Pharmacokinetic and pharmacodynamic properties of canakinumab in patients with gouty arthritis

Post-Marketing Pharmacovigilance of Canakinumab from the FDA Adverse Event Reporting System (FAERS)

Background: Canakinumab, a humanized anti-IL-1β monoclonal antibody, is known for its ability to suppress IL-1β-mediated inflammation. However, continuous monitoring of its safety remains essential. Thus, we comprehensively evaluated the safety signals of canakinumab by data mining from FAERS. Methods: We used a disproportionate analysis to quantify canakinumab-related adverse events (AEs) using four algorithms. Clinical prioritization of the detected signals was assessed with a semiquantitative score method. Serious and non-serious outcomes were compared by statistical methods. Additionally, a stratification analysis of serious infections was conducted at the system organ class (SOC) level. Results: A total of 28,496 canakinumab-related AEs were collected, and 71 suspicious signals detected. Among these, 19 preferred terms (PTs) were identified as unexpected signals, including deafness, appendicitis, brain oedema, cushingoid, cellulitis, and papilledema. Of the AEs, 16 were more likely reported as serious outcomes, such as pneumonia, abdominal pain, deafness, and infection. Based on clinical priority score, 44 PTs were classified as weak, 27 as moderate, and none as strong. Furthermore, 30 PTs demonstrated a high level of evidence, primarily derived from FDA prescribing information, randomized controlled trials, and systematic reviews. Stratification analysis of infections and infestations (serious outcomes) revealed a stronger association of severe infections with canakinumab in older or heavier individuals. All positive signals followed an early failure pattern, with the incidence of canakinumab-associated AEs decreasing over time. Conclusions: We found that most of the suspicious signals were associated with infections. More attention should be paid to serious infections, particularly in males, individuals aged ≥60 years, or those weighing >100 kg, who demonstrated the highest risk of serious infections.

Predicting Human Subcutaneous Bioavailability of Therapeutic Monoclonal Antibodies from Systemic Clearance and Volume of Distribution

Subcutaneous delivery of monoclonal antibody therapeutics is often preferred to intravenous delivery due to better patient compliance and overall lower cost to the healthcare system. However, the systemic absorption of biologics dosed subcutaneously is often incomplete. The aim of this work was to describe a human bioavailability prediction method for monoclonal antibodies delivered subcutaneously that utilizes intravenous pharmacokinetic parameters as input. A two-compartment pharmacokinetic model featuring a parallel-competitive absorption pathway and a presystemic metabolism pathway was employed. A training data set comprised 19 monoclonal antibodies (geometric mean bioavailability of 68%), with previously reported human pharmacokinetic parameters, while a validation set included data compiled from 5 commercial drug products (geometric mean bioavailability of 69%). A single fitted absorption rate constant, paired with compound-specific estimates of presystemic metabolism rate proportional to compound-specific systemic clearance parameters, resulted in calculations of human subcutaneous bioavailability closely mimicking clinical data in the training data set with a root-mean-square error of 5.5%. Application of the same approach to the validation data set resulted in predictions characterized by 12.6% root-mean-square error. Factors that may have impacted the prediction accuracy include a limited number of validation data set compounds and an uncertainty in the absorption rate, which were subsequently discussed. The predictive method described herein provides an initial estimate of the subcutaneous bioavailability based exclusively on pharmacokinetic parameters available from intravenous dosing.

Newer Therapies in Rheumatology

Seven of the 11 newer medications recently or soon to be approved to treat rheumatologic diseases discussed in this article are biologic agents and reflect the current ability of science to target specific components of the immune system. The other agents are molecules that are directed against specific immune pathway targets as well. All have shown superiority to placebo and in some cases have been compared to currently accepted therapies. Safety issues are generally centered around infections due to the immune-interrupting nature of these therapies.

