Production of Psychoactive Metabolites by Gut Bacteria.

The gut microbiome plays a vital role in numerous aspects of physiology, including functions related to metabolism, the immune system, behaviour, brain structure and function. Furthermore, it is now becoming increasingly clear that alterations in microbial composition or diversity are implicated in several disease states, including anxiety, depression, autism spectrum disorder (ASD), Alzheimer's disease (AD), Parkinson's disease (PD), obesity, and diabetes. Therefore, therapeutic targeting of the gut microbiota has the potential to be useful in the treatment of both stress-related disorders and metabolic diseases. An important method by which the gut microbiome can influence the gut-brain axis is through microbial production of psychoactive metabolites. Several bacteria have been shown to produce metabolites which can impact host health, such as short-chain fatty acids, conjugated linoleic acid, antimicrobials, exopolysaccharides, and vitamins. Furthermore, several molecules with neuroactive functions, including serotonin, gamma-aminobutyric acid, catecholamines, and acetylcholine, have been isolated from bacteria within the human gut. This review aims to explore the psychoactive metabolites reported to be produced by gut bacteria, particularly those of relevance to stress-related disorders. Screening methods for psychoactive metabolite production, as well as the challenges and limitations of this research, will also be addressed. Finally, the implications of metabolite production for neuropsychiatric disorders such as depression, anxiety, and stress, behavioural disorders such as ASD, and neurodegenerative disorders such as AD and PD will be discussed.

Is There a Role for Therapeutic Drug Monitoring in Patients with Hidradenitis Suppurativa on Tumor Necrosis Factor-α Inhibitors?

Tumor necrosis factor-α inhibitors, adalimumab and infliximab, are at the forefront of biologic therapy for the management of moderate-to-severe hidradenitis suppurativa, with adalimumab as currently the only approved medication for this condition. In treating patients, primary or secondary lack of response (also termed suboptimal response) is a major burden for both patients and healthcare systems and is a challenge with biologics in part owing to the development of anti-drug antibodies following treatment. To overcome this, therapeutic drug monitoring may be conducted proactively or reactively to a patient's suboptimal response guided by measurements of trough serum drug concentrations and levels of anti-drug antibodies. While strong evidence to support the utility of therapeutic drug monitoring exists in patients with inflammatory bowel disease, current information is limited in the context of hidradenitis suppurativa. We sought to summarize the available evidence and to present the role of therapeutic drug monitoring and other dose optimization strategies in improving clinical response in patients with hidradenitis suppurativa treated with tumor necrosis factor-α inhibitors.

Immunogenicity of biologic agents in rheumatology.

Biologic agents have become a core component of therapeutic strategies for many inflammatory rheumatic diseases. However, perhaps reflecting the specificity and generally high affinity of biologic agents, these therapeutics have been used by rheumatologists with less consideration of their pharmacokinetics than that of conventional synthetic DMARDs. Immunogenicity was recognized as a potential limitation to the use of biologic agents at an early stage in their development, although regulatory guidance was relatively limited and assays to measure immunogenicity were less sophisticated than today. The advent of biosimilars has sparked a renewed interest in immunogenicity that has resulted in the development of increasingly sensitive assays, an enhanced appreciation of the pharmacokinetic consequences of immunogenicity and the development of comprehensive and specific guidance from regulatory authorities. As a result, rheumatologists have a greatly improved understanding of the field in general, including the factors responsible for immunogenicity, its potential clinical consequences and the implications for everyday treatment. In some specialties, immunogenicity testing is becoming a part of routine clinical management, but definitive evidence of its cost-effectiveness in rheumatology is awaited.

A novel protein-based autologous topical serum for skin regeneration.

