The interplay between trehalose and dextran as spray drying precursors for cationic liposomes.

Successful oral delivery of liposomes requires formulations designed to withstand harsh gastrointestinal conditions, e.g., by converting to solid-state followed by loading into gastro-resistant delivery devices. The hypothesis was that the use of dextran-trehalose mixtures for spray drying would improve the rehydration kinetics of dried liposomes. The objectives were to determine the protective capacity of trehalose-dextran dehydration precursors and to increase the concentration of liposomes in the dry formulation volume. The study successfully demonstrated that 8.5% dextran combined with 76.5% trehalose protected CAF®04 liposomes during drying, with the liposome content maintained at 15% of the dry powder. Accordingly, the rehydration kinetics were slightly improved in formulations containing up to 8.5% dextran in the dry powder volume. Additionally, a 2.4-fold increase in lipid concentration (3 mM vs 7.245 mM) was achieved for spray dried CAF®04 liposomes. Ultimately, this study demonstrates the significance of trehalose as a primary carrier during spray drying of CAF®04 liposomes and highlights the advantage of incorporating small amounts of dextran to tune rehydration kinetics of spray-dried liposomes.

Transforming acid whey into a resource by selective removal of lactic acid and galactose using optimized food-grade microorganisms.

The presence of lactic acid and galactose makes spray drying of acid whey (AW) a significant challenge for the dairy industry. In this study, a novel approach is explored to remove these compounds, utilizing food-grade microorganisms. For removing lactic acid, Corynebacterium glutamicum was selected, which has an inherent ability to metabolize lactic acid but does so slowly. To accelerate lactic acid metabolism, a mutant strain G6006 was isolated through adaptive laboratory evolution, which metabolized all lactic acid from AW two times faster than its parent strain. To eliminate galactose, a lactose-negative mutant of Lactococcus lactis that cannot produce lactate was generated. This strain was then co-cultured with G6006 to maximize the removal of both lactic acid and galactose. The microbially "filtered" AW could readily be spray dried into a stable lactose powder. This study highlights the potential of utilizing food-grade microorganisms to process AW, which currently constitutes a global challenge.

Open source anaerobic and temperature-controlled in vitro model enabling real-time release studies with live bacteria.

In vitro release and dissolution models are widely used in the development phases of oral drug delivery systems to measure how an active pharmaceutical ingredient (API) is released from a dosage form. However, additional requirements for these models arise when evaluating probiotic dosage forms since they are often sensitive to temperature and oxygen levels. As a solution to this, we propose a custom-designed anaerobic in vitro release setup, made mainly by 3D printing and laser cutting, to function together with state-of-the-art pharmaceutical dissolution equipment - in this case, a microDISS Profiler™. The in vitro release model makes it possible to study the release rate of oxygen-sensitive probiotics in simulated intestinal conditions, while ensuring their survival due to the anaerobic conditions. This has not been possible so far since the available in vitro dissolution models have not been compatible with anaerobic conditions. With two different case studies, the developed model combined with a microDISS Profiler™ has proven capable of measuring the release of a probiotic and a small-molecule API from microdevices for oral drug delivery. Further, the model facilitated the survival of anaerobic bacteria present in the release medium.

Co-delivery of ciprofloxacin and colistin using microcontainers for bacterial biofilm treatment.

In many infected patients, bacterial biofilms represent a mode of growth that significantly enhances the tolerance to antimicrobials, leaving the patients with difficult-to-cure infections. Therefore, there is a growing need for effective treatment strategies to combat biofilm infections. In this work, reservoir-based microdevices, also known as microcontainers (MCs), are co-loaded with two antibiotics: ciprofloxacin hydrochloride (CIP) and colistin sulfate (COL), targeting both metabolically active and dormant subpopulations of the biofilm. We assess the effect of the two drugs in a time-kill study of planktonic P. aeruginosa and find that co-loaded MCs are superior to monotherapy, resulting in complete killing of the entire population. Biofilm consortia of P. aeruginosa grown in flow chambers were not fully eradicated. However, antibiotics in MCs work significantly faster than simple perfusion of antibiotics (62.5 ± 8.3% versus 10.6 ± 10.1% after 5 h) in biofilm consortia, showing the potential of the MC-based treatment to minimize the use of antimicrobials in future therapies.

3D Printed Stackable Titer Plate Inserts Supporting Three Interconnected Tissue Models for Drug Transport Studies.

Current in vitro drug screening methods often rely on single-cell models and are therefore imprecise in predicting drug absorption, distribution, metabolism, excretion, and toxicity. This study presents a method to fabricate 3D printed inserts that are compatible with commercially available titer plates. Hydrogels can be casted into the inserts and cells can be cultured either in or on the hydrogels. Once individual cell cultures are fully differentiated, the three different cell cultures are stacked on top of each other for biological experiments. To show the possibilities of this approach, three tissue models representing the first pass metabolism is used. The three tissue models are based on gelatin hydrogels and Caco-2, HUVEC, and HepG2 cells to simulate the small intestine, vascular endothelium, and liver, respectively. The device is simple to fabricate, user friendly, and an alternative to microfluidic-based organ on a chip systems. The presented first pass metabolism study allows for gaining information on drug absorption, distribution, metabolism, and, in the future, excretion in one compact device complying the micro titer plate format.