Interleukin-1 in Coronary Artery Disease

Cardiovascular disease is the leading cause of mortality worldwide. Inflammation has long been established as a key component in the pathophysiology of coronary artery disease. The interleukin-1 family consists of 11 members that regulate the inflammatory response through both pro- and anti-inflammatory properties with the Nod-like receptor (NLR) family pyrin domain containing 3 inflammasome having a pivotal role in the process of converting interleukin-1 beta and interleukin- 18, two key inflammatory mediators, into their mature forms. Interleukin-1 affects various cell types that participate in the pathogenesis of atherosclerosis as it enhances the expression of leukocyte adhesion molecules on the surface of endothelial cells and augments the permeability of the endothelial cell barrier, attracting monocytes and macrophages into the vessel wall and aids the migration of smooth muscle cells toward atheroma. It also enhances the aggregation of low-density lipoprotein particles in endothelium and smooth muscle cells and exhibits procoagulant activity by inducing synthesis, cell-surface expression and release of tissue factor in endothelial cells, promoting platelet adhesion. The value of interleukin-1 as a diagnostic biomarker is currently limited, but interleukin-1 beta, interleukin-18 and interleukin-37 have shown promising data regarding their prognostic value in coronary artery disease. Importantly, target anti-inflammatory treatments have shown promising results regarding atherosclerosis progression and cardiovascular events. In this review article, we focus on the immense role of interleukin-1 in atherosclerosis progression, inflammation cascade and in the clinical application of target anti-inflammatory treatments.

Effect of canakinumab on clinical and biochemical parameters in acute gouty arthritis: a meta-analysis

BACKGROUND

Targeted anti-IL-1β therapy may be a valuable option for the management of gouty arthritis. The present meta-analysis has evaluated the effect of canakinumab, an anti-IL-1β monoclonal antibody in gouty arthritis.

METHODS

A standard meta-analysis protocol was developed and after performing a comprehensive literature search in MEDLINE, Cochrane, and International Clinical Trial Registry Platform (ICTRP), reviewers assessed eligibility and extracted data from three relevant articles. A random-effects model was used to estimate the pooled effect size as the mean difference in Visual Analouge Scale (VAS) score, serum hsCRP, serum Amyloid A, and risk ratio for global assessment between the groups. Quality assessment was done using the risk of bias assessment tool and summary of findings was prepared using standard Cochrane methodology with GradePro GDT.

RESULTS

Treatment with canakinumab showed a mean reduction of VAS score by 14.59 mm [95% CI - 19.42 to - 9.77], serum hsCRP by 15.36 mg/L [95% CI 1.62-29.11], serum Amyloid A by 67.18 mg/L [95% CI 17.06-117.31], and improvement in patient global assessment (RR = 1.478; 95% CI 1.29-1.67) and physician global assessment (RR = 1.44; 95% CI 1.28-1.61). The probability that future studies may have a mean difference in VAS score less than zero has been calculated to be 27.3% using a cumulative distribution function (CDF) calculator.

CONCLUSION

This meta-analysis shows the beneficial effect of canakinumab over triamcinolone by reducing VAS score, serum hsCRP, serum amyloid A, and improvement in global assessments in acute gouty arthritis.

New therapies in development for the management of non-infectious uveitis: A review

Uveitis is a spectrum of inflammatory disorders characterized by ocular inflammation and is one of the leading causes of preventable visual loss. The main aim of the treatment of uveitis is to control the inflammation, prevent recurrences of the disease and preserve vision while minimizing the adverse effects associated with the therapeutic agents. Initial management of uveitis relies heavily on the use of corticosteroids. However, monotherapy with high-dose corticosteroids is associated with side effects and cannot be maintained long term. Therefore, steroid-sparing agents are needed to decrease the burden of steroid therapy. Currently, the therapeutic approach for non-infectious uveitis (NIU) consists of a step-ladder strategy with the first-line option being corticosteroids in various formulations followed by the use of first-, second- and third-line agents in cases with suboptimal steroid response. Unfortunately, the agents currently at our disposal have limitations such as having a narrow therapeutic window along with their own individual potential side-effect profiles. Therefore, research has been targeted to identify newer drugs as well as new uses for older drugs that target specific pathways in the inflammatory response. Such efforts are made in order to provide targeted and safer therapy with reduced side effects and greater efficacy. Several specially designed molecular antibodies are currently in various phases of investigations that can potentially halt the inflammation in patients with NIU. In the review, we have provided a comprehensive overview of the current and upcoming therapeutic options for patients with NIU.

