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Intestinal Lipoidal Nanostructures - A Lipid Bridge to Increased Drug Delivery

Periodic Reporting for period 4 - INTESTINANOS (Intestinal Lipoidal Nanostructures - A Lipid Bridge to Increased Drug Delivery)

Reporting period: 2020-03-01 to 2020-08-31

My research program explores molecular interplay between drug, dosage form and the complex environment of the gastrointestinal tract (GIT). Drug molecules currently being discovered to cure e.g. CNS diseases, cancer and the metabolic syndrome show poor water solubility and 70-90% of recently discovered drugs have too poor solubility to allow absorption after oral intake. For such compounds the dosage form can significantly improve the absorption. A major gap in our understanding of drug performance in the intestine is the poor knowledge of the dynamics of solubilizing lipoidal nanostructures (micelles, vesicles, oil droplets) present in the fluid. This project explored restructuring of these lipoidal nanostructures in response to intake of food or dosage forms, enzymatic digestion, absorption and transit along the GIT. A novel experimental platform has been developed to reveal the impact of these nanostructures on drug solubilization, supersaturation and likelihood of precipitation in vivo, all being important for drug absorption. The enabling absorption (ENA) device, developed within INTESTINANOS, allows simultaneous assessment of dissolution, digestion and permeation in a setup mimicking the small intestine. The tool has shown good in vitro - in vivo correlation for lipid based formulations, but is also useful in understanding in vivo performance of other advanced formulation strategies such as amorphous solid dispersion. The experimental results have been fed into in silico models making use of Molecular Dynamics simulations to develop a corresponding computational platform predicting drug performance in the dynamic intestinal milieu. The virtual intestine developed within INTESTINANOS allow mechanistic understanding and molecular insights into colloidal restructuring in response to e.g. digestion or intake of a lipid-based formulations. It has till date been used to study interindividual varibility in the intestinal fluid in response to bile secretion and its role for solubilization of drugs and excipients. It has also been used to understand the role of colloidal systems in shuttling these molecules to to the intestinal wall. The novel tools designed herein now allow dosage forms to be designed and evaluated in significantly improved in silico and in vitro models Hence, optimised formulations will be possible to design prior to in vivo studies which is expected to tremendously reduce the number of animal experiments and time needed in exploration around advanced formulation design. The results of this project, in particular the novel in silico tools exploring rearrangement of lipoidal nanostructures, are highly important to related areas such as GIT disease models and food processing but also have wider applications in e.g. studies of intracellular vesicle rearrangements and transport processes in plants.
INTESTINANOS was designed as to include three different subprojects where understanding of the human intestinal fluid was the main objective in subproject 1, whereas development of improved experimental and computational models were the main objective of subproject 2 and 3. Focus of the project was on project 2 and 3, whereas project 1 was performed in collaboration with partners at KU Leuven (Prof Patrick Augustijns and colleagues) and the results were used to feed into project 3.

In project 2 we designed an assay that simultaneously assess the importance of digestion of lipid-based formulations on absorption of the formulated drug. We chose to work with Caco-2 cells, the gold standard for permeability assessment, as the absorption membrane in the assay developed. This enable detection of both passive and active transporters and their role in absorption of drugs, excipients (and digestion products thereof) as well as naturally available bile components. The chamber-based system has proven to be in vivo predictive of performance of lipid-based formulations, and has recently also shown to be useful for evaluation and head-to-head comparisons with other advanced formulation strategies. We have also showed that the designed method can be used together with cheaper artificial membranes instead of Caco-2. This is very useful for compounds where absorption is not expected to be influenced by active transporters. Through an ERC PoC grant we are also exploring the possibility to scale down the method and make it useful for automated assays.
In project 3, we designed a virtual intestine suitable for characterization of drug solubilization and formulation performance when exposed to the intestinal fluid, and the role of interindividual variability on these processes. Here, the data generated in project 1 was fed into the simulations to base the virtual intestine on real data. We have designed the virtual intestine to enable studies of the fasted and fed state. MD simulation is the backbone. To allow us to produce simulations with a relative high speed, allowing the use of the virtual intestine for future screening projects, we decided to use the coarse grain methodology. This has a lower resolution than the all atom methodology, but allow us to study processes for a longer time and/or to study larger systems; all crucial for the study of the dynamics of the intestinal fluid. Till date the virtual intestine has been used to study partitioning, solubilization of drugs and excipients, interactions with degradation products and the role of intestinal bile micelles as drug shuttles to the intestinal membrane. However, the virtual intestine is highly useful to understand food and nutrients, or other settings where colloidal rearrangements are of interest.

INTESTINANOS has delivered over expectations based on the very ambitious research program rolled out. Till date 24 scientific papers have been published, and data have been presented at 50 conferences through oral presentations, several of which being keynotes. In addition to this, a much higher number of posters and webinars have been provided by the PI and enrolled young researchers. The results achieved are also the basis for several new applications for funding, including those submitted by tenure track assistant professors in my group. Till date, the ENA and the virtual intestine have played key roles in research projects included in the Swedish Drug Delivery Center, a competence center where Uppsala University collaborates with 15 industrial partners and for which the PI is the director. Further, the experimental and computational platforms make up the foundation for research projects supported by the Swedish Research Council and NordForsk.
Our digestion-absorption system enables physiologically relevant studies not only of the lipid-based formulations but is also useful for other formulation strategies as well as for studies of e.g. food processing, performance of nutrition solutions, nutraceuticals and functional foods (to mention a few). The approach towards the virtual intestine is the first of its kind and makes it possible to computationally predict the formulation performance in vivo. The latter is expected to result in optimization of formulations in silico. The combination of improved in silico and in vitro tools is expected to reduce the number of animal and human studies an hence lower the cost for drug development through smarter dosage forms being selected in the early drug development stage.