Nanostructured clay particles supplement orlistat action in inhibiting lipid digestion: An in vitro evaluation for the treatment of obesity.

Obesity is a rapidly growing epidemic, with over one-third of the global population classified as overweight or obese. Consequently, an urgent need exists to develop innovative approaches and technologies that regulate energy uptake, to curb the rising trend in obesity statistics. In this study, nanostructured clay (NSC) particles, fabricated by spray drying delaminated dispersions technologies that regulate energy uptake, to curb the rising trend in obesity statistics. In this study, nanostructured clay (NSC) particles, fabricated by spray drying delaminated dispersions of commercial clay platelets (Veegum® HS and LAPONITE® XLG), were delivered as complimentary, bioactive excipients with the potent lipase inhibitor, orlistat, for the inhibition of fat (lipid) hydrolysis. Simulated intestinal lipolysis studies were performed by observing changes in free fatty acid concentration and revealed that a combinatorial effect existed when NSC particles were co-administered with orlistat, as evidenced by a 1.2- to 1.6-fold greater inhibitory response over 60 min, compared to dosing orlistat alone. Subsequently, it was determined that a multifaceted approach to lipolysis inhibition was presented, whereby NSC particles adsorbed high degrees of lipid (up to 80% of all lipid species present in lipolysis media) and thus physically shielded the lipid-in-water interface from lipase access, while orlistat covalently attached and blocked the lipase enzyme active site. Thus, the ability for NSC particles to enhance the biopharmaceutical performance and potency of orlistat is hypothesised to translate into promising in vivo pharmacodynamics, where this novel approach is predicted to lead to considerably greater weight reductions for obese patients, compared to dosing orlistat alone.

Spray Dried Smectite Clay Particles as a Novel Treatment against Obesity.

PURPOSE: To explore the feasibility of spray dried smectite clay particles fabricated from montmorillonite or laponite materials for adsorbing dietary lipids and reducing rodent weight gain in vivo. METHODS: Spray dried montmorillonite (SD-MMT) and spray dried laponite (SD-LAP) particles were prepared via spray drying. Particle morphology, surface area and redispersion/aggregation properties in aqueous media were characterized. The ability of SD-MMT and SD-LAP particles to inhibit lipid digestion kinetics and adsorb lipid species from solution was assessed during in vitro lipolysis using proton nuclear magnetic resonance analysis. SD-MMT and SD-LAP particles were dosed to rodents fed a high-fat diet and their effect on body weight gain was evaluated. RESULTS: Both SD-MMT and SD-LAP particles adsorbed significant quantities of medium chain triglycerides and lipolytic products from solution during in vitro lipolysis. At a concentration of 50% w/w relative to lipid content, SD-MMT and SD-LAP particles adsorbed 42% and 94% of all lipid species, respectively. SD-MMT and SD-LAP particles also reduced the extent of rodent weight gain relative to the negative control treatment group and performed similarly to orlistat via an alternate mechanism of action. CONCLUSIONS: Spray dried smectite clay particles (SD-MMT and SD-LAP) with significant adsorptive capacities for dietary lipids and digestion products were successfully fabricated. These particles may be developed as novel anti-obesity treatments with fewer adverse effects than currently marketed treatment options.

Inorganic surface chemistry and nanostructure controls lipolytic product speciation and partitioning during the digestion of inorganic-lipid hybrid particles.

