Mechanism of mucosal permeability enhancement of CriticalSorb® (Solutol® HS15) investigated in vitro in cell cultures

Investigation of keratolytic impact of synthetic bolalipids on skin penetration of a model hydrophilic permeant

Synthetic single-chain bolalipids (SSCBs) are novel excipients in drug delivery, with potential as stabilizers or solubilizers. However, their impact on skin barrier function has not been comprehensively studied. Therefore, two SSCBs (PC-C24-PC and PC-C32-PC) were studied in aqueous systems for their impact on penetration of a model permeant into porcine skin. Concentrations of 0.05 - 5 % w/w were tested; PC-C24-PC formulations were low-viscosity liquids while PC-C32-PC formed viscous dispersions to gels at room temperature. Formulations were compared for their ability to enhance sodium fluorescein penetration (SF, 0.1 % w/w) into skin via tape stripping. Using NIR-densitometry, the effect of SSCB formulations on corneocyte cohesion was evaluated. Data were compared with phospholipid mixture Lipoid S-75, sodium dodecyl sulfate (SDS), and polyethylene glycol 12-hydroxystearate (PEG-HS), and distilled water as negative control. Contrary to the hypothesis, both SSCBs failed to increase SF penetration into the stratum corneum, but rather showed a significant decrease in penetration depth compared to water. Both SSCBs exhibited a keratolytic effect at 5 % w/w, leading to substantial removal of proteins from the skin surface. Consequently, SSCBs may not enhance penetration of hydrophilic drugs into skin, but could be used as keratolytic agents.

Mirtazapine loaded polymeric micelles for rapid release tablet: A novel formulation-In vitro and in vivo studies

Major depression is a prevalent disorder characterized by sadness, lack of interest or pleasure, interrupted sleep or food, and impaired concentration. Mirtazapine (MTZ), a tetracyclic antidepressant drug, is commonly used to treat moderate to severe depression. MTZ is classified as a BCS class II drug that has shown bioavailability of 50% due to extensive first-pass metabolism. The aim of this research is to develop a delivery platform with enhanced solubility and oral bioavailability of MTZ through formulating polymeric micelles modeled in a rapid release tablet. Mirtazapine loaded polymeric micelles (MTZ-PMs) were formulated to enhance the solubility. Solutol® HS 15 and Brij 58 were used as combined surfactants in a ratio of (20:1) to MTZ in addition to Transcutol® P as a penetration enhancer. The following in vitro tests were performed: particle size, PDI, zeta potential, solubility factor, stability index, and transmission electron microscopes. Afterward, MTZ-PMs were converted to dry free flowable powder through loading on the adsorptive surface of Aerosil 200; then, the powder mixture was directly compressed (MTZ-PMs-RRT) into 13 mm tablets. MTZ-PMs-RRT was further investigated using in vitro evaluation tests of the tablets, namely, weight variation, thickness, diameter, hardness, friability, disintegration time, drug content, and in vitro dissolution test, which complied with the pharmacopeial limits. The pharmacokinetic parameters of MTZ-PMs-RRT compared to Remeron® tablet were further investigated in rabbits. The results showed enhanced solubility of MTZ with improved percentage relative bioavailability to 153%. The formulation of MTZ in the form of MTZ-PMs-RRT successfully improved the solubility, stability, and bioavailability of MTZ using a simple and scalable manufacturing process.

Enhanced brain distribution of Ginsenoside F1 via intranasal administration in combination with absorption enhancers

Ginsenoside F1 (GF1) is a potential drug candidate for the treatment of Alzheimer's disease. Nevertheless, its low oral bioavailability and poor solubility limit clinical application. By utilizing either a direct or indirect approach, intranasal administration is a non-invasive drug delivery method that can deliver drugs to the brain rapidly. But large molecule drug delivered to the brain through intranasal administration may be insufficient to reach required concentration for therapeutic effect. In this study, using GF1 as a model drug, the feasibility of intranasal administration in combination with absorption enhancers to increase brain distribution of GF1 was explored. First of all, the appropriate absorption enhancers were screened by in situ nasal perfusion study. GF1-HP-β-CD inclusion complex was prepared and characterized. Thereafter, in vivo absorption of GF1 after intranasal or intravenous administration of its inclusion complex with/without absorption enhancers was investigated, and safety of the formulations was evaluated. The results showed that 2% Solutol HS 15 was a superior absorption enhancer. HP-β-CD inclusion complex improved GF1 solubility by 150 fold. Following intranasal delivery, the absolute bioavailability of inclusion complex was 46%, with drug brain targeting index (DTI) 247% and nose-to-brain direct transport percentage (DTP) 58%. Upon further addition of 2% Solutol HS 15, the absolute bioavailability was increased to 75%, with DTI 315% and DTP 66%. Both nasal cilia movement and biochemical substances (total protein and lactate dehydrogenase) leaching studies demonstrated 2% Solutol HS 15 was safe to the nasal mucosa. In conclusion, intranasal administration combining with safe absorption enhancers is an effective strategy to enhance drug distribution in the brain, showing promise for treating disorders related to the central nervous system.

Overcoming biological barriers BBB/BBTB by designing PUFA functionalised lipid-based nanocarriers for glioblastoma targeted therapy

A major obstacle for chemotherapeutics in Glioblastoma (GB) is to reach the tumour cells due to the presence of the blood-brain barrier (BBB) and chemoresistance of anticancer drugs. The present study reports two polyunsaturated fatty acids, gamma-linolenic acid (GLA) and alpha-linolenic acid (ALA) appended nanostructured lipid carriers (NLCs) of a CNS negative chemotherapeutic drug docetaxel (DTX) for targeted delivery to GB. The ligand appended DTX-NLCs demonstrated particle size < 160 nm, PDI < 0.29 and a negative surface charge. The successful linkage of GLA (41 %) and ALA (30 %) ligand conjugation to DTX- NLCs was confirmed by diminished surface amino groups on the NLCs, lower surface charge and FTIR profiling. Fluorophore labelled GLA-DTX-NLCs and ALA-DTX-NLCs permeated the in-vitro 3D BBB model with Papp values of 1.8 × 10-3 and 1.9 × 10-3 cm/s respectively. Following permeation, both formulations showed enhanced uptake by GB immortalised cells while ALA-DTX-NLCs showed higher uptake in patient-derived GB cells as evidenced in an in-vitro 3D blood brain tumour barrier (BBTB) model. Both surface functionalised formulations showed higher internalisation in GB cells as compared to bare DTX-NLCs. ALA-DTX-NLCs and GLA-DTX-NLCs showed 13.9-fold and 6.8-fold higher DTX activity respectively at 24 h as indicated by IC50 values when tested in patient-derived GB cells. ALA-DTX-NLCs displayed better efficacy than GLA-DTX-NLCs when tested against 3D tumour spheroids and patient-derived cells. These novel formulations will contribute widely to overcoming biological barriers for treating glioblastoma.

