Delivery of protein therapeutics is restricted to intravenous infusions due to protein-dependent problems including low solubilities, high viscosities, and physical instabilities. The ability to inject high concentrations of proteins via subcutaneous injections would increase accessibility and compliance. Large particles of a protein in a non-aqueous solvent can decrease the viscosity over a solution of equally concentrated individual protein molecules. The lower viscosity of a particle suspension is due to decreased surface area resulting in reduced electroviscous effects, solvation and deviations of the particle shape from a spherical geometry. Additional studies show that aqueous-based dispersions of antibody nanoclusters can be formed by increasing the attractive interactions between protein molecules using the excluded volume effects of extrinsic crowding agents. These novel, equilibrium, nanoclusters are maintained by a balance of highly attractive interactions and weak electrostatic repulsive interactions near the protein’s pI. These protein nanoclusters are ideal for subcutaneous delivery as they have low interactions between the colloids, are reversible in nature, and dissolve rapidly upon dilution in a buffer media. Through in vivo mouse studies, the bioavailability of a monoclonal antibody in the dispersion is prolonged and higher doses can be administered versus a solution. Overall, these studies with high concentration, low viscosity subcutaneous injections of protein therapeutics open new opportunities in biotechnology. For oral delivery of itraconzole, controlled flocculation of individual polymerically-stabilized nanoparticles is used to increase supersaturation. Flocculation of these nanoparticles is achieved by desolvating the polymer by changing the pH. The flocculated dispersions can then be easily filtered. The final amorphous powder maintains high supersaturation with simulated stomach and small intestine conditions and improves bioavailability of itraconazole, over the commercial product, Sporanox®. / text

Une nouvelle plateforme hydrogel uniquement formée par l’association de nanocapsules lipidiques (NCLs) a été développée en s’inspirant de précédents travaux utilisant une gemcitabine modifiée. Afin de limiter la toxicité de l’hydrogel, la gemcitabine a été remplacée par la cytidine, rendue amphiphile par une chaîne aliphatique (Cyt-C16). Placée à l’interface huile/eau des NCLs, la Cyt-C16 permet la formation d’un réseau tridimensionnel de NCLs à l’origine de la gélification. Un plan de mélange a permis d’optimiser les procédés de formulation de 4 tailles de NCLs modèles. Les propriétés viscoélastiques des hydrogels sont modulables. Plus les concentrations en NCLs et Cyt-C16 sont élevées, plus le gel est « rigide », indépendamment de la taille des NCLs qui doit être supérieure à 50 nm pour permettre la gélification. Les hydrogels sont injectables et permettent une libération prolongée de NCLs (de taille mono-disperse), sans toxicité supplémentaire in vitro, du fait de la présence de la Cyt-C16. De plus, uniquement solubilisée dans l’huile,la Cyt-C16 permet d’obtenir un organogel, dont les propriétés viscoélastiques sont renforcées en augmentant sa concentration. L’injection sous-cutanée (SC) in vivo des deux gels est bien tolérée et entraine une réaction inflammatoire locale comparable à celle provoquée par un excipient pharmaceutiquement acceptable. Ces deux formes pourront être utilisées pour libérer de façon prolongée différents actifs. Deux applications précliniques des hydrogels ont été explorées, l’une utilisant la voie SC pour cibler les ganglions lymphatiques, la seconde permettant un traitement local des suites opératoires d’une résection de glioblastome. / An innovative hydrogel platform obtained by the association of lipid nanocapsules (LNCs) was based on the previous work on modified gemcitabine. To limit the inherent toxicity of the hydrogel, gemcitabine was replaced by cytidine, then modified by an aliphatic chain (Cyt-C16). The hydrogel network was allowed by H-bond interactions between cytidine moieties exposed at the oil/water interfaces of LNCs. An experimental plan provided the formulation processes for 4 optimized sizes of model LNCs. The gelation was only possible for LNC sizes higher than 50 nm, and the hydrogel viscoelastic properties are versatile. The hydrogel is more “rigid” when LNC and Cyt-C16 concentrations increase, independently of the LNC size. The hydrogels are injectable and allow a sustained release of LNCs (withmonodisperse size), without additional in vitrocytotoxicity due to Cyt-C16. Moreover, when solubilized in oil, Cyt-C16 alone produced an organogel platform, whose viscoelastic properties are strengthened increasing its concentration. Both types of gels showed a good biocompatibility after an in vivo subcutaneous (SC) injection, with a local inflammatory response similar to that of induced by an approved excipient. These two forms could be used to sustain the release of various drugs, and two preclinical applications of hydrogels have been explored : one using the SC route to target lymph nodes, and the second for local treatment after glioblastoma resection.

