Evaluation of Cytotoxicity of Self-Emulsifying Formulations Containing Long-Chain Lipids Using Caco-2 Cell Model: Superior Safety Profile Compared to Medium-Chain Lipids

Hydrophobic ion pairing: lipophilicity improvement of anionic macromolecules by divalent cation mediated complex formation

The aim of this study was to develop an alternative strategy to sufficiently increase the lipophilicity of anionic model macromolecules (MM) without the use of cationic counterions. Enoxaparin (ENO), insulin (INS) and poly-L-glutamic acid (PLG) were ion paired with anionic surfactants (sodium decanoate (DEC), sodium dodecyl sulfate (SDS), sodium stearate (SS) and sodium octadecyl sulfate (SOS)), mediated by divalent cations such as magnesium, calcium and zinc. Complexes were evaluated regarding their precipitation efficiency and logDn-butanol/water. SEDDS were developed, loaded with the complexes and characterized for their size and stability. Finally, payloads and logDSEDDS/release medium were determined. Divalent cation mediated ENO, INS and PLG complexes were successfully formed as underlined by high precipitation efficiencies above 90% in case of Zn2+-mediated complexes. Most pronounced increase in logDn-butanol/water was achieved for ENO-Zn2+-SOS (1.85), INS-Zn2+-SOS (0.80) and PLG-Zn2+-SS (0.48) providing suitable solubilities in commonly used SEDDS components. Developed SEDDS displayed droplet sizes below 200 nm without major changes after loading with MM complexes. Payloads up to 18.72 mg/ml could be achieved in developed SEDDS for ENO-Zn2+-SOS, and 2.44 mg/ml and 6.93 mg/ml for INS-Zn2+-SOS and PLG-Zn2+-SS, respectively. In general, highest lipophilicity enhancement and thus solubility in SEDDS was obtained with Zn2+-mediated complexes among the investigated cations and particularly with the highly negatively charged polysaccharide ENO. The formation of complexes between anionic MM and anionic surfactants mediated by divalent cations, substituting normally used cationic counterions exhibiting higher toxicity, offers a promising alternative to enhance their lipophilicity for oral drug delivery.

Development of lipid-based SEDDS using digestion products of long-chain triglyceride for high drug solubility: Formulation and dispersion testing

A self-emulsifying drug delivery system (SEDDS) containing long chain lipid digestion products (LDP) and surfactants was developed to increase solubility of two model weakly basic drugs, cinnarizine and ritonavir, in the formulation. A 1:1.2 w/w mixture of glyceryl monooleate (Capmul GMO-50; Abitec) and oleic acid was used as the digestion product, and a 1:1 w/w mixture of Tween 80 and Cremophor EL was the surfactant used. The ratio between LDP and surfactant was 1:1 w/w. Since the commercially available Capmul GMO-50 is not pure monoglyceride and contained di-and-triglycerides, the digestion product used would provide 1:2 stoichiometric molar ratio of monoglyceride and fatty acid after complete digestion in gastrointestinal fluid. Both cinnarizine and ritonavir had much higher solubility in oleic acid (536 and 72 mg/g, respectively) than that in glyceryl monooleate and glyceryl trioleate. Therefore, by incorporating oleic acid in place of glyceryl trioleate in the formulation, the solubility of cinnarizine and ritonavir could be increased by 5-fold and 3.5-fold, respectively, as compared to a formulation without the fatty acid. The formulation dispersed readily in aqueous media, and adding 3 mM sodium taurocholate, which is generally present in GI fluid, remarkably improved the dispersibility of SEDDS and reduced particle size of dispersions. Thus, the use of digestion products of long-chain triglycerides as components of SEDDS can enhance the drug loading of weakly basic compounds and increase dispersibility in GI fluids.

