Pharmacodynamic Correlations Research Articles

Dried Blood Spots-A Platform for Therapeutic Drug Monitoring (TDM) and Drug/Disease Response Monitoring (DRM).

This review provides an overview on the current applications of dried blood spots (DBS) as matrices for therapeutic drug (TDM) and drug or disease response monitoring (DRM). Compared with conventional methods using plasma/serum, DBS offers several advantages, including minimally invasiveness, a small blood volume requirement, reduced biohazardous risk, and improved sample stability. Numerous assays utilising DBS for TDM have been reported in the literature over the past decade, covering a wide range of therapeutic drugs. Several factors can affect the accuracy and reliability of the DBS sampling method, including haematocrit (HCT), blood volume, sampling paper and chromatographic effects. It is crucial to evaluate the correlation between DBS concentrations and conventional plasma/serum concentrations, as the latter has traditionally been used for clinical decision. The feasibility of using DBS sampling method as an option for home-based TDM is also discussed. Furthermore, DBS has also been used as a matrix for monitoring the drug or disease responses (DRM) through various approaches such as genotyping, viral load measurement, assessment of inflammatory factors, and more recently, metabolic profiling. Although this research is still in the development stage, advancements in technology are expected to lead to the identification of surrogate biomarkers for drug treatment in DBS and a better understanding of the correlation between DBS drug levels and drug responses. This will make DBS a valuable matrix for TDM and DRM, facilitating the achievement of pharmacokinetic and pharmacodynamic correlations and enabling personalised therapy.

Serum Metabolomics Based on GC-MS Reveals the Antipyretic Mechanism of Ellagic Acid in a Rat Model.

Ellagic acid (EA) is a polyphenol dilactone that has been reported to have antipyretic, anti-inflammatory, anti-tumor, and antioxidant activities, but the mechanism of action has not been reported. In this study, serum metabolomics was used to explore the mechanism of EA on rat fever induced by beer yeast, and to screen out marker metabolites to provide a reference for the antipyretic effect of EA. The acute fever model of male Sprague Dawley rats involved subcutaneous injection with 20% aqueous suspension of yeast (15 mL/kg) in their back. At the same time of modeling, EA was given orally by 10 mL/kg intragastric administration for treatment. During the experiment, the temperature and its change values of rats were recorded, and Interleukin-6 (IL-6), Tumor Necrosis Factor-α (TNF-α), Prostaglandin E2 (PGE2), Cyclic Adenosine Monophosphate (cAMP), Superoxide Dismutase (SOD) and Malondialdehyde (MDA)—six physiological and biochemical indexes of rats—were detected after the experiment. In addition, the hypothalamus of each rat was analyzed by Western blot (WB), and the levels of Phospho Nuclear Factor kappa-B (P-NF-κB P65) and IkappaB-alpha (IKB-α) were detected. Then, the serum metabolites of rats in each group were detected and analyzed by gas chromatograph mass spectrometry and the multivariate statistical analysis method. Finally, when screening for differential metabolites, the potential target metabolic pathway of drug intervention was screened for through the enrichment analysis of differential metabolites. Pearson correlation analysis was used to systematically characterize the relationship between biomarkers and pharmacodynamic indicators. EA could reduce the temperature and its change value in yeast induced fever rats after 18 h (p < 0.05). The level of IL-6, TNF-α, PGE2, cAMP, SOD and MDA of the Model group (MG) increased significantly compared to the Normal group (NG) (p < 0.001) after EA treatment, while the levels of the six indexes in the serum and cerebrospinal fluid of yeast-induced rats decreased. The administration of yeast led to a significant increase in Hypothalamus P-NF-κB P65 and IKB-α levels. Treatment with EA led to a significant decrease in P-NF-κB P65 levels. Moreover, combined with VIP > 1 and p < 0.05 as screening criteria, the corresponding retention time and characteristic mass to charge ratio were compared with the NIST library, Match score > 80%, and a total of 15 differential metabolites were screened. EA administration significantly regulated 9 of 15 metabolites in rat serum. The 15 differential metabolites involved linoleic acid metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, galactose metabolism, biosynthesis of unsaturated fatty acids and glycerolipid metabolism. Pharmacodynamic correlation analysis was conducted between 15 different metabolites and six detection indexes. There was a significant correlation between 13 metabolites and six detection indexes. D-(−)-lactic acid, glycerin, phosphoric acid, 5-oxo-L-proline were negatively correlated with TNF-α, and p values were statistically significant except for L-tyrosine. In addition, glycerin was negatively correlated with IL-6, PGE2 and MDA, while phosphoric acid was negatively correlated with IL-6. In conclusion, EA may play an antipyretic anti-inflammatory role through the inhibition of the IKB-α/NF-κB signaling pathway and five metabolic pathways, which may contribute to a further understanding of the therapeutic mechanisms of the fever of EA.

