Enhanced oral absorption of pemetrexed by ion-pairing complex formation with deoxycholic acid derivative and multiple nanoemulsion formulations: preparation, characterization, and in vivo oral bioavailability and anticancer effect

Ciprofloxacin-Loaded Inhalable Formulations against Lower Respiratory Tract Infections: Challenges, Recent Advances, and Future Perspectives

Inhaled ciprofloxacin (CFX) has been investigated as a treatment for lower respiratory tract infections (LRTIs) associated with cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), and bronchiectasis. The challenges in CFX effectiveness for LRTI treatment include poor aqueous solubility and therapy resistance. CFX dry powder for inhalation (DPI) formulations were well-tolerated, showing a remarkable decline in overall bacterial burden compared to a placebo in bronchiectasis patients. Recent research using an inhalable powder combining Pseudomonas phage PEV20 with CFX exhibited a substantial reduction in bacterial density in mouse lungs infected with clinical P. aeruginosa strains and reduced inflammation. Currently, studies suggest that elevated biosynthesis of fatty acids could serve as a potential biomarker for detecting CFX resistance in LRTIs. Furthermore, inhaled CFX has successfully addressed various challenges associated with traditional CFX, including the incapacity to eliminate the pathogen, the recurrence of colonization, and the development of resistance. However, further exploration is needed to address three key unresolved issues: identifying the right patient group, determining the optimal treatment duration, and accurately assessing the risk of antibiotic resistance, with additional multicenter randomized controlled trials suggested to tackle these challenges. Importantly, future investigations will focus on the effectiveness of CFX DPI in bronchiectasis and COPD, aiming to differentiate prognoses between these two conditions. This review underscores the importance of CFX inhalable formulations against LRTIs in preclinical and clinical sectors, their challenges, recent advancements, and future perspectives.

Liposomal drug delivery strategies to eradicate bacterial biofilms: Challenges, recent advances, and future perspectives

Typical antibiotic treatments are often ineffectual against biofilm-related infections since bacteria residing within biofilms have developed various mechanisms to resist antibiotics. To overcome these limitations, antimicrobial-loaded liposomal nanoparticles are a promising anti-biofilm strategy as they have demonstrated improved antibiotic delivery and eradication of bacteria residing in biofilms. Antibiotic-loaded liposomal nanoparticles revealed remarkably higher antibacterial and anti-biofilm activities than free drugs in experimental settings. Moreover, liposomal nanoparticles can be used efficaciously for the combinational delivery of antibiotics and other antimicrobial compounds/peptide which facilitate, for instance, significant breakdown of the biofilm matrix, increased bacterial elimination from biofilms and depletion of metabolic activity of various pathogens. Drug-loaded liposomes have mitigated recurrent infections and are considered a promising tool to address challenges associated to antibiotic resistance. Furthermore, it has been demonstrated that surface charge and polyethylene glycol modification of liposomes have a notable impact on their antibacterial biofilm activity. Future investigations should tackle the persistent hurdles associated with development of safe and effective liposomes for clinical application and investigate novel antibacterial treatments, including CRISPR-Cas gene editing, natural compounds, phages, and nano-mediated approaches. Herein, we emphasize the significance of liposomes in inhibition and eradication of various bacterial biofilms, their challenges, recent advances, and future perspectives.

Influence of Bile Acids on Clindamycin Hydrochloride Skin Permeability: In Vitro and In Silico Preliminary Study

BACKGROUND AND OBJECTIVE

Topical clindamycin formulations are widely used in clinical practice, but poor bioavailability and restricted skin penetration considerably limit their therapeutic efficacy. Penetration enhancement represents a promising and rational strategy to overcome the drawbacks of conventional topical pharmaceutical formulations. We aim to assess the influence of cholic acid (CA) and deoxycholic acid (DCA) on the permeability of clindamycin hydrochloride by performing the in vitro skin parallel artificial membrane permeability assay (skin-PAMPA) at two relevant pH values (5.5 and 6.5) and the interactions of tested substances with skin ATP-binding cassette (ABC) transporters in silico.

METHODS

After the incubation period, the clindamycin hydrochloride concentrations in both compartments were determined spectrophotometrically, and the apparent permeability coefficients (Papp) were calculated. Vienna LiverTox web service was used to predict the interactions of clindamycin and bile acids with potential drug transporters located in human skin.

RESULTS

Both CA and DCA at the highest studied concentration of 100 μM in the tested solutions increased the skin-PAMPA membrane permeability of clindamycin hydrochloride. This effect was more pronounced for CA and at a higher studied pH value of 6.5, which is characteristic of most dermatological indications treated with topical clindamycin preparations. Clindamycin transport may also be mediated by ABC transporters located in skin and facilitated in the presence of bile acids.

CONCLUSIONS

The results of this study provide a solid foundation for further research directed at the improvement of topical formulations using bile acids as penetration-enhancing excipients, as well as the therapeutic efficacy of clindamycin hydrochloride.

