Figure 2 - available via license: Creative Commons Attribution 4.0 International
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Interactions of different PEs with the POPC membrane. Snapshot of (a) initial, representative states, up to 10 ns and (b) final (after 500 ns simulations) system configurations of the POPC membrane with 35% concentrations of the PEs. The pale orange spheres are the phosphate headgroups of the POPC molecules, and the even paler orange in between the upper and lower rows with spheres represents the phospholipid acyl chains of the POPC molecules.
Source publication
Oral administration of drugs is generally considered convenient and patient-friendly. However, oral administration of biological drugs exhibits low oral bioavailability (BA) due to enzymatic degradation and low intestinal absorption. A possible approach to circumvent the low BA of oral peptide drugs is to coformulate the drugs with permeation enhan...
Contexts in source publication
Context 1
... weighted histogram analysis method (WHAM) implemented in Gromacs (gmx wham) was used to extract the PMF along the reaction coordinate from the US simulations. 62 Figure 2A. ...
Context 2
... for SNAC, caprylate, and caprate (both with negatively charged and neutral headgroups), expulsion or flip-flop of a number of molecules from the membrane leaflet occurred. Final snapshots from the simulations consisting of PEs at 35% concentrations are presented in Figure 2B for each PE. It is evident that a number of caprylate, caprate with negatively charged headgroups, and SNAC molecules have moved out to the water phase from the membrane leaflet, while a number of caprate molecules with neutral headgroups changed their location from one leaflet to another through flip-flop events. ...
Citations
... Moreover, the molecules showed only lateral membrane movement during the simulation, remaining confined to the leaflet where they had inserted. These trends align with MD membrane studies on sucrose monododecanoate [27] which, similar to 12-Cel, combines a disaccharide with a 12-carbon lipid tail to yield a charge-neutral molecule. A similar interaction involving neo-glycolipids with a terminal charge would be strongly disfavored because of the positioning of the carboxylate group within the hydrophobic bilayer, likely explaining the lack of membrane insertion for these compounds. ...
Herein, we describe the design and synthesis of 16 neo‐glycolipids that are potential permeation enhancers for oral drug delivery of peptide therapeutics. These amphiphilic neo‐glycolipids are composed of fatty acids and various carbohydrates (d‐glucose, lactose, cellobiose, maltose) via an oxime linker. The ability of the synthesized neo‐glycolipids to enhance permeation of fluorescein‐labelled dextran (4 kDa) or ³H‐mannitol across intestinal epithelium was investigated in vitro using monolayers of human epithelial Caco‐2 cells. Their effects were compared with (pre‐)clinically known enhancers as reference compounds; sodium salts of octanoic, decanoic, and dodecanoic acid, and sodium salcaprozate (SNAC). Most neo‐glycolipids increased the permeation of the model compounds, proving that neo‐glycolipids, which possess vastly different properties from the reference compounds, e. g., in terms of clogD and polar surface area, are effective permeation enhancers. The neo‐glycolipid based on decanoic acid and glucose was more potent than related compounds based on disaccharides. Significant differences in solubility and cellular compatibility were found for neo‐glyolipids based on different carbohydrates. Finally, neo‐glycolipids were evaluated as permeation enhancers for the peptide hormone PYY3‐36. Glucose‐ and maltose‐derived neo‐glycolipids based on decanoic and dodecanoic acid showed promising enhancements in PYY3‐36 permeation in vitro while maintaining good cellular compatibility, relevant for oral delivery of obesity treatments.
... Labrafac™ MC60 and Labrasol® ALF both contain C 8 and C 10 , which interact with bile salts present in fasted-state small intestinal fluid (Kneiszl et al., 2022). Above their critical micelle concentration (CMC), these MCFAs form micelles thereby reducing the amount of free monomer that can interact with the lipid bilayer of intestinal epithelial plasma membranes. ...
... Another alternative is to perform this with the help of an approximate profile coming from other simulations, such as coarse-grained enhanced sampling simulations. We would then know the approximate positions of the energy wells along the reaction coordinate, but those might not match completely between the AA and CG models [74]. Point-wise FE calculations might be specifically useful for generating input data for ML since the solvation energies at these points alone can constitute part of a molecular formulation fingerprint. ...
Theoretical predictions of the solubilizing capacity of micelles and vesicles present in intestinal fluid are important for the development of new delivery techniques and bioavailability improvement. A balance between accuracy and computational cost is a key factor for an extensive study of numerous compounds in diverse environments. In this study, we aimed to determine an optimal molecular dynamics (MD) protocol to evaluate small-molecule interactions with micelles composed of bile salts and phospholipids. MD simulations were used to produce free energy profiles for three drug molecules (danazol, probucol, and prednisolone) and one surfactant molecule (sodium caprate) as a function of the distance from the colloid center of mass. To address the challenges associated with such tasks, we compared different simulation setups, including freely assembled colloids versus pre-organized spherical micelles, full free energy profiles versus only a few points of interest, and a coarse-grained model versus an all-atom model. Our findings demonstrate that combining these techniques is advantageous for achieving optimal performance and accuracy when evaluating the solubilization capacity of micelles.