Gentamicin pharmacokinetics and pharmacodynamic correlation in pediatrics—A systematic review

Study of Renal enzymuria and albuminuria activity in the Petals of Pink Nelumbo nucifera Gaertn.R. V. Saraswathi, F. Gricilda Shoba

Research progress on chemical constituents and pharmacological activities of seabuckthorn and prediction of its Q-markers

Seabuckthorn contains flavonoids, tannins, terpenoids, polysaccharides, and vitamins, which have anti-inflammation,anti-oxidation, liver protection, anti-cardiovascular disease, anti-aging, immune enhancing, anti-tumor, and anti-bacterial activities.We reviewed the papers focusing on the chemical constituents, pharmacological activities, and utilization of seabuckthorn. The quality markers(Q-markers) of seabuckthorn were predicted and analyzed based on original plant phylogeny, chemical composition correlation, traditional medicinal properties, pharmacodynamic correlation, traditional and extended efficacy, pharmacokinetics, metabolic processes, and measurable components. With this review, we aim to provide theoretical reference for the quality control and quality standard establishment of seabuckthorn, so as to promote the rational exploitation and utilization of seabuckthorn resources, and improve the healthy and sustainable development of seabuckthorn industry.

Role and Interpretation of Antifungal Susceptibility Testing for the Management of Invasive Fungal Infections.

Invasive fungal infections (IFIs) are associated with high mortality rates and timely appropriate antifungal therapy is essential for good outcomes. Emerging antifungal resistance among Candida and Aspergillus spp., the major causes of IFI, is concerning and has led to the increasing incorporation of in vitro antifungal susceptibility testing (AST) to guide clinical decisions. However, the interpretation of AST results and their contribution to management of IFIs remains a matter of debate. Specifically, the utility of AST is limited by the delay in obtaining results and the lack of pharmacodynamic correlation between minimal inhibitory concentration (MIC) values and clinical outcome, particularly for molds. Clinical breakpoints for Candida spp. have been substantially revised over time and appear to be reliable for the detection of azole and echinocandin resistance and for outcome prediction, especially for non-neutropenic patients with candidemia. However, data are lacking for neutropenic patients with invasive candidiasis and some non-albicans Candida spp. (notably emerging Candida auris). For Aspergillus spp., AST is not routinely performed, but may be indicated according to the epidemiological context in the setting of emerging azole resistance among A. fumigatus. For non-Aspergillus molds (e.g., Mucorales, Fusarium or Scedosporium spp.), AST is not routinely recommended as interpretive criteria are lacking and many confounders, mainly host factors, seem to play a predominant role in responses to antifungal therapy. This review provides an overview of the pre-clinical and clinical pharmacodynamic data, which constitute the rationale for the use and interpretation of AST testing of yeasts and molds in clinical practice.