<p>Autoinjectors are pen-like devices that typically deliver drug products of 2 mL or less. They shield the needle before and after use, reducing patient anxiety from needle phobia and mitigating the risk of needlestick injuries and accidental contamination. Additionally, automatic delivery ensures more consistent needle penetration depth and injection force than manual injection methods. </p> <p><br></p> <p>To optimize autoinjector design, this thesis presents experimentally validated computational models that describe the processes of needle insertion, drug delivery, and transport of subcutaneously administered therapeutic proteins in the body. A multi-objective optimization framework is also proposed to guide the design of autoinjectors.</p> <p><br></p> <p>This thesis focuses on spring-driven autoinjectors, the most common type of autoinjector. It begins with an overview of the interactions between the spring-driven autoinjector, tissue, and therapeutic proteins. Moving on to Chapter 2, a computational model is presented to accurately predict the kinematics of the syringe barrel and plunger during the needle insertion process.</p> <p><br></p> <p>In Chapter 3, we present a quasi-steady model for the drug delivery process, which considers the rheology of therapeutic proteins. The Carreau model is adopted to describe protein viscosity, and explicit relationships between flow rate and pressure drop in the needle are derived. Furthermore, the applicable regime for the power-law model for protein viscosity is identified.</p> <p><br></p> <p>Chapter 4 quantifies the impact of sloshing and cavitation on therapeutic proteins in the syringe. Additionally, a workflow is presented to integrate available simulation tools to predict the performance of spring-driven autoinjectors. The influence of each design parameter of spring-driven autoinjectors on their performance is also discussed. </p> <p><br></p> <p>The spring-driven autoinjector delivers therapeutic proteins through subcutaneous administration. To gain insights into the transport process of therapeutic proteins, Chapter 5 presents a physiologically-based pharmacokinetic model that has been validated against experimental data for humans and rats. The lymph flow rate significantly affects the bioavailability of therapeutic proteins. This finding highlights the importance of studying the transport of therapeutic proteins in the lymphatic system in future research.</p> <p><br></p> <p>Chapter 6 provides a multi-objective design optimization framework for the spring-driven autoinjector. The computational model is replaced with an accurate deep neural network surrogate to improve the computational efficiency.  Using this surrogate model, we conduct a sensitivity analysis to identify essential design parameters. After that, we perform multi-objective optimization to find promising design candidates.</p> <p><br></p> <p>Chapter 7 presents a model for bubble dynamics in a protein solution. An explicit expression for the bubble dissolution rate is derived, enabling extraction of the interfacial properties of the protein-coated interface from the measured bubble radii. Moreover, analytical solutions for the response of a protein-coated bubble to an imposed acoustic pressure are derived. This work provides insight into protein-coated bubbles, which are used as vehicles to deliver drugs, as active miniature tracers to probe the rheology of soft and biological materials, or as contrast agents to enhance the ultrasound backscatter in ultrasonic imaging.</p> <p><br></p> <p>At last, in Chapter 8, we introduce a model for laser-induced cavitation that considers several key factors, such as liquid compressibility, heat transfer, and non-equilibrium evaporation and condensation. Our model's predictions for the time-course of bubble radii have been validated with experimental data. Moreover, our model reveals that the reduction of the bubble's oscillation amplitude is primarily due to a decrease in the number of vapor molecules inside the bubble, highlighting the crucial role of phase change in laser-induced cavitation bubbles.</p> <p><br></p> <p>The developed computational models and framework provide crucial insights into the development of spring-driven autoinjectors and cavitation bubbles. These studies can also enhance the efficacy and safety of the delivery of therapeutic proteins, ultimately improving patient outcomes.</p>

<p>Biotherapeutics, such as monoclonal antibodies (mAbs), represent a primary mechanism for treatment of human disease, and there has been a steady increase in Food and Drug Administration approvals since the first one in 1982. Subcutaneous (SC) injection of protein-based therapeutics is a convenient and clinically established drug delivery method that increases the convenience and reduces cost compared to other delivery methods. However, progress is needed to optimize bioavailability via this route. This dissertation describes the methods for evaluation of mass transport of high molecular weight proteins, such as mAbs, following SC injection using <em>in vitro</em> and <em>ex vivo</em> modeling developed to describe the factors relevant for optimal distribution prior to uptake into systemic circulation. The first chapter describes a novel collagen and hyaluronic acid (HA) based hydrogel for investigation of macromolecule transport based on the physiochemical properties of the diffusing molecule and the tissue matrix. This initial study demonstrated that, in collagen alone, collagen combined with HA, and HA alone, the molecules demonstrated different transport paradigms dependent primarily on molecule size, matrix viscosity, and electrostatic charge, respectively. This showed