Open flow microperfusion to assess local drug concentrations in the buccal mucosa.

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Ex Vivo Human Skin Model to Study Immediate and Early Local Responses to External Stimuli.

Local responses of skin tissue to external stimuli are complex, thus exceeding the capability of in vitro methods but do not need the complexity of a whole organism to be simulated. Therefore, we established a human ex vivo skin model in our lab to study the local effects of various stimuli, such as burns and local topic treatments. In this chapter, we describe the experimental setup of the ex vivo model and additional technology of collecting dermal interstitial fluid.

Targeted nanoliposomes to improve enzyme replacement therapy of Fabry disease.

The central nervous system represents a major target tissue for therapeutic approach of numerous lysosomal storage disorders. Fabry disease arises from the lack or dysfunction of the lysosomal alpha-galactosidase A (GLA) enzyme, resulting in substrate accumulation and multisystemic clinical manifestations. Current enzyme replacement therapies (ERTs) face limited effectiveness due to poor enzyme biodistribution in target tissues and inability to reach the brain.

Opportunities of topical drug products in a changing dermatological landscape.

Despite the prevalence and the impact on quality of life of dermatological indications, drug products to treat such conditions have rarely been blockbusters. The prevailing perception of a limited commercial potential of dermatological drug products has restricted innovation and encouraged a more conservative development approach. For example, the focus was on repurposing/reformulation of existing active pharmaceutical ingredients (APIs) specifically for the topical delivery route.

Characterization of Inflammatory Mediators and Metabolome in Interstitial Fluid Collected with Dermal Open Flow Microperfusion before and at the End of Dupilumab Treatment in Atopic Dermatitis.

Dupilumab is a monoclonal antibody approved for the treatment of atopic dermatitis (AD); however, its effects on molecular, cellular, and immunological levels remain to be elucidated. In this study, blood and dermal interstitial fluid (ISF) from nonlesional (NL) and lesional (L) skin were collected from eight patients with moderate to severe AD, before (visit 2-v2) and at the end of a 16-week treatment with dupilumab (visit 10-v10). Clinical treatment effect was demonstrated by significantly decreased AD severity scores at the end of treatment.

Cutaneous pharmacokinetics-based bioequivalence: A clinical dermal open flow microperfusion verification study using lidocaine and prilocaine combination topical products.

Background: Using accurate, sensitive, reproducible and efficient in vivo cutaneous pharmacokinetics (PK)-based bioequivalence (BE) approaches can promote the development of topical generic drug products. A clinical dermal open flow microperfusion (dOFM) study has previously demonstrated the BE of topical drug products containing a hydrophilic drug. However, the utility of dOFM to evaluate the topical BE of drug products containing moderately lipophilic drugs, more representative of most topical drugs, has not yet been established.

Comparative Study of Dermal Pharmacokinetics Between Topical Drugs Using Open Flow Microperfusion in a Pig Model.

Purpose: Accurate methods to determine dermal pharmacokinetics are important to increase the rate of clinical success in topical drug development. We investigated in an in vivo pig model whether the unbound drug concentration in the interstitial fluid as determined by dermal open flow microperfusion (dOFM) is a more reliable measure of dermal exposure compared to dermal biopsies for seven prescription or investigational drugs. In addition, we verified standard dOFM measurement using a recirculation approach and compared dosing frequencies (QD versus BID) and dose strengths (high versus low drug concentrations).

Topical Delivery Systems Effectively Transport Analgesics to Areas of Localized Pain via Direct Diffusion.

Topical delivery systems (TDSs) enable the direct transport of analgesics into areas of localized pain and thus minimize the side effects of administration routes that rely on systemic drug distribution. For musculoskeletal pain, clinicians frequently prescribe topical products containing lidocaine or diclofenac. This study assessed whether drug delivery from a TDS into muscle tissue occurs mainly via direct diffusion or systemic transport.

Small volume rapid equilibrium dialysis (RED) measures effects of interstitial parameters on the protein-bound fraction of topical drugs.

