Celecoxib was used as a model compound in fasted state simulated colonic fluid (FaSSCoF) to investigate equilibrium drug solubility (Seq), protein binding using rapid equilibrium dialysis (RED), flux and permeability (Papp) across porcine colonic mucus (PCM), and in vivo colonic absorption using a rat intracolonic instillation model. The primary focus was on the role of bovine serum albumin (BSA) as a solubilizing and binding constituent, while bile salts (sodium taurodeoxycholate, TDC) with lecithin and poloxamer 407 were included as comparative systems to evaluate how differences in solubilizer type influence celecoxib permeability and absorption. BSA demonstrated a pronounced solubilizing effect on celecoxib with a 1:1 molar binding ratio, increasing the apparent Seq from 5.1 µg/mL to 92 µg/mL in FaSSCoF containing 15 mg/mL BSA. Under these conditions, diffusion across PCM increased approximately seven-fold compared with FaSSCoF without BSA, accompanied by a four-fold increase in colonic absorption in vivo. In contrast, when celecoxib concentration was maintained constant and BSA was subsequently added to FaSSCoF, diffusion across PCM decreased up to ten-fold at BSA concentrations of 1.5 mg/mL, accompanied by an approximately 30% decrease in colonic absorption in vivo. This behavior is consistent with an increased BSA-bound fraction and a reduced free drug concentration available for transport. The addition of TDC with lecithin or poloxamer 407 similarly increased celecoxib diffusion across PCM and colonic absorption when celecoxib was dissolved at Seq in FaSSCoF, although no statistically significant differences were observed between the solubilizing systems. Overall, these findings demonstrate that solubilizing constituents in colonic fluids can substantially increase drug solubility, mucus permeation, and colonic absorption, highlighting the importance of accounting for protein–drug interactions when evaluating drug behavior in the colon.

This study evaluated Apis mellifera brood fat extracts as a sustainable alternative to beeswax for anti-inflammatory topical delivery, including their formulation into nanostructured lipid carriers (NLCs). Brood fat was extracted using acetone, ethyl acetate (EA), and hexane, and the resulting extracts were characterized for fatty acid composition and physicochemical properties. Safety was assessed using the hen's egg chorioallantoic membrane test and cytotoxicity testing in RAW 264.7 macrophages. Anti-inflammatory activity was assessed by inhibition of lipopolysaccharide-induced interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) production. The most suitable extract was formulated into NLCs using sugar squalane as liquid lipid, and the effects of lipid ratio and preparation method were investigated. The results showed that the ethyl acetate extract had the highest yield. Compared with beeswax, all fat extracts exhibited a favorable oleic acid-rich fatty acid profile with comparable crystallinity and thermal behavior, while showing significantly enhanced anti-inflammatory activity (p < 0.05). All extracts and their NLCs were non-irritating and non-cytotoxic. Ethyl acetate extract-based NLCs exhibited favorable particle sizes (72.1 ± 0.3 nm) and narrow polydispersity (0.14 ± 0.00), with high-pressure homogenization producing smaller particles compared to probe sonication without affecting IL-6 or TNF-α inhibition. Therefore, A. mellifera brood fat extract is a sustainable anti-inflammatory lipid source with strong potential as an alternative to beeswax in topical nano-formulations.

