Population pharmacokinetics of ramipril in patients with chronic heart failure: A real-world longitudinal study.

In patients with chronic heart failure (CHF), the use of angiotensin-converting enzyme inhibitors, including ramipril, is recommended to reduce the risk of heart failure worsening, hospitalisation, and death. Our aim was to investigate the influence of body composition on the pharmacokinetics of ramipril and its active metabolite ramiprilat and to evaluate the changes in pharmacokinetics after prolonged therapy. Twenty-three patients with CHF who were on regular therapy with ramipril participated at the first study visit ( median age 77 years, 65 % male, and 70 % New York Heart Association Class II); 19 patients attended the second study visit and the median time between the two visits was 8 months. Pharmacokinetics were assessed using a nonlinear mixed-effects parent-metabolite model comprising two compartments for ramipril and one compartment for ramiprilat. The influence of body size and composition was best described by an allometric relationship with fat-free mass. In addition, ramipril clearance was related to patient age and daily ramipril dose, while clearance of ramiprilat was influenced by glome rular filtration rate and daily ramipril dose. There were no clinically relevant changes in the pharmacokinetics of ramipril and ramiprilat between the study visits. Due to the relatively stable pharmacokinetics of ramipril, regular outpatient visits at 6-month intervals seem appropriate to evaluate ramipril therapy.

An LC-MS/MS Method for Quantification of Lamotrigine and Its Main Metabolite in Dried Blood Spots.

BACKGROUND: The antiepileptic drug lamotrigine (LTG) shows high pharmacokinetic variability due to genotype influence and concomitant use of glucuronidation inducers and inhibitors, both of which may be frequently taken by elderly patients. Our goal was to develop a reliable quantification method for lamotrigine and its main glucuronide metabolite lamotrigine-N2-glucuronide (LTG-N2-GLU) in dried blood spots (DBS) to enable routine therapeutic drug monitoring and to identify altered metabolic activity for early detection of drug interactions possibly leading to suboptimal drug response. RESULTS: The analytical method was validated in terms of selectivity, accuracy, precision, matrix effects, haematocrit, blood spot volume influence, and stability. It was applied to a clinical study, and the DBS results were compared to the concentrations determined in plasma samples. A good correlation was established for both analytes in DBS and plasma samples, taking into account the haematocrit and blood cell-to-plasma partition coefficients. It was demonstrated that the method is suitable for the determination of the metabolite-to-parent ratio to reveal the metabolic status of individual patients. CONCLUSIONS: The clinical validation performed confirmed that the DBS technique is a reliable alternative for plasma lamotrigine and its glucuronide determination.

The search for novel proline analogs for viscosity reduction and stabilization of highly concentrated monoclonal antibody solutions.

Administration of monoclonal antibodies (mAbs) is currently focused on subcutaneous injection associated with increased patient adherence and reduced treatment cost, leading to sustainable healthcare. The main bottleneck is low volume that can be injected, requiring highly concentrated mAb solutions. The latter results in increased solution viscosity with pronounced mAb aggregation propensity because of intensive protein-protein interactions. Small molecule excipients have been proposed to restrict the protein-protein interactions, contributing to reduced viscosity. The aim of the study was to discover novel compounds that reduce the viscosity of highly concentrated mAb solution. First, the chemical space of proline analogs was explored and 35 compounds were determined. Viscosity measurements revealed that 18 proline analogs reduced the mAb solution viscosity similar to or more than proline. The compounds forming both electrostatic and hydrophobic interactions with mAb reduced the viscosity of the formulation more efficiently without detrimentally effecting mAb physical stability. A correlation between the level of interaction and viscosity-reducing effect was confirmed with molecular dynamic simulations. Structure rigidity of the compounds and aromaticity contributed to their viscosity-reducing effect, dependent on molecule size. The study results highlight the novel proline analogs as an effective approach in viscosity reduction in development of biopharmaceuticals for subcutaneous administration.

Association between Prescribing and Intoxication Rates for Selected Psychotropic Drugs: A Longitudinal Observational Study.