Metronomic chemotherapy and drug repurposing: A paradigm shift in oncology

Cancer represents a significant global health and economic burden due to its high mortality rates. While effective in some instances, traditional chemotherapy often falls short of entirely eradicating various types of cancer. It can cause severe side effects due to harm to healthy cells. Two therapeutic approaches have risen to the forefront to address these limitations: metronomic chemotherapy (MCT) and drug repurposing. Metronomic chemotherapy is an innovative approach that breaks from traditional models. It involves the administration of chemotherapeutic regimens at lower doses, without long drug-free intervals that have previously been a hallmark of such treatments. This method offers a significant reduction in side effects and improved disease management. Simultaneously, drug repurposing has gained considerable attraction in cancer treatment. This approach involves utilizing existing drugs, initially developed for other therapeutic purposes, as potential cancer treatments. The application of known drugs in a new context accelerates the timeline from laboratory to patient due to pre-existing safety and dosage data. The intersection of these two strategies gives rise to a novel therapeutic approach named 'Metronomics.' This approach encapsulates the benefits of both MCT and drug repurposing, leading to reduced toxicity, potential for oral administration, improved patient quality of life, accelerated clinical implementation, and enhanced affordability. Numerous clinical studies have endorsed the efficacy of metronomic chemotherapy with tolerable side effects, underlining the potential of Metronomics in better cancer management, particularly in low- and middle-income countries. This review underscores the benefits and applications of metronomic chemotherapy and drug repurposing, specifically in the context of breast cancer, showcasing the promising results of pre-clinical and clinical studies. However, we acknowledge the necessity of additional clinical investigations to definitively establish the role of metronomic chemotherapy in conjunction with other treatments in comprehensive cancer management.

Oral lipid nanocomplex of BRD4 PROteolysis TArgeting Chimera and vemurafenib for drug-resistant malignant melanoma

BRAF inhibitors (BRAFi) like vemurafenib (VEM) provide initial regression in mutated melanoma but rapidly develop resistance. Molecular pathways responsible for development of resistance against VEM finally converge towards the activation of oncogenic c-Myc. We identified an epigenetic approach to inhibit the c-Myc expression and resensitize BRAFi-resistant melanoma cells. ARV-825 (ARV) was employed as a BRD4 targeted PROteolysis TArgeting Chimera that selectively degrades the BRD4 to downregulate c-Myc. ARV synergistically enhanced the cytotoxicity of VEM in vitro to overcome its resistance in melanoma. Development of ARV and VEM-loaded lipid nanocomplex (NANOVB) significantly improved their physicochemical properties for oral delivery. Most importantly, oral administration of NANOVB substantially inhibited tumor growth at rate of 41.07 mm3/day in nude athymic mice. NANOVB treatment resulted in prolonged survival with 50% of mice surviving until the experimental endpoint. Histopathological analysis revealed significant tumor necrosis and downregulation of Ki-67 and BRD4 protein in vivo. Promising in vivo antitumor activity and prolonged survival demonstrated by NANOVB signifies its clinical translational potential for BRAFi-resistant melanoma.

Synthetic molecular motor activates drug delivery from polymersomes

The design of stimuli-responsive systems in nanomedicine arises from the challenges associated with the unsolved needs of current molecular drug delivery. Here, we present a delivery system with high spatiotemporal control and tunable release profiles. The design is based on the combination of an hydrophobic synthetic molecular rotary motor and a PDMS-b-PMOXA diblock copolymer to create a responsive self-assembled system. The successful incorporation and selective activation by low-power visible light (λ = 430 nm, 6.9 mW) allowed to trigger the delivery of a fluorescent dye with high efficiencies (up to 75%). Moreover, we proved the ability to turn on and off the responsive behavior on demand over sequential cycles. Low concentrations of photoresponsive units (down to 1 mol% of molecular motor) are shown to effectively promote release. Our system was also tested under relevant physiological conditions using a lung cancer cell line and the encapsulation of an Food and Drug Administration (FDA)-approved drug. Similar levels of cell viability are observed compared to the free given drug showing the potential of our platform to deliver functional drugs on request with high efficiency. This work provides an important step for the application of synthetic molecular machines in the next generation of smart delivery systems.

First-in-class multifunctional TYMS nonclassical antifolate inhibitor with potent in vivo activity that prolongs survival

Although thymidylate synthase (TYMS) inhibitors have served as components of chemotherapy regimens, the currently available inhibitors induce TYMS overexpression or alter folate transport/metabolism feedback pathways that tumor cells exploit for drug resistance, limiting overall benefit. Here we report a small molecule TYMS inhibitor that i) exhibited enhanced antitumor activity as compared with current fluoropyrimidines and antifolates without inducing TYMS overexpression, ii) is structurally distinct from classical antifolates, iii) extended survival in both pancreatic xenograft tumor models and an hTS/Ink4a/Arf null genetically engineered mouse tumor model, and iv) is well tolerated with equal efficacy using either intraperitoneal or oral administration. Mechanistically, we verify the compound is a multifunctional nonclassical antifolate, and using a series of analogs, we identify structural features allowing direct TYMS inhibition while maintaining the ability to inhibit dihydrofolate reductase. Collectively, this work identifies nonclassical antifolate inhibitors that optimize inhibition of thymidylate biosynthesis with a favorable safety profile, highlighting the potential for enhanced cancer therapy.

