Intestinal membrane transporter-mediated approaches to improve oral drug delivery

Use of novel taurine-chitosan mediated liposomes for enhancing the oral absorption of doxorubicin via the TAUT transporter

Our research aimed to enhance the oral bioavailability of doxorubicin hydrochloride (DOX·HCl) while minimizing the potential for myocardial toxicity. To achieve this goal, we developed a new method that utilizes a coating material to encapsulate the drug in liposomes, which can specifically target intestinal taurine transporter proteins. This coating material, TAU-CS, was created by combining taurine with chitosan. We characterized TAU-CS using various methods, including 1H NMR, FT-IR, and scanning electron microscopy (SEM). The resulting liposomes exhibited a regular spherical morphology, with a particle size of 195.7 nm, an encapsulation efficiency of 91.23 %, and a zeta potential of +11.65 mV. Under simulated gastrointestinal conditions, TAU-CS/LIP@DOX·HCl exhibited good stability and slow release. Pharmacokinetic studies revealed that, compared with DOX·HCl, TAU-CS/LIP@DOX·HCl had a relative bioavailability of 342 %. Intracellular uptake, immunofluorescence imaging, and permeation assays confirmed that the taurine transporter protein mediates the intestinal uptake of these liposomes. Our study suggested that liposomes coated with TAU-CS could serve as an effective oral delivery system and that targeting the taurine transporter protein shows promise in enhancing drug absorption.

Design of chimeric GLP-1A using oligomeric bile acids to utilize transporter-mediated endocytosis for oral delivery

BACKGROUND

Despite the effectiveness of glucagon-like peptide-1 agonist (GLP-1A) in the treatment of diabetes, its large molecular weight and high hydrophilicity result in poor cellular permeability, thus limiting its oral bioavailability. To address this, we developed a chimeric GLP-1A that targets transporter-mediated endocytosis to enhance cellular permeability to GLP-1A by utilizing the transporters available in the intestine, particularly the apical sodium-dependent bile acid transporter (ASBT).

METHODS

In silico molecular docking and molecular dynamics simulations were used to investigate the binding interactions of mono-, bis-, and tetra-deoxycholic acid (DOCA) (monoDOCA, bisDOCA, and tetraDOCA) with ASBT. After synthesizing the chimeric GLP-1A-conjugated oligomeric DOCAs (mD-G1A, bD-G1A, and tD-G1A) using a maleimide reaction, in vitro cellular permeability and insulinotropic effects were assessed. Furthermore, in vivo oral absorption in rats and hypoglycemic effect on diabetic db/db mice model were evaluated.

RESULTS

In silico results showed that tetraDOCA had the lowest interaction energy, indicating high binding affinity to ASBT. Insulinotropic effects of GLP-1A-conjugated oligomeric DOCAs were not different from those of GLP-1A-Cys or exenatide. Moreover, bD-G1A and tD-G1A exhibited improved in vitro Caco-2 cellular permeability and showed higher in vivo bioavailability (7.58% and 8.63%) after oral administration. Regarding hypoglycemic effects on db/db mice, tD-G1A (50 μg/kg) lowered the glucose level more than bD-G1A (50 μg/kg) compared with the control (35.5% vs. 26.4%).

CONCLUSION

GLP-1A was conjugated with oligomeric DOCAs, and the resulting chimeric compound showed the potential not only for glucagon-like peptide-1 receptor agonist activity but also for oral delivery. These findings suggest that oligomeric DOCAs can be used as effective carriers for oral delivery of GLP-1A, offering a promising solution for enhancing its oral bioavailability and improving diabetes treatment.