Psychotropic prescription drugs are commonly involved in intoxication events. The study's aim was to determine a comparative risk for intoxication in relation to prescribing rates for individual drugs. This was a nationwide observational study in Slovenian adults between 2015 and 2021. Intoxication events with psychotropic drugs were collected from the National Register of intoxications. Dispensing data, expressed in defined daily doses, were provided by the Health Insurance Institute of Slovenia. Intoxication/prescribing ratio values were calculated. The correlation between trends in prescribing and intoxication rates was assessed using the Pearson correlation coefficient. In total, 2640 intoxication cases with psychotropic prescription drugs were registered. Anxiolytics and antipsychotics were the predominant groups. Midazolam, chlormethiazole, clonazepam, sulpiride, and quetiapine demonstrated the highest risk of intoxication, while all antidepressants had a risk several times lower. The best trend correlation was found for the prescribing period of 2 years before the intoxication events. An increase of 1,000,000 defined daily doses prescribed resulted in an increase of fifty intoxication events for antipsychotics, twenty events for antiepileptics, and five events for antidepressants. Intoxication/prescribing ratio calculation allowed for a quantitative comparison of the risk for intoxication in relation to the prescribing rates for psychotropic drugs, providing additional understanding of their toxicoepidemiology.

Predictive Potential of Acido-Basic Properties, Solubility and Food on Bioequivalence Study Outcome: Analysis of 128 Studies.

BACKGROUND AND OBJECTIVES: Risk assessment related to bioequivalence study outcome is critical for effective planning from the early stage of drug product development. The objective of this research was to evaluate the associations between solubility and acido-basic parameters of an active pharmaceutical ingredient (API), study conditions and bioequivalence outcome. METHODS: We retrospectively analyzed 128 bioequivalence studies of immediate-release products with 26 different APIs. Bioequivalence study conditions and acido-basic/solubility characteristics of APIs were collected and their predictive potential on the study outcome was assessed using a set of univariate statistical analyses. RESULTS: There was no difference in bioequivalence rate between fasting and fed conditions. The highest proportion of non-bioequivalent studies was for weak acids (10/19 cases, 53%) and neutral APIs (23/95 cases, 24%). Lower non-bioequivalence occurrence was observed for weak bases (1/15 cases, 7%) and amphoteric APIs (0/16 cases, 0%). The median dose numbers at pH 1.2 and pH 3 were higher and the most basic acid dissociation constant (pKa) was lower in the non-bioequivalent group of studies. Additionally, APIs with low calculated effective permeability (cPeff) or low calculated lipophilicity (clogP) had lower non-bioequivalence occurrence. Results of the subgroup analysis of studies under fasting conditions were similar as for the whole dataset. CONCLUSION: Our results indicate that acido-basic properties of API should be considered in bioequivalence risk assessment and reveal which physico-chemical parameters are most relevant for the development of bioequivalence risk assessment tools for immediate-release products.

External validation of population pharmacokinetic models of gentamicin in paediatric population from preterm newborns to adolescents.

The aim of this study was to externally validate the predictive performance of published population pharmacokinetic models of gentamicin in all paediatric age groups, from preterm newborns to adolescents. We first selected published population pharmacokinetic models of gentamicin developed in the paediatric population with a wide age range. The parameters of the literature models were then re-estimated using the PRIOR subroutine in NONMEM®. The predictive ability of the literature and the tweaked models was evaluated. Retrospectively collected data from a routine clinical practice (512 concentrations from 308 patients) were used for validation. The models with covariates characterising developmental changes in clearance and volume of distribution had better predictive performance, which improved further after re-estimation. The tweaked model by Wang 2019 performed best, with suitable accuracy and precision across the complete paediatric population. For patients treated in the intensive care unit, a lower proportion of patients would be expected to reach the target trough concentration at standard dosing. The selected model could be used for model-informed precision dosing in clinical settings where the entire paediatric population is treated. However, for use in clinical practice, the next step should include additional analysis of the impact of intensive care treatment on gentamicin pharmacokinetics, followed by prospective validation.

Predictive Potential of BCS and Pharmacokinetic Parameters on Study Outcome: Analysis of 198 In Vivo Bioequivalence Studies.