Oral delivery of posaconazole-loaded phospholipid-based nanoformulation: Preparation and optimization using design of experiments, machine learning, and TOPSIS

Phospholipid-based nanosystems show promising potentials for oral administration of hydrophobic drugs. The study introduced a novel approach to optimize posaconazole-loaded phospholipid-based nanoformulation using the design of experiments, machine learning, and Technique for Order of Preference by Similarity to the Ideal Solution. These approaches were used to investigate the impact of various variables on the encapsulation efficiency (EE), particle size, and polydispersity index (PDI). The optimized formulation, with %EE of ∼ 74 %, demonstrated a particle size and PDI of 107.7 nm and 0.174, respectively. The oral pharmacokinetic profiles of the posaconazole suspension, empty nanoformulation + drug suspension, and drug-loaded nanoformulation were evaluated. The nanoformulation significantly increased maximum plasma concentration and the area under the drug plasma concentration-time curve (∼3.9- and 6.2-fold, respectively) and could be administered without regard to meals. MTT and histopathological examinations were carried out to evaluate the safety of the nanoformulation and results exhibited no significant toxicity. Lymphatic transport was found to be the main mechanism of oral delivery. Caco-2 cell studies demonstrated that the mechanism of delivery was not based on an increase in cellular uptake. Our study represents a promising strategy for the development of phospholipid-based nanoformulations as efficient and safe oral delivery systems.

Effect of Digested Selected Food Items on Markers of Oxidative Stress and Inflammation in a Caco-2-Based Human Gut Epithelial Model

The human gut epithelium presents a crucial interface between ingested food items and the host. Understanding how different food items influence oxidative stress and inflammation in the gut is of great importance. This study assessed the impact of various digested food items on oxidative stress, inflammation, and DNA/RNA damage in human gut epithelial cells. Differentiated Caco-2 cells were exposed to food items and their combinations (n = 22) selected from a previous study, including sausage, white chocolate, soda, coffee, orange juice, and curcumin. Following stimulation with TNF-α/IFN-1β/LPS and H2O2 for 4 h, the cells were exposed to digested food items or appropriate controls (empty digesta and medium) for a further 16 h. Cell viability, antioxidant capacity (ABTS, FRAP), IL-6, IL-8, F2-isoprostanes, lipid peroxidation (MDA), and DNA/RNA oxidative damage were assessed (3 independent triplicates). The ABTS assay revealed that cells treated with "white chocolate" and "sausage + coffee" exhibited significantly reduced antioxidant capacity compared to stimulated control cells (ABTS = 52.3%, 54.8%, respectively, p < 0.05). Similar results were observed for FRAP (sausage = 34.9%; white chocolate + sausage = 35.1%). IL-6 levels increased in cells treated with "white chocolate + sausage" digesta (by 101%, p < 0.05). Moreover, MDA levels were significantly elevated in cells treated with digested "sausage" or sausage in combination with other food items. DNA/RNA oxidative damage was found to be higher in digesta containing sausage or white chocolate (up to 550%, p < 0.05) compared to stimulated control cells. This investigation provides insights into how different food items may affect gut health and underscores the complex interplay between food components and the epithelium at this critical interface of absorption.

Peptide Antibiotic-Polyphosphate Nanoparticles: A Promising Strategy to Overcome the Enzymatic and Mucus Barrier of the Intestine

The aim of this study was to develop peptide antibiotic-polyphosphate nanoparticles that are able to overcome the enzymatic and mucus barriers providing a targeted drug release directly on the intestinal epithelium. Polymyxin B-polyphosphate nanoparticles (PMB-PP NPs) were formed via ionic gelation between the cationic peptide and the anionic polyphosphate (PP). The resulting NPs were characterized by particle size, polydispersity index (PDI), zeta potential, and cytotoxicity on Caco-2 cells. The protective effect of these NPs for incorporated PMB was evaluated via enzymatic degradation studies with lipase. Moreover, mucus diffusion of NPs was investigated with porcine intestinal mucus. Isolated intestinal alkaline phosphatase (IAP) was employed to trigger the degradation of NPs and consequent drug release. PMB-PP NPs exhibited an average size of 197.13 ± 14.13 nm, a PDI of 0.36, a zeta potential of -11.1 ± 3.4 mV and a concentration and time-dependent toxicity. They provided entire protection toward enzymatic degradation and exhibited significantly (p < 0.05) higher mucus permeating properties than PMB. When incubated with isolated IAP for 4 h, monophosphate and PMB were constantly released from PMB-PP NPs and zeta potential raised up to -1.9 ± 0.61 mV. According to these findings, PMB-PP NPs are promising delivery systems to protect cationic peptide antibiotics against enzymatic degradation, to overcome the mucus barrier and to provide drug release directly at the epithelium.