Nose-to-brain delivery of 18β-Glycyrrhetinic acid using optimized lipid nanocapsules: A novel alternative treatment for Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder and the most relevant form of dementia affecting people worldwide. AD was reported to be associated with increased oxidative stress ending up with neuronal damage. 18β-Glycyrrhetinic acid (GA), triterpenoid aglycone of glycyrrhizin, was reported for its powerful antioxidant activities. However, its high molecular weight and lipophilicity are two major obstacles that limit its use and cause very low brain bioavailability. The aim of the present study was to formulate the GA in lipid nanocapsules (LNCs) for enhanced nose-to-brain delivery, as well as to elucidate its potential neuroprotective effect in AD. The optimized GA-loaded LNCs exhibited nanometric size range, good stability over 6 months, sustained drug release over 24 h and high steady state flux and permeability coefficient across nasal mucosa over 8 h. In-vivo studies were conducted on five groups; control, scopolamine (SCOP)-treated, SCOP + GA-LNCs, SCOP + oral GA suspension, and SCOP + intranasal GA suspension groups. Intranasal administration of GA-LNCs, at a reduced dose of 1 mg/kg, improved scopolamine-induced memory impairment in rats evidenced by behavioral testing, histological examination, and oxidative stress markers; catalase and superoxide dismutase. Collectively, GA-loaded LNCs (with 50 times lower dose) may provide a promising remedy for AD patients worldwide.

Radiolabelled folate micellar carriers as proposed diagnostic aid for CNS tumors by nasal route

Glioma refers to the most atypical variant of the malignant central nervous system tumors posturing massive challenge to the research fraternity owing to the flimsy improvement in the patient survival rate over the past years. The aim of the proposed work was developing a diagnostic aid for brain tumors, which could be administered via the non-invasive intranasal route. Since overexpression of folate receptors in the central nervous system tumors is 500 times more than the normal healthy cells, we aimed at fabricating a radiolabeled folate encapsulated micellar delivery system to be given via the nasal route. Folate conjugated bifunctional chelating agent was synthesized, radiolabeled with 99mTc, and encapsulated in a micellar carrier. The fabricated micelles were further evaluated for in vivo nasal toxicity in rats and the same were found safe for intranasal administration. The fabricated micelles owing to their nano size, mucoadhesive nature, and enhanced permeation were observed to have a higher uptake into the brain (around 16% in 4 h) than as compared to the radiolabeled conjugated folate solution when studied for in vivo biodistribution in mice. Single-photon emission computerized tomography imaging performed in higher animals upon intranasal administration of the micellar formulation revealed enhanced uptake of the micelles into the animal brain. It is believed that the aforementioned formulation can be of a great diagnostic value in the detection of not only brain tumors but also other folate expressing cancers such as cervical, breast, and lungs as the system is fast, non-toxic, accurate, non-invasive, and simple.

Recent development of polymer nanomicelles in the treatment of eye diseases

The eye, being one of the most intricate organs in the human body, hosts numerous anatomical barriers and clearance mechanisms. This highlights the importance of devising a secure and efficacious ocular medication delivery system. Over the past several decades, advancements have been made in the development of a nano-delivery platform based on polymeric micelles. These advancements encompass diverse innovations such as poloxamer, chitosan, hydrogel-encapsulated micelles, and contact lenses embedded with micelles. Such technological evolutions allow for sustained medication retention and facilitate enhanced permeation within the eye, thereby standing as the avant-garde in ocular medication technology. This review provides a comprehensive consolidation of ocular medications predicated on polymer nanomicelles from 2014 to 2023. Additionally, it explores the challenges they pose in clinical applications, a discussion intended to aid the design of future clinical research concerning ocular medication delivery formulations.

Impact of formulation design and lyophilisation on the physicochemical characteristics of finasteride nanosystems

The fundamental purpose of this study was to develop a stable lyophilised finasteride nanosystem (FNS-NS) for topical delivery. The FNS-NS was fabricated using an ultrasonication technique. The impact of two different cryoprotectants on the physicochemical characteristics of FNS-NS before and after lyophilisation was thoroughly investigated. The lyophilised FNS-NS had spherical shape with particle size lied between 188.6 nm ± 4.4 and 298.7 nm ± 4.7, low PDI values (0.26 ± 0.02 to 0.32 ± 0.02) and zeta potential ranging from -38.3 to +53.3 mV. The confocal laser microscopy depicted a comparatively higher cellular internalisation achieved for undecorated FNS-NS with respect to its chitosan-decorated counterpart. The lyophilised FNS-NS was stable for 90 days at proper storage conditions. The FNS-NS with 15% trehalose had appropriate physicochemical attributes that could be a promising carrier for topical delivery to treat androgenic alopecia.

Synthesis and Properties of Sucrose- and Lactose-Based Aromatic Ester Surfactants as Potential Drugs Permeability Enhancers

The delivery of therapeutics across biological membranes (e.g., mucosal barriers) by avoiding invasive routes (e.g., injection) remains a challenge in the pharmaceutical field. As such, there is the need to discover new compounds that act as drug permeability enhancers with a favorable toxicological profile. A valid alternative is represented by the class of sugar-based ester surfactants. In this study, sucrose and lactose alkyl aromatic and aromatic ester derivatives have been synthesized with the aim to characterize them in terms of their physicochemical properties, structure-property relationship, and cytotoxicity, and to test their ability as permeability enhancer agents across Calu-3 cells. All of the tested surfactants showed no remarkable cytotoxic effect on Calu-3 cells when applied both below and above their critical micelle concentration. Among the explored molecules, lactose p-biphenyl benzoate (URB1420) and sucrose p-phenyl benzoate (URB1481) cause a reversible ~30% decrease in transepithelial electrical resistance (TEER) with the respect to the basal value. The obtained result matches with the increased in vitro permeability coefficients (Papp) calculated for FTIC-dextran across Calu-3 cells in the presence of 4 mM solutions of these surfactants. Overall, this study proposes sucrose- and lactose-based alkyl aromatic and aromatic ester surfactants as novel potential and safe permeation enhancers for pharmaceutical applications.

In vitro evaluation of NA1-115-7-loaded nanoemulsions, an MCL-1-specific inhibitor of natural origin, intended to treat B-cell lymphoproliferative disorders after oral administration

MCL-1, an anti-apoptotic member of the BCL-2 protein family, is overexpressed in many types of cancer and contributes to chemotherapy resistance. The drimane derivative NA1-115-7 is a natural compound isolated from Zygogynum pancheri that can be considered as a very promising lead for treating MCL-1-dependent hematological malignancies. As this drug suffers from low stability in acidic conditions and poor aqueous solubility, we evaluated the potential oral use of NA1-115-7 by encapsulating it in lipid nanoemulsions (NA-NEs) prepared by spontaneous emulsification. NA-NEs showed a particle size of 41.9 ± 2.2 nm, PDI of 0.131 ± 0.016, zeta potential of -5.8 ± 3.4 mV, encapsulation efficiency of approximately 100 % at a concentration of 24 mM. The stability of NA-1-115-7 was sixfold higher than that of the unencapsulated drug in simulated gastric fluid. NA-NEs significantly restored apoptosis and halved the effective doses of NA1-115-7 on BL2, a Burkitt lymphoma cell line, without toxicity in normal cells. Such a drug-delivery system appears to be particularly interesting for the oral administration of NA1-115-7, as it improves its solubility and stability, as well as efficacy, by reducing the therapeutic dose, making it possible to further consider in-vivo studies of this promising drug in BL2 xenografted mice.