Graphical abstract
All-atom (AA) and coarse-grained (CG) umbrella sampling (US) simulations and point-wise free energy (FE) calculations were compared to their efficiency to computationally analyze the solubilization of active pharmaceutical ingredients in intestinal fluid colloids.
... 38 Different research groups estimated FA dissociation constants in different lipid membranes using MD simulations, 38−40 and a detailed MD study showed the change in FA mobility depending on the charge and chain length. 41 However, previous simulation studies do not explicitly evaluate the permeability at the molecular level for both neutral and deprotonated FAs, thus disregarding the effect of pH and the dissociation constants altogether. Therefore, in this paper, we measure the effect on the permeability for both neutral and deprotonated FAs in liposomes. ...
... The deprotonated FA charges can cause repulsive forces, increasing the distance between FAs and counteracting the "diluting" effect of FAs which was mentioned earlier in this section. Interestingly, a recent study by Larsson et al. investigated the effect of C10-n on the APL of a POPC membrane using an allatom force field at 310.15 K. 41 The APL was also computed differently, dividing the simulation box by the number of phospholipid molecules without counting the number of C10n, so the trends in the APL cannot be compared directly with our results. They found a modest increase of about 3% in the area per POPC molecule caused by the incorporation of 10% C10-n. ...
... The reduced thickness is particularly evident in systems with deprotonated FAs, with the smallest thickness of 37.5 Å observed for F-30C10-n (see Supporting Information). This reduction was also seen for C10-n's effect on a flat POPC membrane in a combined all-atom and CG computational study by Larsson and coauthors, 41 where it was reported that by including 10% C10-n in the membrane, the membrane thickness decreased by about 1%. They associated this reduction to the C10-n tendency to stay near the headgroup region, pushing the POPC molecules apart and disrupting the lipid tail packing. ...
... 275 Kneiszl, Hossain, and Larsson studied how intestinal permeation enhancers interact with membranes to lay the basis for improving the efficacy of oral administration drugs. 280 Sabin et al. studied polyethylenimine and its interactions with membranes using simulations and showed that polyethylenimine induces pore-forming in the membrane, contributing to an understanding of the DNA cell transfection process. 15 Winslow and Robinson developed a new phase-sensitive membrane raft probe through QM/MM simulations of different probes in the membrane. ...
Molecular dynamics simulations of membranes and membrane proteins serve as computational microscopes, revealing coordinated events at the membrane interface. As G protein-coupled receptors, ion channels, transporters, and membrane-bound enzymes are important drug targets, understanding their drug binding and action mechanisms in a realistic membrane becomes critical. Advances in materials science and physical chemistry further demand an atomistic understanding of lipid domains and interactions between materials and membranes. Despite a wide range of membrane simulation studies, generating a complex membrane assembly remains challenging. Here, we review the capability of CHARMM-GUI Membrane Builder in the context of emerging research demands, as well as the application examples from the CHARMM-GUI user community, including membrane biophysics, membrane protein drug-binding and dynamics, protein-lipid interactions, and nano-bio interface. We also provide our perspective on future Membrane Builder development.
... Nevertheless, C8 has a lower permeation-enhancing potency compared to C10, probably due to its insufficient chain length because it is composed of carbon numbers close to the threshold of MCFAs that have a PE effect [72,74]. According to a recent molecular dynamics simulation study, since C8 has a greater membrane expulsion tendency after being inserted into the membrane than C10, the ratio of the remaining C8 inserted into the membrane is small, and is thought to reduce the membrane disruption effect [75]. ...
... More recently, there have been ongoing in silico studies to predict the molecular dynamic interaction between surfactant-based PEs such as C10 and the lipid membrane. This is an experimental technique that can further characterize C10 membrane perturbation by computing the insertion fraction of C10 into the membrane on the micro-second level [72] and predicting the behavior after membrane insertion, i.e., flip-flop or migration from the membrane to the aqueous phase [75]. However, since it is currently simulated in a simple virtual membrane composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC), evaluating the effect of the perturbation of such a membrane on TJ proteins or intracellular changes by C10, including an increase in intracellular Ca 2+ , is challenging. ...
... In a recent in silico-based research model, the tendency of SNAC to disrupt the membrane was calculated to be less than that of MCFA due to the presumed salicylamide structure. Moreover, the tendency of expulsion from the membrane leaflet after insertion into the membrane was also greater [75]. ...