Understanding of Ovarian Cancer Cell-Derived Exosome Tropism for Future Therapeutic Applications

Exosomes, a subtype of extracellular vesicles, ranging from 50 to 200 nm in diameter, and mediate cell-to-cell communication in normal biological and pathological processes. Exosomes derived from tumors have multiple functions in cancer progression, resistance, and metastasis through cancer exosome-derived tropism. However, there is no quantitative information on cancer exosome-derived tropism. Such data would be highly beneficial to guide cancer therapy by inhibiting exosome release and/or uptake. Using two fluorescent protein (mKate2) transfected ovarian cancer cell lines (OVCA4 and OVCA8), cancer exosome tropism was quantified by measuring the released exosome from ovarian cancer cells and determining the uptake of exosomes into parental ovarian cancer cells, 3D spheroids, and tumors in tumor-bearing mice. The OVCA4 cells release 50 to 200 exosomes per cell, and the OVCA8 cells do 300 to 560 per cell. The uptake of exosomes by parental ovarian cancer cells is many-fold higher than by non-parental cells. In tumor-bearing mice, most exosomes are homing to the parent cancer rather than other tissues. We successfully quantified exosome release and uptake by the parent cancer cells, further proving the tropism of cancer cell-derived exosomes. The results implied that cancer exosome tropism could provide useful information for future cancer therapeutic applications.

Development of a sorafenib-loaded solid self-nanoemulsifying drug delivery system: Formulation optimization and characterization of enhanced properties

Sorafenib, marketed under the brand name Nexavar®, is a multiple tyrosine kinase inhibitor drug that has been actively used in the clinical setting for the treatment of several cancers. However, the low solubility and bioavailability of sorafenib constitute a significant barrier to achieving a good therapeutic outcome. We developed a sorafenib-loaded self-nanoemulsifying drug delivery system (SNEDDS) formulation composed of capmul MCM, tween 80, and tetraglycol, and demonstrated that the SNEDDS formulation could improve drug solubility with excellent self-emulsification ability. Moreover, the sorafenib-loaded SNEDDS exhibited anticancer activity against Hep3B and KB cells, which are the most commonly used hepatocellular carcinoma and oral cancer cell lines, respectively. Subsequently, to improve the storage stability and to increase the possibility of commercialization, a solid SNEDDS for sorafenib was further developed through the spray drying method using Aerosil® 200 and PVP K 30. X-ray diffraction and differential scanning calorimeter data showed that the crystallinity of the drug was markedly reduced, and the dissolution rate of the drug was further improved in formulation in simulated gastric and intestinal fluid conditions. In vivo study, the bioavailability of the orally administered formulation increases dramatically compared to the free drug. Our results highlight the use of the solid-SNEDDS formulation to enhance sorafenib's bioavailability and outlines potential translational directions for oral drug development.

Oral lymphatic delivery of alpha-galactosylceramide and ovalbumin evokes anti-cancer immunization

We developed an orally delivered nanoemulsion that induces cancer immunization. It consists of tumor antigen-loaded nano-vesicles carrying the potent invariant natural killer T-cell (iNKT) activator α-galactosylceramide (α-GalCer), to trigger cancer immunity by effectively activating both innate and adaptive immunity. It was validated that adding bile salts to the system boosted intestinal lymphatic transport as well as the oral bioavailability of ovalbumin (OVA) via the chylomicron pathway. To increase intestinal permeability further and amplify the antitumor responses, an ionic complex of cationic lipid 1,2-dioleyl-3-trimethylammonium propane (DTP) with sodium deoxycholate (DA) (DDP) and α-GalCer were anchored onto the outer oil layer to form OVA-NE#3. As expected, OVA-NE#3 exhibited tremendously improved intestinal cell permeability as well as enhanced delivery to mesenteric lymph nodes (MLNs). Subsequent activation of dendritic cells and iNKTs, in MLNs were also observed. Tumor growth in OVA-expressing mice with melanoma was more strongly suppressed (by 71%) after oral administration of OVA-NE#3 than in untreated controls, confirming the strong immune response induced by the system. The serum levels of OVA-specific IgG1 and IgG2a were 3.52- and 6.14-fold higher than in controls. Treating OVA-NE#3 increased the numbers of tumor-infiltrating lymphocytes, including cytotoxic T-cell and M1-like macrophage. Antigen- and α-GalCer-associated enrichment of dendritic cells and iNKTs in tumor tissues also increased after OVA-NE#3 treatment. These observations indicate that our system induces both cellular and humoral immunity by targeting the oral lymphatic system. It may offer a promising oral anti-cancer vaccination strategy that involves the induction of systemic anti-cancer immunization.