BACKGROUND: As skin ages, a functional decrement occurs. To avoid future vulnerability to dermatologic diseases, an optimal cutaneous regeneration is mandatory. Biological therapies based on blood-derived autologous proteins are gaining attention of scientists and dermatologists. OBJECTIVES: A novel 100% autologous topical serum has been developed using plasma rich in growth factors technology. The physicochemical characterization and the biologic potential of the novel formulation have been studied. METHODS: Rheological and mechanical properties and the biological capacity of the formulation were characterized. Human dermal fibroblast culture and 3D organotypic skin explants were used as in vitro and ex vivo cutaneous models, respectively. RESULTS: The autologous topical serum presented an optimal spreadability index and appropriate shear thinning behavior that allowed an easy handling and rapid integration within the cutaneous tissue. The formulation has a high growth factor load with the ability to progressively penetrate into the dermal/epidermal layers of the skin. It is biocompatible and promotes cell proliferation and chemotactic activity. The autologous topical serum promotes the biosynthetic activity of cells by the stimulation of collagen and hyaluronic acid expression. CONCLUSIONS: These findings present an in situ and easy to prepare autologous topical serum based on the patient's own blood with physicochemical and bioactive properties that may be used for skin regeneration purposes.

Clinical Pharmacokinetic and Pharmacodynamic Considerations in the Treatment of Ulcerative Colitis.

Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) of unknown etiology, probably caused by a combination of genetic and environmental factors. The treatment of patients with active UC depends on the severity, localization and history of IBD medication. According to the classic step-up approach, treatment with 5-aminosalicylic acid compounds is the first step in the treatment of mild to moderately active UC. Corticosteroids, such as prednisolone are used in UC patients with moderate to severe disease activity, but only for remission induction therapy because of side effects associated with long-term use. Thiopurines are the next step in the treatment of active UC but monotherapy during induction therapy in UC patients is not preferred because of their slow onset. Therapeutic drug monitoring (TDM) of the pharmacologically active metabolites of thiopurines, 6-thioguanine nucleotide (6-TGN), has proven to be beneficial. Thiopurine S-methyltransferase (TMPT) plays a role in the metabolic conversion pathway of thiopurines and exhibits genetic polymorphism; however, the clinical benefit and relevance of TPMT genotyping is not well established. In patients with severely active UC refractory to corticosteroids, calcineurin inhibitors such as ciclosporin A (CsA) and tacrolimus are potential therapeutic options. These agents usually have a rather rapid onset of action. Monoclonal antibodies (anti-tumor necrosis factor [TNF] agents, vedolizumab) are the last pharmacotherapeutic option for UC patients before surgery becomes inevitable. Body weight, albumin status and antidrug antibodies contribute to the variability in the pharmacokinetics of anti-TNF agents. Additionally, the use of concomitant immunomodulators (thiopurines/methotrexate) lowers the rate of immunogenicity, and therefore the concomitant use of anti-TNF therapy with an immunomodulator may confer some advantage compared with monotherapy in certain patients. TDM of anti-TNF agents could be beneficial in patients with primary nonresponse and secondary loss of response. The potential benefit of applying TDM during vedolizumab treatment has yet to be determined.

Interchangeability of biosimilar and biological reference product: updated regulatory positions and pre- and post-marketing evidence.

INTRODUCTION: Since 2006, biosimilars have been available in several countries worldwide, thus allowing for potential savings in pharmaceutical expenditure. However, there have been numerous debates about the interchangeability of biosimilars and reference products based on concerns of immunogenicity by switching between biological products, which may cause lack of effect and toxicity. AREAS COVERED: The authors provide the reader with an overview of the different positions of regulatory authorities on the interchangeability and automatic substitution of biosimilars and reference products. Presently, the FDA allows automatic substitution without prescriber intervention if the biosimilar is interchangeable with reference products, while the European Medicines Agency delegate to each single EU member state. EXPERT OPINION: Different approaches in defining interchangeability and automatic substitution call for harmonization to increase confidence of healthcare professionals and patients about the clinical impact of switching. Networks of electronic healthcare records and administrative databases, potentially linkable to clinical charts and registries may rapidly assess frequency and benefit-risk profile of different switching patterns in routine care at different levels, thus integrating and strengthening pre-marketing evidence.