Characterization of the selective in vitro and in vivo binding properties of crenezumab to oligomeric A\u03b2

BackgroundAccumulation of amyloid β (Aβ) in the brain is proposed as a cause of Alzheimer’s disease (AD), with Aβ oligomers hypothesized to be the primary mediators of neurotoxicity. Crenezumab is a humanized immunoglobulin G4 monoclonal antibody that has been shown to bind to synthetic monomeric and aggregated Aβ in vitro; however, less is known about the binding characteristic in vivo. In this study, we evaluated the binding patterns of crenezumab to synthetic and native forms of Aβ both in vitro and in vivo.MethodsCrenezumab was used to immunoprecipitate Aβ from synthetic Aβ preparations or brain homogenates from a PS2APP mouse model of AD to determine the forms of Aβ that crenezumab interacts with. Following systemic dosing in PS2APP or nontransgenic control mice, immunohistochemistry was used to localize crenezumab and assess its relative distribution in the brain, compared with amyloid plaques and markers of neuritic dystrophies (BACE1; LAMP1). Pharmacodynamic correlations were performed to investigate the relationship between peripheral and central target engagement.ResultsIn vitro, crenezumab immunoprecipitated Aβ oligomers from both synthetic Aβ preparations and endogenous brain homogenates from PS2APP mice. In vivo studies in the PS2APP mouse showed that crenezumab localizes to regions surrounding the periphery of amyloid plaques in addition to the hippocampal mossy fibers. These regions around the plaques are reported to be enriched in oligomeric Aβ, actively incorporate soluble Aβ, and contribute to Aβ-induced neurotoxicity and axonal dystrophy. In addition, crenezumab did not appear to bind to the dense core region of plaques or vascular amyloid.ConclusionsCrenezumab binds to multiple forms of amyloid β (Aβ), particularly oligomeric forms, and localizes to brain areas rich in Aβ oligomers, including the halo around plaques and hippocampal mossy fibers, but not to vascular Aβ. These insights highlight a unique mechanism of action for crenezumab of engaging Aβ oligomers.

Pharmacokinetic and Pharmacodynamic Correlations From 2 Studies Evaluating Abuse Potential of Hydrocodone Extended-Release Tablets.

Pharmacokinetic (PK)/pharmacodynamic (PD) correlations were explored in 2 human abuse potential studies of orally and intranasally administered hydrocodone extended-release (ER) 45mg in healthy, nondependent opioid users. In a crossover study design, subjects received intact hydrocodone ER, finely milled hydrocodone ER, and hydrocodone powder in solution in the oral study and finely milled hydrocodone ER, hydrocodone powder, and finely milled Zohydro® ER in the intranasal study. Spearman ρ2 and Pearson r2 values were calculated for PD (maximum effect [Emax ] for "at the moment" Drug Liking, Overall Drug Liking, and Take Drug Again visual analog scales [VAS]) vs PK (partial area under the concentration-time curve [AUC], maximum drug concentration [Cmax ], time to Cmax [Tmax ], and abuse quotient [PK AQ; Cmax /Tmax ]) for all treatments. In the oral study, correlations were strongest between Emax of "at the moment" Drug Liking and PK parameters (Cmax [ρ2 =0.4446], PK AQ [ρ2 =0.5179], Tmax [ρ2 =0.5093], and early systemic exposure [ρ2 =0.4782]). For Overall Drug Liking and Take Drug Again VAS, ρ2 values for correlations with PK parameters ranged from 0.2620 to 0.3637. In the intranasal study, no clear correlations between PK and PD parameters were apparent.

Phase IIa study of dabigatran etexilate in children with venous thrombosis: pharmacokinetics, safety, and tolerability