Nanoformulations-Based Metronomic Chemotherapy: Mechanism, Challenges, Recent Advances, and Future Perspectives

Cancer-related death is a significant health and economic burden worldwide, and some conventional chemotherapy is associated with limited effectiveness in completely curing various cancers, severe adverse effects, and destruction of healthy cells. To overcome the complications associated with conventional treatment, metronomic chemotherapy (MCT) is extensively suggested. In this review, we aim to highlight the importance of MCT over conventional chemotherapeutic approach with emphasis on nanoformulations-based MCT, their mechanism, challenges, recent advances, and future perspectives. Nanoformulations-based MCT revealed remarkable antitumor activity in both preclinical and clinical settings. For example, the metronomic scheduling of oxaliplatin-loaded nanoemulsion and polyethylene glycol-coated stealth nanoparticles incorporating paclitaxel were proven very effective in tumor-bearing mice and rats, respectively. Additionally, several clinical studies have demonstrated the benefit of MCT with acceptable tolerance. Moreover, metronomic might be a promising treatment strategy for improving cancer care in low- and middle-income nations. However, an appropriate alternative to a metronomic regimen for an individual ailment, suitable combinational delivery and scheduling, and predictive biomarkers are certain parts that remain unanswered. Further clinical-based comparative research studies are mandatory to be performed before entailing this treatment modality in clinical practice as alternative maintenance therapy or in place of transferring to therapeutic management.

Biodegradable Cationic and Ionizable Cationic Lipids: A Roadmap for Safer Pharmaceutical Excipients

Cationic and ionizable cationic lipids are broadly applied as auxiliary agents, but their use is associated with adverse effects. If these excipients are rapidly degraded to endogenously occurring metabolites such as amino acids and fatty acids, their toxic potential can be minimized. So far, synthesized and evaluated biodegradable cationic and ionizable cationic lipids already showed promising results in terms of functionality and safety. Within this review, an overview about the different types of such biodegradable lipids, the available building blocks, their synthesis and cleavage by endogenous enzymes is provided. Moreover, the relationship between the structure of the lipids and their toxicity is described. Their application in drug delivery systems is critically discussed and placed in context with the lead compounds used in mRNA vaccines. Moreover, their use as preservatives is reviewed, guidance for their design is provided, and an outlook on future developments is given.

Pluronic® triblock copolymer-based nanoformulations for cancer therapy: A 10-year overview

This paper provides a review of the literature on the use of Pluronic® triblock copolymers for drug encapsulation over the last 10 years. A special focus is given to the progress of drug delivery systems (e.g., micelles, liposomes, micro/nanoemulsions, hydrogels and nanogels, and polymersomes and niosomes); the beneficial aspects of Pluronic® triblock copolymers as biological response modifiers and as pharmaceutical additives, adjuvants, and stabilizers, are also discussed. The advantages and limitations encountered in developing site-specific targeting approaches based on Pluronic-based nanostructures in cancer treatment are highlighted, in addition to innovative examples for improving tumor cytotoxicity while reducing side effects.

Encapsulation of Benzyl Isothiocyanate with β-Cyclodextrin Using Ultrasonication: Preparation, Characterization, and Antibacterial Assay

Benzyl isothiocyanate (BITC) is widely utilized in multiple biomedical fields, due to its significant antibacterial properties and low toxicity. However, poor water solubility and pungent odor has limited its application in the food industry. In this study, we first prepared inclusion complexes of BITC in GLU-β-CD and HP-β-CD using ultrasound, which is able to overcome the hindrance of poor water solubility and high volatility. Then, the BITC-β-CD inclusion complexes were characterized by using high-performance liquid chromatography (HPLC), nuclear magnetic resonance hydrogen spectra (¹H-NMR), infrared absorption spectra (IR), and differential scanning calorimetry (DSC) to confirm their stability. Further, the evaluation of antibacterial and antitumor effects of the BITC-β-CD inclusion complexes showed that they had great bactericidal activity against both Escherichia coli and Staphylococcus aureus cells, and also inhibited the growth of HepG2 cells in vitro. In addition, our results indicated that BITC-β-CD complexes were able to inhibit the growth of S. aureus in broccoli juice and extend the shelf life of broccoli juice, demonstrating the potential of β-cyclodextrin to improve the stability and controlled release of BITC. Taken together, our results show that BITC-β-CD complexes have good potential for application in the food industry.

Ethyl lauroyl arginate-based hydrophobic ion pair complex in lipid nanocapsules: A novel oral delivery approach of rosmarinic acid for enhanced permeability and bioavailability

Limited oral bioavailability due to high hydrophilicity restricts the beneficial use of Rosmaranic acid (RM) that is characterized by many biological and pharmacological effects. The present work was addressed to extract RM from Rosmarinus officinalis L. leaves and then increase its lipophilicity and permeability through the application of hydrophobic ion pair (HIP) approach using ethyl lauroyl arginate (ELA) as a novel counter-ion. Different RM:ELA ratios were screened to optimize HIP formation process. The encapsulation of the optimized HIP into lipid nanocapsules (LNCs) was then achieved to facilitate oral administration. The results of % transmittance, % complexation efficiency (87.32 ± 0.19%) and partition coefficient revealed the successful formation of the HIP complex occurred at RM:ELA molar ratio of 1:2. The formed HIP was successfully loaded into spherical small sized (39.32 ± 0.18 nm) LNCs. The ex vivo permeability studies across porcine intestine showed that the cumulative RM amount permeated/area after 6 h from HIP and LNCs were 3.79 ± 0.57 and 5.71 ± 0.32 µg/cm², respectively. Pharmacokinetic study results showed that the maximum RM concentrations in plasma (C_max) can be arranged in a descending manner as follows; 61.33 ± 8.89 < 42.13 ± 11.22 < 20.96 ± 3.12 ng/ml attained after 4.80, 8.00 and 10.40 h in case of LNC, HIP and solution, respectively. Moreover, the HIP and LNC formulae showed higher total drug amounts in plasma reaching 1.46 and 1.88-fold relative to RM solution, respectively. In conclusion, the HIP complex and HIP loaded LNCs prosper in enhancing the permeability and absorption of the low permeable drugs.