Abstract Unraveling the structural evolution of organic crystals during dehydration remains a formidable challenge, particularly for phases obtained through rapid precipitation or those exhibiting reversible dehydration behavior. Here, we demonstrate that the intrinsic high-vacuum environment of three-dimensional electron diffraction (3D ED) can be leveraged as a transformative strategy for driving dehydration. Using tailored 3D ED methodologies, we first identified three novel osimertinib hydrate polymorphs (α, β and γ), their moisture-sensitive dehydrated forms (VI, V and III), and form II from phase transition of VI, while directly capturing dehydration reversibility. While α and β were characterized by SCXRD, the determination of microcrystalline γ, II, and moisture-sensitive dehydrated forms required strategic environmental control. Cryogenic 3D ED preserves hydrates, whereas the diffractometer vacuum induces in situ dehydration, enabling full structural elucidation. Reversibility from VI to α was confirmed by cryo-transfer reanalysis after air exposure, from V to β and III to γ by PXRD. Theoretical analysis revealed dehydration pathways of reconstruction, anisotropic layer-expansion and template-retentive contraction, dictated by initial hydrate architecture. Both reversibility and dehydration kinetics arise from thermodynamically metastable anhydrates retaining key structural features. Our strategy, combining vacuum-driven dehydration with cryogenic conditions for hydrates and reversibility validation, offers a generalizable platform for capturing moisture-sensitive materials and monitoring solid-state reactions.

Approved mRNA vaccines administered intramuscularly (i.m.) induce strong systemic immune responses, but provide limited protection at the respiratory mucosa, where many infections are initiated. Designing safe and efficacious mucosal vaccines is challenging because it requires vaccine administration at the mucosa that is equipped with protective barriers and characterized by tolerogenic predominance. Here we show that i.m. prime immunization of mice with lipid nanoparticles (LNPs) loaded with mRNA encoding the SARS-CoV-2 spike protein, followed by pulmonary pull immunization with either mRNA-LNPs or spike protein adjuvanted with cationic adjuvant formulation (CAF)01 induce high systemic immune responses and virus-neutralizing spike-specific antibody responses in the lungs. However, only pulmonary pull immunization with CAF01-adjuvanted spike protein induces spike-specific mucosal antibody and lung-resident T-cell responses in the respiratory tract. This suggests that i.m. priming of strong immune responses with mRNA-LNPs combined with mucosal pull immunization with a subunit vaccine can re-direct the immune response to the respiratory mucosa.

Background: Plant-derived essential oils possess valuable bioactivities, but their application is limited by volatility and irritation, which may be addressed through natural polymer encapsulation. This study aimed to investigate the bioactivity of Hedychium coronarium rhizome essential oil and evaluate the effect of microencapsulation on its physicochemical characteristics, biological stability, and irritation profile. Methods: Essential oil was extracted from H. coronarium rhizomes by hydrodistillation and chemically characterized. Enzyme inhibitory activities against elastase, hyaluronidase, and tyrosinase were assessed. Microencapsulation was performed using gum Arabic or maltodextrin at 1–5% w/w oil loadings. The resulting powders were evaluated for morphology, entrapment efficiency, hygroscopicity, water activity, biological stability, and irritation potential using the hen’s egg test on the chorioallantoic membrane. Results: The essential oil demonstrated strong enzyme inhibition, particularly against hyaluronidase (IC50 = 0.1 ± 0.0 µg/mL), along with notable elastase and tyrosinase inhibition. Encapsulation significantly reduced irritation scores from 13.3 ± 1.4 for the free oil to 3.6–4.2 for encapsulated systems (p < 0.05). Gum Arabic produced rough, porous particles with lower hygroscopicity, while maltodextrin yielded smoother particles with lower water activity. Both encapsulated powders significantly enhanced biological stability compared with the ethanolic solution. Conclusions: Natural polymer-based microencapsulation effectively reduced the irritation potential and improved the handling properties of H. coronarium essential oil, supporting its potential application in topical bioactive delivery systems.