Background The current standard-of-care treatments for pediatric venous thromboembolism (VTE) have limitations. Dabigatran etexilate (DE), a direct thrombin inhibitor, may offer an alternative therapeutic option. Objectives To assess the pharmacokinetics, pharmacodynamics, safety, and tolerability of a DE oral liquid formulation (OLF) in pediatric patients with VTE. Patients/Methods Patients who had completed planned treatment with low molecular weight heparin or oral anticoagulants for VTE were enrolled in two age groups (2 to < 12 years and 1 to < 2 years), and received a DE OLF based on an age-adjusted and weight-adjusted nomogram. Originally, patients were to receive a DE OLF twice daily for 3 days, but the protocol was amended to a single dose on day 1. The primary endpoints were pharmacokinetics/pharmacodynamics-related: plasma concentrations of DE and its metabolites; activated partial thromboplastin time (APTT), ecarin clotting time (ECT), and dilute thrombin time (dTT); and pharmacokinetic (PK)-pharmacodynamic (PD) correlation. Safety endpoints included incidence rates of bleeding events and all other adverse events (AEs). Results Eighteen patients entered the study and received the DE OLF (an exposure equivalent to a dose of 150 mg twice daily in adults). The projected steady-state dabigatran trough concentrations were largely comparable between pediatric patients and adults. The PK/PD relationship was linear for ECT and dTT, and non-linear for APTT. No serious or severe AEs, bleeding events, or recurrent VTEs were reported. Mild AEs were reported in three patients in the single-dose group (screening period) and in one patient in the multiple-dose group (on-treatment period). Conclusion The current study supports the further evaluation of DE OLFs in pediatric patients with VTE.

Correlation of pharmacokinetics and brain penetration data of adult zebrafish with higher mammals including humans

IntroductionAdult zebrafish pharmacology is evolving rapidly for creating efficacy and safety models for drug discovery. However, there is very limited research in understanding pharmacokinetics (PK) in adult zebrafish. Methods for understanding PK will help in conducting pharmacokinetic – pharmacodynamic (PK-PD) correlations and improving the quality and applicability of data obtained using zebrafish. MethodsWe conducted adult zebrafish PK and brain penetration studies on two known compounds (irinotecan and lorcaserin) with distinct PK and brain penetration properties using validated LCMS/MS method. Irinotecan was studied at a dose of 100mg/kg i.p. and levels of the parent drug and active metabolite SN-38 were measured. Loracserin was studies at a dose of 10mg/kg by two routes i.p. and p.o. ResultsZebrafish PK and brain penetration profiles for both compounds were very similar to that of higher mammals including humans. Irinotecan was metabolised to SN-38 in ratios similar to ratios seen in other species and the compound had long half life with very low brain penetration in our studies. Loracasin was highly permeable in brain as compared to the exposure in blood, with long half life and high relative bioavailability, similar to other mammalian species including humans. DiscussionAdult zebrafish PK studies are relatively an unexplored area of zebrafish research. The zebrafish data for key parameters of irinotecan and loracserin shows a high correlation to the data from higher species, including human. This report explores and discusses the use of adult zebrafish as a predictive PK tool for higher animal studies.

Abstract 3219: Prior vaccination is critical to PD1/PDL-1 treatment efficacy in a mouse breast cancer allograft

Abstract We previously generated the MuPrime® mBR6004 model, by engrafting the breast adenocarcinoma derived from MMTV-PyVT transgenic mice (GEMM)1 into the syngeneic FVB/N mice2,3. The allograft grows robustly, maintains the histopathology features of the original GEMM, and metastasizes to the lungs in all examined cases when implanted orthotopically2. Additionally, histopathology shows that the models is HER2++, but ER-/PR-. We profiled drug responses to standard of care (SoC)2 and checkpoint inhibitors3. Interestingly, among all checkpoints inhibitors tested, our model is insensitive to PD1/PDL-1 inhibitors, but responds to CTLA-4 inhibitors3. To further explore the underlying mechanism of response, we performed extensive tumor immuno-profiling for the presence of infiltrating immune cells, e.g. TIL, CTL, Treg, immune-suppressive macrophages, NK, etc3. We observed a good pharmacodynamic (PD) correlation between the presence of tumor infiltrating T-cells, particularly CD8+ TIL, and NK and a positive response to therapy, regardless the treatment type. Given this preliminary observation, we attempted animal vaccination with tumor lysates prior to tumor engraftment or treatments. Interestingly, while vaccination had minimal effects on the engraftment take rate (100% take for all animals) and on the growth kinetics of the engraftments, it had profound effects on the tumor response to anti-PD1/anti-PDL-1 antibody treatments, significantly enhancing tumor response to these agents in a model that was otherwise unresponsive. Our results suggest that the immunological status of the animal, at least with regard to the specific anti-tumor immunity, is critically important to determine the response to checkpoint inhibitors. Our observations suggest that vaccination is critical for the overall success of immunotherapy (I/O) treatments utilizing checkpoint inhibitors as well other treatment strategies.