Biologic agents for severe asthma patients: clinical perspectives and implications.

Asthma is a chronic inflammatory multifactorial disorder of the airways characterized by the involvement of immune cells and mediators in its onset and maintenance. Traditional therapeutic strategies have been unsatisfactory in controlling the underlying pathology, especially in the more severe states. Hence in the last couple of decades, new biological approaches targeting molecular mediators have been developed. In this narrative review we examine biological agents currently available for the management of severe asthma, focusing our attention on their clinical application, pros and cons, and in particular on gaps regarding the use of these agents. The most well-known and used biologic agent in clinical practice is omalizumab, though there is emerging evidence for mepolizumab too. The future of these biological therapies is to broaden our knowledge of their practical use and ascertain predictive biomarkers, or define an algorithm, useful in the optimal application of these 'biological weapons'.

Functional Modulation of Tight Junction to Enhance the Permeability of Biological Products (Biologics) in Biomembranes.

In recent years, biological products (biologics), including blood components, recombinant therapeutic proteins, antibodies, gene therapeutic materials, and so on, have been produced by biotechnology methods and other novel technologies. These products are essential therapeutic materials in progressive medicine. However, we often encounter the lower permeability of these biologics through biomembranes, due to their high molecular mass. In the last three decades, we have investigated drug delivery systems, including several enhancement methods for the permeability of biologics such as recombinant therapeutic proteins and viral vectors in epithelial cells. This review focuses the development of novel delivery systems for biologics in rectal and nasal administration, and includes an interesting observation of modulators of the tight junction (TJ) function. From cellular biology perspective, the interaction between permeability enhancing materials and targeted molecules in the TJ of epithelial cells was investigated. We elucidated that a TJ modulator will interact with a major constituent protein, for instance claudins, in playing an essential role in the tissue-specific barrier function of the TJ. Furthermore, useful enhancement of gene transfer in cells (for instance, in Caco-2 cells) was found in the combination of an adenovirus vector and capric acid sodium salt (C10), a TJ modulator.

Safety, dosing, and pharmaceutical quality for studies that evaluate medicinal products (including biological products) in neonates.

The study of medications among pediatric patients has increased worldwide since 1997 in response to new legislation and regulations, but these studies have not yet adequately addressed the therapeutic needs of neonates. Additionally, extant guidance developed by regulatory agencies worldwide does not fully address the specificities of neonatal drug development, especially among extremely premature newborns who currently survive. Consequently, an international consortium from Canada, Europe, Japan, and the United States was organized by the Critical Path Institute to address the content of guidance. This group included neonatologists, neonatal nurses, parents, regulators, ethicists, clinical pharmacologists, specialists in pharmacokinetics, specialists in clinical trials and pediatricians working in the pharmaceutical industry. This group has developed a comprehensive, referenced White Paper to guide neonatal clinical trials of medicines - particularly early phase studies. Key points include: the need to base product development on neonatal physiology and pharmacology while making the most of knowledge acquired in other settings; the central role of families in research; and the value of the whole neonatal team in the design, implementation and interpretation of studies. This White Paper should facilitate successful clinical trials of medicines in neonates by informing regulators, sponsors, and the neonatal community of existing good practice.

Is there potential for therapeutic drug monitoring of biologic agents in rheumatoid arthritis?

The use of biologics has significantly changed the management of rheumatoid arthritis over the last decade, becoming the cornerstone treatment for many patients. The current therapeutic arsenal consists of just under 10 biologic agents, with four different mechanisms of action. Several studies have demonstrated a large interindividual pharmacokinetic variability, which translates to unpredictability in clinical response among individuals. The present review focuses on the pharmacokinetics and pharmacodynamics of biologic agents approved for rheumatoid arthritis. The literature relating to their concentration-effect relationship and the use of pharmacokinetic-pharmacodynamic modelling to optimize drug regimens is analysed. Due to the scarcity and complexity of these studies, the current dosing strategy is based on clinical indexes/aspects. In general, dose individualization for biologics should be implemented increasingly in clinical practice as there is a direct benefit for treated rheumatoid arthritis patients. Moreover, there is an indirect benefit in terms of cost-effectiveness.