Pharmacokinetics, bioavailability, and plasma protein binding study of glytrexate, a novel multitarget antifolate

Glytrexate, developed by our team, as a novel multitarget folate antagonist, has inhibitory effects on a variety of cancer cell types, especially KB tumor cells (IC₅₀ 0.078 nM), and thus has antitumor drug development prospects. However, its pharmacokinetics and plasma protein binding properties remain unknown. In this study a selective and sensitive liquid chromatography-tandem mass spectrometry (LC‒MS/MS) method was developed and verified to facilitate biological analysis. The bioanalysis method was applied to evaluate the stability, plasma protein binding, and pharmacokinetics of glytrexate. Glytrexate is more stable in human plasma than in rat plasma and in human liver microsomes. The binding of glytrexate to human plasma proteins was higher than that to rat plasma proteins, both of which were less than 30%, suggesting that glytrexate may be at a higher concentration at the pharmacologic target receptor(s) in tissues. Pharmacokinetic characteristics were determined by noncompartmental analysis after administration of single oral (12.5, 25 and 50 mg/kg) and intravenous (2 mg/kg) doses in rats. According to the rat oral pharmacokinetic characteristics, glytrexate had linear dynamics in a dose range of 12.5–50 mg/kg and a poor oral bioavailability of 0.57–1.15%. The investigation revealed that the intravenous half-life, AUC, and C_max of glytrexate were higher than those of pemetrexed. Pemetrexed is generally produced as an injection preparation. This provides ideas for the development of glytrexate formulations. Therefore, glytrexate injection has clinical application prospects compared to oral administration. This study provides a basis for further investigations into the pharmacological effects and clinical uses of glytrexate.

Enhanced oral absorption of teriparatide with therapeutic potential for management of osteoporosis

In this study, a system for oral delivery of recombinant human parathyroid hormone [rhPTH(1-34); teriparatide (TRP)] was developed to enhance oral absorption and to demonstrate an equivalent therapeutic effect to that of subcutaneous (SC) TRP injection. The solid oral formulation of TRP was prepared by electrostatic complexation with l-lysine-linked deoxycholic acid (LDA) and deoxycholic acid (DA) at a molar ratio of 1:5:7 in the aqueous dispersion of non-ionic n-dodecyl-β-d-maltoside (DM) at a 1:15 weight ratio, followed by freeze-drying the dispersal, yielding TRP(1:5:7)-15. As expected, TRP(1:5:7)-15 showed a 414% increase in permeability across the Caco-2/HT29-MTX-E12 cell monolayer, resulting in a 13.0-fold greater oral bioavailability compared with free TRP. In addition, the intestinal transport mechanisms in the presence of specific inhibitors of clathrin-mediated endocytosis, macropinocytosis, and bile acid transporters revealed 44.4%, 28.7%, and 51.2% decreases in transport, respectively, confirming that these routes play crucial roles in the permeation of TRP in TRP(1:5:7)-15. Notably, this formulation showed similar activation of the release of cyclic adenosine monophosphate (cAMP) compared with TRP, suggesting equivalent efficacy in the parathyroid hormone receptor-adenylate cyclase system of osteosarcoma cells. Furthermore, oral TRP(1:5:7)-15 (equivalent to 0.4 mg/kg TRP) demonstrated increases in bone mineral density (36.9%) and trabecular thickness (31.3%) compared with untreated glucocorticoid-induced osteoporotic mice. Moreover, the elevated levels of biomarkers of bone formation, including osteocalcin, were also comparable with those after SC injection of TRP (0.02 mg/kg). These findings suggest that TRP(1:5:7)-15 can be used as an effective oral therapy for the management of osteoporosis.

Co-encapsulation of flavonoids with anti-cancer drugs: a challenge ahead

Flavonoids have been considered as promising molecules for cancer treatment due to their pleiotropic properties such as anti-carcinogenic, anti-angiogenic or efflux proteins inhibition. However, due to their lipophilic properties and their chemical instability, vectorization seems compulsory to administer flavonoids. Flavonoids have been co-encapsulated with other anti-cancer agents in a broad range of nanocarriers aiming to i) achieve a synergistic/additive effect at the tumor site, ii) delay drug resistance apparition by combining agents with different action mechanisms or iii) administer a lower dose of the anti-cancer drug, reducing its toxicity. However, co-encapsulation could lead to a change in the nanoparticles' diameter and drug-loading, as well as a decrease in their stability during storage. The preparation process should also take into accounts the physico-chemical properties of both the flavonoid and the anti-cancer agent. Moreover, the co-encapsulation could affect the release and activity of each drug. This review aims to study the formulation, preparation and characterization strategies of these co-loaded nanomedicines, as well as their stability. The in vitro assays to predict the nanomedicines' behavior in biological fluids, as well as their in vivo efficacy, are also discussed. A special focus concerns the evaluation of their synergistic effect on tumor treatment.