HYPOTHESIS: Solid-state lipid formulations, whereby liquid lipids are encapsulated in inorganic particle matrices, have attracted significant interest for drug/nutrient delivery in recent years. We hypothesized that the surface chemistry of the inorganic material used to encapsulate lipids impacts the lipase-mediated digestion and partitioning of lipolytic species between the solubilized aqueous and insoluble pellet phases. EXPERIMENTS: Medium chain triglycerides were spray dried with silica nanoparticles, montmorillonite or laponite platelets to form inorganic-lipid hybrid particles. In vitro lipolysis studies were conducted under gastric (pH 1.6) and intestinal (pH 7.5) conditions, and the speciation and partitioning of lipolytic products between the aqueous and pellet phases was characterized using solution-state proton nuclear magnetic resonance and fourier transform infrared spectroscopy. FINDINGS: Under gastric conditions, greater than 80% of all lipid species remained adsorbed within each lipolysis pellet after 60 min. Approximately 40%, 50-60% and 80-90% of all lipid species were adsorbed from solution by silica-, montmorillonite- and laponite-based particle matrices during intestinal lipolysis. Monoglycerides were preferentially adsorbed by silica, whereas triglycerides and fatty acids were adsorbed by montmorillonite and laponite. Adsorption of lipolytic products from solution is expected to impact significantly on drug/nutrient solubilization and absorption in vivo. To the best of our knowledge, this is the first report characterizing the speciation and phase behavior of lipolytic products released from solid-state lipid formulations during in vitro lipolysis studies.

Supersaturated silica-lipid hybrids (super-SLH): An improved solid-state lipid-based oral drug delivery system with enhanced drug loading.

The method of supersaturation for achieving high drug loads in lipid-based formulations is under exploited and relatively unexplored, especially in the case of solid-state lipid-based formulations. Silica-lipid hybrids are solid-state lipid-based formulations designed for improving the oral delivery of poorly water-soluble drugs. However, their application to compounds of low potency and requiring large doses is limited by their low drug loading capacity. Here, an innovative technique to fabricate supersaturated silica-lipid hybrid formulations (super-SLH) has been established and the relationship between drug load and performance investigated. Using the model poorly water-soluble drug, ibuprofen, super-SLH was fabricated possessing drug loads ranging from 8 to 44% w/w, i.e. greater than the previously developed standard ibuprofen silica-lipid hybrids (5.6% w/w). Drug crystallinity of the encapsulated ibuprofen ranged from non-crystalline to part-crystalline with an increase in drug load. Super-SLH achieved improved rates and extents of dissolution when compared to pure ibuprofen, regardless of the drug load. The percentage increase in dissolution extent at 60 min varied from 200 to 600%. The results of the current study indicate that supersaturation greatly improves drug loading and that 16-25% w/w is the optimum loading level which retains optimal dissolution behaviour for the oral delivery of ibuprofen, which has the potential to be translated to other poorly water-soluble drugs.

Taking the Silver Bullet Colloidal Silver Particles for the Topical Treatment of Biofilm-Related Infections.

Biofilms are aggregates of bacteria residing in a self-assembled matrix, which protects these sessile cells against external stress, including antibiotic therapies. In light of emerging multidrug-resistant bacteria, alternative strategies to antibiotics are emerging. The present study evaluated the activity of colloidal silver nanoparticles (AgNPs) of different shapes against biofilms formed by Staphylococcus aureus (SA), methicillin-resistant SA (MRSA), and Pseudomonas aeruginosa (PA). Colloidal quasi-spherical, cubic, and star-shaped AgNPs were synthesized, and their cytotoxicity on macrophages (THP-1) and bronchial epithelial cells (Nuli-1) was analyzed by the lactate dehydrogenase assay. The antibiofilm activity was assessed in vitro by the resazurin assay and in an in vivo infection model in Caenorhabditis elegans. Cubic and star-shaped AgNPs induced cytotoxicity, while quasi-spherical AgNPs were not toxic. Quasi-spherical AgNPs showed substantial antibiofilm activity in vitro with 96% (±2%), 97% (±1%), and 98% (±1%) biofilm killing of SA, MRSA, and PA, respectively, while significantly reducing mortality of infected nematodes. The in vivo antibiofilm activity was linked to the accumulation of AgNPs in the intestinal tract of C. elegans as observed by 3D X-ray tomography. Quasi-spherical AgNPs were physically stable in suspension for over 6 months with no observed loss in antibiofilm activity. While toxicity and stability limited the utilization of cubic and star-shaped AgNPs, quasi-spherical AgNPs could be rapidly synthesized, were stable and nontoxic, and showed substantial in vitro and in vivo activity against clinically relevant biofilms. Quasi-spherical AgNPs hold potential as pharmacotherapy, for example, as topical treatment for biofilm-related infections.