Utility of a Bayesian Mathematical Model to Predict the Impact of Immunogenicity on Pharmacokinetics of Therapeutic Proteins.

The impact of an anti-drug antibody (ADA) response on pharmacokinetic (PK) of a therapeutic protein (TP) requires an in-depth understanding of both PK parameters and ADA characteristics. The ADA and PK bioanalytical assays have technical limitations due to high circulating levels of TP and ADA, respectively, hence, significantly hindering the interpretation of this assessment. The goal of this study was to develop a population-based modeling and simulation approach that can identify a more relevant PK parameter associated with ADA-mediated clearance. The concentration-time data from a single dose PK study using five monoclonal antibodies were modeled using a non-compartmental analysis (NCA), one-compartmental, and two-compartmental Michaelis-Menten kinetic model (MMK). A novel PK parameter termed change in clearance time of the TP (α) derived from the MMK model could predict variations in α much earlier than the time points when ADA could be bioanalytically detectable. The model could also identify subjects that might have been potentially identified as false negative due to interference of TP with ADA detection. While NCA and one-compartment models can estimate loss of exposures, and changes in clearance, the two-compartment model provides this additional ability to predict that loss of exposure by means of α. Modeling data from this study showed that the two-compartment model along with the conventional modeling approaches can help predict the impact of ADA response in the absence of relevant ADA data.

Biological drugs for the treatment of moderate-to-severe psoriasis by subcutaneous route: determining statistical equivalence according to evidence-based methods.

BACKGROUND: Although several evidence-based analyses have found that in patients with moderate-to-severe psoriasis, biological agents for subcutaneous use show no difference in efficacy (no proof of difference), there is limited evidence on whether or not there is also proof of no difference. METHODS: The clinical material was the same as that reported in previous meta-analyses. Our methodology was a combination of meta-analysis and equivalence testing. The endpoint was the rate of Psoriasis Area and Severity Index (PASI) 75 achievement. The agents examined for equivalence testing included etanercept, high-dose etanercept, adalimumab, ustekinumab, and high-dose ustekinumab. The equivalence margin [±18 % as risk difference (RD)] was derived from statistical power information from the original trials; a more conservative margin at ±10 % was also tested. RESULTS: Our analysis involved 16 randomized trials including 8,257 patients. Ten head-to-head indirect comparisons were made and the respective values of RD were estimated. The 95 % confidence intervals for RDs remained within the margins of ±18 and ±10 % in six and two cases, respectively. A post hoc margin of about ±25 % was satisfied in all cases. All analyses assumed α = 2.5 %. CONCLUSION: Our study indicates that some of these five biological treatments can be equivalent, but results are strongly influenced by the margins adopted. Our findings can be helpful to develop local acquisition tenders on these drugs.

Biologics: an update and challenge of their pharmacokinetics.

Biologics, including but not limited to monoclonal antibodies (mAbs), cytokines, growth factors, enzymes, hormones, vaccines, antibody fragments (e.g. Fabs), and antibody drug conjugates (ADCs), have a powerful clinical impact on the management of a wide variety of diseases. When compared to small molecules (SMs), they have different physicochemical properties and demonstrate unique and complex pharmacokinetic (PK) characteristics that are dependent on several factors such as net charge, neonatal Fc receptor [FcRn], Fcγ receptor [FcγR], glycosylation, PEGylation or aggregation. While PK principles are consistent, the underlying mechanisms that determine processes of absorption, distribution, metabolism, and excretion (ADME) of biologics are quite different from those of SMs. Furthermore, the immunogenicity, especially formation of anti-drug antibody (ADA) and cellular immune responses, may play an important role in their PK. Investigating the drug interaction (DI) potentials of biologics is inherently complicated, and the most well documented DI mechanism involves cytokine-mediated changes in drug-metabolizing enzymes. Population PK (Pop-PK) analyses have been successfully applied in assessing covariates in the disposition of biologics. The mechanism-based (target-mediated drug disposition [TMDD]) and physiologically based PK (PBPK) models are applied to predict PK characteristics of biologics. Developing a validated bioanalytical assay (mass assay, activity assay and immunogenicity assay) is critical in determining the PK properties of biologics. In this review, we will highlight the current knowledge, as well as the challenges around the PK-related issues in optimization of drug development and clinical practice of biologics.