BACKGROUND AND OBJECTIVES: Understanding predictive potential of parameters to perform early bioequivalence (BE) risk assessment is crucial for good planning and risk mitigation during product development. The objective of the present study was to evaluate predictive potential of various biopharmaceutical and pharmacokinetic parameters on the outcome of BE study. METHODS: Retrospective analysis was performed on 198 Sandoz (Lek Pharmaceuticals d.d., A Sandoz Company, Verovskova 57, 1526 Ljubljana, Slovenia) sponsored BE studies [52 active pharmaceutical ingredients (API)] where characteristics of BE study and APIs were collected for immediate-release products and their predictive potential on the study outcome was assessed using univariate statistical analysis. RESULTS: Biopharmaceutics Classification System (BCS) was confirmed to be highly predictive of BE success. BE studies with poorly soluble APIs were riskier (23% non-BE) than with highly soluble APIs (0.1% non-BE). APIs with either lower bioavailability (BA), presence of first-pass metabolism, and/or being substrate for P-glycoprotein substrate (P-gP) were associated with higher non-BE occurrence. In silico permeability and time at peak plasma concentrations (Tmax) were shown as potentially relevant features for predicting BE outcome. In addition, our analysis showed significantly higher occurrence of non-BE results for poorly soluble APIs with disposition described by multicompartment model. The conclusions for poorly soluble APIs were the same on a subset of fasting BE studies; for a subset of fed studies there were no significant differences between factors in BE and non-BE groups. CONCLUSION: Understanding the association of parameters and BE outcome is important for further development of early BE risk assessment tools where focus should be first in finding additional parameters to differentiate BE risk within a group of poorly soluble APIs.

Potential Drug-Drug Interactions among Patients with Schizophrenia Spectrum Disorders: Prevalence, Association with Risk Factors, and Replicate Analysis in 2021.

Background and Objectives: Patients with schizophrenia are often exposed to polypharmacotherapy, which may lead to drug-drug interactions. The aim of the study was to investigate the prevalence of potential drug-drug interactions (pDDIs) in hospitalized patients with schizophrenia spectrum disorders and to identify factors associated with pDDIs and manifested symptoms and signs. Materials and Methods: This cross-sectional observational study included 311 inpatients admitted to a psychiatric hospital. The LexiComp drug interaction program was used to identify pDDIs in 2014. Factors associated with the prevalence of pDDIs and factors related to clinically observed symptoms and signs were assessed using multivariable regression. In addition, replicate analysis of pDDI was performed using 2021 program updates. Results: The prevalence of pDDIs was 88.7%. Our study showed that more than half of the patients received at least one drug combination that should be avoided. The most common pDDIs involved combinations of two antipsychotics or combinations of antipsychotics and benzodiazepines, which can lead to cardio-respiratory depression, sedation, arrhythmias, anticholinergic effects, and neuroleptic malignant syndrome. The number of prescribed drugs was a risk factor for pDDIs (OR 2.85; 95% CI 1.84-5.73). All groups of clinically observed symptoms and signs were associated with the number of drugs. In addition, symptoms and signs characteristic of the nervous system and psychiatric disorders were associated with antipsychotic dosage (IRR 1.33; 95% CI 1.12-1.58), which could contribute to the development of extrapyramidal syndrome, insomnia, anxiety, agitation, and bipolar mania. The 2021 version of the drug interaction program showed a shift in drug interactions toward a lower risk rating, implying less severe patient management and possibly less alert fatigue. Conclusions: Patients with schizophrenia spectrum disorders are at high risk of developing drug-drug interactions. Optimization of drug therapy, patient monitoring, and use of drug interaction programs could help to prevent pDDIs and subsequent adverse drug events.

Population pharmacokinetics of cisplatin in small cell lung cancer patients guided with informative priors.

PURPOSE: Cisplatin-etoposide treatment is recommended as a first line in small cell lung cancer patients (SCLC). However, the prognosis is poor and the dosing is not tailored beyond the body surface area, which is related with indeterminate cisplatin exposure-response relationship. We aimed to evaluate cisplatin pharmacokinetics (PK) and the exposure to unbound cisplatin in SCLC patients using the informative priors, and assess the relationship between the cisplatin exposure and probability of neutropenia. METHODS: Observational clinical study was performed including 17 cisplatin-treated SCLC patients. External population cisplatin PK models were identified and NONMEM® software and $PRIOR subroutine were used for the model evaluation. The bias and precision of the model-predicted cisplatin concentrations were evaluated. The best models were combined in a final model including several sets of informative priors, which was used to estimate individual cisplatin exposure, analyze the relationship between the exposure and neutropenia and simulate several cisplatin dosing regimens in a virtual patient cohort. RESULTS: The models by Urien with the informative priors best fitted the data. The individual cisplatin exposure ranged between 2430 and 4560 µg*h/L. There was a trend of increasing probability of neutropenia and febrile neutropenia with increasing cisplatin exposure. Approximately 50%, 75% and 90% of patients receiving 60 mg/m2, 70 mg/m2 and 80 mg/m2, respectively, achieved the previously identified exposure threshold of 2860 µg*h/L. CONCLUSION: We developed a tool to individualize cisplatin dosing based on the estimated probability of neutropenia. The benefit of more intense dosing regimens in SCLC patients should be further assessed.