that the local tissue heterogeneity and therapeutic properties could be determining factors for molecule transport and bioavailability. The second, third, and fourth chapters describe two novel platforms for the investigation of injection plume formation in SC tissue utilizing three-dimensional X-ray tomography. Injection plume analysis has been studied comprehensively in the context of insulin transport using co-injection of radiopaque dyes to track the protein distribution. However high molecular weight therapeutics have vastly different physiochemical properties than insulin and are injected under different rates, concentrations, volumes, and viscosities due to dosing considerations. To address the gap mAb distribution, we first developed a novel protein conjugated to an x-ray contrast agent to directly track injection plume formation and investigated the effects of injection rate and tissue location through injections into ex vivo porcine tissue, described in chapters three and four. Ex vivo tissue analysis showed that the rate did not influence the distribution, however, plume volume was lower in porcine belly compared to neck tissue. Whereas porcine tissue is an excellent model to represent the structural features of human injection, the large heterogeneity between animal subjects and collected samples is a disadvantage. Therefore, the fourth chapter describes the fabrication of a gelatin hydrogel-based injection platform representing the dermal and subcutaneous tissue layers for controlled injection plume analysis. In summary, all three models represent useful platforms for the assessment of macromolecular mass transport, pharmaceutical autoinjector performance, as well as the potential impact of tissue properties and intersubject heterogeneity on plume formation. Overall, the findings in these studies might better inform drug designers and clinicians on how to most optimally engineer an injection to deliver the most efficient patient outcomes through better dosing and increased cost savings. </p>

<p>The overall time and cost for a drug to go from the drug discovery to the consumer market is  significant,  showing  a  need  for  improved  drug  testing  and  discovery  methods.    Work  on nonlinear  optical  methods  for  both  small  active  pharmaceutical  ingredient  drug  formulation analysis and large biological therapeutic stability testing has been shown to improve testing times for formulation, stability and dissolution testing.  Herein, we review the existing and conventional approaches to address stability testing that the pharmaceutical industry uses, and how leveraging nonlinear optical (NLO) methods can improve the current challenges.  The specificity, sensitivity and low limit of detection of second harmonic generation is discussed in application to crystal formation in small-molecule active pharmaceutical ingredients.  The nonlinear optical methods second harmonic generation and two-photon excited ultraviolet fluorescence are directly compared to  ‘gold  standard’  powder  X-ray  diffraction,  which  is  commonly  used  for  measuring  crystal formation and growth of active pharmaceutical ingredients in amorphous solid dispersions.  In addition, the existing FRAP method (with multiple limitations) is improved upon with the ability to  perform  recovered  diffusion  coefficient  data  analysis  in  the  spatial  Fourier  domain.    The collective results discussed in this thesis are just a small subset of the total breadth of investigations marrying the new challenges in the pharmaceutical industry with the new NLO tools tailored to meet them</p>

<p dir="ltr">Subcutaneous injection for self-administration of biotherapeutics, such as monoclonal antibodies (mAbs), is becoming increasingly prominent within the pharmaceutical sector due to its benefits in patient compliance and cost-effectiveness. The success of this drug delivery process depends on the coupled mechanical and transport phenomena within the subcutaneous tissue, both during and after the injection. Yet, the details of these processes are not well-elucidated, sparking a surge in computational efforts to fill this knowledge gap. Remarkably, there are very few computational studies on subcutaneous injection into three-dimensional porous media that account for large tissue deformations, drug transport and absorption, the use medical devices, and human factors. Here, we develop a high-fidelity computational framework to study large-volume subcutaneous injection of mAbs. Our investigation begins with a linear poroelastic model without drug transport, which we employ to study the effect of tissue deformation on injection dynamics. We progressively enhance this model, advancing to a nonlinear porohyperelastic framework that include drug transport and absorption. To capture the anisotropy of subcutaneous tissue, we employ a fibril-reinforced porohyperelastic model. Furthermore, we integrate the multi-layered structure of skin tissue by creating data-driven geometrical models of the tissue layers derived from histological data. Our analysis explores the impact of different handheld autoinjectors on the injection dynamics for various patient-applied forces. We investigate the effect of different pre-injection techniques, such as the pinch and stretch methods, on the drug transport and absorption. Additionally, we evaluate the impact of several physiological variables, including flow rate, injection depth, and body mass index. Our simulations yield crucial insights essential for comprehending and improving subcutaneous drug administration of mAbs. Additionally, they offer a deeper understanding of the human aspect of the injection procedure, thereby paving the way for advancements in the development of patient-centered injection devices and techniques.</p>