Influence of Antigen Mass on the Pharmacokinetics of Therapeutic Antibodies in Humans

Therapeutic antibodies are increasingly used to treat various diseases, including neoplasms and chronic inflammatory diseases. Antibodies exhibit complex pharmacokinetic properties, notably owing to the influence of antigen mass, i.e. the amount of antigenic targets to which the monoclonal antibody binds specifically. This review focuses on the influence of antigen mass on the pharmacokinetics of therapeutic antibodies quantified by pharmacokinetic modelling in humans. Out of 159 pharmacokinetic studies, 85 reported an influence of antigen mass. This influence led to non-linear elimination decay in 50 publications, which was described using target-mediated drug disposition or derived models, as quasi-steady-state, irreversible binding and Michaelis-Menten models. In 35 publications, the pharmacokinetics was apparently linear and the influence of antigen mass was described as a covariate of pharmacokinetic parameters. If some reported covariates, such as the circulating antigen level or tumour size, are likely to be correlated to antigen mass, others, such as disease activity or disease type, may contain little information on the amount of antigenic targets. In some cases, antigen targets exist in different forms, notably in the circulation and expressed at the cell surface. The influence of antigen mass should be soundly described during the early clinical phases of drug development. To maximise therapeutic efficacy, sufficient antibody doses should be administered to ensure the saturation of antigen targets by therapeutic antibodies in all patients. If necessary, antigen mass should be taken into account in routine clinical practice.

Canakinumab for the treatment of adult-onset Still's disease

Introduction: Adult-onset Still's disease (AOSD) is a rare multisystem autoinflammatory disorder of unknown etiology, with clinical and biological similarities with the juvenile form (sJIA).The pivotal role of interleukin (IL)-1 gives rise to the use of IL-1 inhibitors in treating resistant cases.Areas covered: This review focuses on canakinumab, a fully human anti-IL-1β antibody, as treatment for AOSD. The data obtained from case reports and case series on AOSD and two double-blind, randomized, placebo-controlled Phase III trial on sJIA are analyzed. Efficacy and safety profiles of canakinumab are discussed.Expert opinion: There is no unanimous consensus on how to treat with IL-1 inhibitors. Many reviews have focused primarily on anakinra, but the accumulating data for canakinumab have emerged. The choice of treatment is a relevant issue for patients and the national health services. The available data for canakinumab indicate that this drug in AOSD patients is effective and well tolerated.

Understanding Inter-Individual Variability in Monoclonal Antibody Disposition

Monoclonal antibodies (mAbs) are currently the largest and most dominant class of therapeutic proteins. Inter-individual variability has been observed for several mAbs; however, an understanding of the underlying mechanisms and factors contributing to inter-subject differences in mAb disposition is still lacking. In this review, we analyze the mechanisms of antibody disposition and the putative mechanistic determinants of inter-individual variability. Results from in vitro, preclinical, and clinical studies were reviewed evaluate the role of the neonatal Fc receptor and Fc gamma receptors (expression and polymorphism), target properties (expression, shedding, turnover, internalization, heterogeneity, polymorphism), and the influence of anti-drug antibodies. Particular attention is given to the influence of co-administered drugs and disease, and to the physiological relevance of covariates identified by population pharmacokinetic modeling, as determinants of variability in mAb pharmacokinetics.