A novel oral metronomic chemotherapy provokes tumor specific immunity resulting in colon cancer eradication in combination with anti-PD-1 therapy

In this study, we investigated the immune-modulating effects of a novel metronomic chemotherapy (MCT) featuring combined oral oxaliplatin (OXA) and pemetrexed (PMX) for colon cancer. OXA and PMX were ionically complexed with lysine derivative of deoxycholic acid (DCK), and incorporated into nanoemulsions or colloidal dispersions, yielding OXA/DCK-NE and PMX/DCK-OP, respectively, to improve their oral bioavailabilities. MCT was not associated with significant lymphotoxicity whereas the maximum tolerated dose (MTD) afforded systemic immunosuppression. MCT was associated with more immunogenic cell death and tumor cell MHC-class I expression than was MTD. MCT improved the tumor antigen presentation of dendritic cells and increased the number of functional T cells in the tumor. MCT also helped to enhance antigen-specific memory responses both locally and systemically. By combining MCT with anti-programmed cell death protein-1 (αPD-1) therapy, the tumor volume was suppressed by 97.85 ± 84.88% compared to the control, resulting in a 95% complete response rate. Upon re-challenge, all tumor-free mice rejected secondary tumors, indicating the induction of a tumor specific memory response. Thus, MCT using an OXA and PMX combination, together with αPD-1, successfully treated colon cancer by activating both innate and adaptive immune cells and elicited tumor-specific long-term immune memory while avoiding toxicity caused by MTD treatment.

Cyclodextrin-Modified Nanomaterials for Drug Delivery: Classification and Advances in Controlled Release and Bioavailability

In drug delivery, one widely used way of overcoming the biopharmaceutical problems present in several active pharmaceutical ingredients, such as poor aqueous solubility, early instability, and low bioavailability, is the formation of inclusion compounds with cyclodextrins (CD). In recent years, the use of CD derivatives in combination with nanomaterials has shown to be a promising strategy for formulating new, optimized systems. The goals of this review are to give in-depth knowledge and critical appraisal of the main CD-modified or CD-based nanomaterials for drug delivery, such as lipid-based nanocarriers, natural and synthetic polymeric nanocarriers, nanosponges, graphene derivatives, mesoporous silica nanoparticles, plasmonic and magnetic nanoparticles, quantum dots and other miscellaneous systems such as nanovalves, metal-organic frameworks, Janus nanoparticles, and nanofibers. Special attention is given to nanosystems that achieve controlled drug release and increase their bioavailability during in vivo studies.

Metronomic delivery of orally available pemetrexed-incorporated colloidal dispersions for boosting tumor-specific immunity

In this study, we developed oral pemetrexed (PMX) for metronomic dosing to enhance antitumor immunity. PMX was electrostatically complexed with positively charged lysine-linked deoxycholic acid (DL) as an intestinal permeation enhancer, forming PMX/DL, to enhance its intestinal permeability. PMX/DL was also incorporated into a colloidal dispersion (CD) comprised of the block copolymer of poly(ethylene oxide) and poly(propylene oxide), and caprylocaproyl macrogol-8 glycerides (PMX/DL-CD). CD-containing PMX/DL complex in a 1:1 molar ratio [PMX/DL(1:1)-CD] showed 4.66- and 7.19-fold greater permeability than free PMX through the Caco-2 cell monolayer and rat intestine, respectively. This resulted in a 282% improvement in oral bioavailability in rats. In addition, low-dose metronomic PMX led to more immunogenic cell death in CT26.CL25 cells compared to high PMX concentrations at the maximum tolerated dose. In CT26.CL25 tumor-bearing mice, oral metronomic PMX/DL-CD elicited greater antitumor immunity not only by enhancing the number of tumor-infiltrating lymphocytes but also by suppressing T cell functions. Oral PMX/DL-CD substantially increased programmed cell death protein ligand-1 (PD-L1) expression on tumor cells compared to the control and PMX-IV groups. This increased antitumor efficacy in combination with anti-programmed cell death protein-1 (aPD-1) antibody in terms of tumor rejection and immunological memory compared to the combination of PMX-IV and aPD-1. These results suggest that oral metronomic scheduling of PMX/DL-CD in combination with immunotherapy has synergistic antitumor effects.

Bile acid transporter-mediated oral absorption of insulin via hydrophobic ion-pairing approach

Despite many ongoing and innovative approaches, there are still formidable challenges in the clinical translation of oral peptide drugs into marketable products due to their low absorption and poor bioavailability. Herein, a novel nanocarrier platform was developed that employs a hydrophobic ion-pairing (HIP) of model peptide (insulin) and the anionic bile salt (sodium glycodeoxycholate, SGDC), and markedly improves intestinal absorption via the bile acid pathway. The developed HIP-nanocomplexes (C1 and C2) were optimized, characterized, and in vitro and in vivo evaluation were performed to assess oral efficacy of these system. The optimal molar ratios of C1 and C2-nanocomplexes were 30:1 and 6:1 (SGDC:insulin), respectively. Compared to the insulin solution, the C1 and C2 nanocomplexes significantly enhanced the permeation of insulin across the Caco-2 cell monolayers, with 6.36- and 4.05-fold increases in apparent permeability, respectively. Uptake mechanism studies were conducted using different endocytosis inhibitors and apical sodium-dependent bile acid transporter (ASBT)-transfected MDCK cells, which demonstrated the involvement of the energy-dependent ASBT-mediated active transport. Furthermore, the intrajejunal administration of C1 and C2 resulted in their pharmacological availabilities (PA) being 6.44% and 0.10%, respectively, indicating increased potential for C1, when compared to C2. Similarly, the PA and the relative bioavailability with intrajejunal administration of the C1 were 17.89-fold and 16.82-fold greater than those with intracolonic administration, respectively, confirming better jejunal absorption of C1. Overall, these findings indicate that the HIP-nanocomplexes could be a prominent platform for the effective delivery of peptides with improved intestinal absorption.