This study aimed to investigate the cosmeceutical effects of cricket extracts and assess their delivery through a nanoemulsion system. Different species of crickets (Gryllus bimaculatus, Teleogryllus mitratus, and Acheta domesticus) were freeze-dried, defatted, and extracted using aqueous, enzyme-assisted, and protein isolation methods. Extracts were evaluated for total protein content, amino acid composition, anti-tyrosinase, and anti-hyaluronidase activities. The most bioactive extract was incorporated into an oil-in-water nanoemulsion, which was characterized for droplet size, polydispersity index (PDI), zeta potential, morphology, entrapment efficiency (EE), release profile, in vitro permeation and retention. The Subtilisin A-assisted extract of T. mitratus (TMS) contained the highest protein content (76.0 ± 1.1% w/w) and potent bioactivity, with tyrosinase IC50 values of 65.4 ± 6.9 μg/mL (L-tyrosine) and 395.9 ± 77.2 μg/mL (L-DOPA), and an anti-hyaluronidase IC50 of 12.5 ± 3.5 μg/mL. Nanoemulsion incorporation achieved 46.36 ± 1.69% EE and 0.20 ± 0.01% loading capacity, with nanoscale droplet sizes (288.3 ± 11.3 nm) and high stability (PDI < 0.3; zeta potential < -30 mV). Therefore, the TMS-loaded nanoemulsion provided multifunctional cosmeceutical benefits.

This study aimed to enhance the topical delivery of Teleogryllus mitratus protein hydrolysate (TM) by forming hydrophobic ion-pair (HIP) complexes with dioctyl sodium sulfosuccinate (DS) and incorporating them into lipid-based nanocarriers. TM was extracted via an enzyme-assisted method and complexed with DS to form TM-HIP. Chitosan nanoparticles (CNP), nanoemulsions (NE), and nanostructured lipid carriers (NLC) containing TM or TM-DS were prepared and characterized for particle size, polydispersity, zeta potential, encapsulation efficiency (EE), loading capacity (LC), and in vitro release. Membrane retention was assessed using Strat-M® membranes in Franz diffusion cells. The results showed that TM successfully formed a HIP complex with DS, resulting in an increased diffusion coefficient. All nanocarriers exhibited nanoscale particle sizes (∼70-300 nm), narrow distributions (PDI 0.17-0.26), and stable zeta potentials (-30 to -37 mV). Lipid-based nanocarriers containing TM-DS demonstrated the highest EE (TM-DS-NE: 76.8 ± 0.5%; TM-DS-NLC: 81.9 ± 2.4%) and sustained release, while CNP showed lower EE (17.6 ± 3.1%). Membrane retention studies revealed that TM-DS-NE (49.9 ± 0.7 μg/cm2) and TM-DS-NLC (50.1 ± 3.1 μg/cm2) achieved significantly higher protein deposition than TM-CNP (1.6 ± 0.8 μg/cm2), TM-NE (6.4 ± 1.2 μg/cm2), TM-NLC (9.2 ± 1.7 μg/cm2), or TM solution (1.2 ± 0.7 μg/cm2), with NLC identified as the most effective carrier. Therefore, it can be concluded that hydrophobic ion-pairing of TM with DS enhanced compatibility with lipid-based nanocarriers, resulting in improved encapsulation and membrane retention. The combination of protein lipophilicity, carrier composition, and nanoscale size effectively promoted delivery into the Strat-M® membranes. Further clinical studies are recommended to validate efficacy and safety under physiologically relevant conditions.

Salmon calcitonin (sCT) is a peptide with poor enzymatic stability and permeability, limiting its oral delivery. This study investigated how hydrophobic ion pair (HIP) type and self-nanoemulsifying drug delivery systems (SNEDDS) composition influence the oral delivery of sCT, and whether in vitro findings correlate with in vivo outcomes. HIPs were prepared with sodium caprate (C10) or sodium docusate (DOC) and incorporated into two SNEDDS differing in a single excipient: F1 contained 10% lysophosphatidylcholine (LPC), a natural permeation enhancer, while F2 replaced LPC with propylene glycol. In vitro, sCT:C10 provided no protection against trypsin, whereas sCT:DOC did (p < 0.05 vs native sCT). Incorporating HIPs into SNEDDS enhanced sCT proteolytic stability against trypsin relative to native sCT, but the extent was formulation-dependent, with F1 showing lower protection than F2 for the same HIP. Permeability in Caco-2 cells was mainly driven by SNEDDS, with F1 consistently showing lower FD4 transport than F2, indicating no additional benefit from LPC. In vivo, sCT:C10 showed no significant difference in relative pharmacological activity (PArel) over native sCT, whereas sCT:DOC significantly increased activity. HIP-loaded SNEDDS enhanced sCT activity compared with native sCT, yet F1 did not improve activity beyond F2. Among all groups, sCT:DOC in F2 achieved the highest PArel (8.8 ± 0.8%), indicating more favourable conditions for sCT oral delivery. In addition, in vitro trends correlated well with in vivo outcomes. Overall, HIP type and SNEDDS composition significantly influenced oral sCT delivery, highlighting the need to co-optimize these parameters to achieve effective oral peptide delivery.