Hyperphosphatemic Familial Tumoral Calcinosis With Galnt3 Mutation: Transient Response to Anti-Interleukin-1 Treatments

Hyperphosphatemic familial tumoral calcinosis (HFTC) is a rare autosomal recessive disease caused by mutations in genes involved in phosphate homeostasis and characterized by high serum phosphate concentration and occurrence of ectopic calcifications. Management of the disease includes lowering of phosphate concentration and, when clinically necessary, debulking surgery of calcifications. In addition, high inflammatory disease flares can occur. Our case is about a patient with GALNT3 mutation and several localizations of refractory calcinosis. Assuming HFTC acts like an auto-inflammatory syndrome, we report the effect of anti-interleukine-1 therapies on the evolution of the disease. Anakinra (100 mg, then 200 mg subcutaneous daily) and canakinumab (300 mg every 4 weeks) were sequentially given to the patient. Anti-IL-1 therapy was effective in controlling inflammatory flares; however, it did not prevent extension of calcinosis. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Uricase-containing coacervate microdroplets as enzyme active membrane-free protocells for detoxification of uric acid in serum

Based on the unique property of preferential sequestration of guest molecules, coacervate microdroplets are proposed as enzyme active membrane-free protocells, in which uricase is loaded for efficient detoxification of uric acid in serum.

Engineered pH-dependent recycling antibodies enhance elimination of Staphylococcal enterotoxin B superantigen in mice

A new modality in antibody engineering has emerged in which the antigen affinity is designed to be pH dependent (PHD). In particular, combining high affinity binding at neutral pH with low affinity binding at acidic pH leads to a novel antibody that can more effectively neutralize the target antigen while avoiding antibody-mediated antigen accumulation. Here, we studied how the in vivo pharmacokinetics of the superantigen, Staphylococcal enterotoxin B (SEB), is affected by an engineered antibody with pH-dependent binding. PHD anti-SEB antibodies were engineered by introducing mutations into a high affinity anti-SEB antibody, 3E2, by rational design and directed evolution. Three antibody mutants engineered in the study have an affinity at pH 6.0 that is up to 68-fold weaker than the control antibody. The pH dependency of each mutant, measured as the pH-dependent affinity ratio (PAR - ratio of affinity at pH 7.4 and pH 6.0), ranged from 6.7-11.5 compared to 1.5 for the control antibody. The antibodies were characterized in mice by measuring their effects on the pharmacodynamics and pharmacokinetics (PK) of SEB after co-administration. All antibodies were effective in neutralizing the toxin and reducing the toxin-induced cytokine production. However, engineered PHD antibodies led to significantly faster elimination of the toxin from the circulation than wild type 3E2. The area under the curve computed from the SEB PK profile correlated well with the PAR value of antibody, indicating the importance of fine tuning the pH dependency of binding. These results suggest that a PHD recycling antibody may be useful to treat intoxication from a bacterial toxin by accelerating its clearance.

Inflammasome biology, molecular pathology and therapeutic implications

Inflammasomes are intracellular multiprotein signaling complexes, mainly present in myeloid cells. They commonly assemble around a cytoplasmic receptor of the nucleotide-binding leucine-rich repeat containing receptor (NLR) family, although other cytoplasmic receptors like pyrin have been shown to form inflammasomes. The nucleation of the multiprotein scaffolding platform occurs upon detection of a microbial, a danger or a homeostasis pattern by the receptor that will, most commonly, associate with the adaptor protein ASC (apoptosis-associated speck-like protein containing a CARD) through homotypic domain interactions resulting in recruitment of procaspase-1. This will lead to the autoproteolytic activation of caspase-1, which regulates the secretion of proinflammatory IL1β and IL18 cytokines and pyroptosis, a caspase-1-mediated form of cell death. Pyroptosis occurs through cleavage of Gasdermin D, a membrane pore forming protein. Recently, non-canonical inflammasomes have been described, which directly sense intracellular pathogens through caspase-4 and -5 in humans, leading to pyroptosis. Inflammasomes are important in host defense; however, a deregulated activity is associated with a number of inflammatory, immune and metabolic disorders. Furthermore, mutations in inflammasome receptor coding genes are causal for an increasing number of rare autoinflammatory diseases. Biotherapies targeting the products of inflammasome activation as well as molecules that directly or indirectly inhibit inflammasome nucleation and activation are promising therapeutic areas. This review discusses recent advances in inflammasome biology, the molecular pathology of several inflammasomes, and current therapeutic approaches in autoinflammatory diseases and in selected common multifactorial inflammasome-mediated disorders.