The importance of plasma protein binding in the early stages of drug development is well recognized. Free and bound drug fractions in plasma are routinely determined with well-established methods. However, for physiological fluids with a small accessible volume and low protein concentrations, such as dermal interstitial fluid (dISF) validated methods are currently missing.

Quantification of the Therapeutic Antibody Ocrelizumab in Mouse Brain Interstitial Fluid Using Cerebral Open Flow Microperfusion and Simultaneous Monitoring of the Blood-Brain Barrier Integrity.

The increasing relevance of improved therapeutic monoclonal antibodies (mAbs) to treat neurodegenerative diseases has strengthened the need to reliably measure their brain pharmacokinetic (PK) profiles. The aim of this study was, therefore, to absolutely quantify the therapeutic antibody ocrelizumab (OCR) as a model antibody in mouse brain interstitial fluid (ISF), and to record its PK profile by using cerebral open flow microperfusion (cOFM). Further, to monitor the blood-brain barrier (BBB) integrity using an endogenous antibody with a similar molecular size as OCR.

Detailed pharmacokinetic characterization of advanced topical acyclovir formulations with IVPT and in vivo Open Flow Microperfusion.

Successful treatment of herpes simplex viruses is currently limited by a lack of effective topical drugs. Commonly used topical acyclovir products only reduce the duration of lesions by a few days. Optimizing topical formulations to achieve an enhanced acyclovir solubility and penetration could increase the efficacy of topically applied acyclovir, but new formulations need to show reliable acyclovir delivery into at least the epidermis/dermis and need to provide sustained acyclovir release for extended time periods.

Atraumatic access to human glioblastoma in a xenograft animal model by cerebral open flow microperfusion.

Background: Orthotopic xenograft studies promote the development of targeted/personalized therapies to improve the still poor life expectancy of glioblastoma patients.

New Method: We implemented an atraumatic access to glioblastoma with cerebral Open Flow Microperfusion (cOFM) by implantation of xenograft cells in rat brain with intact blood brain barrier (BBB) and subsequent development of a xenograft glioblastoma at the interface between the cOFM probe and surrounding brain tissue. Human glioma U87MG cells were implanted at a well-defined position into immunodeficient Rowett nude rat´s brain via cOFM (cOFM group) and syringe (control group).

In vivo monitoring of brain pharmacokinetics and pharmacodynamics with cerebral open flow microperfusion.

In vivo investigation of brain pharmacokinetics and pharmacodynamics (PK/PD) is an integral part of neurological drug development. However, drugs intended to act in the brain may reach it at very low concentrations due to the protective effect of the blood-brain barrier (BBB). Consequently, very sensitive measurement methods are required to investigate PK/PD of drugs in the brain.

Dermal open flow microperfusion for PK-based clinical bioequivalence studies of topical drug products.

Topically applied drug products have experienced an extraordinary price increase in the United States, mostly due to a lack of generic products. Generic drug development is hindered by high costs and risks associated with clinical endpoint studies required to show bioequivalence (BE) of prospective generic products relative to their reference products. There is a continued need for cost- and time-efficient alternatives to clinical endpoint studies to determine BE of topically applied dermal drug products.

ImmUniverse Consortium: Multi-omics integrative approach in personalized medicine for immune-mediated inflammatory diseases.

Immune mediated inflammatory diseases (IMIDs) are a heterogeneous group of debilitating, multifactorial and unrelated conditions featured by a dysregulated immune response leading to destructive chronic inflammation. The immune dysregulation can affect various organ systems: gut (e.g.

Advanced Online Monitoring of In Vitro Human 3D Full-Thickness Skin Equivalents.

Skin equivalents and skin explants are widely used for dermal penetration studies in the pharmacological development of drugs. Environmental parameters, such as the incubation and culture conditions affect cellular responses and thus the relevance of the experimental outcome. However, available systems such as the Franz diffusion chamber, only measure in the receiving culture medium, rather than assessing the actual conditions for cells in the tissue.

The Impact of Prolonged Inflammation on Wound Healing.