Rosemary (Rosmarinus officinalis L.) is a rich source of rosmarinic acid (RA), a bioactive compound with strong in vitro evidence supporting its cosmeceutical potential. However, RA has moderate polarity (log P = 1.7), which limits its skin penetration. This study aimed to identify formulations and application methods capable of delivering RA into the skin at cosmetically relevant concentrations while minimizing systemic absorption. Rosemary extract containing RA (76% w/w) was characterized for solubility and incorporated into various liquid formulations, including an aqueous solution, propylene glycol solution, an oil-in-water (o/w) nanoemulsion, and a water-in-oil (w/o) nanoemulsion. Dissolving microneedle (DMN) patches containing the liquid formulations were also fabricated and evaluated. Three delivery strategies were compared: (i) liquid formulations applied to intact skin, (ii) liquid formulations applied after pretreatment of the skin with a metal microneedle (MMN) device, and (iii) DMN patches applied to intact skin. Among these, DMN patches loaded with rosemary extract (DMN-F1) achieved significantly lower transdermal permeation (0.99 ± 0.16%) than when an aqueous RA solution was applied to the skin after MMN pretreatment (56 ± 13%), but a higher skin retention (1.51 ± 0.05%) compared with rosemary extract aqueous solution applied to intact skin (0.24 ± 0.05%). Overall, the application of RA-loaded DMN patch to the skin proved the most effective approach, enabling efficient dermal delivery of RA while reducing transdermal delivery and, hence, potentially also systemic absorption. These findings highlight DMNs as a promising delivery platform for rosemary extract in anti-aging cosmetic applications.

The barrier properties of the skin constitute a major challenge to topical drug delivery, motivating strategies to increase transmembrane flux. This study evaluates a multiple prodrug approach using salicylic acid and eight structurally related salicylate esters as a model system, hypothesising that saturated suspensions of several prodrugs could maximise thermodynamic activity and enhance total salicylic acid flux. Saturated aqueous suspensions of single, binary, and quinary prodrug systems were prepared to achieve maximal thermodynamic activity and permeation. Steady-state flux across silicone membranes was evaluated using a side-by-side diffusion cell setup under sink conditions. Solid-state characterisation by XRPD and DSC confirmed the presence of pure crystalline prodrug phases, while solubility was assessed using the shake-flask method. Prodrug solubility in multi-prodrug systems was generally unchanged or decreased, the latter indicating non-ideal solution behaviour. Individual prodrug fluxes were often reduced when co-administered with one or more prodrugs, with additive fluxes observed in 1/8 binary systems. However, total salicylic acid flux increased significantly in 2/8 binary and 2/3 quinary systems compared to the highest-performing single prodrug. Results showed that the prodrug solubilities did not govern the membrane flux. These findings suggest that, beyond thermodynamic activity, interactions affecting membrane partitioning play a key role in flux. The multiple prodrug strategy shows potential to enhance topical delivery, but its effective implementation would depend on balancing increased total flux with formulation complexity arising from non-ideal behaviour and intermolecular interactions.