Relative bioavailability enhancement of simvastatin via dry emulsion systems: Comparison of spray drying and fluid bed layering technology.

Comprehensive comparisons of similar lipid based drug delivery systems produced by different technologies are scarce. Spray drying and fluid bed layering technologies were compared with respect to the process and product characteristics of otherwise similar simvastatin loaded dry emulsion systems. Fluid bed layering provided higher process yield (83.3% vs 71.5%), encapsulation efficiency (80.0% vs 68.4%), relative one month product stability (93.8% vs 85.5%), larger and more circular particles (336 µm vs 56 µm) and lower median oil droplet size after product reconstitution in water (2.85 µm vs 4.27 µm), compared to spray drying. However, spray dried products exhibited higher drug content (22.2 mg/g vs 9.34 mg/g). An in-vivo pharmacokinetic study in rats was performed and a pharmacokinetic model was developed in order to compare the optimised simvastatin loaded dry emulsion systems, a simvastatin glyceride mimetic loaded in the dry emulsion and a simvastatin loaded SMEDDS with a reference physical mixture. Of the formulation tested, fluid bed layered pellets excelled and provided a 115% relative increase in bioavailability. Among the two technologies, fluid bed layering provided dry emulsion products with higher relative bioavailability and better product characteristics for further processing into final dosage forms.

Design of experiments and multivariate analysis approach to study dissolution stability of a modified-release drug product to support lean design strategies.

OBJECTIVE: The purpose of this paper is to present the use of Design of Experiments and multivariate analysis for evaluation of a modified-release drug product stability to support post-approval lean stability approaches. The focus of the paper was to investigate potential root-causes for acceleration of dissolution upon stability. METHODS: For statistical evaluation of stability data, multiple linear regression statistics was used. The design space of the stability study was modeled using MODDE 12.1 software. For experimental set-up, parameters such as Temperature, Time, Packaging, Batch, and Active Pharmaceutical Ingredient supplier were selected. RESULTS: With multiple linear regression modeling of the all generated stability data until six months, we were able to identify or confirm the Stability-related quality attributes and Shelf life limiting attributes. From the multiple linear regression correlation coefficients, we have evaluated that decrease of an antioxidant upon stability could cause potential shift in dissolution. However, main factors for accelerated dissolution can be attributed to other material and process variables. In the last part of the study, we have shown the usefulness of these methodologies for supporting lean stability approaches. With enhanced drug product knowledge, we designed two reduced long-term stability studies and showed that with 'One-half' reduced design, we would still be able to confirm 24-month shelf life. CONCLUSIONS: Implementing Quality by design approaches on stability studies could reduce the need for excessive analytical testing, help to evaluate meaningfulness of the data and set a risk-based stability testing strategy.

Ustekinumab Dosing Individualization in Crohn's Disease Guided by a Population Pharmacokinetic-Pharmacodynamic Model.

Ustekinumab is a monoclonal antibody used in Crohn's disease (CD). Dose optimization in case of non-response and the role of pharmacokinetic-pharmacodynamic (PK-PD) monitoring remain unresolved dilemmas in clinical practice. We aimed to develop a population PK-PD model for ustekinumab in CD and simulate efficacy of alternative dosing regimens. We included 57 patients and recorded their characteristics during 32 weeks after starting with ustekinumab therapy. Serum ustekinumab concentration was prospectively measured and fecal calprotectin (FC) concentration was used to monitor the disease activity. Ustekinumab PK-PD was described by a two-compartment target-mediated drug disposition model linked to an indirect response model. Lower fat-free mass, higher serum albumin, previous non-exposure to biologics, FCGR3A-158 V/V variant and lower C-reactive protein were associated with higher ustekinumab exposure. Model-based simulation suggested that 41.9% of patients receiving standard dosing achieve biochemical remission at week 32. In patients not achieving remission with standard dosing at week 16, transition to 4-weekly subcutaneous maintenance dosing with or without intravenous reinduction resulted in comparably higher remission rates at week 32 (51.1% vs. 49.2%, respectively). Our findings could be used to guide stratified ustekinumab treatment in CD, particularly in patients with unfavorable characteristics, who might benefit from early transition to 4-weekly maintenance dosing.