Mastering the Gram-negative bacterial barrier - Chemical approaches to increase bacterial bioavailability of antibiotics

To win the battle against resistant, pathogenic bacteria, novel classes of anti-infectives and targets are urgently needed. Bacterial uptake, distribution, metabolic and efflux pathways of antibiotics in Gram-negative bacteria determine what we here refer to as bacterial bioavailability. Understanding these mechanisms from a chemical perspective is essential for anti-infective activity and hence, drug discovery as well as drug delivery. A systematic and critical discussion of in bacterio, in vitro and in silico assays reveals that a sufficiently accurate holistic approach is still missing. We expect new findings based on Gram-negative bacterial bioavailability to guide future anti-infective research.

Bile acids as novel enhancers of CNS targeting antitumor drugs: a comprehensive review

Despite a relatively low prevalence of primary brain tumors, they continuously attract scientific interest because of the complexity of their treatment due to their location behind the blood-brain barrier. The main challenge in treatment of brain tumors is not the efficacy of the drugs, per se, but the low efficiency of drug delivery to malignant cells. At the core of the problem is the complex structure of the blood-brain barrier. Nowadays, there is evidence supporting the claim that bile acids have the ability to cross the blood-brain barrier. That ability can be exploited by taking a part in novel drug carrier designs. Bile acids represent a drug carrier system as a part of a mixed micelle composition, bilosomes and conjugates with various drugs. This review discusses the current knowledge related to bile acid molecules as drug penetration modifying agents, with the focus on central nervous system antitumor drug delivery.

Research Progress on Synthesis and Application of Cyclodextrin Polymers

Cyclodextrins (CDs) are a series of cyclic oligosaccharides formed by amylose under the action of CD glucosyltransferase that is produced by Bacillus. After being modified by polymerization, substitution and grafting, high molecular weight cyclodextrin polymers (pCDs) containing multiple CD units can be obtained. pCDs retain the internal hydrophobic-external hydrophilic cavity structure characteristic of CDs, while also possessing the stability of polymer. They are a class of functional polymer materials with strong development potential and have been applied in many fields. This review introduces the research progress of pCDs, including the synthesis of pCDs and their applications in analytical separation science, materials science, and biomedicine.

Pluronic-based nanovehicles: Recent advances in anticancer therapeutic applications

Pluronics are a class of amphiphilic tri-block copolymers with wide pharmaceutical applicability. In the past decades, the ability to form biocompatible nanosized micelles was exploited to formulate stable drug nanovehicles with potential use in antitumor therapy. Due to the great potential for tuning physical and structural properties of Pluronic unimers, a panoply of drug or polynucleotide-loaded micelles was prepared and tested for their antitumoral activity. The attractive inherent antitumor properties of Pluronic polymers in combination with cell targeting and stimuli-responsive ligands greatly improved antitumoral therapeutic effects of tested drugs. In spite of that, the extraordinary complexity of biological challenges in the delivery of micellar drug payload makes their therapeutic potential still not exploited to the fullest. In this review paper we attempt to present the latest developments in the field of Pluronic based nanovehicles and their application in anticancer therapy with an overview of the chemistry involved in the preparation of these nanovehicles.

Hydrophobic ion pair loaded self-emulsifying drug delivery system (SEDDS): A novel oral drug delivery approach of cromolyn sodium for management of bronchial asthma

The aim of the present study is to develop a self-emulsifying drug delivery system (SEDDS) for the hydrophobic ion pair (HIP) complex of cromolyn sodium (CS), in order to enhance its intestinal absorption and biological activity. Two ion pairing agents (IPAs) were investigated: hexadecyl pyridininum chloride (HPC) and myristyl trimethyl ammonium bromide (MTAB). The optimum binding efficiency for complexation between investigated IPAs and CS was observed at a molar ratio of 1.5:1, where CS binding efficiency was found to be 76.10 ± 2.12 and 91.37 ± 1.73% for MTAB and HPC, respectively. The two prepared complexes exhibited a significant increase in partition coefficient indicating increased lipophilicity. The optimized CS-HIP complex was incorporated into SEDDS formulations. SEDDS formulations F2 (40% oleic acid, 40% Brij^TM98, 20% propylene glycol) and F3 (25% oleic acid, 50% Brij^TM98, 25% propylene glycol) exhibited nanometric droplet diameters with monodisperse distribution and nearly neutral zeta potential values. Ex vivo intestinal permeation study, using the non-everted gut sac technique, revealed a significantly higher cumulative amount of permeated drug, after 2 h, for F2 and F3 (53.836 and 77.617 µg/cm², respectively) compared to 8.649 µg/cm² for plain CS solution. The in vivo evaluation of plain CS solution compared to F2 and F3 was conducted in an ovalbumin sensitization-induced bronchial asthma rat model. Lung function parameters (tidal volume and peak expiratory flow), biochemical parameters (interleukin-5, immunoglobulin-E, myeloperoxidase and airway remodelling parameters) were assessed in addition to histopathological examination. The results indicated the superiority of F3 followed by F2 compared to plain CS solution for prophylaxis of bronchial asthma in rats.