Nanostructured Montmorillonite Clay for Controlling the Lipase-Mediated Digestion of Medium Chain Triglycerides.

Biocompatible lipid hybrid particles composed of montmorillonite and medium chain triglycerides were engineered for the first time by spray drying oil-in-water emulsions stabilized by montmorillonite platelets to form montmorillonite-lipid hybrid (MLH) microparticles containing up to 75% w/w lipid. In vitro lipolysis studies under simulated intestinal conditions indicated that the specific porous nanoarchitecture and surface chemistry of MLH particles significantly increased the rate (>10-fold) and extent of lipase-mediated digestion compared to that of coarse and homogenized submicrometer triglyceride emulsions. Proton nuclear magnetic resonance studies verified the rapid and enhanced production of fatty acids for MLH particles; these are electrostatically repelled by the negatively charged montmorillonite platelet faces and avoid the "interfacial poisoning" caused by incomplete digestion that retards lipid droplet digestion. MLH particles are a novel biomaterial and encapsulation system that optimize lipase enzyme efficiency and have excellent potential as a smart delivery system for lipophilic biomolecules owing to their exceptional physicochemical and biologically active properties. These particles can be readily fabricated with varying lipid loads and thus may be tailored to optimize the solubilization of specific bioactive molecules requiring reformulation.

Preclinical development of Ramizol, an antibiotic belonging to a new class, for the treatment of Clostridium difficile colitis.

Antibiotic-resistant bacteria is a major threat to human health and is predicted to become the leading cause of death from disease by 2050. Despite the recent resurgence of research and development in the area, few antibiotics have reached the market, with most of the recently approved antibiotics corresponding to new uses for old antibiotics, or structurally similar derivatives thereof. We have recently reported an in silico approach that led to the design of an entirely new class of antibiotics for the bacteria-specific mechanosensitive ion channel of large conductance: MscL. Here, we present the preclinical development of one such antibiotic, Ramizol, a first generation antibiotic belonging to that class. We present the lack of interaction between Ramizol and other mammalian channels adding credibility to its MscL selectivity. We determine the pharmacokinetic profile in a rat model and show <0.1% of Ramizol is absorbed systemically. We show this non-systemic nature of the antibiotic translates to over 70% survival of hamsters in a Clostridium difficile colitis model. Lastly, initial in vitro data indicate that resistance to Ramizol occurs at a low frequency. In conclusion, we establish the potential of Ramizol as an effective new treatment for C. difficile associated disease.

A lipid based multi-compartmental system: Liposomes-in-double emulsion for oral vaccine delivery.

The gastric mucosa provides the entry point for the majority of pathogens, as well as being the induction site for protective immunity; however, there remain few examples of oral vaccines due to the challenges presented by the gastrointestinal route. In this study, we develop a lipid-based multi-compartmental system for oral vaccine delivery. Specifically, we have optimised the formulation of a water-in-oil-in-water double emulsion prepared from a triglyceride - soya bean oil, using surfactants Span 80/Tween 80 and Pluronic F127 to stabilise the internal and external water phases, respectively. Into the internal water phase, we also incorporated a PEGylated liposome, prepared using hydrogenated phosphatidyl choline as a carrier for our model protein, FITC-labelled ovalbumin. We demonstrated the successful incorporation of intact liposomes into the internal water phase of the double emulsion using imaging techniques including cryo-SEM and confocal microscopy. Finally, we use in vitro release studies of FITC-ovalbumin, to provide further confirmation of the multi-compartmental structure of the double emulsion system and demonstrate significant extended release of the entrapped model antigen compared with PEG-liposomes; these characteristics are attractive for oral vaccine delivery.

Silica-lipid hybrid (SLH) formulations enhance the oral bioavailability and efficacy of celecoxib: An in vivo evaluation.