Acheta domesticus protein hydrolysate (PH) is a natural anti-skin aging compound, but its effectiveness is hindered by poor skin penetration due to its hydrophilicity and high molecular weight. This study aimed to compare the enhancement of PH skin delivery by increasing lipophilicity with nanostructured lipid carriers (NLCs) and bypassing the skin barrier using physical techniques, including Derma Stamp and dissolving microneedles (MNs). Fluorescein isothiocyanate (FITC)-tagged PH was prepared to track the transdermal transport, and complexed with dioctyl sodium sulfosuccinate (DSS) to be encapsulated into NLCs, prepared using a melt emulsification method. Skin delivery was evaluated in terms of skin permeation and skin retention using Franz diffusion cells. The FITC-PH loaded NLCs had a particle size of 238.9 f 0.8 nm, a polydispersity index of 0.3 f 0.0, a zeta potential of -23.6 f 1.0 mV, and an encapsulation efficiency of 65.1 f 2.1 %. The MNs, prepared with polyvinylpyrrolidone K30 and polyvinyl alcohol (38:15 wt ratio), had uniform sharp needles and a high FITC-PH loading capacity of 97.2 f 1.9 %. PH permeation was most effectively enhanced through physical barrier bypassing, particularly with the Derma Stamp, followed by MNs and finally due to incorporation into NLCs. Notably, when utilizing the Derma Stamp, converting the aqueous solution of PH into an NLC formulation added positive benefits by significantly improving skin retention. In conclusion, it was suggested that while physical enhancement methods are crucial for permeation of the PH, optimizing formulation characteristics, such as incorporation into NLCs, further increased the overall effectiveness of skin delivery.

Bovine colostrum is a bioactive compound with potential in cosmetic applications but has a limited shelf life. This study aimed to develop an effective encapsulation system for bovine colostrum using the complex coacervation method and incorporate it into powder formulations for facial masks. The research explored various gelatin-to-gum Arabic ratios to optimize the physical and chemical stability, encapsulation efficiency, and loading capacity of the encapsulated bovine colostrum (EBC). The EBC was further incorporated into powder formulations for clay masks, peel-off gel masks, and sleeping gel masks. The optimal gelatin-to-gum Arabic ratio was found to be 2:1, yielding the highest entrapment efficiency (66.6 ± 3.3% w/w) and loading capacity (67.6 ± 3.4% w/w) of bovine colostrum. For clay masks, the most effective powder blend incorporating EBC enhanced the moisture content, water solubility, and hygroscopicity, without affecting the drying time (9.7 ± 0.6 min). Additionally, peel-off gel masks incorporating EBC significantly reduced water activity and improved moisture content and hygroscopicity, while the drying time decreased from 44.3 ± 0.6 to 25.0 ± 1.7 min. For sleeping gel masks, the formulation with EBC increased water activity, while other parameters remained stable. In conclusion, the EBC with enhanced stability was effectively integrated into various powders for facial mask formulations.

Background: It is generally accepted that water as a plasticizer can decrease the glass transition temperatures (Tgs) of amorphous drugs and drug delivery systems, resulting in physical instabilities. However, a recent study has reported an anti-plasticizing effect of water on amorphous lidocaine (LID). In co-amorphous systems, LID might be used as a co-former to impair the plasticizing effect of water. Method: Flurbiprofen (FLB) was used to form a co-amorphous system with a mole fraction of LID of 0.8. The effect of water on the stability of co-amorphous FLB-LID upon hydration was investigated. The crystallization behaviors of anhydrous and hydrated co-amorphous FLB-LID systems were measured by an isothermal modulated differential scanning calorimetric (iMDSC) method. The relaxation times of the co-amorphous FLB-LID system upon hydration were measured by a broadband dielectric spectroscopy (BDS), and the differences in Gibbs free energy (ΔG) and entropy (ΔS) between the amorphous and crystalline phases were determined by differential scanning calorimetry (DSC). Results: It was found that the crystallization tendency of co-amorphous FLB-LID decreased with the addition of water. Molecular mobility and thermodynamic factors were both investigated to explain the difference in crystallization tendencies of co-amorphous FLB-LID upon hydration. Conclusions: The results of the study showed that LID could be used as an effective co-former to decrease the crystallization tendency of co-amorphous FLB-LID upon hydration by enhancing the entropic (ΔS) and thermodynamic activation barriers (TΔS)3/ΔG2) to crystallization.