Alternative Excipients for Protein Stabilization in Protein Therapeutics: Overcoming the Limitations of Polysorbates

Given their safety and efficiency in protecting protein integrity, polysorbates (PSs) have been the most widely used excipients for the stabilization of protein therapeutics for years. In recent decades, however, there have been numerous reports about visible or sub-visible particles in PS-containing biotherapeutic products, which is a major quality concern for parenteral drugs. Alternative excipients that are safe for parenteral administration, efficient in protecting different protein drugs against various stress conditions, effective in protein stabilization in high-concentrated liquid formulations, stable under the storage conditions for the duration of the product's shelf-life, and compatible with other formulation components and the primary packaging are highly sought after. The aim of this paper is to review potential alternative excipients from different families, including surfactants, carbohydrate- and amino acid-based excipients, synthetic amphiphilic polymers, and ionic liquids that enable protein stabilization. For each category, important characteristics such as the ability to stabilize proteins against thermal and mechanical stresses, current knowledge related to the safety profile for parenteral administration, potential interactions with other formulation components, and primary packaging are debated. Based on the provided information and the detailed discussion thereof, this paper may pave the way for the identification or development of efficient excipients for biotherapeutic protein stabilization.

Cyclosporine-loaded micelles for ocular delivery: Investigating the penetration mechanisms

Cyclosporine is an immunomodulatory drug commonly used for the treatment of mild-to-severe dry eye syndrome as well as intermediate and posterior segment diseases as uveitis. The ocular administration is however hampered by its relatively high molecular weight and poor permeability across biological barriers. The aim of this work was to identify a micellar formulation with the ability to solubilize a considerable amount of cyclosporine and promote its transport across ocular barriers. Non-ionic amphiphilic polymers used for micelles preparation were tocopherol polyethylene glycol 1000 succinate (TPGS) and Solutol® HS15. Furthermore, the addition of alpha-linolenic acid was assessed. A second aim was to evaluate micelles fate in the ocular tissues (cornea and sclera) to shed light on penetration mechanisms. This was possible by extracting and quantifying both drug and polymer in the tissues, by studying TPGS hydrolysis in a bio-relevant environment and by following micelles penetration with two-photon microscopy. Furthermore, TPGS role as permeation enhancer on the cornea, with possible irreversible modifications of tissue permeability, was analyzed. Results showed that TPGS micelles (approx. 13 nm in size), loaded with 5 mg/ml of cyclosporine, promoted drug retention in both the cornea and the sclera. Data demonstrated that micelles behavior strictly depends on the tissue: micelles disruption occurs in contact with the cornea, while intact micelles diffuse in the interfibrillar pores of the sclera and form a reservoir that can sustain over time drug delivery to the deeper tissues. Finally, cornea quickly restore the barrier properties after TPGS removal from the tissue, demonstrating its potential good tolerability for ocular application.

Investigating bolalipids as solubilizing agents for poorly soluble drugs: Effects of alkyl chain length on solubilization and cytotoxicity

Synthetic single-chain bolalipids with symmetrical headgroups have shown potential in various pharmaceutical applications, such as the stabilization of liposome bilayers. Despite their amphiphilic character, synthetic bolalipids have not yet been investigated for their suitability as solubilizing agents for poorly soluble drug compounds. In this study, three synthetic single-chain bolalipids with increasing alkyl chain lengths (C22, C24 and C26) were investigated. All three bolalipids were able to achieve an increased solubility of the model drug, mefenamic acid, by approximately 180% in a pH 7.4 buffer compared to only a 102-105% increase achieved by sodium dodecyl sulfate (SDS) or the non-ionic surfactant pegylated hydroxystearate (PEG-HS). Subsequently, interfacial activity of bolalipids and their ability to destabilize liposomal bilayers were investigated. The C22 bolalipid exhibited a consistently lower interfacial activity, which was consistent with its significantly lower cytotoxicity in the macrophage-like cell line, J774. A1, compared to C24 and C26 counterparts. The mean IC₅₀ values of the bolalipids tested (0.035-0.093 mM) were approximately 4-100-fold lower than that of SDS (0.401 mM) or PEG-HS (0.922 mM), with the mechanism of toxicity linked to increased cell membrane permeability, as is expected for surfactants. In summary, evidence from this study shows that decreasing the length of the bolalipid alkyl linker from C26 to C22 resulted in a significantly decreased cytotoxicity with no loss in drug solubilization efficiency.

Enhanced permeation by amphiphilic surfactant is spatially heterogenous at membrane and cell level

In the context of increased interest in permeability enhancement technologies to achieve mucosal delivery of drugs and biologics, we report our study on effects of the amphiphilic surfactant at cell membrane and cell population levels. Our results show that modulation in membrane order and fluidity initially occurs on insertion of individual surfactant molecules into the outer leaflet of membrane lipid bilayer; a process occurring at concentrations below surfactant's critical micellar concentration. The surfactant insertion, and consequent increase in membrane fluidity, are observed to be spatially heterogenous, i.e. manifested as 'patches' of increased membrane fluidity. At the cell population level, spatially heterogeneous activity of surfactant is also manifested, with certain cells displaying high permeability amongst a 'background' population. We propose that this heterogeneity is further manifested in a broad profile of intracellular and nuclear exposure levels to a model drug (doxorubicin) observed in cell population. The study points to heterogeneous nature of surfactant effects at cell membrane and cells in population levels.

TPGS2000-DOX Prodrug Micelles for Improving Breast Cancer Therapy

Background

Doxorubicin (DOX) is an anthracycline antibiotic that inhibits the growth of several solid and hematologic malignant tumors. Increasing the targeting ability of DOX and reducing the multi-drug resistance (MDR) of tumor cells to DOX are major aims for researchers.

Purpose

In this study, to increase therapeutic efficiency, reduce the side effects and the MDR of tumor cells to DOX, D-alpha-tocopheryl polyethylene glycol 2000 succinate monoester (TPGS2000)-DOX prodrug micelles were developed by grafting DOX to TPGS2000 via an amide bond that release DOX in the slightly acidic conditions in tumor tissue.

Materials and Methods

The TPGS2000-DOX micelles were constructed using polyethylene glycol 12-hydroxy stearate (Solutol HS15) as the carrier. The in vitro drug release profile and dilution stability of the nanomicelles were determined. The in vitro cytotoxicity and distribution of the nanomicelles in the tumor cells were also investigated. Moreover, we explored the therapeutic outcomes using the MCF-7/ADR tumor-bearing murine model.