This study is the first to demonstrate in canines the ability of silica-lipid hybrid (SLH) microparticles to enhance the bioavailability and efficacy of a poorly water-soluble drug after oral administration. Spray-dried SLH microparticles comprising Capmul MCM (mono-diglycerides of C8/C12 fatty acids) and silica nanoparticles (Aerosil® 380) were shown to significantly enhance the fasted state oral bioavailability of celecoxib (CEL) (6.5 fold, relative to an aqueous suspension and more than 2-fold higher relative to the fed state) after oral administration to beagle dogs. Comparable bioavailability was observed between the SLH microparticle formulation and a conventional Capmul lipid solution, however, plasma concentrations were observed to be higher (Cmax, 1.1±0.06 vs. 0.8±0.03µg/mL) (p≤0.05) with the SLH microparticle system. The enhanced bioavailability of CEL observed with the SLH microparticles was reflected in a subsequent efficacy study conducted in an adjuvant-induced arthritis model in the rat. Reduced clinical and histological severity was observed at a dose of 3mg/kg/day, with the progression of arthritic symptoms and tissue damage reduced to a similar degree to that of a higher dose administered at 5mg/kg/day and prepared in an aqueous suspension., The enhanced bioavailability and improved efficacy observed with the SLH microparticles were attributed to the maintenance of CEL in a solubilised form during digestion of the lipid vehicle. We hypothesise that the presence of silica in the formulation may have contributed to the prevention of drug precipitation in the intestinal lumen by providing an alternative binding site for CEL to adsorb to prior to re-solubilisation and absorption. The study highlights the potential utility of novel SLH microparticle formulations as stable dry powders that possess the properties of a lipid-based formulation for the enhanced delivery and efficacy of poorly water-soluble drugs.

Silica-lipid hybrid microcapsules: influence of lipid and emulsifier type on in vitro performance.

This study reports on the physicochemical characterisation and in vitro investigations of macro-porous silica-lipid hybrid (SLH) microcapsules when formulated using various lipids: long-chain triglycerides (LCT), medium-chain triglycerides (MCT), medium-chain mono-, diglycerides (MCMDG); and emulsifiers: anionic lecithin and cationic oleylamine. For the lipophilic compound coumarin 102 (logP=4.09), a complete and immediate in vitro release was attained for the SLH microcapsules under simulated intestinal sink conditions. The in vitro digestion study of various types of SLH microcapsules demonstrates: (i) reduced variability and enhanced lipid digestibility for the MCMDG-based microcapsules (i.e. 90-100% lipolysis) in comparison with an equivalent lipid solution and emulsion (50-90% lipolysis); and (ii) more controllable digestion kinetics for the LCT-based microcapsules which produce a lipolysis rate higher than that of a lipid solution but lower than that of a lipid emulsion. The drug phase partition results show approximately 5- to 17-fold increase in the drug solubilisation degree resulting from the digestion of MCT and MCMDG-based microcapsules (116 µg/mL), and LCT-based microcapsules (416 µg/mL) in comparison with the blank micellar medium (24 µg/mL). In conclusion, the SLH microcapsules could be tailored to manipulate the digestion patterns of both medium- and long-chain lipids in order to maximise the drug solubilisation capacity.

Mechanistic insight into the dermal delivery from nanoparticle-coated submicron O/W emulsions.

The influence of silica nanoparticle coating of negatively and positively charged submicron emulsion oil droplets on the dermal delivery of a lipophilic fluorescent probe, acridine orange 10-nonyl bromide (AONB) using an ex vivo porcine skin model is reported. The skin retention and depth of the penetration of AONB significantly increased (p

Synergistic effect of silica nanoparticles and charged surfactants in the formation and stability of submicron oil-in-water emulsions.

The influence of hydrophilic silica nanoparticles on the emulsification of a triglyceride oil (Miglyol812) in the presence of charged surfactants (lecithin or oleylamine) and the long term stability of the resultant oil-in-water emulsions are reported. A synergistic effect of nanoparticles and surfactants in improving emulsification and stability to coalescence is evident only when the silica nanoparticles are initially added to the oil phase. When nanoparticles are included from the water phase, no synergistic stabilisation was observed due to electrostatic bridging or unfavourable attachment due to the repulsive electrostatic and hydration forces. Free energies of adsorption for silica nanoparticles at the oil-water interface calculated from experimentally determined interfacial tensions and three phase contact angles can be correlated to long-term emulsion stability only when silica is added from oil phase.