Insights into Hydrophobic Ion Pairing from Molecular Simulation and Experiment

Hydrophobic ion pairing (HIP) is the process by which a charged hydrophilic molecule of interest is electrostatically coupled with an oppositely charged hydrophobic counterion to produce a complex with greater hydrophobicity than the original molecule. This process is of interest in drug delivery, but a molecular-based mechanistic understanding is still incomplete. In this work, we used molecular simulation and experiment to study a model system of Polymyxin B (drug) and oleic acid (hydrophobic counterion). Validation of the simulation system was performed by assessing HIP complex stability under various solvent conditions, and the results were found to be in good agreement with experiment. The effects of solvent composition, particle size, and charge ratio on the observed hydrophobicity, morphology, and stability were studied through the simulation of small HIP clusters. Microsecond simulation of a larger system was then used to characterize the kinetics of assembly. Particle formation over longer length (μm) and time scales (ms) was studied experimentally via flash nanoprecipitation, and the formation of electrostatically stabilized nanoparticles was observed. These results provide a mechanistic and morphological picture of the HIP event and will help inform the development of future formulations that utilize HIP.

Theranostic application of nanoemulsions in chemotherapy

Theranostics has the potential to revolutionize the diagnosis, treatment, and prognosis of cancer, where novel drug delivery systems could be used to detect the disease at an early stage with instantaneous treatment. Various preclinical approaches of nanoemulsions with entrapped contrast and chemotherapeutic agents have been documented to act specifically on the tumor microenvironment (TME) for both diagnostic and therapeutic purposes. However, bringing these theranostic nanoemulsions through preclinical trials to patients requires several fundamental hurdles to be overcome, including the in vivo behavior of the delivery tool, degradation, and clearance from the system, as well as long-term toxicities. Here, we discuss recent advances in the application of nanoemulsions in molecular imaging with simultaneous therapeutic efficacy in a single delivery system.

Modulating tumor immunity by metronomic dosing of oxaliplatin incorporated in multiple oral nanoemulsion

In this study, a system for oral delivery of oxaliplatin (OXA) was prepared for metronomic chemotherapy to enhance antitumor efficacy and modulate tumor immunity. OXA was complexed with N^α-deoxycholyl-l-lysyl-methylester (DCK) (OXA/DCK) and formulated as a nanoemulsion (OXA/DCK-NE). OXA/DCK-NE showed 3.35-fold increased permeability across a Caco-2 cell monolayer, resulting in 1.73-fold higher oral bioavailability than free OXA. In addition, treatment of the B16F10.OVA cell line with OXA/DCK-NE resulted in successful upregulation of immunogenic cell death (ICD) markers both in vitro and in vivo. In a B16F10.OVA tumor-bearing mouse model, treatment with OXA/DCK-NE substantially impeded tumor growth by 63.9 ± 13.3% compared to the control group, which was also greater than the intravenous (IV) OXA group. Moreover, treatment with a combination of oral OXA/DCK-NE and anti-programmed cell death protein-1 (αPD-1) antibody resulted in 78.3 ± 9.67% greater inhibition compared to controls. More important, OXA/DCK-NE alone had immunomodulatory effects, such as enhancement of tumor antigen uptake, activation of dendritic cells in tumor-draining lymph nodes, and augmentation of both the population and function of immune effector cells in tumor tissue as well as in the spleen; no such effects were seen in the OXA IV group. These observations provide a rationale for combining oral metronomic OXA with immunotherapy to elicit synergistic antitumor effects.

Hydrophobic ion pairing: encapsulating small molecules, peptides, and proteins into nanocarriers

Hydrophobic ion pairing has emerged as a method to modulate the solubility of charged hydrophilic molecules ranging in class from small molecules to large enzymes. Charged hydrophilic molecules are ionically paired with oppositely-charged molecules that include hydrophobic moieties; the resulting uncharged complex is water-insoluble and will precipitate in aqueous media. Here we review one of the most prominent applications of hydrophobic ion pairing: efficient encapsulation of charged hydrophilic molecules into nano-scale delivery vehicles - nanoparticles or nanocarriers. Hydrophobic complexes are formed and then encapsulated using techniques developed for poorly-water-soluble therapeutics. With this approach, researchers have reported encapsulation efficiencies up to 100% and drug loadings up to 30%. This review covers the fundamentals of hydrophobic ion pairing, including nomenclature, drug eligibility for the technique, commonly-used counterions, and drug release of encapsulated ion paired complexes. We then focus on nanoformulation techniques used in concert with hydrophobic ion pairing and note strengths and weaknesses specific to each. The penultimate section bridges hydrophobic ion pairing with the related fields of polyelectrolyte coacervation and polyelectrolyte-surfactant complexation. We then discuss the state of the art and anticipated future challenges. The review ends with comprehensive tables of reported hydrophobic ion pairing and encapsulation from the literature.

Intestinal transport mechanism and in vivo anticancer efficacy of a solid oral formulation incorporating an ion-pairing complex of pemetrexed with deoxycholic acid derivative

Objective

The rational combination of immunotherapy with standard chemotherapy shows synergistic clinical activities in cancer treatment. In the present study, an oral powder formulation of pemetrexed (PMX) was developed to enhance intestinal membrane permeability and investigate its application in metronomic chemotherapy in combination with immunotherapy.

Methods

PMX was ionically complexed with a bile acid derivative (N^α-deoxycholyl-l-lysyl-methylester; DCK) as a permeation enhancer and mixed with dispersing agents, such as poloxamer 188 (P188) and Labrasol, to form an amorphous oral powder formulation of PMX/DCK (PMX/DCK-OP).