Results

The average particle size was approximately 30 nm with a narrow distribution, which was conducive for solid tumor accumulation. The results of in vivo imaging and in vitro cellular uptake assays demonstrated that the TPGS2000-DOX micelles increased the tumor-targeting ability and cellular uptake of DOX. The anticancer potential of TPGS2000-DOX micelles was higher than that of DOX, as revealed by in vitro cytotoxic assays with MCF-7/ADR cells and in vivo antitumor assays with MCF-7 tumor-bearing nude mice.

Conclusion

TPGS2000-DOX prodrug micelles reverse the MDR of tumor cells, achieve passive targeting by forming nanomicelles, and subsequently enhance the efficacy and reduce the toxicity of DOX.

Topical Triamcinolone Acetonide-Loaded Liposome Formulation Used as an Adjuvant to Intravitreal Ranibizumab Therapy for Neovascular Age-Related Macular Degeneration

Novel strategies have been developed to reduce or avoid intravitreal injections (IVTs) of the antiangiogenic (ranibizumab (RBZ)) and anti-inflammatory (triamcinolone acetonide (TA)) agents used to treat vitreoretinal diseases. One of the strategies includes liposomes. This study evaluated the safety and efficacy of a topical triamcinolone-loaded liposome formulation (TALF) as an adjuvant to intravitreal RBZ therapy in treatment- naïve patients with neovascular age-related macular degeneration (nAMD). Subjects were randomly assigned to the RBZ-TALF or the RBZ-pro re nata (RBZ-PRN) groups. Patients from the RBZ-TALF group were instructed to apply TALF for 12 months after a single dose of RBZ. Patients from the RBZ-PRN group received three monthly RBZ-IVTs. Retreatment with RBZ was considered in the case of nAMD reactivation. Regarding safety, non-ocular abnormalities were observed during TALF therapy. Concerning efficacy, non-significant differences were identified in terms of visual acuity or central foveal thickness when the RBZ-PRN and RBZ-TALF groups were compared. It is worth noting that the average number of RBZ injections was significantly lower in the RBZ-TALF group (2.5 ± 1.4 vs. 6.1 ± 1.3 IVTs; p = 0.0004). Therefore, TALF used as an adjuvant to RBZ reduces the need for RBZ-IVT retreatment with optimal visual and anatomic results.

Topical tacrolimus nanocapsules eye drops for therapeutic effect enhancement in both anterior and posterior ocular inflammation models

Tacrolimus has shown efficacy in eye inflammatory diseases. However, due to the drug lability, its formulation into a stable ophthalmic product remains a challenge. Tacrolimus-loaded nanocapsules (NCs) were designed for ocular instillation. Further, the stability and effects of the formulation were analyzed under different experimental conditions. Physicochemical characterization of the NCs revealed suitable homogeneous size and high encapsulation efficiency. Moreover, the lyophilized formulation was stable at ICH long term and accelerated storage conditions, for at least 18 and 3 months, respectively. The tacrolimus NCs did not elicit any eye irritation in rabbits after single- and multiple-dose applications. Additionally, ex vivo penetration assays on isolated porcine cornea and pharmacokinetics analyses in various rabbit eye compartments demonstrated the superiority of the NCs in retention and permeation into the anterior chamber of the eye compared to the free drug dissolved in oil. Moreover, multiple dose ocular instillation of the NCs in rats allowed high tacrolimus levels in the eye with very low plasma concentrations. Finally, the developed delivery system achieved a significant decrease in four typical inflammatory markers in a murine model of keratitis, an anterior chamber inflammation. Furthermore, these NCs, applied as eye drops, displayed clinical and histological efficacy in the mainly posterior chamber inflammation model of murine, experimental auto-immune uveitis.

Permeability-enhancing effects of three laurate-disaccharide monoesters across isolated rat intestinal mucosae

Laurate (C₁₂)-sucrose esters are established intestinal epithelial permeation enhancers (PEs) with potential for use in oral delivery. Most studies have examined blends of ester rather than specific monoesters, with little variation on the sugar moiety. To investigate the influence of varying the sugar moiety on monoester performance, we compared three monoesters: C₁₂-sucrose, C₁₂-lactose, and C₁₂-trehalose. The assays were: critical micellar concentration (CMC) in Krebs-Henseleit buffer, MTS and lactate dehydrogenase assays in Caco-2 cells, transepithelial electrical resistance (TEER) and apparent permeability coefficient (P_app) of [¹⁴C] mannitol across isolated rat intestinal mucosae, and tissue histology. For CMC, the rank order was C₁₂-trehalose (0.21 mM) < C₁₂-sucrose (0.34 mM) < C₁₂-lactose (0.43 mM). Exposure to Caco-2 cells for 120 min produced TC₅₀ values in the MTS assay from 0.1 to 0.4 mM. Each ester produced a concentration-dependent decrease in TEER across rat mucosae with 80% reduction seen with 8 mM in 5 min, but C₁₂-trehalose was less potent. C₁₂-sucrose and C₁₂-lactose increased the P_app of [¹⁴C] mannitol across mucosae with similar potency and efficacy, whereas C₁₂-trehalose was not as potent or efficacious, even though it still increased flux. In the presence of the three esters, gross intestinal histology was unaffected except at 8 mM for C₁₂-sucrose and C₁₂-lactose. In conclusion, the three esters enhanced permeability likely via tight junction modulation in rat intestinal tissue. C₁₂-trehalose was not quite as efficacious, but neither did it damage tissue to the same extent. All three can be considered as potential PEs to be included in oral formulations.

Target specific tight junction modulators

Intercellular tight junctions represent a formidable barrier against paracellular drug absorption at epithelia (e.g., nasal, intestinal) and the endothelium (e.g., blood-brain barrier). In order to enhance paracellular transport of drugs and increase their bioavailability and organ deposition, active excipients modulating tight junctions have been applied. First-generation of permeation enhancers (PEs) acted by unspecific interactions, while recently developed PEs address specific physiological mechanisms. Such target specific tight junction modulators (TJMs) have the advantage of a defined specific mechanism of action. To date, merely a few of these novel active excipients has entered into clinical trials, as their lack in safety and efficiency in vivo often impedes their commercialisation. A stronger focus on the development of such active excipients would result in an economic and therapeutic improvement of current and future drugs.

Development and in vivo evaluation of intranasal formulations of parathyroid hormone (1-34)

For efficient intranasal transport of parathyroid hormone (1-34) [PTH(1-34)], there is a great medical need to investigate permeation enhancers for intranasal formulations. In this study, the development of PTH(1-34) intranasal formulations was conducted. Based on conformation and chemical stability studies, the most preferable aqueous environment was determined to be 0.008 M acetate buffer solution (ABS). Subsequently, citric acid and Kolliphor^® HS·15 were compared as permeation enhancers. The mechanisms of action of citric acid and Kolliphor^® HS·15 were investigated using an in vitro model of nasal mucosa, and Kolliphor^® HS·15 led to higher permeability of fluorescein isothiocyanate-labeled PTH(1-34) (FITC-PTH) by enhancing both the transcellular and paracellular routes. Moreover, citric acid showed severe mucosal toxicity resulting in cilia shedding, while Kolliphor^® HS·15 did not cause obvious mucosa damage. Finally, Kolliphor^® HS·15 was studied as a permeation enhancer using a liquid chromatography tandem mass spectrometry (LC-MS/MS) method. The results showed that 5% and 10% Kolliphor^® HS·15 increased the bioavailability of PTH(1-34) to 14.76% and 30.87%, respectively. In conclusion, an effective and biosafe PTH(1-34) intranasal formulation was developed by using 10% Kolliphor^® HS·15 as a permeation enhancer. Intranasal formulations with higher concentrations of Kolliphor^® HS·15 for higher bioavailability of PTH(1-34) could be further researched.