Ustekinumab concentrations shortly after escalation to monthly dosing may identify endoscopic remission in refractory Crohn's disease.

OBJECTIVES: Some patients with Crohn's disease do not achieve remission with the approved maintenance dosing of ustekinumab every 8 weeks, possibly due to insufficient drug exposure. We aimed to study the exposure-response relationship for endoscopic remission and biomarker normalization with ustekinumab dose escalation to every 4 weeks. METHODS: Out of 135 consecutive patients, 44 with active Crohn's disease despite standard maintenance dosing [at least one of C-reactive protein (CRP) >5 mg/L, fecal calprotectin >100 mg/kg, simple endoscopic score (SES) for Crohn's disease >3] underwent dose escalation to every 4 weeks. Subsequent endoscopic remission (SES-CD ≤3 without ulceration) and biomarker normalization were compared against ustekinumab concentrations. RESULTS: Dose escalation led to endoscopic remission in 28.6% (8/28), CRP normalization 29.2% (7/24) and fecal calprotectin normalization 51.7% (15/29) of patients. Ustekinumab concentrations after escalation were higher in patients with endoscopic remission (6.90 vs. 4.29 mg/L; P = 0.025) and fecal calprotectin normalization (6.65 vs. 3.74 mg/L; P = 0.001). A threshold of 6.00 mg/L identified endoscopic remission [area under the receiver operating curve (AUROC): 0.775; 95% confidence interval (CI), 0.551-0.999), a threshold of 4.40 mg/L (AUROC 0.755; 95% CI, 0.545-0.964) two months after escalation identified patients with fecal calprotectin normalization at the end of follow-up. Concentrations <3.5 mg/L after escalation precluded endoscopic remission or biomarker normalization. CONCLUSION: Endoscopic remission was associated with higher ustekinumab concentrations after dose escalation. Patients with concentrations <3.5 mg/L after dose escalation are unlikely to achieve endoscopic remission or biomarker normalization.

The Evolving Role of Microsampling in Therapeutic Drug Monitoring of Monoclonal Antibodies in Inflammatory Diseases.

Monoclonal antibodies (mAbs) have been extensively developed over the past few years, for the treatment of various inflammatory diseases. They are large molecules characterized by complex pharmacokinetic and pharmacodynamic properties. Therapeutic drug monitoring (TDM) is routinely implemented in the therapy with mAbs, to monitor patients' treatment response and to further guide dose adjustments. Serum has been the matrix of choice in the TDM of mAbs and its sampling requires the visit of the patients to laboratories that are not always easily accessible. Therefore, dried blood spots (DBS) and various microsampling techniques have been suggested as an alternative. DBS is a sampling technique in which capillary blood is deposited on a special filter paper. It is a relatively simple procedure, and the patients can perform the home-sampling. The convenience it offers has enabled its use in the quantification of small-molecule drugs, whilst in the recent years, studies aimed to develop microsampling methods that will facilitate the TDM of mAbs. Nevertheless, hematocrit still remains an obstacle that hinders a more widespread implementation of DBS in clinical practice. The introduction of novel analytical techniques and contemporary microsampling devices can be considered the steppingstone to the attempts made addressing this issue.

Peak Concentrations of Ustekinumab After Intravenous Induction Therapy Identify Patients With Crohn's Disease Likely to Achieve Endoscopic and Biochemical Remission.