Gastrointestinally absorbable lactoferrin-heparin conjugate with anti-angiogenic activity for treatment of brain tumor

Glioblastoma multiforme (GBM) is a central nervous system disease with poor prognosis. Curative treatments for GBM involve chemotherapy, radiotherapy, and surgical pathways. Recently, antiangiogenic therapy through medications has been tried to slow tumor growth, but the drugs can induce side effects. To overcome these limitations, we developed a new orally absorbable form of heparin that can attenuate angiogenic activity by binding to growth factors around the tumor tissue. We conjugated lactoferrin (Lf) to heparin because Lf can be orally absorbed, and it interacts with the lactoferrin receptor (Lf-R) expressed on the intestine, blood-brain barrier (BBB), and glioma tumor masses. We successfully conjugated Lf and heparin by amide bond formation, as evidenced by advanced physicochemical properties such as pharmacokinetics and stability in acidic condition. This new material inhibited angiogenesis in vitro without toxicity. In addition, Lf-heparin administered orally to GBM orthotopic mice was absorbed in the small intestine and delivered specifically to the brain tumor by receptor transcytosis (Lf-R). Lf-heparin further attenuated angiogenesis progression in GBM orthotopic mice. Based on these results, Lf-heparin shows potential as a new oral medication for treatment of glioblastoma.

Gastrointestinal Permeation Enhancers for the Development of Oral Peptide Pharmaceuticals

Recently, two oral-administered peptide pharmaceuticals, semaglutide and octreotide, have been developed and are considered as a breakthrough in peptide and protein drug delivery system development. In 2019, the Food and Drug Administration (FDA) approved an oral dosage form of semaglutide developed by Novo Nordisk (Rybelsus^®) for the treatment of type 2 diabetes. Subsequently, the octreotide capsule (Mycapssa^®), developed through Chiasma's Transient Permeation Enhancer (TPE) technology, also received FDA approval in 2020 for the treatment of acromegaly. These two oral peptide products have been a significant success; however, a major obstacle to their oral delivery remains the poor permeability of peptides through the intestinal epithelium. Therefore, gastrointestinal permeation enhancers are of great relevance for the development of subsequent oral peptide products. Sodium salcaprozate (SNAC) and sodium caprylate (C8) have been used as gastrointestinal permeation enhancers for semaglutide and octreotide, respectively. Herein, we briefly review two approved products, Rybelsus^® and Mycapssa^®, and discuss the permeation properties of SNAC and medium chain fatty acids, sodium caprate (C10) and C8, focusing on Eligen technology using SNAC, TPE technology using C8, and gastrointestinal permeation enhancement technology (GIPET) using C10.

β-Cyclodextrin-Grafted Chitosan Enhances Intestinal Drug Absorption and Its Preliminary Mechanism Exploration

β-Cyclodextrin (CD) and chitosan (CS) have attracted great attention due to their unique properties and structures. β-Cyclodextrin-grafted chitosan (CD-CS) has been widely used as a drug carrier to prepare nano-formulations for drug delivery. However, few researches have been conducted to investigate the effect of CD-CS as an excipient on cellular uptake and intestinal absorption. Herein, Caco-2 cells were used to investigate the influence of CD-CS on cellular uptake. The MTT assay showed that CD-CS was non-toxic to Caco-2 cells in concentrations ranging from 15.62 to 125 μg/mL. Confocal laser microscopy and flow cytometry measurements indicated that the uptake ability of Caco-2 cells was significantly enhanced after being treated with CD-CS at a concentration of 31.25 μg/mL or incubation for 0.5 h, and the uptake enhancement gradually increased with increasing CD-CS concentration and incubation time. The Caco-2 monolayer cell model and the everted intestinal sac method were employed to preliminarily explore the mechanism of the improved intestinal absorption. The results demonstrated that CD-CS might open the tight junctions and enhance the clathrin-dependent endocytosis, macro-pinocytosis, and phagocytosis of the intestinal epithelial cells. Such findings can serve as references and inspiration for the design of absorption enhancers.