Tailoring functional nanostructured lipid carriers for glioblastoma treatment with enhanced permeability through in-vitro 3D BBB/BBTB models

The blood-brain barrier (BBB) and blood-brain tumour barrier (BBTB) pose a significant challenge to drug delivery to brain tumours, including aggressive glioblastoma (GB). The present study rationally designed functional nanostructured lipid carriers (NLC) to tailor their BBB penetrating properties with high encapsulation of CNS negative chemotherapeutic drug docetaxel (DTX). We investigated the effect of four liquid lipids, propylene glycol monolaurate (Lauroglycol® 90), Capryol® propylene glycol monocaprylate, caprylocaproylmacrogol-8-glycerides (Labrasol®) and polyoxyl-15-hydroxystearate (Kolliphor® HS15) individually and in combination to develop NLCs with effective permeation across in-vitro 3D BBB model without alteration in the integrity of the barrier. With desirable spherical shape as revealed by TEM and an average particle size of 123.3 ± 0.642 nm and zeta potential of -32 mV, DTX-NLCs demonstrated excellent stability for six months in its freeze-dried form. The confocal microscopy along with flow cytometry data revealed higher internalisation of DTX-NLCs in U87MG over SVG P12 cells. Micropinocytosis was observed to be one of the dominant pathways for internalisation in U87MG cells while clathrin-mediated pathway was more predominat in patient-derived glioblastoma cells. The NLCs readily penetrated the actively proliferating peripheral cells on the surface of the 3D tumour spheroids as compared to the necrotic core. The DTX-NLCs induced cell arrest through G2/M phase with a significant decrease in the mitochondrial reserve capacity of cells. The NLCs circumvented BBTB with high permeability followed by accumulation in glioblastoma cells with patient-derived cells displaying ~2.4-fold higher uptake in comparison to U87MG when studied in a 3D in-vitro model of BBTB/GB. We envisage this simple and industrially feasible technology as a potential candidate to be developed as GB nanomedicine.

Thymoquinone-Loaded Soluplus®-Solutol® HS15 Mixed Micelles: Preparation, In Vitro Characterization, and Effect on the SH-SY5Y Cell Migration

Thymoquinone (TQ) is the main active ingredient of Nigella sativa essential oil, with remarkable anti-neoplastic activities with anti-invasive and anti-migratory abilities on a variety of cancer cell lines. However, its poor water solubility, high instability in aqueous solution and pharmacokinetic drawbacks limits its use in therapy. Soluplus^® and Solutol^® HS15 were employed as amphiphilic polymers for developing polymeric micelles (SSM). Chemical and physical characterization studies of micelles are reported, in terms of size, homogeneity, zeta potential, critical micelle concentration (CMC), cloud point, encapsulation efficiency (EE%), load capacity (DL), in vitro release, and stability. This study reports for the first time the anti-migratory activity of TQ and TQ loaded in SSM (TQ-SSM) in the SH-SY5Y human neuroblastoma cell line. The inhibitory effect was assessed by the wound-healing assay and compared with that of the unformulated TQ. The optimal TQ-SSM were provided with small size (56.71 ± 1.41 nm) and spherical shape at ratio of 1:4 (Soluplus:Solutol HS15), thus increasing the solubility of about 10-fold in water. The entrapment efficiency and drug loading were 92.4 ± 1.6% and 4.68 ± 0.12, respectively, and the colloidal dispersion are stable during storage for a period of 40 days. The TQ-SSM were also lyophilized to obtain a more workable product and with increased stability. In vitro release study indicated a prolonged release of TQ. In conclusion, the formulation of TQ into SSM allows a bio-enhancement of TQ anti-migration activity, suggesting that TQ-SSM is a better candidate than unformulated TQ to inhibit human SH-SY5Y neuroblastoma cell migration.

Novel Triamcinolone Acetonide-Loaded Liposomal Topical Formulation Improves Contrast Sensitivity Outcome After Femtosecond Laser-Assisted Cataract Surgery

Purpose: To assess visual results, macular modifications, and the incidence of clinically significant macular edema (CSME) in patients using a topical triamcinolone acetonide-loaded liposomal formulation (TA-LF) after femtosecond laser-assisted cataract surgery (FLACS). Methods: Fifty-six eyes after FLACS were selected. Twenty-eight eyes in the combined therapy group (P + N) were treated with prednisolone 1% and nepafenac 0.1% for 21 days postoperatively, whereas 28 eyes in the TA-LF group received a liposomal formulation containing 2 mg/mL of TA (0.2%) for the same period of time. Follow-up visits at 1 day, 6 weeks, and 12 weeks after surgery consisted of visual acuity, contrast sensitivity (CS), central foveal thickness (CFT), total macular volume (TMV) measurements, and the detection of CSME. Results: CS improved in the TA-LF group (basal value: 1.087 ± 0.339 vs. 1.276 ± 0.147 at week 12, P = 0.0346), whereas in the P + N group, CS was not different from the baseline (basal value: 1.130 ± 0.331 vs. 1.274 ± 0.133 at week 12, P = 0.1276). There were similar increases in postoperative CFT and TMV in both groups. CFT and TMV significantly correlate with CS only in the TA-LF group. The r² for CFT and CS was 0.1963 (P = 0.0206), whereas the r² for TMV and CS was 0.3615 (P = 0.0007) at 12 weeks. No difference was observed in the incidence of CSME between the groups. Conclusion: TA-LF is associated with better CS outcomes compared to combined therapy after FLACS.

Transmucosal Absorption Enhancers in the Drug Delivery Field

Drug delivery systems that safely and consistently improve transport of poorly absorbed compounds across epithelial barriers are highly sought within the drug delivery field. The use of chemical permeation enhancers is one of the simplest and widely tested approaches to improve transmucosal permeability via oral, nasal, buccal, ocular and pulmonary routes. To date, only a small number of permeation enhancers have progressed to clinical trials, and only one product that includes a permeation enhancer has reached the pharmaceutical market. This editorial is an introduction to the special issue entitled Transmucosal Absorption Enhancers in the Drug Delivery Field (https://www.mdpi.com/journal/pharmaceutics/special_issues/transmucosal_absorption_enhancers). The guest editors outline the scope of the issue, reflect on the results and the conclusions of the 19 articles published in the issue and provide an outlook on the use of permeation enhancers in the drug delivery field.