Pharmacodynamic correlations using fresh and cryopreserved tissue following use of vaginal rings containing dapivirine and/or maraviroc in a randomized, placebo controlled trial.

Background:The ex vivo challenge assay is a bio-indicator of drug efficacy and was utilized in this randomized, placebo controlled trial as one of the exploratory endpoints. Fresh and cryopreserved tissues were evaluated for human immunodeficiency virus (HIV) infection and pharmacokinetic (PK)/pharmacodynamic (PD) relationships.Methods:HIV-negative women used vaginal rings containing 25 mg dapivirine (DPV)/100 mg maraviroc (MVC) (n = 12), DPV only (n = 12), MVC only (n = 12), or placebo (n = 12) for 28 days. Blood plasma, cervicovaginal fluid (CVF), and cervical biopsies were collected for drug quantification and the ex vivo challenge assay; half (fresh) were exposed immediately to HIV while the other half were cryopreserved, thawed, then exposed to HIV. HIV replication was monitored by p24 enzyme-linked immunosorbent assay from culture supernatant. Data were log-transformed and analyzed by linear least squared regression, nonlinear Emax dose–response model and Satterthwaite t test.Results:HIV replication was greater in fresh compared to cryopreserved tissue (P = 0.04). DPV was detected in all compartments, while MVC was consistently detected only in CVF. Significant negative correlations between p24 and DPV levels were observed in fresh cervical tissue (P = 0.01) and CVF (P = 0.03), but not plasma. CVF MVC levels showed a significant negative correlation with p24 levels (P = 0.03); drug levels in plasma and tissue were not correlated with HIV suppression. p24 levels from cryopreserved tissue did not correlate to either drug from any compartment.Conclusion:Fresh tissue replicated HIV to greater levels and defined PK/PD relationships while cryopreserved tissue did not. The ex vivo challenge assay using fresh tissue could prioritize drugs being considered for HIV prevention.

Pharmacokinetic and pharmacodynamic correlation of plasma concentrations and blood pressure in hypertensive patients: A study

Objective: The aim of this study was to determine the correlation between the pharmacokinetic (PK) parameter (plasma concentration) and pharmacodynamic (PD) parameter (blood pressure [BP]) in hypertensive patients on metoprolol therapy. Materials and Methods: High-performance liquid chromatography (HPLC) method for the measurement of plasma concentrations was developed and validated, following which the Ethical Committee approval was obtained. Patients admitted with hypertension and above 18 years of age were randomized into two groups based on the time of administration of metoprolol. Patients for whom metoprolol therapy was contraindicated were excluded from the study. Results: One hundred and six patients were enrolled in the study; patients with 61-70 years formed majority, 51.8% of males were associated with hypertension compared to 48.2% of the females. Patients receiving morning dose of the drug showed higher plasma concentrations in comparison with evening dose. PK and PD correlation was carried out and correlation coefficient R2 was calculated by the formula y = mx + c. For systolic BP of morning administration, R2 for peak concentration was found to be 0.913 and R2 for trough concentration was found to be 0.903. R2 value for diastolic BP of morning administration was found to be 0.873 for peak concentration and 0.969 for trough concentration. Systolic BP of evening exhibited R2 value of 0.986 and 0.955 for peak and trough concentrations, respectively. Diastolic BP of evening showed R2 value of 0.931 and 0.896 for peak and trough concentrations. Statistical analysis was done using Pearson's correlation test, and it was observed that there is a significant correlation (P Conclusion: The PK and PD parameters are at par with each other. It can be concluded that there is a significant correlation between the BP and plasma concentrations. This can be considered as the preliminary finding to ascertain the various PK parameters to optimize the dosing schedule for hypertensive patients.

Inter-study variability of preclinical in vivo safety studies and translational exposure-QTc relationships--a PKPD meta-analysis.