Using a Cellular System to Directly Assess the Effects of Cosmetic Microemulsion Encapsulated DeoxyArbutin

DeoxyArbutin (dA) is a tyrosinase inhibitor that has effective skin-lightening activity and has no obvious cytotoxicity toward melanocytes. With the aim of directly evaluating the effects of microemulsions containing dA on cells, we developed oil-in-water (O/W) microemulsions with relatively lower cytotoxicities by using polysorbate-series surfactants. Measurement of the transparent properties and particle size analysis at different storage time periods revealed that the developed microemulsions were stable. Moreover, the developed microemulsions had direct effects on B16-F10 mouse melanoma cells. The anti-melanogenesis activities of dA-containing microemulsions were evidently better than that of the free dA group. The results demonstrated that the developed microemulsion encapsulating dA may allow the use of deoxyArbutin instead of hydroquinone to treat dermal hyperpigmentation disorders in the future.

Effect Of Surfactant Chain Length On Emulsification Dynamics Of Self Emulsifying Formulation Of Poorly Soluble Drug

AIM

In this work the aim was to study the chain length of surfactant on the self emulsifying system of a poorly soluble drug, aceclofenac. The selection of almond oil as a lipid vehicle was done on basis of solubility and compatibility of the vehicle with the drug.

METHODS

The effect of varying chain length of different surfactants of Tween series namely Tween 20, Tween 40, Tween 60 and Tween 80 was evaluated on self emulsifying efficiency by constructing pseudoternary diagrams. PEG-400 was used as co-surfactant in a definite ratio with all the surfactants to minimize their concentration. The best self emulsifying ability was exhibited by Tween 80: PEG-400 combination followed by Tween 60: PEG-400, Tween 40: PEG-400, Tween 20: PEG-400. This observation indicates that as the chain length of Tweens increases their ability to form a good microemulsion increases if same co-surfactant is used.

RESULTS

However it has also been found that the presence of unsaturated bond in Tween 80 provides it an elasticity which supports good intermixing of oil and water and leading to formation of a fine microemulsion. Six different formulations were prepared using combination of almond oil, Tween 80, PEG-400 and the drug aceclofenac.

CONCLUSION

The formulations were subjected to various evaluation parameters such as dispersibility, transmittance, pH, globule size, polydispersibility, zeta potential, viscosity, refractive index and in vitro dissolution. The best formulation was found to have globule size of less than 100 nm, zeta potential of -3.35 ± 0.60 mV which indicates formation of a microemulsion of aceclofenac with good stability.

Development of self-microemulsifying lipid-based formulations of trans-resveratrol by systematically constructing lipid-surfactant-water phase diagrams using long-chain lipids

The aim of this work was to develop self-microemulsifying lipid-based formulations of trans-resveratrol in cod liver oil, a long chain lipid, to increase its solubility, dissolution rate and oral bioavailability. Ternary phase diagrams of cod liver oil with surfactant and water as well as pseudo-ternary phase diagrams of the same by mixing cod liver oil (triglyceride) with glycerol monooleate (monoglyeride) were constructed to identify regions where microemulsions were formed. Kolliphor RH 40, Tween 80 and their 1:1-mixtures were evaluated as surfactants. No organic cosolvents were added. It was observed that cod liver oil alone did not form microemulsion with any of the surfactants used, and a 1:1 mixture of cod liver oil and glycerol monooleate was necessary to enable the formation of microemulsion. Among the surfactants, Kolliphor RH 40 provided the maximum microemulsification effect. Several formulations containing 6:4, 1:1, and 4:6 w/w ratios of lipid to surfactant using the 1:1 mixture of cod liver oil and glycerol monooleate as lipid components and Kolliphor RH 40 or its mixture with Tween 80 as surfactants were identified, and trans-resveratrol solubility in these formulations were determined. Drug concentrations used in the formulations were 80% of saturation solubility, and no organic cosolvents were used in any formulations to increase drug solubility or enable emulsification. In vitro dispersion testing in 250 mL of 0.01 N HCl (pH 2) according to the USP method 2 at 50 RPM showed that the formulations rapidly dispersed in aqueous media forming microemulsions and there was no drug precipitation.