Enhanced Oral Bioavailability of MT-102, a New Anti-inflammatory Agent, via a Ternary Solid Dispersion Formulation

This study aimed to develop a solid dispersion (SD) of MT-102, a new anti-inflammatory agent, to improve its oral bioavailability. The ternary SD formulations of MT-102 (a poorly soluble extract of Isatis indigotica and Juglans mandshurica) were prepared using a solvent evaporation method with various drug/excipient ratios. Following that, the effectiveness of various SDs as an oral formulation of MT-102 was investigated using indirubin as a marker component. By forming SDs with hydrophilic polymers, the aqueous solubility of indirubin was significantly increased. SD-F4, containing drug, poloxamer 407 (P407), and povidone K30 (PVP K30) at a 1:2:2 weight ratio, exhibited the optimal dissolution profiles in the acidic to neutral pH range. Compared to pure MT-102 and a physical mixture, SD-F4 increased indirubin’s dissolution from MT-102 by approximately 9.86-fold and 2.21-fold, respectively. Additionally, SD-F4 caused the sticky extract to solidify, resulting in improved flowability and handling. As a result, compared to pure MT-102, the oral administration of SD-F4 significantly improved the systemic exposure of MT-102 in rats. Overall, the ternary SD formulation of MT-102 with a blended mixture of P407 and PVP K30 appeared to be effective at improving the dissolution and oral absorption of MT-102.

Nano-strategies as Oral Drug Delivery Platforms for Treatment of Cancer: Challenges and Future Perspectives

Oral drug administration is the oldest and widely used method for drug administration. The objectives behind developing an oral drug delivery for the treatment of cancer are to achieve low cost treatment by utilizing novel techniques to target cancer through gut-associated lymphoid tissue (GALT) and to enhance patient comfort and compliance through a hospital-free treatment leading to "Chemotherapy at Home." Unfortunately, due to the physiological environment of the GIT and physicochemical properties of drug candidate, the efficacy of oral drug delivery methods is limited in the treatment of cancer. Due to their low hydrophilicity, high P-gp efflux and restricted intestinal permeability most of the anti-cancer drugs fail to achieve oral bioavailability. The review focuses on the efforts, challenges, opportunities and studies conducted by scientists worldwide on the oral administration of anticancer medications via nanocarriers such as liposomes, SLNs and dendrimers, because of their potential to overcome the epithelial barrier associated with GALT, as well as the applications of different polymers in targeting the cancer. The oral delivery can set newer horizons in cancer therapy to make it more patient friendly.

Pharmacokinetics of Nafamostat, a Potent Serine Protease Inhibitor, by a Novel LC-MS/MS Analysis

Nafamostat, a synthetic serine protease inhibitor, has been used for the treatment of inflammatory diseases such as pancreatitis. Recently, an increasing number of studies have shown the promising antiviral effects of nafamostat for the treatment of coronavirus disease-19 (COVID-19). This study aimed to develop a novel liquid chromatography–tandem mass spectrometry (LC-MS/MS) analysis and to characterize the pharmacokinetics of nafamostat in rats. Nafamostat in the rat plasma was extracted by solid phase extraction, and ¹³C₆-nafamostat was used as an internal standard. The quantification limit of nafamostat in the rat plasma was 0.5 ng/mL. The LC-MS/MS method was fully validated and applied to characterize the pharmacokinetics of nafamostat in rats. Following intravenous injection (2 mg/kg), nafamostat in the plasma showed a multiexponential decline with an average elimination half-life (t_1/2) of 1.39 h. Following oral administration of nafamostat solutions (20 mg/kg) in 10% dimethyl sulfoxide (DMSO) and in 10% DMSO with 10% Tween 80, nafamostat was rapidly absorbed, and the average oral bioavailability was 0.95% and 1.59%, respectively. The LC-MS/MS method and the pharmacokinetic information of nafamostat could be helpful for the further preclinical and clinical studies of nafamostat.

Effects of 1α,25-dihydroxyvitamin D3 on the pharmacokinetics and biodistribution of ergothioneine, an endogenous organic cation/carnitine transporter 1 substrate, in rats

Purpose

This study aimed to investigate the effects of 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) on the expression levels of organic cation/carnitine transporter 1 (OCTN1) as well as the pharmacokinetics and biodistribution of ergothioneine, an OCTN1 substrate, in rats.