Preclinical cardiovascular safety studies (CVS) have been compared between facilities with respect to their sensitivity to detect drug-induced QTc prolongation (ΔQTc). Little is known about the consistency of quantitative ΔQTc predictions that are relevant for translation to humans. We derived typical ΔQTc predictions at therapeutic exposure (ΔQTcTHER ) with 95% confidence intervals (95%CI) for 3 Kv 11.1 (hERG) channel blockers (moxifloxacin, dofetilide and sotalol) from a total of 14 CVS with variable designs in the conscious dog. Population pharmacokinetic-pharmacodynamic (PKPD) analysis of each study was followed by a meta-analysis (pooling 2-6 studies including 10-32 dogs per compound) to derive meta-predictions of typical ΔQTcTHER . Meta-predictions were used as a reference to evaluate the consistency of study predictions and to relate results to those found in the clinical literature. The 95%CIs of study-predicted ΔQTcTHER comprised in 13 out of 14 cases the meta-prediction. Overall inter-study variability (mean deviation from meta-prediction at upper level of therapeutic exposure) was 30% (range: 1-69%). Meta-ΔQTcTHER predictions for moxifloxacin, dofetilide and sotalol overlapped with reported clinical QTc prolongation when expressed as %-prolongation from baseline. Consistent exposure-ΔQTc predictions were obtained from single preclinical dog studies of highly variable designs by systematic PKPD analysis, which is suitable for translational purposes. The good preclinical-clinical pharmacodynamic correlations obtained suggest that such an analysis should be more routinely applied to increase the informative and predictive value of results obtained from animal experiments.

Discovery and optimization of novel antagonists to the human neurokinin-3 receptor for the treatment of sex-hormone disorders (Part I).

Neurokinin-3 receptor (NK3R) has recently emerged as important in modulating the tonic pulsatile gonadotropin-releasing hormone (GnRH) release. We therefore decided to explore NK3R antagonists as therapeutics for sex-hormone disorders that can potentially benefit from lowering GnRH pulsatility with consequent diminished levels of plasma luteinizing hormone (LH) and correspondingly attenuated levels of circulating androgens and estrogens. The discovery and lead optimization of a novel N-acyl-triazolopiperazine NK3R antagonist chemotype achieved through bioisosteric lead change from the high-throughput screening (HTS) hit is described. A concomitant improvement in the antagonist bioactivity and ligand lipophilic efficiency (LLE) parameter were the principal guidelines in the lead optimization efforts. Examples of advanced lead analogues to demonstrate the amenability of this chemotype to achieving a suitable pharmacokinetic (PK) profile are provided as well as pharmacokinetic-pharmacodynamic (PKPD) correlations to analyze the trends observed for LH inhibition in castrated rats and monkeys that served as preliminary in vivo efficacy models.

Pharmacokinetics and dose response of three different anti-TB drugs in rat (balb/c) infection model of tuberculosis

IntroductionRobust and physiologically relevant infection models are required to investigate pharmacokinetic–pharmacodynamic (PK/PD) correlations for anti-tuberculosis agents at preclinical discovery. Material and methodsThis study has validated an inhalation-based rat infection model of tuberculosis (TB) harboring mycobacteria in a replicating state that is suitable for investigating pharmacokinetics and drug action of anti-tubercular agents. A reproducible and actively replicating lung infection was established in Wistar rats by inhalation of a series of graded inocula of Mycobacterium tuberculosis (MTB). Following an initial instillation of ∼20(10)log10CFU/lung, MTB grew logarithmically for the first 3weeks, and then entered into a chronic phase with no net increase in pulmonary bacterial loads. Dose response of front-line anti-TB drugs was investigated following pharmacokinetic measurements in the plasma of infected rats. ResultsRifampicin, Isoniazid, and pyrazinamide dosed per orally exhibited bactericidality and good dose response with maximal effect of 6.77, 3.55, and 5.901.92log10CFU reductions in the lungs, respectively. In contrast, ethambutol was merely bacteriostatic with 5.90log10CFU/lung reduction and did not reduce the bacterial burden beyond the initial bacterial loads present at the beginning of treatment in spite of high blood ethambutol levels. Rat infection model with actively replicating bacilli provides a physiologically distinct and pharmacologically relevant model that can be exploited to distinguish investigational compounds into bacteriostatic or bactericidal scaffolds. ConclusionsThe present study proposes that this rat infection model – although it needs more drug substance – can be used in early discovery settings to investigate the pharmacology of novel anti-tubercular agents for the treatment of active pulmonary tuberculosis.