Nasal Administration and Plasma Pharmacokinetics of Parathyroid Hormone Peptide PTH 1-34 for the Treatment of Osteoporosis

Nasal delivery of large peptides such as parathyroid 1-34 (PTH 1-34) can benefit from a permeation enhancer to promote absorption across the nasal mucosa into the bloodstream. Previously, we have published an encouraging bioavailability (78%), relative to subcutaneous injection in a small animal preclinical model, for a liquid nasal spray formulation containing the permeation enhancer polyethylene glycol (15)-hydroxystearate (Solutol^® HS15). We report here the plasma pharmacokinetics of PTH 1-34 in healthy human volunteers receiving the liquid nasal spray formulation containing Solutol^® HS15. For comparison, data for a commercially manufactured teriparatide formulation delivered via subcutaneous injection pen are also presented. Tc-99m-DTPA gamma scintigraphy monitored the deposition of the nasal spray in the nasal cavity and clearance via the inferior meatus and nasopharynx. The 50% clearance time was 17.8 min (minimum 10.9, maximum 74.3 min). For PTH 1-34, mean plasma C_max of 5 pg/mL and 253 pg/mL were obtained for the nasal spray and subcutaneous injection respectively; relative bioavailability of the nasal spray was ≤1%. Subsequently, we investigated the pharmacokinetics of the liquid nasal spray formulation as well as a dry powder nasal formulation also containing Solutol^® HS15 in a crossover study in an established ovine model. In this preclinical model, the relative bioavailability of liquid and powder nasal formulations was 1.4% and 1.0% respectively. The absolute bioavailability of subcutaneously administered PTH 1-34 (mean 77%, range 55-108%) in sheep was in agreement with published human data for teriparatide (up to 95%). These findings have important implications in the search for alternative routes of administration of peptides for the treatment of osteoporosis, and in terms of improving translation from animal models to humans.

Nanofibrous Scaffolds Support a 3D in vitro Permeability Model of the Human Intestinal Epithelium

Advances in drug research not only depend on high throughput screening to evaluate large numbers of lead compounds but also on the development of in vitro models which can simulate human tissues in terms of drug permeability and functions. Potential failures, such as poor permeability or interaction with efflux drug transporters, can be identified in epithelial Caco-2 monolayer models and can impact a drug candidate's progression onto the next stages of the drug development process. Whilst monolayer models demonstrate reasonably good prediction of in vivo permeability for some compounds, more developed in vitro tools are needed to assess new entities that enable closer in vivo in vitro correlation. In this study, an in vitro model of the human intestinal epithelium was developed by utilizing nanofibers, fabricated using electrospinning, to mimic the structure of the basement membrane. We assessed Caco-2 cell response to these materials and investigated the physiological properties of these cells cultured on the fibrous supports, focusing on barrier integrity and drug-permeability properties. The obtained data illustrate that 2D Caco-2 Transwell® cultures exhibit artificially high trans-epithelial electrical resistance (TEER) compared to cells cultured on the 3D nanofibrous scaffolds which show TEER values similar to ex vivo porcine tissue (also measured in this study). Furthermore, our results demonstrate that the 3D nanofibrous scaffolds influence the barrier integrity of the Caco-2 monolayer to confer drug-absorption properties that more closely mimic native gut tissue particularly for studying passive epithelial transport. We propose that this 3D model is a suitable in vitro model for investigating drug absorption and intestinal metabolism.

Solutol HS15 based binary mixed micelles with penetration enhancers for augmented corneal delivery of sertaconazole nitrate: optimization, in vitro, ex vivo and in vivo characterization

Keratomycosis is a serious corneal disease that can cause a permanent visual disability if not treated effectively. Sertaconazole nitrate (STZ), a novel broad spectrum antifungal drug, was suggested as a promising treatment. However, its utility in the ocular route is restricted by its poor solubility, along with other problems facing the ocular delivery like short residence time, and the existing corneal barrier. Therefore, the objective of this study was to formulate STZ loaded binary mixed micelles (STZ-MMs) enriched with different penetration enhancers using thin-film hydration method, based on a 3¹.2² mixed factorial design. Different formulation variables were examined, namely, type of auxiliary surfactant, type of penetration enhancer, and total surfactants: drug ratio, and their effects on the solubility of STZ in MMs (S_M), particle size (PS), polydispersity index (PDI), and zeta potential (ZP) were evaluated. STZ-MMs enhanced STZ aqueous solubility up to 338.82-fold compared to free STZ. Two optimized formulations (MM-8 and MM-11) based on the desirability factor (0.891 and 0.866) were selected by Design expert^® software for further investigations. The optimized formulations were imaged by TEM which revealed nanosized spherical micelles. Moreover, they were examined for corneal mucoadhesion, stability upon dilution, storage effect, and ex vivo corneal permeation studies. Finally, both in vivo corneal uptake and in vivo corneal tolerance were investigated. MM-8 showed superiority in the ex vivo and in vivo permeation studies when compared to the STZ-suspension. The obtained results suggest that the aforementioned STZ loaded mixed micellar system could be an effective candidate for Keratomycosis-targeted therapy.

Strategies to Enhance Drug Absorption via Nasal and Pulmonary Routes

New therapeutic agents such as proteins, peptides, and nucleic acid-based agents are being developed every year, making it vital to find a non-invasive route such as nasal or pulmonary for their administration. However, a major concern for some of these newly developed therapeutic agents is their poor absorption. Therefore, absorption enhancers have been investigated to address this major administration problem. This paper describes the basic concepts of transmucosal administration of drugs, and in particular the use of the pulmonary or nasal routes for administration of drugs with poor absorption. Strategies for the exploitation of absorption enhancers for the improvement of pulmonary or nasal administration are discussed, including use of surfactants, cyclodextrins, protease inhibitors, and tight junction modulators, as well as application of carriers such as liposomes and nanoparticles.

Exposure to a Nonionic Surfactant Induces a Response Akin to Heat-Shock Apoptosis in Intestinal Epithelial Cells: Implications for Excipients Safety

Amphipathic, nonionic, surfactants are widely used in pharmaceutical, food, and agricultural industry to enhance product features; as pharmaceutical excipients, they are also aimed at increasing cell membrane permeability and consequently improving oral drugs absorption. Here, we report on the concentration- and time-dependent succession of events occurring throughout and subsequent exposure of Caco-2 epithelium to a "typical" nonionic surfactant (Kolliphor HS15) to provide a molecular explanation for nonionic surfactant cytotoxicity. The study shows that the conditions of surfactant exposure, which increase plasma membrane fluidity and permeability, produced rapid (within 5 min) redox and mitochondrial effects. Apoptosis was triggered early during exposure (within 10 min) and relied upon an initial mitochondrial membrane hyperpolarization (5-10 min) as a crucial step, leading to its subsequent depolarization and caspase-3/7 activation (60 min). The apoptotic pathway appears to be triggered prior to substantial surfactant-induced membrane damage (observed ≥60 min). We hence propose that the cellular response to the model nonionic surfactant is triggered via surfactant-induced increase in plasma membrane fluidity, a phenomenon akin to the stress response to membrane fluidization induced by heat shock, and consequent apoptosis. Therefore, the fluidization effect that confers surfactants the ability to enhance drug permeability may also be intrinsically linked to the propagation of their cytotoxicity. The reported observations have important implications for the safety of a multitude of nonionic surfactants used in drug delivery formulations and to other permeability enhancing compounds with similar plasma membrane fluidizing mechanisms.