Effect of supersaturation on absorption of indomethacin and tadalafil in a single pass intestinal perfusion rat model, in the absence and presence of a precipitation inhibitor.

The effect of the degree of supersaturation (DS) on absorption of the model drugs indomethacin and tadalafil was elucidated in a single-pass intestinal perfusion (SPIP) model in rats. In addition, the performance of the precipitation inhibitor (PI) hydroxypropylmethylcellulose (HPMC) was evaluated when added at a concentration of 0.1% (w/v) to fasted state simulated intestinal fluid (FaSSIF and FaSSIFHPMC) used as perfusion medium. A supersaturated state was created by a solvent shift method where indomethacin or tadalafil dissolved in dimethyl sulfoxide (DMSO) were administered to a segment of the small intestine, which subsequently was perfused with FaSSIF or FaSSIFHPMC. The perfusate was collected for 60 min, and for one group of rats dosed with 30 mg tadalafil, for 120 min. Blood samples were drawn every 15 min. The solubility of indomethacin and tadalafil in the perfusate was determined. The DS of each drug in the perfusate was calculated by dividing the concentration in the perfusate at selected time points with the solubility. The DS was above one for all timepoints for both drugs, thus showing supersaturation during the time of perfusion. For indomethacin, no improvement of the DS was seen when perfusing with FaSSIFHPMC, compared to FaSSIF. For tadalafil, a higher DS was achieved when perfusing with FaSSIFHPMC compared to FaSSIF. Perfusing the drugs with FaSSIFHPMC resulted in a significantly lower area under the curve (AUC0-60 min) for plasma concentrations of indomethacin, and no increase in the AUC0-60 min of plasma concentrations of tadalafil compared to perfusion with FaSSIF. The importance of simultaneously estimating the intraluminal DS and absorption of a drug was demonstrated by the SPIP model in the present study. Further, the study highlights the discrepancy between optimal in vitro supersaturation, intraluminal supersaturation and in vivo performance of two poorly soluble drugs, and further emphasizes the importance of optimization of in vitro methods in order to predict in vivo supersaturation and precipitation of drugs.

Investigation of Mucoadhesion and Degradation of PCL and PLGA Microcontainers for Oral Drug Delivery.

Microfabricated devices have been introduced as a promising approach to overcome some of the challenges related to oral administration of drugs and, thereby, improve their oral bioavailability. In this study, we fabricate biodegradable microcontainers with different polymers, namely poly-ɛ-caprolactone (PCL), poly(lactic-co-glycolic acid) (PLGA) 50:50 and PLGA 75:25 by hot punching. The mucoadhesion of the microcontainers is assessed with an ex vivo retention model on porcine intestinal tissue. Finally, in vitro degradation studies of the biodegradable microcontainers are completed for six weeks in simulated intestinal medium with the addition of pancreatic enzymes. Through SEM inspection, the PLGA 50:50 microcontainers show the first signs of degradation already after two weeks and complete degradation within four weeks, while the other polymers slowly degrade in the medium over several weeks.

Ex vivo intestinal perfusion model for investigating mucoadhesion of microcontainers.

Micro fabricated delivery systems have shown promise in increasing oral bioavailability of drugs. Micrometer-sized polymeric devices (microcontainers) have the potential to facilitate unidirectional drug release directly into the intestinal mucosa whereby, drug absorption can be enhanced. The aim of this study was to develop an ex vivo model to investigate mucosal adhesion and orientation of microcontainers. Furthermore, to investigate how microcontainers with varying height, shape and material behave in regards to mucoadhesion and orientation. Microcontainers were placed at the top of an inclined piece of porcine small intestine. The tissue was perfused with biorelevant medium followed by microscopic examination to observe the orientation and amount of microcontainers on the tissue. The mucoadhesion of the microcontainers were evaluated based on the observed position on the tissue after being exposed to flow. When comparing the varying types of microcontainers, good adhesion was in general observed since most of the microcontainers were located in the beginning of the intestine. Microcontainers fabricated from the epoxy-based photoresist SU-8 had a slightly better adherence than those fabricated from poly-ɛ-caprolactone (PCL). The orientation of the microcontainers appeare to be dictated mainly by the height. In general, the model showed promising results in evaluating mucoadhesion and orientation.

Evaluation of the solid state form of tadalafil in sub-micron thin films using nanomechanical infrared spectroscopy.

Assessing physical stability of drugs is important both in the development as well as in the production phase in the pharmaceutical industry. We used nanomechanical infrared (NAM-IR) spectroscopy based on photothermal response of a nanomechanical resonator, to investigate the solid state forms of tadalafil (TAD), under various storage conditions in sub-micron thin films. The amorphous TAD was stable, when kept at normal storage conditions of 24 °C, 45% relative humidity (RH) and shielded from light, however, it crystallized after four days when it was at stress storage conditions (40 °C, 70% RH, and direct sunlight). Additionally, we found that the signals recorded with NAM-IR were comparable with the attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and that NAM-IR proved to be a suitable and time efficient method when evaluating TAD in sub 500 nm layers.