Inflammasomes in neurological diseases: emerging pathogenic and therapeutic concepts

Inflammasome activation in the central nervous system occurs in both health and disease. Inflammasomes are cytosolic protein complexes that sense specific infectious or host stimuli and initiate inflammatory responses through caspase activation. Assembly of inflammasomes results in caspase-1-mediated proteolytic cleavage and release of the pro-inflammatory cytokines, interleukin-1β and interleukin-18, with initiation of pyroptosis, an inflammatory programmed cell death. Recent developments in the inflammasome field have uncovered novel molecular mechanisms that contribute to a broad range of neurological disorders including those associated with specific mutations in inflammasome genes as well as diseases modulated by inflammasome activation. This update focuses on recent developments in the field of inflammasome biology highlighting different inflammasome activators and pathways discovered in the nervous system. We also discuss targeted therapies that regulate inflammasomes and improve neurological outcomes.

Feasibility randomised multicentre, double-blind, double-dummy controlled trial of anakinra, an interleukin-1 receptor antagonist versus intramuscular methylprednisolone for acute gout attacks in patients with chronic kidney disease (ASGARD): protocol study

INTRODUCTION

Acute gout occurs in people with chronic kidney disease, who are commonly older people with comorbidities such as hypertension, heart disease and diabetes. Potentially harmful treatments are administered to these vulnerable patients due to a lack of clear evidence. Newly available treatment that targets a key inflammatory pathway in acute gout attacks provides an opportunity to undertake the first-ever trial specifically looking treating people with kidney disease. This paper describes the protocol for a feasibility randomised controlled trial (RCT) comparing anakinra, a novel interleukin-1 antagonist versus steroids in people with chronic kidney disease (ASGARD).

METHODS AND ANALYSIS

ASGARD is a two-parallel group double-blind, double-dummy multicentre RCT comparing anakinra 100 mg, an interleukin-1 antagonist, subcutaneous for 5 days against intramuscular methylprednisolone 120 mg. The primary objective is to assess the feasibility of the trial design and procedures for a definitive RCT. The specific aims are: (1) test recruitment and retention rates and willingness to be randomised; (2) test eligibility criteria; (3) collect and analyse outcome data to inform sample and power calculations for a trial of efficacy; (4) collect economic data to inform a future economic evaluation estimating costs of treatment and (5) assess capacity of the project to scale up to a national multicentre trial. We will also gather qualitative insights from participants. It aims to recruit 32 patients with a 1:1 randomisation. Information from this feasibility study will help design a definitive trial and provide general information in designing acute gout studies.

ETHICS AND DISSEMINATION

The London-Central Ethics Committee approved the protocol. The results will be disseminated in peer-reviewed journals and at scientific conferences.

TRIAL REGISTRATION NUMBER

EudraCT No. 2015-001787-19, NCT/Clinicalstrials.gov No. NCT02578394, pre-results, WHO Universal Trials Reference No. U1111-1175-1977. NIHR Grant PB-PG-0614-34090.

Interleukin-1β, lipocalin 2 and nitric oxide synthase 2 are mechano-responsive mediators of mouse and human endothelial cell-osteoblast crosstalk