Results

The apparent permeability (P_app) of PMX/DCK-OP across a Caco-2 cell monolayer was 2.46- and 8.26-fold greater than that of PMX/DCK and free PMX, respectively, which may have been due to the specific interaction of DCK with bile acid transporters, as well as the alteration of membrane fluidity due to Labrasol and P188. Furthermore, inhibition of bile acid transporters by actinomycin D in Caco-2 cell monolayers decreased the P_app of PMX/DCK-OP by 75.4%, suggesting a predominant role of bile acid transporters in the intestinal absorption of PMX/DCK-OP. In addition, caveola/lipid raft-dependent endocytosis, macropinocytosis, passive diffusion, and paracellular transport mechanisms significantly influenced the permeation of PMX/DCK-OP through the intestinal membrane. Therefore, the oral bioavailability of PMX/DCK-OP in rats was 19.8%±6.93%, which was 294% higher than that of oral PMX. Moreover, an in vivo anticancer efficacy study in B16F10 cell-bearing mice treated with a combination of oral PMX/DCK-OP and intraperitoneal anti-PD1 exhibited significant suppression of tumor growth, and the tumor volume was maximally inhibited by 2.03- and 3.16-fold compared to the oral PMX/DCK-OP and control groups, respectively.

Conclusion

These findings indicated the therapeutic potential of a combination of low-dose oral chemotherapy and immunotherapy for synergistic anticancer efficacy.

Anti-Angiogenic Effect of Orally Available Pemetrexed for Metronomic Chemotherapy

Metronomic chemotherapy (MCT) is defined as the frequent administration of low-dose chemotherapeutics, without long drug-free periods, with the exertion of antitumor activity exclusively through anti-angiogenic mechanisms. In this study, we have developed an orally available formulation of pemetrexed (PMX) for MCT. PMX was first complexed ionically with N^α-deoxycholyl-l-lysyl-methylester (DCK) as the permeation enhancer. This was followed by dispersion with poloxamer 188 and Labrasol to form the solid oral formulation of PMX (PMX/DCK-OP). PMX/DCK-OP exhibited a 10.6-fold increase in permeability across a Caco-2 cell monolayer compared to PMX alone. This resulted in a 70-fold increase in the oral bioavailability of PMX/DCK-OP in mice over oral PMX alone. In the A549 xenograft model, tumor volume was reduced by 51.1% in the PMX/DCK-OP treated group compared to only 32.8% in the maximum tolerated dose (MTD)-treated group. Furthermore, PMX/DCK-OP exhibited a significant anti-angiogenic effect on the A549 xenograft mice when compared to the MTD-treated group, as indicated by microvessel density quantification for CD-31. In addition, PMX/DCK-OP enhanced the release of an endogenous angiogenesis inhibitor, thrombospondin-1 (TSP-1), into both the blood circulation and the tumor microenvironment. Therefore, due to its oral route of administration, PMX/DCK-OP appears to be a better alternative to the conventional treatment of PMX.

Phospholipid complex based nanoemulsion system for oral insulin delivery: preparation, in vitro, and in vivo evaluations

Purpose: The aim of this research was to develop a phospholipid complex based nanoemulsion system for oral insulin delivery.

Methods: Insulin-phospholipid complex (IPC) was firstly prepared by an anhydrous co-solvent lyophilization method, and then encapsulated into the oil phase of nanoemulsion to obtain the IPC-based nanoemulsion (IPC-NE). Both water-in-oil (W/O) IPC-NE and oil-in-water (O/W) IPC-NE were formulated and evaluated for comparison.

Results: The obtained W/O IPC-NE and O/W IPC-NE were both spherical in shape with a mean particle size of 18.6±0.79 nm and 27.3±1.25 nm, respectively. While both IPC-NEs exhibited enhanced Caco-2 cell monolayers permeability than IPC and insulin solution, W/O IPC-NE showed relatively greater protective effects against enzymatic degradation than O/W IPC-NE. Moreover, oral administration of W/O IPC-NE exhibited significant hypoglycemic effects, with 12.4-fold and 1.5-fold higher oral bioavailability compared with insulin solution and O/W IPC-NE, respectively.

Conclusion: IPC-NEs, especially the W/O IPC-NE showed promising efficiency in vitro and in vivo, thus could be a potential strategy for oral insulin delivery.

Co-amorphous solid dispersion systems of lacidipine-spironolactone with improved dissolution rate and enhanced physical stability

Co-amorphous solid dispersion (C-ASD) systems have attracted great attention to improve the solubility of poorly soluble drugs, but the selection of an appropriate stabilizer to stabilize amorphous forms is still a huge challenge. Herein, C-ASD system of two clinical combined used drugs (lacidipine (LCDP) and spironolactone (SPL)) as stabilizers to each other, was prepared by solvent evaporation method. The effects of variation in molar ratio of LCDP and SPL (3:1, 1:1, 1:3, 1:6, and 1:9) on the drug release characteristics were explored. Polarized light microscopy (PLM), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were employed to evaluate the solid states. Prepared C-ASDs were further studied for their stability under the high humidity (RH 92.5%). Further analysis of C-ASDs via Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy confirmed that hydrogen bond interactions between the two drugs played a significant role in maintaining the stability of the C-ASDs systems. Moreover, molecular dynamic (MD) simulations provided a clear insight into the stability mechanism at the molecular level. This study demonstrated the novel drug-drug C-ASDs systems is a promising formulation strategy for improved dissolution rate and enhanced physical stability of poorly soluble drugs.