Rosa damascena Mill., widely recognized for its remarkable skincare benefits, is extensively used in the cosmeceutical industry. This study introduces a novel green approach to extract bioactive compounds from R. damascena for cosmeceutical applications while also evaluating its stability in terms of physical, chemical, and biological properties. R. damascena petals were extracted using deionized water instead of organic solvents, using various green extraction methods, including infusion, microwave, ultrasound, pulsed electric field, and micellar extraction. Their chemical composition was analyzed using high-performance liquid chromatography. The extract with the highest concentration of bioactive compounds was further evaluated for its cosmeceutical properties and stability and compared with its individual chemical components. Various factors influencing stability were evaluated, including pH level (5, 7, and 9), temperature (4 °C, 30 °C, and 45 °C), and light exposure. The findings indicate that the extract obtained through microwave-assisted extraction (MAE) contained the highest concentration of bioactive constituents, with corilagin being the most abundant, followed by cyanidin-3,5-O-diglucoside, gallic acid, ellagic acid, L-ascorbic acid, and rutin, respectively. Additionally, MAE exhibited excellent antioxidant, whitening, and anti-skin-aging effects, demonstrating significantly higher activities than both the positive control (L-ascorbic acid for antioxidant effects, kojic acid for anti-tyrosinase effects, and epigallocatechin gallate and oleanolic acid for anti-skin-aging effects) and the individual chemical constituents. However, the physico-chemical and biological stability of MAE was influenced by pH, temperature, and light exposure, and as such, light-protected and controlled temperature (not exceeding 30 °C) is essential to maintain the extract’s efficacy in skincare products, and optimal formulation strategies are strongly recommended to ensure long-term stability.

In this proof-of-concept study, we aimed to develop an anti-inflammatory patch that in contrast to the semi-solid standard therapy is dry and non-greasy, and only needs to be changed once a day due to continuous release of the active ingredient over 24 h. While fiber materials for the treatment of inflammatory skin diseases have been reported in the literature, the majority of studies focuses solely on material characterization including in vitro release studies; however, there is a lack of ex vivo permeation studies as well as comparison with standard therapy. However, such experiments are crucial to deduct the potential efficacy of the drug delivery system, as skin absorption of the drug may be the rate-limiting step and not the drug release. Therefore, we set out to investigate different types of electrospun fiber systems based on polycaprolactone, a polymer with a well-established safety profile widely used for fabricating electrospun patches. The electrospun fiber patches were loaded with the anti-inflammatory drug hydrocortisone and characterized not only for their drug release properties, but for the first time also for their skin permeation and retention as well as their cytocompatibility and anti-inflammatory properties on human skin. While in the release studies, the layer-by-layer fiber system proved to be best suited for an application time of 24 h, this was not reflected in the permeation studies, where all fiber systems showed a similar skin permeation and retention of the drug. In our study set-up, a comparison with standard cream formulations revealed that electrospun fibers offer an advantage in terms of the permeated amount of hydrocortisone. Overall, this study supports the importance of conducting comparisons with standard therapies and, additionally, confirms that electrospun fibers are a promising dosage form for the controlled release of anti-inflammatory drugs for the treatment of inflammatory skin diseases.