Investigation of in vitro absorption, distribution, metabolism, and excretion and in vivo pharmacokinetics of paromomycin: Influence on oral bioavailability

OBJECTIVE:

The objective of this study is to investigate in vitro Caco2 permeability, metabolism and in vivo pharmacokinetic (PK) properties of paromomycin to develop an efficient dosage form with improved oral bioavailability.

MATERIALS AND METHODS:

For the purpose, Caco2 permeability assay, mouse microsomal stability assay and in vivo PKs in male BALB/c mice were performed.

RESULTS:

In Caco-2 permeability assay, paromomycin showed negligible permeability in the apical to basolateral (A-to-B) direction and vice versa (B-to-A). Marginal increase in permeability with the use of P-glycoprotein (P-gp) inhibitor, namely, verapamil suggesting paromomycin could be a P-gp substrate. Paromomycin was unstable in liver microsomes of mouse. Paromomycin showed good PK properties after intravenous dose in male BALB/c mice which included low plasma clearance, i.e., <10% of hepatic blood flow in mice, high volume of distribution (V_d), and half-life (T_½) of 2.6 h. Following per oral dose, it exhibits low oral bioavailability (0.3%) with carboxymethyl cellulose formulation. Oral plasma exposure increased in mice by 10% and 15% after pretreatment with P-gp inhibitor verapamil and CYP inhibitor 1-Aminobenztriazole, respectively.

CONCLUSION:

Comparatively significant increase in oral plasma exposure of paromomycin was observed with an alternative oral formulation approach, use of P-gp and CYP inhibitors resulting in improved oral bioavailability up to 16%.

Improved oral bioavailability of magnolol by using a binary mixed micelle system

The aim of this study was to prepare two novel magnolol (MO)-loaded binary mixed micelles (MO-M) using biocompatible copolymers of Soluplus (SOL) and Solutol^® HS15 (HS15), SOL and d-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS), to improve magnolol's poor solubility and its oral bioavailability. The organic solvent evaporation method was used to obtain two MO-M by optimization; one was prepared by using SOL and HS15 (MO-H), and the other was prepared by using SOL and TPGS (MO-T). The entrapment efficiency (EE%) and drug loading (DL%) of MO-T were 94.61 ± 0.91% and 4.03 ± 0.19%, respectively, and the MO-H has higher EE% and DL% (98.37 ± 1.23%, 4.12 ± 0.16%). TEM results showed that the morphology of MO-M was homogeneous and was spherical in shape. The dilution stability of MO-M did not undergo significant changes. Permeability of MO-M across a Caco-2 cell monolayer was enhanced in Caco-2 cell transport models. The pharmacokinetics study showed that the relative oral bioavailability of MO-T and MO-H increased by 2.39- and 2.98-fold, respectively, compared to that of raw MO. This indicated that MO-H and MO-T could promote absorption of MO in the gastrointestinal tract. Collectively, the mixed micelles demonstrated greater efficacy as a drug delivery system. The development of these novel mixed micelles is valuable for resolving the poor solubility and bioavailability of drugs.

3D printed, controlled release, tritherapeutic tablet matrix for advanced anti-HIV-1 drug delivery

PURPOSE

A 3D-Bioplotter® was employed to 3D print (3DP) a humic acid-polyquaternium 10 (HA-PQ10) controlled release fixed dose combination (FDC) tablet comprising of the anti-HIV-1 drugs, efavirenz (EFV), tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC).

METHODS

Chemical interactions, surface morphology and mechanical strength of the FDC were ascertained. In vitro drug release studies were conducted in biorelevant media followed by in vivo study in the large white pigs, in comparison with a market formulation, Atripla®. In vitro-in vivo correlation of results was undertaken.

RESULTS

EFV, TDF and FTC were successfully entrapped in the 24-layered rectangular prism-shaped 3DP FDC with a loading of ∼12.5 mg/6.3 mg/4 mg of EFV/TDF/FTC respectively per printed layer. Hydrogen bonding between the EFV/TDF/FTC and HA-PQ10 was detected which was indicative of possible drug solubility enhancement. The overall surface of the tablet exhibited a fibrilla structure and the 90° inner pattern was determined to be optimal for 3DP of the FDC. In vitro and in vivo drug release profiles from the 3DP FDC demonstrated that intestinal-targeted and controlled drug release was achieved.

CONCLUSION

A 3DP FDC was successfully manufactured with the aid of a 3D-Bioplotter in a single step process. The versatile HA-PQ10 entrapped all drugs and achieved an enhanced relative bioavailability of EFV, TDF, and FTC compared to the market formulation for potentially enhanced HIV treatment.

Characterization and Pharmacokinetics of Triamcinolone Acetonide-Loaded Liposomes Topical Formulations for Vitreoretinal Drug Delivery

PURPOSE

To achieve a safer alternative to intravitreal injection of corticosteroids, we developed and characterized triamcinolone acetonide-loaded liposomes formulations (TA-LFs) to be used topically for vitreoretinal drug delivery.

METHODS

Four different 0.2% TA-LFs (TA-LF1 to TA-LF4) were generated and submitted to physicochemical characterization. Posteriorly, an ex vivo diffusion assay was performed using rabbit corneas as membranes. Finally, concentrations of triamcinolone acetonide (TA) were determined by high-performance liquid chromatography in ocular tissues from New Zealand white rabbits after multiple topical doses of TA-LF2 (6 times per day, 14 days). In addition, toxicity and tolerability of TA-LF2 was evaluated by cell viability assay and eye examination of study animals, respectively.

RESULTS

TA-LF2 was the most stable formulation maintaining a stable hidrogenion potential (pH) at 30 and 40°C and even improving encapsulation with higher temperature. TA-LF2 and TA-LF3 presented the best diffusion performance in vitro reaching the highest TA concentrations after 8 h of follow-up. In vivo diffusion and pharmacokinetics analysis showed that concentrations of TA in retina and vitreous reached the highest peak at 12 h after topical administration of TA-LF2 (252.10 ± 90.00 ng/g and 32.6 ± 10.27 ng/g, respectively) and subsequently decline to 24.0 ± 11.72 ng/g and 19.5 ± 13.14 ng/g, respectively, at 14 days of follow-up. Finally, cell viability was unaffected by TA-LF2, and no increase in intraocular pressure nor ocular alterations were observed after topical administration of this formulation in rabbits.

CONCLUSION

TA-loaded liposomes, administered topically, can deliver TA in the vitreous cavity and reach the retina efficiently.