Endothelial cells are spatially close to osteoblasts and regulate osteogenesis. Moreover, they are sensitive to mechanical stimuli, therefore we hypothesized that they are implicated in the regulation of bone metabolism during unloading. Conditioned media from endothelial cells (EC-CM) subjected to simulated microgravity (0.08g and 0.008g) increased osteoblast proliferation and decreased their differentiation compared to unit gravity (1g) EC-CM. Microgravity-EC-CM increased the expression of osteoblast Rankl and subsequent osteoclastogenesis, and induced the osteoblast de-differentiating factor, Lipocalin 2 (Lcn2), whose downregulation recovered osteoblast activity, decreased Rankl expression and reduced osteoclastogenesis. Microgravity-EC-CM enhanced osteoblast NO-Synthase2 (NOS2) and CycloOXygenase2 (COX2) expression. Inhibition of NOS2 or NO signaling reduced osteoblast proliferation and rescued their differentiation. Nuclear translocation of the Lcn2/NOS2 transcription factor, NF-κB, occurred in microgravity-EC-CM-treated osteoblasts and in microgravity-treated endothelial cells, alongside high expression of the NF-κB activator, IL-1β. IL-1β depletion and NF-κB inhibition reduced osteoblast proliferation and rescued differentiation. Lcn2 and NOS2 were incremented in ex vivo calvarias cultured in microgravity-EC-CM, and in vivo tibias and calvarias injected with microgravity-EC-CM. Furthermore, tibias of botulin A toxin-treated and tail-suspended mice, which featured unloading and decreased bone mass, showed higher expression of IL-1β, Lcn2 and Nos2, suggesting their pathophysiologic involvement in endothelial cell-osteoblast crosstalk.

Pharmacokinetics and Pharmacodynamics of Canakinumab in Patients With Systemic Juvenile Idiopathic Arthritis

The characterization of the pharmacokinetic (PK) and pharmacodynamic (PD) properties in pediatric patients is essential in supporting the recommended dosage of canakinumab in the relevant population. Here the PK and PD properties of canakinumab-a monoclonal antibody-in pediatric patients with systemic juvenile idiopathic arthritis (SJIA) are presented. Blood samples were obtained from 4 phase 2/3 clinical studies in patients with SJIA. Canakinumab PK properties and total interleukin (IL)-1β kinetic properties were characterized by a population-based PK-binding model. On administration, canakinumab increased total IL-1β complex in SJIA patients. Canakinumab clearance and volume of distribution were not impacted by age in pediatric patients after correction for the patient's body weight. The estimated serum clearance of canakinumab was 0.106 ± 0.00689 L/day, with a corresponding volume of distribution at steady state of 3.2 L and an estimated half-life of 22 days, based on a model typical body weight of 33 kg. Body-weight-based dosing provided comparable canakinumab exposure across the age groups in patients 2 to <20 years with SJIA. In younger children, a modest increase in the turnover rate of IL-1β was observed. Compared to other indications, IL-1β production rate was higher and clearance was slower in patients with SJIA. Low immunogenicity incidence of 3.1% was observed, and none of the patients had neutralizing antibodies. In conclusion, the PK/PD findings further support dose selection of canakinumab in patients with SJIA.

De novo isolation of antibodies with pH-dependent binding properties

pH-dependent antibodies are engineered to release their target at a slightly acidic pH, a property making them suitable for clinical as well as biotechnological applications. Such antibodies were previously obtained by histidine scanning of pre-existing antibodies, a labor-intensive strategy resulting in antibodies that displayed residual binding to their target at pH 6.0. We report here the de novo isolation of pH-dependent antibodies selected by phage display from libraries enriched in histidines. Strongly pH-dependent clones with various affinity profiles against CXCL10 were isolated by this method. Our best candidate has nanomolar affinity for CXCL10 at pH 7.2, but no residual binding was detected at pH 6.0. We therefore propose that this new process is an efficient strategy to generate pH-dependent antibodies.

Targeting chemokines: Pathogens can, why can't we?

Chemoattractant cytokines, or chemokines, are the largest sub-family of cytokines. About 50 distinct chemokines have been identified in humans. Their principal role is to stimulate the directional migration of leukocytes, which they achieve through activation of their receptors, following immobilization on cell surface glycosaminoglycans (GAGs). Chemokine receptors belong to the G protein-coupled 7-transmembrane receptor family, and hence their identification brought great promise to the pharmaceutical industry, since this receptor class is the target for a large percentage of marketed drugs. Unfortunately, the development of potent and efficacious inhibitors of chemokine receptors has not lived up to the early expectations. Several approaches to targeting this system will be described here, which have been instrumental in establishing paradigms in chemokine biology. Whilst drug discovery programs have not yet elucidated how to make successful drugs targeting the chemokine system, it is now known that certain parasites have evolved anti-chemokine strategies in order to remain undetected by their hosts. What can we learn from them?