Messenger RNA (mRNA) vaccines based on lipid nanoparticles (LNPs) are stabilized with cholesterol, which is thought to be a critical LNP component because it is essential for membrane integrity and endosomal escape. Here, it is shown that cholesterol in LNPs can be replaced with an immunopotentiating lipid, i.e., a synthetic analogue of the C-type lectin receptor agonist monomycoloyl glycerol (MMG-1), without compromising physicochemical properties, in vivo transfection efficiency, and immunogenicity of the mRNA-loaded LNPs (mRNA-LNPs). Replacement of cholesterol with MMG-1 results in LNPs that mediate intracellular delivery of mRNA, which is translated into high levels of protein in vivo. Replacement of cholesterol with MMG-1 in LNPs improves the transfection efficiency in T cells, B cells, and macrophages in the spleen and lymph nodes of mice. In mice, MMG-1-based LNPs loaded with mRNA encoding the spike (S) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induce S-specific CD8+ T-cell responses and virus-neutralizing antibody responses, which are on par with the responses induced by cholesterol-based LNPs. Upon vaccination and a subsequent SARS-CoV-2 challenge of Syrian golden hamsters, replacement of cholesterol with MMG-1 in mRNA-LNPs enhances S-specific immunoglobulin G titers and reduces the SARS-CoV-2 load in the nasal cavity. These findings provide insights for improved design of LNPs for mRNA vaccine delivery.

The formation of a biomolecular corona on nanoparticles in blood is a well-known phenomenon influencing in vivo performance. Analogous phenomena in other biological fluids, such as the formation of a gastrointestinal (GI) corona, remain under-investigated. The ingestion of medicines leads to the generation of drug particles in the GI fluids. Consequently, an understanding of the behavior of drug particles in the gut requires determination of the adsorption of bile components onto these drug particles. This work aims to elucidate the factors affecting adsorption of bile salts onto ritonavir (RTV) particles. Crystalline RTV particles were incubated with non-micellar or micellar bile salts and bile salt depletion from solution was measured using HPLC and small angle X-ray scattering (SAXS). HPLC results show that bile salts adsorb onto RTV particles, with greater adsorption observed for more hydrophobic bile salts, following the order sodium glycodeoxycholate (SGDC)>sodium taurodeoxycholate (STDC)>sodium glycochenodeoxycholate SGCDC>sodium glycocholate (SGC)>sodium taurocholate (STC). Increasing the ionic strength of the solution led to increased adsorption of STDC, where buffer containing 300 mM NaCl resulted in greater adsorption than 150 mM NaCl. Additionally, micellar bile salts showed greater affinity for RTV particles than unimeric bile salts. In contrast, the extent of bile salt depletion was unaltered by addition of phospholipid to form mixed micelles. SAXS analysis of mixed micelles after incubation with RTV particles confirms depletion of bile salt from the supernatant, evidenced by reduced intensity of the micellar scattering feature. In conclusion, this study investigated factors influencing bile salt adsorption onto drug particles, highlighting the need to consider adsorption of bile components in forming the GI-corona.

The ability to predict the absorption of exenatide (Ex), a GLP-1 analogue, after oral dosing to rats in self-nanoemulsifying drug delivery systems (SNEDDS), using in vitro methods, was assessed. Ex was complexed with soybean phosphatidylcholine (SPC) prior to loading into SNEDDS. A design of experiments (DoE) approach was employed to develop SNEDDS incorporating medium-chain triglycerides (MCT), medium-chain mono- and diglycerides (MGDG), Kolliphor® RH40, and monoacyl phosphatidylcholine. SNEDDS with higher proportions of MGDG and Kolliphor® RH40 demonstrated a 9-fold reduction in droplet size (230 to 26 nm), a 1.5-fold decrease in lipolysis (0.23 to 0.34 mmol of FFA), and a 2-fold enhancement in exenatide protection against proteolysis (73 % to 38 %) compared to those with higher MCT content. Permeability studies in Caco-2 cells showed that SNEDDS with higher proportion of MGDG displayed a 40-fold increase in apparent permeability of FD4, when compared to SNEDDS with higher proportion of MCT. An oral gavage study in rats revealed a 1.8-fold higher absorption of Ex in SNEDDS with a higher proportion of MGDG and Kolliphor®RH40 compared to SNEDDS with higher MCT. These results establish a clear in vitro-in vivo correlation, demonstrating that the selected in vitro methods effectively differentiated formulations with high and low absorption of exenatide after oral dosing in rats.