BACKGROUND & AIMS: Little is known about the relationship between ustekinumab exposure during the first 2 weeks of treatment and outcomes of patients with Crohn's disease (CD). We investigated the relationship between serum concentrations of ustekinumab during the first 2 weeks of treatment and endoscopic and biochemical remission in patients with CD. METHODS: In a prospective observational study, we measured concentrations of ustekinumab in serum samples from 41 consecutive patients who started treatment with ustekinumab (approximately 6 mg/kg, intravenously, then 90 mg every 8 weeks), due to endoscopic markers of active CD, at a single center from October 2017 through January 2019. We measured ustekinumab exposure parameters during the first 2 weeks (peak concentration measured immediately after intravenous infusion, week 2 concentration, and area under the curve through week 2). We investigated the correlation between these parameters and endoscopic remission (simple endoscopic score for CD scores of 3 or less without ulceration, assessed centrally) and biochemical remission (level of fecal calprotectin below 100 mg/kg) using the Mann-Whitney U test. RESULTS: Endoscopic remission was achieved in 10 patients (24.4%) at week 24; biochemical remission was achieved in 17 patients (41.5%) at week 8, 17 patients (41.5%) at week 16, and 21 patients (51.2%) at week 24. Peak concentrations associated with endoscopic remission (area under the receiver operating characteristic curve, 0.717; 95% CI, 0.517-0.916); 6 of 13 patients (46%) with peak concentrations above 105 µg/mL (upper tercile) achieved endoscopic remission, compared with only 1 of 14 patients (7%) with peak concentrations below 88 µg/mL (lower tercile). All exposure parameters during the first 2 weeks were associated with biochemical remission. There was no significant difference between the associations of peak concentrations, week-2 concentrations, area under the curve through week 2, or later exposure measures (at weeks 4 and 8) with biochemical or endoscopic remission. CONCLUSIONS: In a prospective study, we found that serum concentrations of ustekinumab as early as 1 hour after intravenous infusion might be used to identify patients with CD most likely to achieve endoscopic remission. This early measurement might be used to optimize treatment of CD.

Echinacea angustifolia DC. Lipophilic Extract Patch for Skin Application: Preparation, In Vitro and In Vivo Studies.

Dodeca-2E,4E,8Z,10E/Z-tetraenoic isobutylamide (tetraene) is the main component of Echinacea angustifolia DC. lipophilic extract, the bioavailability and immunomodulatory effect after oral administration in soft gel capsules in healthy volunteers of which we have already demonstrated. In the present work, we assessed the transdermal administration as an alternative route of administration of such an alkamide. The first step, therefore, encompassed the preparation of a drug-in-adhesive patch with an area of 868 mm2 and containing a dose of 0.64 mg of tetraene. In vitro skin permeation studies in Franz-type diffusion chambers resulted in a tetraene flux of (103 ± 10) ng × cm-2 × h-1 with a very good linearity (r = 0.99). The relatively low lag time of just 13 min indicates low binding and the accumulation of tetraene in the skin. Finally, the patch was administered to six healthy volunteers, and the pharmacokinetic analysis was performed by nonlinear mixed effects modelling with soft gel oral capsules serving as the reference formulation. The in vivo results correlated well with the in vitro permeation and indicated an initial burst tetraene absorption from the patch that was in parallel with the zero-order kinetics of absorption. The rate of the latter process was in good agreement with the one estimated in vitro. The tetraene absorption rate was therefore slow and prolonged with time, resulting in a bioavailability of 39% relative to the soft gel capsules and a very flat plasma concentration profile.

Prediction of saxagliptin stability using a new approach based on Partial Least Squares and Design of Experiments.

The objective of this study was to assess the possibility of applying Partial Least Squares (PLS) statistics with the use of experimental design approach towards stability evaluation of the Saxagliptin drug product. The influences of temperature, time, dose, packaging, batch, and oxygen protection were analyzed for identification of critical factors responsible for degradation of saxagliptin and prediction of impurity levels at various storage conditions. Predicted levels of the impurity DP-2 were lower for at least 0.2 % when the drug product was protected from oxygen after its manufacture. Additionally, the PLS model revealed that the lower strength is at least twice less stable concerning impurity DP-1. Based on this analysis shelf life for Zone II was proposed at 24 months with high reliability. Comparison of the PLS model estimates with the measured stability data at shelf life revealed good predictive ability of the developed model. Moreover, PLS predictions of DP-1 and Total impurities were more accurate than those obtained with a standard linear least squares regression, while DP-2 predictions were at least as accurate. We can thus propose a more extensive use of this approach for stability evaluation of pharmaceuticals.

Preliminary toxicokinetic study of BPA in lactating dairy sheep after repeated dietary and subcutaneous administration.