Systemic delivery of biotherapeutics through the lung: opportunities and challenges for improved lung absorption.

The development of Exubera(®) (inhaled insulin) has paved the way for consideration of future inhaled biotherapeutic products for systemic delivery. This route of drug delivery favors highly potent small peptides without self-association and large proteins resistant to enzymatic degradation for high bioavailability, while likely resulting in transient therapeutic effects. Improved therapeutic benefits with a needle-free delivery, such as inhaled insulin, are also rational pursuits. Molecules and their formulations must be carefully chosen and designed to optimize the rates of lung absorption and nonabsorptive loss. Novel molecular or formulation approaches, for example, Technosphere(®), Fc-/scFv-fusion protein, PEGylation, polymeric or lipid-based micro/nanoparticles and liposomes, offer opportunities to improve lung absorption and therapeutic duration of some biotherapeutics. Critical assessments are now essential as to their therapeutic benefits, safety, patient acceptance and market competition, as carried out for Exubera.

Pharmacokinetics and tissue distribution of a novel marine fibrinolytic compound in Wistar rat following intravenous administrations.

We investigated a novel marine fibrinolytic compound for use in thrombolytic therapy. Pharmacokinetics and the tissue distribution of this novel marine fibrinolytic compound, FGFC1(2) (fungi fibrinolytic compound 1), were investigated in Wistar rats after intravenous (IV) bolus administration of two concentrations (10 and 20mg/kg). Plasma FGFC1 and tissue extracts were measured using HPLC with UV detection. FGFC1 was detected using a C18 column with a gradient eluted mobile phase of acetonitrile-water (0.1% trifluoroacetic acid), 1.0mL/min. Chromatograms were monitored at 265nm (column temperature: 40°C). Pharmacokinetic data indicate that FGFC1 fitted well to a two-compartment model. Elimination half-lives (t1/2) of FGFC1 were 21.51±2.17 and 23.22±2.11min for 10 and 20mg/kg, respectively. AUC0-t were 412.19±19.09, 899.09±35.86µg/mLmin, systemic clearance (CL) was 0.023±0.002, 0.022±0.002 ((mg/kg)/(µg/mL)/min) and the mean residence time (MRT) was 10.15±0.97, 9.65±1.40min at 10 and 20mg/kg, respectively. No significant differences were observed in the systemic clearance and mean residence time at the tested doses, suggesting linear pharmacokinetics in rats. Tissue distribution data reveal that FGFC1 distributed rapidly in most tissues except the brain and that the highest concentration of the drug was in the liver. In the small intestine, FGFC1 initially increased and then declined, but remained comparatively high 60min after administration, suggesting that enterohepatic circulation may exist.

Impact of anti-drug antibodies in preclinical pharmacokinetic assessment.