Methods

Rats pretreated with 1,25(OH)₂D₃ (2.56 nmol/kg/day) for four days were administered ergothioneine (2 mg/kg) intravenously. The expression levels of rat OCTN1 (rOCTN1) in organs were determined using real-time quantitative polymerase chain reaction. Ergothioneine levels in plasma, urine, and organs (with and without intravenous injection of exogenous ergothioneine) were determined using liquid chromatography-tandem mass spectrometry.

Results

1,25(OH)₂D₃ pretreatment resulted in a significant decrease in rOCTN1 mRNA expression levels in the kidney and brain, a significant increase in basal plasma levels of ergothioneine (from 48 h), and a significant decrease in the tissue-plasma partition coefficient (K_p) in all tissues (except the heart and lungs) and the basal urine levels of ergothioneine. After intravenous administration, the pharmacokinetic profiles of ergothioneine were consistent with the basal levels of endogenous ergothioneine, with an increase in AUC_∞ by 85%, a significant decrease in total clearance by 49%, and a decrease in V_ss by 32% in 1,25(OH)₂D₃-treated rats. The K_p value and urinary recovery of ergothioneine also decreased in the 1,25(OH)₂D₃-treated group.

Conclusion

This study showed the effects of 1,25(OH)₂D₃ on the expression and function of rOCTN1 by investigating the interaction between 1,25(OH)₂D₃ and ergothioneine. Dose adjustment and possible changes in bioavailability should be considered before the co-administration of vitamin D or its active forms and OCTN1 substrates.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40005-022-00563-1.

Negligible Effect of Quercetin in the Pharmacokinetics of Sulfasalazine in Rats and Beagles: Metabolic Inactivation of the Interaction Potential of Quercetin with BCRP

Breast cancer resistance protein (BCRP) mediates pharmacokinetic drug interactions. This study evaluated the potential of quercetin to inhibit and induce BCRP in vitro and in vivo. The inhibition of BCRP was investigated for quercetin and its metabolites using BCRP/mBcrp1-overexpressing MDCKII cells by flow cytometry. The induction of BCRP was investigated in LS174T cells using quantitative PCR. The expression of rat BCRP in rat small intestine, liver, and kidney was also measured after multiple administrations of quercetin in rats (50, 100, and 250 mg/kg, seven days). The in vivo pharmacokinetic changes of sulfasalazine following single or multiple administration of quercetin in rats and beagles were investigated. Although the induction effect of quercetin on BCRP was observed in vitro, the in vivo expression of rat BCRP was not changed by multiple quercetin administrations. Oral administration of quercetin did not affect the plasma concentration or pharmacokinetic parameters of sulfasalazine, regardless of dose and dosing period in either rats or beagles. In addition, the inhibitory effect of quercetin metabolites on BCRP/mBcrp1 was not observed. These results suggest that the in vivo drug interaction caused by quercetin via BCRP was negligible, and it may be related to the metabolic inactivation of quercetin for the inhibition of BCRP.

Nanocarriers for Biomedicine: From Lipid Formulations to Inorganic and Hybrid Nanoparticles

Encapsulation of cargoes in nanocontainers is widely used in different fields to solve the problems of their solubility, homogeneity, stability, protection from unwanted chemical and biological destructive effects, and functional activity improvement. This approach is of special importance in biomedicine, since this makes it possible to reduce the limitations of drug delivery related to the toxicity and side effects of therapeutics, their low bioavailability and biocompatibility. This review highlights current progress in the use of lipid systems to deliver active substances to the human body. Various lipid compositions modified with amphiphilic open-chain and macrocyclic compounds, peptide molecules and alternative target ligands are discussed. Liposome modification also evolves by creating new hybrid structures consisting of organic and inorganic parts. Such nanohybrid platforms include cerasomes, which are considered as alternative nanocarriers allowing to reduce inherent limitations of lipid nanoparticles. Compositions based on mesoporous silica are beginning to acquire no less relevance due to their unique features, such as advanced porous properties, well-proven drug delivery efficiency and their versatility for creating highly efficient nanomaterials. The types of silica nanoparticles, their efficacy in biomedical applications and hybrid inorganic-polymer platforms are the subject of discussion in this review, with current challenges emphasized.