Recently, two oral-administered peptide pharmaceuticals, semaglutide and octreotide, have been developed and are considered as a breakthrough in peptide and protein drug delivery system development. In 2019, the Food and Drug Administration (FDA) approved an oral dosage form of semaglutide developed by Novo Nordisk (Rybelsus®) for the treatment of type 2 diabetes. Subsequently, the octreotide capsule (Mycapssa®), developed through Chiasma’s Transient Permeation Enhancer (TPE) technology, also received FDA approval in 2020 for the treatment of acromegaly. These two oral peptide products have been a significant success; however, a major obstacle to their oral delivery remains the poor permeability of peptides through the intestinal epithelium. Therefore, gastrointestinal permeation enhancers are of great relevance for the development of subsequent oral peptide products. Sodium salcaprozate (SNAC) and sodium caprylate (C8) have been used as gastrointestinal permeation enhancers for semaglutide and octreotide, respectively. Herein, we briefly review two approved products, Rybelsus® and Mycapssa®, and discuss the permeation properties of SNAC and medium chain fatty acids, sodium caprate (C10) and C8, focusing on Eligen technology using SNAC, TPE technology using C8, and gastrointestinal permeation enhancement technology (GIPET) using C10.
... Several clinical studies have demonstrated how modified release coatings can enable the delivery of antibodies for the treatment of IBD, these have recently been reviewed by Brayden [33]. Where systemic delivery of biologics is desired, formulations may need to incorporate permeation enhancers, such as medium chain fatty acids or salcaprozate sodium, to enable passage across the colonic epithelium [161,162]. At present there are 5 FDA-approved products that deliver peptides orally for systemic action, these include Rybelsus® (semaglutide) and Mycapssa® (octreotide) [33]. ...
... From a drug development perspective, MD has many potential applications for formulation design. MD could be used to definitively map the drug loading and release mechanisms of stimuli-responsive formulations and as such design targeted dosage forms with highly explainable in vivo behaviours [161,252]. MD has also been used to understand the formation of polymer coated nanoparticles produced by flow nanoprecipitation, exemplifying how atom-level insight could be used to optimise colontargeted nanoformulations [257,258]. ...
Colonic drug delivery can facilitate access to unique therapeutic targets and has the potential to enhance drug bioavailability whilst reducing off-target effects. Delivering drugs to the colon requires considered formulation development, as both oral and rectal dosage forms can encounter challenges if the colon's distinct physiological environment is not appreciated. As the therapeutic opportunities surrounding colonic drug delivery multiply, the success of novel pharmaceuticals lies in their design. This review provides a modern insight into the key parameters determining the effective design and development of colon-targeted medicines. Influential physiological features governing the release, dissolution, stability, and absorption of drugs in the colon are first discussed, followed by an overview of the most reliable colon-targeted formulation strategies. Finally, the most appropriate in vitro, in vivo, and in silico preclinical investigations are presented, with the goal of inspiring strategic development of new colon-targeted therapeutics.
... 10 is a fatty acid that has effects both on the integrity of the lipid membrane and the tight junctions of the intestinal epithelium, but reassuringly, most of the tight junction expression changes seen for C 10 -treated mice resolved after the washout period.46 Very few studies have quantitatively assessed gene expression changes following permeation enhancer treatment, but one recent study showed that the use of a permeation enhancing polymeric nanoparticle caused downregulation of claudin 4 protein expression after 2 h with corresponding upregulation of claudin 4 gene expression in the hours after the permeation enhancer treatment was removed. ...
Although protein drugs are powerful biologic therapeutics, they cannot be delivered orally because their large size and hydrophilicity limit their absorption across the intestinal epithelium. One potential solution is the incorporation of permeation enhancers into oral protein formulations; however, few have advanced clinically due to toxicity concerns surrounding chronic use. To better understand these concerns, we conducted a 30‐day longitudinal study of daily oral permeation enhancer use in mice and resultant effects on intestinal health. Specifically, we investigated three permeation enhancers: sodium caprate (C10), an industry standard, as well as 1‐phenylpiperazine (PPZ) and sodium deoxycholate (SDC). Over 30 days of treatment, all mice gained weight, and none required removal from the study due to poor health. Furthermore, intestinal permeability did not increase following chronic use. We also quantified the gene expression of four tight junction proteins (claudin 2, claudin 3, ZO‐1, and JAM‐A). Significant differences in gene expression between untreated and permeation enhancer‐treated mice were found, but these varied between treatment groups, with most differences resolving after a 1‐week washout period. Immunofluorescence microscopy revealed no observable differences in protein localization or villus architecture between treated and untreated mice. Overall, PPZ and SDC performed comparably to C10, one of the most clinically advanced enhancers, and results suggest that the chronic use of some permeation enhancers may be therapeutically viable from a safety standpoint.