The administration of human biotherapeutics is often associated with a higher incidence of immunogenicity in preclinical species. The presence of anti-drug antibodies (ADAs) in the test samples can affect the accurate measurement of therapeutic protein (TP) in bioanalytical methods designed to support pharmacokinetic (PK) and toxicokinetic (TK) assessments. The impact can vary depending on the bioanalytical method platform and study dosing design. The goal of this study is to evaluate the impact of ADA response on the bioanalytical methods in support of PK/TK and the associated study data interpretation. Sprague Dawley rats were administered with four weekly doses of 50 mg/kg TP, a humanized monoclonal antibody. The TP in serum samples was measured using three bioanalytical methods that quantified bound and/or unbound TP to ADA. The ADA response in the animals was classified into negative, low, medium, and high based on the magnitude of the response. The presence of ADA in samples led to discrepant TP measurements between the methods, especially at time points where the TP concentrations were low. This could be due to ADA interference to the accurate measurement of ADA-bound TP concentrations. The TP concentration at last time point (C last) was reduced by 82.8%, 98.6%, and 99.8%, respectively, for samples containing low, medium, and high levels of ADA. The interfering effects of the ADA on bioanalytical methods and exposure were evident as early as 2 weeks post-dosing. This modeling approach can provide the better understanding of ADA impact on PK exposure in multiple doses.

Antagonism of chemokine receptor CCR8 is ineffective in a primate model of asthma.

BACKGROUND: Expression of the T-cell-associated chemokine receptor CCR8 and its ligand CCL1 have been demonstrated to be elevated in patients with asthma. CCR8 deficiency or inhibition in models of allergic airway disease in mice resulted in conflicting data. OBJECTIVE: To investigate the effects of a selective small molecule CCR8 inhibitor (ML604086) in a primate model of asthma. METHODS: ML604086 and vehicle were administered by intravenous infusion to 12 cynomolgus monkeys during airway challenge with Ascaris suum. Samples were collected throughout the study to measure pharmacokinetics (PK) and systemic CCR8 inhibition, as well as inflammation, T helper 2 (Th2) cytokines and mucus in bronchoalveolar lavage (BAL). Airway resistance and compliance were measured before and after allergen challenge, and in response to increasing concentrations of methacholine. RESULTS: ML604086 inhibited CCL1 binding to CCR8 on circulating T-cells>98% throughout the duration of the study. However, CCR8 inhibition had no significant effect on allergen-induced BAL eosinophilia and the induction of the Th2 cytokines IL-4, IL-5, IL-13 and mucus levels in BAL. Changes in airway resistance and compliance induced by allergen provocation and increasing concentrations of methacholine were also not affected by ML604086. CONCLUSIONS: These results clearly demonstrate a dispensable role for CCR8 in ameliorating allergic airway disease in atopic primates, and suggest that strategies other than CCR8 antagonism should be considered for the treatment of asthma.

Pharmacokinetic study of major bioactive components in rats after oral administration of extract of Ilex hainanensis by high-performance liquid chromatography/electrospray ionization mass spectrometry.

Ilex hainanensis Merr. is commonly used as a folk remedy for treating hypertension, dyslipidemia and inflammation in Traditional Chinese Medicine (TCMs) and it also has great potential to treat non-alcoholic fatty liver disease (NAFLD). Chlorogenic acid, kaempferol-7-O-ß-d-glucoside, and ilexgenin A are three major bioactive components in I. hainanensis extract. In this study, a rapid, sensitive and convenient LC-MS method was developed for their simultaneous determination in the plasma of normal and NAFLD rats. The method was validated in terms of selectivity, linearity and sensitivity, and shows advantages in monitoring the pharmacokinetic behaviors of these three compounds. Results revealed the pharmacokinetic behaviors of chlorogenic acid, kaempferol-7-O-ß-d-glucoside, and ilexgenin A could be significantly changed in NAFLD rats after oral administration of I. hainanensis extract compared with normal rats. The areas under the plasma concentration-time curve (AUC) and maximum plasma concentration (Cmax) of the three analytes were greatly decreased and the plasma clearance (CL) for kaempferol-7-O-ß-d-glucoside, Ilexgenin A were greatly increased in NAFLD rats. Meanwhile, the mean residence time (MRT) of kaempferol-7-O-ß-d-glucoside and Ilexgenin A were increased in the NAFLD rats. This is the first report on the determination of the major bioactive components in rat plasma after oral administration of I. hainanensis extract. These results provided a meaningful basis for evaluating the clinical application of this medicine.