Fungal infections pose a significant threat to individuals with compromised immune systems and despite advancements in diagnosis and treatment, they continue to jeopardize patient’s health.... Show moreFungal infections pose a significant threat to individuals with compromised immune systems and despite advancements in diagnosis and treatment, they continue to jeopardize patient’s health. Maximizing the effectiveness of existing antifungal drugs is imperative. Among these, fluconazole and posaconazole are commonly prescribed to treat severe and life-threatening fungal infections. In this thesis, among others, we aimed to understand better how well different posaconazole formulations are absorbed. Through computational modeling and simulation, we learned that posaconazole is best taken with food to reduce the risk of inadequate drug absorption and subsequent therapeutic failure. This applies not only to the suspension but also to the tablet, which results in higher and more predictable absorption even though it does not achieve concentrations similar to those upon intravenous administration. Fluconazole was studied in individuals with obesity. Our findings indicate that heavier adult males may require a higher dose to achieve the desired exposure. Consequently, we proposed dosing recommendations for treating obese patients. In summary, this research, a result of the long-term collaboration between Leiden University and Radboudumc, enhanced our knowledge of factors that reduce exposure to antifungal drugs, allowing us to guide how to individualize and optimize antifungal treatment in individual patients. Show less
Particles are omnipresent in biopharmaceutical products. In protein-based therapeutics such particles are generally associated with impurities, either derived from the drug product itself (e.g.... Show moreParticles are omnipresent in biopharmaceutical products. In protein-based therapeutics such particles are generally associated with impurities, either derived from the drug product itself (e.g. protein aggregates), or from extrinsic contaminations (e.g. cellulose fibers). These impurities can affect product stability, as well as cause adverse effects once introduced into the human body. Particulate impurities are present over a wide range of sizes (from nanometers to millimeters) making them difficult to characterize by using a single method.Novel drug products may also contain particles that act as the active pharmaceutical ingredient (e.g., living cells) or a drug delivery vehicle (e.g., lipid nanoparticles). Unwanted immunotoxicity and inconsistent in vivo functionality can result from particle instability and aggregate formation. Therefore, the efficacy and safety of these therapeutics is dependent on the particle composition, quantity and size distribution.Consequently, well-established methods are required to quantify and characterize particles in the submicron- and micron-size ranges. In this thesis, we developed new approaches which allow for comprehensive characterization of the particle populations present in biopharmaceutical products, both as impurities or as API. Furthermore, the performed work focused on comparing different particle characterization techniques to allow a better understanding of the limitations and strengths of each method applied. Show less
Hoogendoorn, K.H.; Crommelin, D.J.A.; Jiskoot, W. 2021
The formulation of cell-based medicinal products (CBMPs) poses major challenges because of their complexity, heterogeneity, interaction with their environment (e.g., the formulation buffer,... Show moreThe formulation of cell-based medicinal products (CBMPs) poses major challenges because of their complexity, heterogeneity, interaction with their environment (e.g., the formulation buffer, interfaces), and susceptibility to degradation. These challenges can be quality, safety, and efficacy related. In this commentary we discuss the current status in formulation strategies of off-the-shelf and non-off-the-shelf (patient-specific) CBMPs and highlight advantages and disadvantages of each strategy. Analytical tools for the characterization and stability assessment of CBMP formulations are addressed as well. Finally, we discuss unmet needs and make some recommendations regarding the formulation of CBMPs. (C) 2020 American Pharmacists Association?. Published by Elsevier Inc. All rights reserved. Show less
The skin is our natural barrier and lipids are a key part of this barrier. In the outer skin layer, the stratum corneum (SC), lipids form a densely organized structure dependent on the composition... Show moreThe skin is our natural barrier and lipids are a key part of this barrier. In the outer skin layer, the stratum corneum (SC), lipids form a densely organized structure dependent on the composition of these lipids. Multiple skin diseases are characterized by alterations in SC lipid composition. These alterations are related to pathological barrier defects. This thesis describes the next steps towards a treatment modifying the lipid composition and thereby restoring this barrier. We developed a novel method to quantify a key SC lipid group called ceramides. This method was applied to compare SC regeneration of skin models to healthy volunteers. Regeneration in such an ex vivo skin model proved to be a potent model for formulation development. Ensuing, a clinical study was performed to determine the mechanistic effects of a formulation on barrier repair in healthy skin. The results warranted follow up analysis of the formulation in atopic dermatitis patients. This thesis also describes a detailed analysis of the ceramide fraction that is covalently attached to the cells in the SC. It was shown that a selected group of ceramides becomes bound. Further analysis showed that this group of ceramides was also affected in atopic dermatitis patients SC. Show less
Therapeutic proteins have become very successful in the treatment of various chronic and life-threatening diseases. However, besides their benefits, therapeutic proteins seem to have a common... Show moreTherapeutic proteins have become very successful in the treatment of various chronic and life-threatening diseases. However, besides their benefits, therapeutic proteins seem to have a common problem - the response of a patient’s immune system against the protein. This means that the immune system of the patient actively removes the drug from the body, thereby potentially decreasing or reversing the effect of the therapy. By now there is strong consensus that damaged and aggregated proteins are important risk factors. Protein aggregates are, due to their heterogeneity and often low quantity, challanging to characterize. Further, there is a large academic interest in understanding the mechanisms of aggregation and the role of non-proteinaceous particles in the process of protein aggregation and unwanted immunogenicity in order to design more effective and safe protein-based medicines. This PhD thesis supported that research effort by developing and improving analytical methodologies to detect the size, quantity and other properties of protein aggregates and particles, especially in the relevant nano- and micrometer size range. These techniques were then applied to study a so far unknown nanoparticulate impurity in pharmaceutical-grade sugars. Further, the results shown in this thesis revealed that these nanoparticulate impurities pose a threat to protein stability. Show less
Current seasonal influenza vaccines rely on the induction of antibodies to neutralize the virus. However, influenza viruses frequently undergo genetic mutations due to antigenic drift and shift,... Show moreCurrent seasonal influenza vaccines rely on the induction of antibodies to neutralize the virus. However, influenza viruses frequently undergo genetic mutations due to antigenic drift and shift, altering the surface proteins hemagglutinin and neuraminidase to which antibodies usually bind. This could render vaccine-induced antibody responses ineffective, resulting in an ineffective influenza vaccine. Influenza vaccines based on the induction of T cell responses might be cross-reactive, since they target conserved influenza epitopes that do not tend to mutate. However, the peptide antigens that are able to induce such T cell responses are often poorly immunogenic. In this thesis, several formulation strategies are described that could improve the immunogenicity of influenza T cell peptide antigens. Using combinations of delivery systems and immunostimulators, the peptide antigens were able to induce influenza-specific T cell responses in mice. Furthermore, a model was developed that could predict the in vitro adjuvanticity of liposomes according to the liposomal lipid composition. In addition, the recent advances in influenza vaccine development are discussed. Finally, an alternative delivery system, the Bioneedle, was evaluated for the delivery of several influenza vaccines. Show less