Polyamorphism in organic molecules is a poorly understood and controversial phenomenon related to amorphous materials. Although very few studies, including our own, have demonstrated the existence of polyamorphism in drug molecules, this solid-state phenomenon is still very elusive and the investigation of its occurrence in other drugs is fundamental to understand its formation. Indomethacin (IND) has been recently discussed in the literature as a potential drug exhibiting polyamorphism. Its amorphous forms obtained by quench-cooling (QC) at different temperatures have shown distinct dissolution and physical stability properties. However, temperature can induce degradation which can potentially influence the physicochemical properties of the drugs. Here we have investigated what role degradation products may play in the physicochemical properties of amorphous IND obtained at different QC temperatures and explored the potential formation of polyamorphism in IND. Amorphous IND obtained by QC at 165-220 °C revealed similar molecular near order, suggesting lack of structural variation between the differently prepared amorphous forms. The glass transition temperature slightly decreased when the QC temperature increased. Both the onset of crystallization and relaxation time consistently increased (being more notorious at a QC temperature of 180 °C), suggesting that the amorphous IND obtained at higher QC temperatures presents lower molecular mobility and as a consequence higher physical stability. Thermogravimetric analysis revealed that IND degradation starts to occur right after its melting temperature (i.e., 165 °C), being more evident after 180 °C. Considering that a melting point depression was observed for all amorphous IND samples, especially for the ones obtained at higher temperatures (i.e., higher than 180 °C), we hypothesized that the formation of degradation products is the cause for the observed differences in the thermal and physical stability properties of the amorphous IND obtained at different QC temperatures. Moreover, real-time dissolution experiments of amorphous IND films, QC from different temperatures, demonstrated that the dissolution performance decreased gradually, but substantially, as the preparation temperature of the samples increased. Similar experiments where amorphous IND was QC from different temperatures in the absence of oxygen and where amorphous IND was spiked with highly thermally degraded amorphous IND at 2%, 5% and 10% w/w prepared by QC from 165 °C to room temperature, unequivocally demonstrated that the degradation products formed during exposure of IND to high temperatures substantially inhibit the dissolution of amorphous IND. This study demonstrates that the differences in the physicochemical properties of differently prepared amorphous forms of drugs are not necessarily a result of polyamorphism and that special attention should be paid to the potential formation of degradation products and their influence on amorphous drug performance.

Ternary co-amorphous systems, comprising a drug, a low molecular weight co-former, and a polymer, are a promising approach to address the solubility and stability challenges of poorly water-soluble drugs. However, it is unclear how the addition of a third component influences the stability of the binary system and how to identify the optimal composition of a ternary system. In previous studies we calculated weight percentages of the components via a modified Gordon-Taylor equation assuming the measured glass transition temperature reflected the composition of the ternary system. In this study, the underlying assumptions for these calculations are experimentally verified using a range of ternary mixtures of the system carvedilol-tryptophan- hydroxypropyl methylcellulose. Samples were prepared either by ball-milling all three components simultaneously or by establishing different binary systems and subsequently adding the third component. Design of experiments combined with multivariate analysis of differential scanning calorimetry and X-ray powder diffraction results was used to investigate the influence of preparation time and pathway on thermal and diffractometric properties of the systems, as well as their physical stability. It was hypothesized that the composition with least dependence on the input variables (i.e. the most robust composition) would be the most stable one. The study confirmed this hypothesis. The calculation method proposed in previous studies was verified and the most stable composition found in this study matched the calculated composition.