Dual-Acting Zeta-Potential-Changing Micelles for Optimal Mucus Diffusion and Enhanced Cellular Uptake after Oral Delivery

Context: Overcoming the intestinal mucosal barrier can be a challenge in drug delivery. Nanoemulsions with negative zeta potentials can effectively permeate the mucus layer, but those with positive zeta potentials are better taken up by cells; a nanoemulsion with capricious zeta potential from negative to positive can achieve both good permeation and high uptake. Objective: This study aimed to develop dual-acting zeta-potential-amphoteric micelles enabling optimal muco-permeation and enhancement of cellular uptake. Methods: A micellar pre-concentrate was prepared from 15% Labrasol, 15% Kolliphor EL, 30% Kolliphor RH 40, and 40% dimethylsulfoxide. The micellar pre-concentrate was loaded with anionic stearic acid (SA), forming ionic complexes with cationic polymers at a ratio of 25:1 with Eudragit RS 100 and Eudragit RL 100. Blank micelles and those containing complexes were separately diluted in physiological buffers and examined for their droplet sizes, polydispersity indices (PDIs), zeta potentials, and cytotoxicity. The SA release from the micellar complexes was evaluated in 0.1 mM phosphate buffer (pH 6.8) containing 0.001% fluorescein, thereby enabling an instant decrease in fluorescence. Finally, the micelles were loaded with the model drug fluorescein diacetate (FDA) and evaluated for their muco-permeation behavior and cellular uptake. Results: The micellar dilutions formed micelles at the critical micelle concentration (CMC) of 312 µg/mL and showed a uniform average droplet size of 14.2 nm, with a PDI < 0.1. Micellar dilutions were non-cytotoxic when used at 1:100 in a physiological medium. Micelles loaded with ionic complexes achieved a sustained release of 95.5 ± 3.7% of the SA in 180 min. Moreover, the zeta potential of the complex-loaded micelles shifted from −5.4 to +1.8 mV, whereas the blank micelles showed a stabilized zeta potential of −10 mV. Furthermore, the negatively charged blank and complex-loaded micelles exhibited comparable muco-permeation, with an overall average of 58.2 ± 3.7% diffusion of FDA. The complex-loaded micellar droplets, however, provided a significantly higher cellular uptake of the model drug FDA (2.2-fold, p ≤ 0.01) Conclusion: Due to undergoing a shift in zeta potential, the modified micelles significantly enhanced cellular uptake while preserving mucus-permeating properties.

Charge reversal self-emulsifying drug delivery systems: A comparative study among various phosphorylated surfactants

HYPOTHESIS

Phosphorylated surfactants having ethoxylate spacer arms are promising excipients for charge reversal self-emulsifying drug delivery systems (SEDDS).

EXPERIMENTS

1,2-Dipalmitoyl-sn-glycero-3-phosphatidic acid disodium salt (PA), 2-((2,3-bis(oleoyloxy)propyl)dimethylammonio)ethyl hydrogen phosphate (DOCP), nonylphenol monophosphate ester (PNPP), C12-15 alcohol 3 ethoxylate phosphate ester (PME) and polyoxyethylene (9) dioctanoyl glycerol pyrophosphate (DGPP) loaded SEDDS were developed and characterized. Zeta potential of SEDDS was measured before and after incubation with intestinal alkaline phosphatase (IAP). Phosphate release was monitored by incubation of SEDDS with isolated as well as cell-associated IAP. Primary amine content on the surface of SEDDS was determined in parallel. Cytotoxicity was evaluated on Caco-2 cells and in vitro hemolysis test was performed. Cellular uptake studies were performed by confocal scanning microscopy.

