from infants and mothers at the same visit, 5 to 20 weeks after birth. Concentrations of antiepileptic drugs in infants at less than the lower limit of quantification were assessed as half of the lower limit. Additional measures collected were the total duration of all daily breastfeeding sessions and/or the volume of pumped breast milk ingested from a bottle.

Results

A total of 351 women (of 865 screened and 503 eligible individuals) were enrolled, along with their 345 infants (179 female children [51.9%]; median [range] age, 13 [5-20] weeks). Of the 345 infants, 222 (64.3%) were breastfed; the data collection yielded 164 matching infant-mother concentration pairs from 138 infants. Approximately 49% of all antiepileptic drug concentrations in nursing infants were less than the lower limit of quantification. The median percentage of infant-to-mother concentration for all 7 antiepileptic drugs and 1 metabolite (carbamazepine, carbamazepine-10,11-epoxide, levetiracetam, lamotrigine, oxcarbazepine, topiramate, valproate, and zonisamide) ranged from 0.3% (range, 0.2%-0.9%) to 44.2% (range, 35.2%-125.3%). In multiple linear regression models, maternal concentration was a significant factor associated with lamotrigine concentration in infants (Pearson correlation coefficient, 0.58; P < .001) but not levetiracetam concentration in infants.

Conclusions and Relevance

Overall, antiepileptic drug concentrations in blood samples of infants who were breastfed were substantially lower than maternal blood concentrations. Given the well-known benefits of breastfeeding and the prior studies demonstrating no ill effects when the mother was receiving antiepileptic drugs, these findings support the breastfeeding of infants by mothers with epilepsy who are taking antiepileptic drug therapy.

Use of Herbal Medicine by Pregnant Women: What Physicians Need to Know

About 80% of the consumers worldwide use herbal medicine (HMs) or other natural products. The percentage may vary significantly (7%-55%) among pregnant women, depending upon social status, ethnicity, and cultural traditions. This manuscript discusses the most common HMs used by pregnant women, and the potential interactions of HMs with conventional drugs in some medical conditions that occur during pregnancy (e.g., hypertension, asthma, epilepsy). It also includes an examination of the characteristics of pregnant HM consumers, the primary conditions for which HMs are taken, and a discussion related to the potential toxicity of HMs taken during pregnancy. Many cultures have used HMs in pregnancy to improve wellbeing of the mother and/or baby, or to help decrease nausea and vomiting, treat infection, ease gastrointestinal problems, prepare for labor, induce labor, or ease labor pains. One of the reasons why pregnant women use HMs is an assumption that HMs are safer than conventional medicine. However, for pregnant women with pre-existing conditions like epilepsy and asthma, supplementation of conventional treatment with HMs may further complicate their care. The use of HMs is frequently not reported to healthcare professionals. Providers are often not questioning HM use, despite little being known about the HM safety and HM-drug interactions during pregnancy. This lack of knowledge on potential toxicity and the ability to interact with conventional treatments may impact both mother and fetus. There is a need for education of women and their healthcare professionals to move away from the idea of HMs not being harmful. Healthcare professionals need to question women on whether they use any HMs or natural products during pregnancy, especially when conventional treatment is less efficient and/or adverse events have occurred as herbal-drug interactions could be the reason for these observations. Additionally, more preclinical and clinical studies are needed to evaluate HM efficacy and toxicity.

Effect of various anticoagulants on the bioanalysis of drugs in rat blood: implication for pharmacokinetic studies of anticancer drugs