Dietary intake is the predominant route of human exposure to bisphenol A and one of the important food commodities is milk. The aim of our study was to preliminarily evaluate the bisphenol A exposure and disposition in sheep milk after repeated dietary and subcutaneous administration of a relatively low dose (100 µg/kg of b. w./day) of bisphenol A to a sheep. On the basis of blood plasma sampling, milk sampling and HPLC analysis, we developed the toxicokinetic model. With the toxicokinetic model we showed that most likely only free bisphenol A passes into the mammary gland and is subsequently conjugated there. The percentage of the dose eliminated with milk was less than 0.1%, regardless of the route of bisphenol A administration. It is proven that the bisphenol A is eliminated through the milk of lactating sheep. However, the amounts excreted in the milk that were detected in this study are minimal.

Maturation of midazolam clearance in critically ill children with severe bronchiolitis: A population pharmacokinetic analysis.

PURPOSE: The aim of the present study was to develop a population pharmacokinetic model of midazolam, and to evaluate the influence of maturation process and other variability factors in critically ill children with severe acute bronchiolitis, who received a long-term intravenous infusion of midazolam. METHODS: In the study were included 49 critically ill children of both genders (from 0 to 130 weeks of age) with severe acute bronchiolitis hospitalised in intensive care units. Nonlinear mixed effects modelling approach was applied for data analyses and simulations. RESULTS: The final model is a two-compartment model that includes the effects of body weight using allometric scaling with fixed exponents and maturation of clearance. For a typical subject, scaled to the adult body weight of 70 kg, population pharmacokinetic values were estimated at 8.52 L/h for clearance (when maturation function was 1), 25.5 L/h for intercompartmental clearance, and 5.71 L and 39.8 L for the volume of the central and peripheral compartment, respectively. Based on the final model, maturation reaches 50% of the adult clearance in 45.9 weeks of postmenstrual age. The influence of gender, ABCB1 genotype and biochemical parameters on midazolam clearance was not detected. Results of simulations indicate the need for reduced dosing in certain groups of patients in order to maintain plasma concentrations of midazolam within recommended values. CONCLUSIONS: The developed population pharmacokinetic model can contribute to the dosing optimisation of midazolam, especially in critically ill children as it includes the influence of size and maturation of clearance, which are important parameters for achieving the desired plasma concentrations of midazolam.

Combined extracts of Echinacea angustifolia DC. and Zingiber officinale Roscoe in softgel capsules: Pharmacokinetics and immunomodulatory effects assessed by gene expression profiling.

BACKGROUND AND OBJECTIVE: Echinacea angustifolia DC. and Zingiber officinale Roscoe are two natural products with documented immunomodulatory activity, both able to modulate the expression of important immune-related genes. Thus, their use in combination seems to be particularly promising. In this context, we have considered the oral supplementation of a highly standardized lipophilic extract combining both above-mentioned phytocomplexes, formulated in attractive softgel capsules, with two objectives: on the one hand to study oral pharmacokinetic of main active extracts' components and on the other hand to examine the immunomodulation and anti-inflammatory properties by gene expression profiling. METHODS: Softgel capsules containing a combination of E. angustifolia DC. and Z. officinale Roscoe (5 mg and 25 mg, respectively) were given by oral administration to 10 healthy volunteers. The plasma concentrations of dodeca-2E,4E,8Z,10E/Z-tetraenoic isobutylamide (tetraene) for E. angustifolia DC., 6-gingerol and 6-shogaol (free and glucuronide) for Z. officinale Roscoe were determined by LC-MS analysis, and the pharmacokinetic analysis was performed. To understand the functional mechanisms responsible for the documented health benefits, we also examined the overall transcriptional remodeling induced in the peripheral blood mononuclear cells and performed an integrative functional analysis on the generated gene expression. RESULTS: All bioactive components were absorbed very rapidly, and their tmax were detected in plasma from 30 min to 1.40 h. The peak concentrations of tetraene, 6-gingerol, 6-shogaol and their glucuronide metabolites were 14.74, 5.66, 9.25, 29.2 and 22.24 ng/ml, respectively. Integrated analysis performed on the generated gene expression data highlighted immunomodulatory and anti-inflammatory effects similar to those exerted by hydrocortisone. CONCLUSION: These data demonstrated that the bioactive ingredients are highly and rapidly absorbed from softgel capsules containing the combination of the above-mentioned lipophilic extracts, providing evidence to support their immunomodulatory and anti-inflammatory properties. These data also help in defining the mechanistic pathways underlying the health benefits of these plant-derived bioactive compounds.