FINDINGS

SEDDS formulations exhibited a size in the range of 17 and 193 nm and a polydispersity index (PDI) ≤ 0.5. Charge reversal from negative to positive values could be achieved in case of PNPP and PME loaded SEDDS with a zeta potential changing from -13 mV to +9 mV and from -7 to +2 mV, respectively, within 6 h. Significant amounts of phosphate were released from PNPP and PME loaded SEDDS incubated with isolated IAP and from all formulations incubated with cell-associated IAP in accordance with an increase in primary amines on the surface of oily droplets. SEDDS exhibited a concentration and time-dependent cytotoxicity. PNPP and PME SEDDS displayed an increased cellular uptake.

Self-Nano-Emulsifying Drug-Delivery Systems: From the Development to the Current Applications and Challenges in Oral Drug Delivery

Approximately one third of newly discovered drug molecules show insufficient water solubility and therefore low oral bio-availability. Self-nano-emulsifying drug-delivery systems (SNEDDSs) are one of the emerging strategies developed to tackle the issues associated with their oral delivery. SNEDDSs are composed of an oil phase, surfactant, and cosurfactant or cosolvent. SNEDDSs characteristics, their ability to dissolve a drug, and in vivo considerations are determinant factors in the choice of SNEDDSs excipients. A SNEDDS formulation can be optimized through phase diagram approach or statistical design of experiments. The characterization of SNEDDSs includes multiple orthogonal methods required to fully control SNEDDS manufacture, stability, and biological fate. Encapsulating a drug in SNEDDSs can lead to increased solubilization, stability in the gastro-intestinal tract, and absorption, resulting in enhanced bio-availability. The transformation of liquid SNEDDSs into solid dosage forms has been shown to increase the stability and patient compliance. Supersaturated, mucus-permeating, and targeted SNEDDSs can be developed to increase efficacy and patient compliance. Self-emulsification approach has been successful in oral drug delivery. The present review gives an insight of SNEDDSs for the oral administration of both lipophilic and hydrophilic compounds from the experimental bench to marketed products.

Brain Targeting of Duloxetine HCL via Intranasal Delivery of Loaded Cubosomal Gel: In vitro Characterization, ex vivo Permeation, and in vivo Biodistribution Studies

Purpose

Duloxetine (DLX) is dual serotonin and norepinephrine reuptake inhibitor suffering from limited bioavailability (≈ 40%) due to extensive hepatic metabolism. This work aims to formulate and evaluate DLX intranasal thermoreversible cubosomal gels to enhance its bioavailability and ensure efficient brain targeting.

Materials and Methods

Cubo-gels were prepared by 3³ central composite design with three independent factors, lipid ratio (glycerol monooleate: glycerol tripalmitate), Pluronic F127%, and Pluronic F68%. The prepared formulations were evaluated for their particle size (PS), gelling temperature (GT), entrapment efficiency (EE%), and in vitro release. The cubo-gel with the highest desirability (0.88) was chosen as the optimized formulation. DLX cubo-gel was evaluated using differential scanning calorimetry, Fourier-transform infrared spectroscopy, X-ray powder diffraction, and transmission electron microscopy. Cytotoxicity study, ex vivo permeation study and in vivo bio-distribution study were conducted to evaluate the safety and efficacy of brain targeting.

Results

The optimum cubo-gel was composed of 3.76 lipid ratio, 20% w/v PF127, and 5% w/v PF68. It had PS of 265.13 ± 9.85 nm, GT of 32 ± 0.05°C, EE% of 98.13 ± 0.50%, and showed controlled release behavior where 33% DLX was released within 6 hrs. The plain in situ cubo-gel had a significantly higher IC₅₀ compared to DLX solution and DLX-loaded in situ cubo-gel. The ex vivo permeation study showed 1.27 enhancement in the drug permeation from DLX in situ cubo-gel. According to the in vivo bio-distribution study in plasma and brain, the intranasal DLX in situ cubo-gel showed a 1.96 fold improvement in brain bioavailability compared to the intranasal solution. Its BTE% and DTP% were 137.77 and 10.5, respectively, indicating efficient brain targeting after intranasal administration.

Conclusion

Accordingly, intranasal DLX in situ cubo-gel can be considered as an innovative nano-carrier delivery system for bioavailability enhancement and efficient brain targeting of DLX to maximize its effect.