Rhamnolipids as epithelial permeability enhancers for macromolecular therapeutics

The use of surfactants as drug permeability enhancers across epithelial barriers remains a challenge. Although many studies have been performed in this field using synthetic surfactants, the possibility of employing surfactants produced by bacteria (the so called biosurfactants") has not been completely explored. Among them, one of the most well characterized class of biosurfactants are rhamnolipids. The aim of the study was to investigate the effect of rhamnolipids on the epithelial permeability of fluorescein isothiocyanate-labelled dextrans 4kDa and 10kDa (named FD4 and FD10, respectively) as model for macromolecular drugs, across Caco-2 and Calu-3monolayers. These cell lines were selected as an in vitro model for the oral and respiratory administration of drugs. Before performing permeability studies, rhamnolipids mixture was analysed in terms of chemical composition and quantification through mass analysis and HPLC. Cytotoxicity and transepithelial electrical resistance (TEER) studies were also conducted using Caco-2 and Calu-3 cell lines. A dose-dependent effect of rhamnolipids on TEER and FD4 or FD10 permeability across both cell lines was observed at relatively safe concentrations. Overall, results suggest the possibility of using rhamnolipids as absorption enhancers for macromolecular drugs through a reversible tight junction opening (paracellular route), despite more investigations are required to confirm their mechanism of action in term of permeability.

A microemulsion co-loaded with Schizandrin A-docetaxel enhances esophageal carcinoma treatment through overcoming multidrug resistance

Multidrug resistance (MDR) is the major underlying cause of the low 5-year survival rate of esophageal carcinoma. In this study, we developed a novel microemulsion system (SD-ME) co-loaded with docetaxel (DTX) and Schizandrin A, a potent chemotherapeutic agent and a potential drug resistance modulator, respectively. In the physicochemical characterization studies, SD-ME displayed a well-defined spherical shape and size (56.62 ± 4.16 nm), a narrow polydispersity index (PDI, 0.132 ± 0.002), and a negative surface charge (−19.81 ± 3.11 mv). In the cellular uptake studies, SD-ME with a DTX concentration of 30 μg/mL exhibited a 3.9-fold enhancement of DTX internalization in DTX-resistant EC109 (EC109/DDR) cells in comparison to that observed for EC109 cells, and the mechanisms were associated with reducing P-gp expression and inhibiting P-gp ATPease. The half-maximal inhibitory concentrations (IC₅₀) of DTX and SD-ME against EC109/DDR cells were 40.57 ± 0.39 and 3.59 ± 0.06 μg/mL, respectively. Likewise, the apoptotic rate of EC109/DDR treated with SD-ME increased up to 20-fold compared to that observed with free DTX. In anticancer efficacy studies in vivo, SD-ME markedly retarded the tumor growth of nude mice bearing EC109/DDR tumor xenografts compared with D-ME and free DTX throughout the duration of study. Consequently, mice treated with SD-ME had the highest survival rate (37.5%) during the observation period (70 days). In addition, there were no apparent side effects after the administration of SD-ME. Overall, our study provides evidence for SD-ME as an effective drug delivery system for enhanced MDR tumor treatment.

Cytotoxicity and genotoxicity of lipid nanocapsules

Lipid nanocapsules (LNCs) offer a promising method for the entrapment and nanovectorisation of lipophilic molecules. This new type of nanocarrier, formulated according to a solvent-free process and using only regulatory-approved components, exhibits many prerequisites for being well tolerated. Although toxicological reference values have already been obtained in mice, interaction of LNCs at the cell level needs to be elucidated. LNCs, measuring from 27.0±0.1nm (25nm LNCs) and 112.1±1.8nm (100nm LNCs) and with a zeta potential between -38.7±1.2mV and +9.18±0.4mV, were obtained by a phase inversion process followed by post-insertion of carboxy- or amino-DSPE-PEG. Trypan blue, MTS and neutral red uptake (NRU) assays were performed to evaluate the cytotoxicity of LNCs on mouse macrophage-like cells RAW264.7 after 24h of exposure. The determination of 50% lethal concentration (LC50) showed a size effect of LNCs on toxicity profiles: LC50 ranged from 1.036mg/L (MTS) and 0.477mg/mL (NRU) for 25nm LNCs, to 4.42mg/mL (MTS) and 2.18mg/mL (NRU) for 100nm LNCs. Surfactant Solutol® HS15 has been shown to be the only constituent to exhibit cytotoxicity; its LC50 reached 0.427mg/mL. Moreover, LNCs were not more toxic than their components in simple mixtures. At sublethal concentration, 100nm LNCs only were able to induce a significant production of nitric oxide (NO) by RAW264.7 cells, as assessed by the Griess reaction. Again, surfactant was the only component responsible for an increased NO release (1.8±0.2-fold). Genotoxicity assays revealed no DNA damage on human lymphocytes in both the in vitro Comet and micronucleus assays using 4-hour and 24-hour treatments, respectively.

Improved oral bioavailability and anticancer efficacy on breast cancer of paclitaxel via Novel Soluplus(®)-Solutol(®) HS15 binary mixed micelles system

The aim of this study was to develop a novel drug delivery system using two biocompatible copolymers of Solutol(®)HS15 and Soluplus(®) to improve solubility, oral bioavailability and anticancer activity of paclitaxel (PTX). The PTX-loaded mixed micelles (PTX-M) were prepared by ethanol thin-film hydration method. The optimal PTX-M were provided with small size (164.8±2.0nm) and spherical shape at ratio of 1: 3 (Solutol(®)HS15: Soluplus(®)), thus increasing the solubility to 15.76±0.15mg/mL in water. The entrapment efficiency and drug loading of PTX-M were 98.48±0.91% and 10.59±0.09% respectively. In vitro release study indicated a sustained release of PTX-M. Transcellular transport study showed that the efflux ratio were decreased by 89.72% dramatically in Caco-2 cell transport models, and the pharmacokinetics study of PTX-M compared with PTX, showed a 3.68-fold increase in relative oral bioavailability, indicating the mixed micelles may promote absorption in the gastrointestinal tract. In addition, the MTT assay demonstrated that the IC50 value of PTX-M was reduced by 40.21% (PTX-M: 22.6±2.1μg/mL, PTX: 37.8±1.4μg/mL), and in vivo anti-tumor study (15days' therapy) showed PTX-M achieved higher anti-tumor efficacy (57.66%) compared with PTX (41.13%). Furthermore, a gastrointestinal safety assay also provided the reliability and safety of PTX-M. Collectively, these findings present an oral micelle formulation with increased solubility, oral bioavailability and anticancer activity of PTX.

Unsaturated fatty acids lactose esters: cytotoxicity, permeability enhancement and antimicrobial activity

Sugar based surfactants conjugated with fatty acid chains are an emerging broad group of highly biocompatible and biodegradable compounds with established and potential future applications in the pharmaceutical, cosmetic and food industries. In this work, we investigated absorption enhancing and antimicrobial properties of disaccharide lactose, monoesterified with unsaturated fatty acids through an enzymatic synthetic approach. After chemical and cytotoxicity characterizations, their permeability enhancing activity was demonstrated using intestinal Caco-2 monolayers through transepithelial electrical resistance (TEER) and permeability studies. The synthesized compounds, namely lactose palmitoleate (URB1076) and lactose nervonate (URB1077), were shown to exhibit antimicrobial activity versus eight pathogenic species belonging to Gram-positive, Gram-negative microorganisms and fungi.