The treatment of chronic wounds still challenges modern medicine because of these wounds' heterogenic pathophysiology. Processes such as inflammation, ischemia and bacterial infection play major roles in the progression of a chronic wound. In recent years, preclinical wound models have been used to understand the underlying processes of chronic wound formation.

Optimization of topical formulations using a combination of in vitro methods to quantify the transdermal passive diffusion of drugs.

This paper describes a new approach to the early-stage optimization of topical products and selection of lead formulation candidates. It demonstrates the application of open flow microperfusion in vitro in conjunction with the Franz diffusion cell to compare time-resolved, 24-hour profiles of diclofenac passive diffusion through all skin layers (including the skin barrier, dermis, and subcutis) resulting from nine topical formulations of different composition. The technique was successfully validated for in vitro sampling of diclofenac in interstitial fluid.

miRNAs as Regulators of the Early Local Response to Burn Injuries.

In burn injuries, risk factors and limitations to treatment success are difficult to assess clinically. However, local cellular responses are characterized by specific gene-expression patterns. MicroRNAs (miRNAs) are single-stranded, non-coding RNAs that regulate mRNA expression on a posttranscriptional level.

Characterizing Cutaneous Drug Delivery Using Open-Flow Microperfusion and Mass Spectrometry Imaging.

Traditionally, cutaneous drug delivery is studied by skin accumulation or skin permeation, while alternative techniques may enable the interactions between the drug and the skin to be studied in more detail. Time-resolved skin profiling for pharmacokinetic monitoring of two Janus Kinase (JAK) inhibitors, tofacitinib and LEO 37319A, was performed using dermal open-flow microperfusion (dOFM) for sampling of perfusate in an and setup in pig skin. Additionally, matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) was performed to investigate depth-resolved skin distributions at defined time points in human skin.

OFM-recirculation and OFM-suction: advanced in-vivo open flow microperfusion (OFM) methods for direct and absolute quantification of albumin in interstitial fluid.

Objective: To implement OFM-recirculation and OFM-suction capable of direct and absolute in-vivo quantification of albumin in the ISF of pigs.

Approach: OFM-recirculation and OFM-suction were used to collect ISF in-vivo in pigs and lymph was collected from the same pigs after OFM sampling. Blood was collected before and after OFM sampling, plasma was isolated and mean albumin plasma concentrations per pig were used to yield albumin ISF-to-plasma ratios.

A novel human ex vivo skin model to study early local responses to burn injuries.

Burn injuries initiate numerous processes such as heat shock response, inflammation and tissue regeneration. Reliable burn models are needed to elucidate the exact sequence of local events to be able to better predict when local inflammation triggers systemic inflammatory processes. In contrast to other ex vivo skin culture approaches, we used fresh abdominal skin explants to introduce contact burn injuries.

Evaluating Dermal Pharmacokinetics and Pharmacodymanic Effect of Soft Topical PDE4 Inhibitors: Open Flow Microperfusion and Skin Biopsies.

Purpose: To investigate the difference in clinical efficacy in AD patients between two topical PDE4 inhibitors using dermal open flow microperfusion and cAMP as a pharmacodynamic read-out in fresh human skin explants.

Methods: Clinical formulations were applied to intact or barrier disrupted human skin explants and both skin biopsy samples and dermal interstitial fluid was sampled for measuring drug concentration. Furthermore, cAMP levels were determined in the skin biopsies as a measure of target engagement.

Variability of Skin Pharmacokinetic Data: Insights from a Topical Bioequivalence Study Using Dermal Open Flow Microperfusion.

Purpose: Dermal open flow microperfusion (dOFM) has previously demonstrated its utility to assess the bioequivalence (BE) of topical drug products in a clinical study. We aimed to characterize the sources of variability in the dermal pharmacokinetic data from that study.

Methods: Exploratory statistical analyses were performed with multivariate data from a clinical dOFM-study in 20 healthy adults evaluating the BE, or lack thereof, of Austrian test (T) and U.