<p>Subcutaneous administration has become a common approach for drug delivery of biotherapeutics, such as monoclonal antibodies, which is achieved mainly by absorption through the lymphatic system. This dissertation focuses on the computational modeling of the fluid flow and solute transport in the skin tissue and the quantitative investigation of lymphatic uptake. First, the various mechanisms governing drug transport and lymphatic uptake of biotherapeutics through subcutaneous injection are investigated quantitatively through high-fidelity numerical simulations, including lymphatic drainage, blood perfusion, binding, and metabolism. The tissue is modeled as a homogeneous porous medium using both a single-layered domain and a multi-layered domain, which includes the epidermis, dermis, hypodermis (subcutaneous tissue), and muscle layers. A systematic parameter study is conducted to understand the roles of different properties of the tissue in terms of permeability, porosity, and vascular permeability. The role of binding and metabolism on drug absorption is studied by varying the binding parameters for different macromolecules after coupling the transport equation with a pharmacokinetic equation. The interstitial pressure plays an essential role in regulating the absorption of unbound drug proteins during the injection, while the binding and metabolism of drug molecules reduce the total free drugs. </p> <p>  </p> <p>The lymphatic vessel network is essential to achieve the functions of the lymphatic system. Thus, the drug transport and lymphatic uptake through a three-dimensional hybrid discrete-continuum vessel network in the skin tissue are investigated through high-fidelity numerical simulations. The explicit heterogeneous vessel network is embedded into the continuum model to investigate the role of explicit heterogeneous vessel network in drug transport and absorption. The solute transport across the vessel wall is investigated under various transport conditions. The diffusion of the drug solutes through the explicit vessel wall affects the drug absorption after the injection, while the convection under large interstitial pressure dominates the drug absorption during the injection. The effect of diffusion cannot be captured by the previously developed continuum model. Furthermore, the effects of injection volume and depth on the lymphatic uptake are investigated in a multi-layered domain. The injection volume significantly affects lymphatic uptake through the heterogeneous vessel network, while the injection depth has little influence. At last, the binding and metabolism of drug molecules are studied to bridge the simulation to the experimentally measured drug clearance. </p> <p><br></p> <p>Convective transport of drug solutes in biological tissues is regulated by the interstitial fluid pressure, which plays a crucial role in drug absorption into the lymphatic system through the subcutaneous (SC) injection.  An approximate continuum poroelasticity model is developed to simulate the pressure evolution in the soft porous tissue during an SC injection. This poroelastic model mimics the deformation of the tissue by introducing the time variation of the interstitial fluid pressure. The advantage of this method lies in its computational time efficiency and simplicity, and it can accurately model the relaxation of pressure. The interstitial fluid pressure obtained using the proposed model is validated against both the analytical and the numerical solution of the poroelastic tissue model. The decreasing elasticity elongates the relaxation time of pressure, and the sensitivity of pressure relaxation to elasticity decreases with the hydraulic permeability, while the increasing porosity and permeability due to deformation alleviate the high pressure. </p> <p><br></p> <p>At last, an improved Kedem-Katchalsky model is developed to study solute transport across the lymphatic vessel network, including convection and diffusion in the multi-layered poroelastic tissue with a hybrid discrete-continuum vessel network embedded inside. The effect of different drug solutes with different Stokes radii and different structures of the lymphatic vessel network, such as fractal trees and Voronoi structure, on the lymphatic uptake is investigated. The drug solute with a small size has a larger partition coefficient and diffusivity across the openings of the lymphatic vessel wall, which favors drug absorption. The Voronoi structure is found to be more efficient in lymphatic uptake. </p> <p><br></p> <p>The systematic and quantitative investigation of subcutaneous absorption based on high-fidelity numerical simulations can provide guidance on the optimization of drug delivery systems and is valuable for the translation of bioavailability from the pre-clinical species to humans. We provide a novel approach to studying the diffusion and convection of drug molecules into the lymphatic system by developing the hybrid discrete-continuum vessel network. The study of the solute transport across the discrete lymphatic vessel walls further improves our understanding of lymphatic uptake. The novel and time-efficient computational model for solute transport across the lymphatic vasculature connects the microscopic properties of the lymphatic vessel membrane to macroscopic drug absorption. The comprehensive hybrid vessel network model developed here can be further used to improve our understanding of the diseases caused by the disturbed lymphatic system, such as lymphedema, and provide insights into the treatment of diseases caused by the malfunction of lymphatics.</p>