Interleukin-1 and acute brain injury

Inflammation is the key host-defense response to infection and injury, yet also a major contributor to a diverse range of diseases, both peripheral and central in origin. Brain injury as a result of stroke or trauma is a leading cause of death and disability worldwide, yet there are no effective treatments, resulting in enormous social and economic costs. Increasing evidence, both preclinical and clinical, highlights inflammation as an important factor in stroke, both in determining outcome and as a contributor to risk. A number of inflammatory mediators have been proposed as key targets for intervention to reduce the burden of stroke, several reaching clinical trial, but as yet yielding no success. Many factors could explain these failures, including the lack of robust preclinical evidence and poorly designed clinical trials, in addition to the complex nature of the clinical condition. Lack of consideration in preclinical studies of associated co-morbidities prevalent in the clinical stroke population is now seen as an important omission in previous work. These co-morbidities (atherosclerosis, hypertension, diabetes, infection) have a strong inflammatory component, supporting the need for greater understanding of how inflammation contributes to acute brain injury. Interleukin (IL)-1 is the prototypical pro-inflammatory cytokine, first identified many years ago as the endogenous pyrogen. Research over the last 20 years or so reveals that IL-1 is an important mediator of neuronal injury and blocking the actions of IL-1 is beneficial in a number of experimental models of brain damage. Mechanisms underlying the actions of IL-1 in brain injury remain unclear, though increasing evidence indicates the cerebrovasculature as a key target. Recent literature supporting this and other aspects of how IL-1 and systemic inflammation in general contribute to acute brain injury are discussed in this review.

Pharmacokinetic modeling of the subcutaneous absorption of therapeutic proteins

Subcutaneous injection is an important route of administration for therapeutic proteins that provides several advantages over other modes of parenteral delivery. Despite extensive clinical use, the exact mechanism underlying subcutaneous absorption of proteins is not completely understood, and the accuracy of prediction of absorption of biotherapeutics in humans remains unsatisfactory. This review summarizes a variety of models that have been developed for describing the pharmacokinetics of therapeutic proteins administered by subcutaneous injection, including single- and dual-pathway absorption models. Modeling of the lymphatic uptake and redistribution, absorption of monoclonal antibodies and insulin, and population analysis of protein absorption are discussed. The review also addresses interspecies modeling and prediction of absorption in humans, highlights important factors affecting the absorption processes, and suggests approaches for future development of mechanism-based absorption models.

Pharmacokinetics considerations for gout treatments

INTRODUCTION

Patients with gout often have comorbid conditions such as renal failure, cardiovascular disease and metabolic syndrome. The presence and required treatment of these conditions can make the treatment of gout challenging. Knowledge of the pharmacokinetics of the available drugs for the management of gout is mandatory.

AREAS COVERED

A MEDLINE PubMed search for articles published in English from January 1990 to January 2014 was completed using the terms: pharmacokinetics, colchicine, canakinumab, allopurinol, febuxostat, pegloticase, gout, toxicity, drug interaction.

EXPERT OPINION

Colchicine is a drug with a narrow therapeutic-toxicity window. Co-prescription with strong CYP3A4 or P-glycoprotein inhibitors can greatly modify its pharmacokinetics and is to be avoided. Elimination of canakinumab mainly occurs via intracellular catabolism, following receptor mediator endocytosis. Canakinumab appears to be a good alternative for patients with contraindications to colchicine, NSAIDs and corticosteroids. For patients with renal impairment, some authors recommend that the allopurinol maximum dosage should be adjusted to creatinine clearance. If the urate target cannot be achieved, the therapy should be switched to febuxostat, which is appropriate with mild-to-moderate renal failure. Anti-pegloticase antibodies affect the pharmacokinetics of the drug because they increase its clearance, with loss of pegloticase activity.