Relationship between plasma levels and the anti-neuropathic pain effect of Lamotrigine in rat model

BackgroundThe study was undertaken to assess the pharmacokinetic and pharmacodynamic correlation of Lamotrigine (LMT) was determined following oral administration to prove that there was a direct relationship between daily dose, plasma level of LMT and analgesic effects. MethodsNeuropathic pain was induced by chronic constriction injury of the sciatic nerve. This technique allows consecutive measurements of the paw withdrawal thresholds and paw withdrawal duration on hyperalgesia and allodynia respectively. Increase in threshold and decrease in the duration of paw withdrawals was used as an analgesic effect against neuropathy. Results and discussionThe results demonstrate that there was a positive correlation between plasma correlation and pharmacodynamic effects in neuropathic pain. ConclusionSince there was a positive correlation between plasma correlation and pharmacodynamic effects in neuropathic pain, the plasma levels of Lamotrigine are good indicators of efficacy of the same in animal models of neuropathic pain.

Selective inhibition of spleen tyrosine kinase (SYK) with a novel orally bioavailable small molecule inhibitor, RO9021, impinges on various innate and adaptive immune responses: implications for SYK inhibitors in autoimmune disease therapy

IntroductionSpleen tyrosine kinase (SYK) is a key integrator of intracellular signals triggered by activated immunoreceptors, including Bcell receptors (BCR) and Fc receptors, which are important for the development and function of lymphoid cells. Given the clinical efficacy of Bcell depletion in the treatment of rheumatoid arthritis and multiple sclerosis, pharmacological modulation of Bcells using orally active small molecules that selectively target SYK presents an attractive alternative therapeutic strategy.MethodsA SYK inhibitor was developed and assayed in various in vitro systems and in the mouse model of collagen-induced arthritis (mCIA).ResultsA novel ATP-competitive inhibitor of SYK, 6-[(1R,2S)-2-Amino-cyclohexylamino]-4-(5,6-dimethyl-pyridin-2-ylamino)-pyridazine-3-carboxylic acid amide, designated RO9021, with an adequate kinase selectivity profile and oral bioavailability, was developed. In addition to suppression of BCR signaling in human peripheral blood mononuclear cells (PBMC) and whole blood, FcγR signaling in human monocytes, and FcϵR signaling in human mast cells, RO9021 blocked osteoclastogenesis from mouse bone marrow macrophages in vitro. Interestingly, Toll-like Receptor (TLR) 9 signaling in human Bcells was inhibited by RO9021, resulting in decreased levels of plasmablasts, immunoglobulin (Ig) M and IgG upon B-cell differentiation. RO9021 also potently inhibited type I interferon production by human plasmacytoid dendritic cells (pDC) upon TLR9 activation. This effect is specific to TLR9 as RO9021 did not inhibit TLR4- or JAK-STAT-mediated signaling. Finally, oral administration of RO9021 inhibited arthritis progression in the mCIA model, with observable pharmacokinetics (PK)-pharmacodynamic (PD) correlation.ConclusionsInhibition of SYK kinase activity impinges on various innate and adaptive immune responses. RO9021 could serve as a starting point for the development of selective SYK inhibitors for the treatment of inflammation-related and autoimmune-related disorders.