BACKGROUND

Pharmacokinetic studies are vital in development and optimization of drugs. While blood samples can be collected either in EDTA, heparin or citrate containing tubes for the estimation of drug levels in plasma, EDTA tubes are more commonly used. The purpose of this study was to evaluate the effects of anticoagulants on bioanalysis of drugs. Six drugs used extensively in cancer therapy were selected. Albino wistar rats (N = 6 per drug) were dosed with one of the following drugs intraperitoneally-pemetrexed (50 mg/kg), imatinib (50 mg/kg), erlotinib (25 mg/kg), meropenem (60 mg/kg), 6-mercaptopurine (20 mg/kg) and voriconazole (6 mg/kg). Blood samples were collected 2 h after dosing (1 h in 6-mercaptopurine group due to short half-life) by terminal bleeding from the retro-orbital plexus. Blood was collected in each of Disodium ETDA, heparin, trisodium citrate (TSC) and no anticoagulant (plain) tubes. Drug levels in these samples were determined by validated HPLC assays. ANOVA with Tukey's post hoc test was performed to identify statistically significant differences in drug concentrations in anticoagulant tubes. p < 0.05 was considered statistically significant.

RESULTS

Significant differences in concentration between anticoagulant tubes was observed in case of erlotinib (p = 0.013) and meropenem (p = 0.00), while borderline statistical significance for pemetrexed (p = 0.076). TSC tubes overestimated erlotinib levels, heparin tubes underestimated meropenem concentrations and EDTA tubes overestimated pemetrexed concentrations.

CONCLUSIONS

Careful selection of anti-coagulant is necessary for accurate characterization of pharmacokinetics of drugs. Routine use of EDTA tubes may lead to erroneous interpretation of pharmacokinetic data.

Equilibrium based analytical model for estimation of pressure magnification during deflagration of hydrogen air mixtures

During postulated accident sequences in nuclear reactors, hydrogen may get released from the core and form a flammable mixture in the surrounding containment structure. Ignition of such mixtures and the subsequent pressure rise are an imminent threat for safe and sustainable operation of nuclear reactors. Methods for evaluating post ignition characteristics are important for determining the design safety margins in such scenarios. This study presents two thermo-chemical models for determining the post ignition state. The first model is based on internal energy balance while the second model uses the concept of element potentials to minimize the free energy of the system with internal energy imposed as a constraint. Predictions from both the models have been compared against published data over a wide range of mixture compositions. Important differences in the regions close to flammability limits and for stoichiometric mixtures have been identified and explained. The equilibrium model has been validated for varied temperatures and pressures representative of initial conditions that may be present in the containment during accidents. Special emphasis has been given to the understanding of the role of dissociation and its effect on equilibrium pressure, temperature and species concentrations.

The impact of age and severity of comorbid illness on outcomes after isolated aortic valve replacement for aortic stenosis

OBJECTIVES

This study examines outcomes in a national sample of patients undergoing isolated aortic valve replacement (AVR) for aortic stenosis, with particular focus on advanced-age patients and those with extreme severity of comorbid illness (SOI).

METHODS

Data were obtained from the Nationwide Inpatient Sample and included all patients undergoing AVRs performed from January 1, 2006 to December 31, 2008. Patients with major concomitant cardiac procedures, as well as those aged, 20 years, and those with infective endocarditis or aortic insufficiency without aortic stenosis, were excluded from analysis. The analysis included 13,497 patients. Patients were stratified by age and further stratified by All Patient Refined Diagnosis Related Group SOI into mild/moderate, major, and extreme subgroups.

RESULTS

Overall in-hospital mortality was 2.96% (n=399); in-hospital mortality for the ≥80-year-old group (n=139, 4.78%) was significantly higher than the 20- to 49-year-old (n=9, 0.84%, P<0.001) or 50- to 79-year-old (n=251, 2.64%, P<0.001) groups. In-hospital mortality was significantly higher in the extreme SOI group (n=296, 15.33%) than in the minor/moderate (n=22, 0.35%, P<0.001) and major SOI groups (n=81, 1.51%, P<0.001). Median in-hospital costs in the mild/moderate, major, and extreme SOI strata were $29,202.08, $36,035.13, and $57,572.92, respectively.

CONCLUSION

In the minor, moderate, and major SOI groups, in-hospital mortality and costs are low regardless of age; these groups represent >85% of patients undergoing isolated AVR for aortic stenosis. Conversely, in patients classified as having extreme SOI, surgical therapy is associated with exceedingly high inpatient mortality, low home discharge rates, and high resource utilization, particularly in the advanced age group.