Individualised vancomycin doses for paediatric burn patients to achieve PK/PD targets

BackgroundThe objective of the study was to investigate vancomycin dose adjustment in pediatric burn patients by evaluating trough drug concentrations and the pharmacokinetic and pharmacodynamic (PK/PD) correlation. MethodsStudy subjects included 13 patients who were 6.0 years old, 25kg (median). with normal renal function. These had at least a 30% total burn surface area and inhalation injury were present in 7/13 patients. The patients were investigated prospectively. Plasma monitoring and PK assessments were performed by serial blood sample collections (30 sets). Only 0.2mL of each plasma sample was required for our plasma measurements, which were made by high performance liquid chromatography. The vancomycin PK/PD target was set at AUC0–24ss/MIC>400. ResultsTrough values less than 10μg/mL were obtained in 16/30 sets (53%) as a consequence of increased plasma clearance and the apparent volume of distribution. The daily dose was subsequently increased from 43.4±9.0mg/kg (mean±SD) to 98.0±17.9mg/kg, p<0.05. The PK/PD target was reached for pathogens with 0.5mg/L, 1mg/L, 2mg/L and 4mg/L MIC in 93.3% (28/30), 66.7% (20/30), 33.3% (10/30) and 3.3% (1/30) of the sets, respectively. ConclusionsTo more rapidly achieve the PK/PD targets in pediatric burn patients with normal renal function, an initial dose of approximately 90–100mg/kg/day is recommended; however, this higher dosage regimen should be further evaluated in this population in terms of efficacy and toxicity as well as in terms of achieving pharmacodynamic goals.

Enantiospecific determination of dl-methylphenidate and dl-ethylphenidate in plasma by liquid chromatography–tandem mass spectrometry: Application to human ethanol interactions

In humans, concomitant dl-methylphenidate ( dl-MPH) and ethanol results in the carboxylesterase 1 (hCES1) mediated biotransformation of MPH to the transesterification metabolite dl-ethylphenidate ( dl-EPH). The separate enantiomers of MPH and EPH are found at low ng/ml to pg/ml plasma concentrations. Substantial pharmacological differences exist between d- and l-isomers of MPH and EPH, both in terms of pharmacological potencies and receptor selectivity, as well as in pharmacokinetic properties. Accordingly, a sensitive, accurate and precise enantiospecific analytical method is required in order to fully explore pharmacokinetic–pharmacodynamic correlations regarding the MPH–ethanol interaction. The present study describes a novel liquid chromatographic-tandem mass spectrometric method for simultaneous analysis of d- and l-MPH as well as d- and l-EPH concentrations from human plasma. This assay provides baseline resolution of the individual MPH and EPH isomers utilizing a vancomycin-based chiral column. The lower limit of quantification was 0.025 ng/ml for each isomer when extracting 0.5 ml plasma aliquots. Calibration curves were linear over the range from 0.025 ng/ml to 25 ng/ml for all analytes ( r 2 > 0.995). Assay accuracy and precision were excellent and stability studies and assessment of potential matrix effects contributed to the validation of the method. Application of the method to human plasma samples collected after the administration of dl-MPH with or without ethanol is included, and the implications of this pharmacokinetic drug interaction discussed.

A novel approach on pharmacokinetic / pharmacodynamic correlations of risperidone: understanding its safety and efficacy profiles

The pharmacokinetic characteristics of a compound as well as the immediate consequences of its physicochemical behavior during interactions with biological structures, represent the key issues for its pharmacodynamic profile, starting from the most fundamental global aspects (i.e. central and / or peripheral action) to the most detailed ones (i.e. molecular mechanism of action). Successive metabolic reactions lead to either bioactivation or bioinactivation of the molecular entity. A particular importance is currently assigned to several molecular physicochemical descriptors, for instance the polarity degree (mirroring the changes of partition coefficients and of the permeability of biological structures), and emphasizing on distribution and renal excretion rate. The active metabolite (9-hydroxy-risperidone) of the atypical antipsychotic agent risperidone has an increased polar character and, consequently, its pharmacokinetic profile is modified compared to the parent drug: especially the penetration through the bood brain barrier and the efflux pump mediated transport were considered. In this context, the kinetic characteristics and their correlation with the pharmacodynamic properties for the two active entities, as well as the consequences dealing with the antipsychotic efficacy, the safety and efficacy profiles can be anticipated. The present approach critically asseses the available data from literature corroborated with the personal findings over the last years.