Ionic co-aggregates (ICAs) based oral drug delivery: Solubilization and permeability improvement

Solidified ionic liquid-based formulations of metformin with enhanced GI epithelial permeability

Active Pharmaceutical Ingredient-Ionic Liquids (API-ILs) can enhance intestinal epithelial membrane permeability of poorly bioavailable APIs, improving bioavailability. However, clinical and commercial application is to date limited due to challenging physical handling properties. Lipid-based formulations (LBFs) are commonly used to enhance intestinal drug absorption but face challenges including low drug-loading capacity and limited stability. To address these issues, a method for transforming liquid API-ILs and LBFs into high-loading solid forms via spray-encapsulation with polymers was developed. Here the method was applied to a lipophilic API-IL of BCS Class III, namely metformin, and multi-component API-IL solutions containing known intestinal permeation enhancers (Labrasol®, docusate). The spray-encapsulated solid formulations exhibited improved handling, self-emulsified in both phosphate buffer (pH 6.8) and fasted state simulated intestinal fluid (FaSSIF), while exhibiting superior in vitro release profiles compared to the liquid formulations. Ex vivo permeability studies on metformin docusate formulations using rat intestinal mucosae in Ussing chambers demonstrated a 2.3- to 6.3-fold increase in permeability (Papp) for solidified formulations, with metformin hydrochloride as the control. Further studies revealed a correlation between docusate concentration and permeability enhancement. These findings highlight the potential of solidified docusate-based lipophilic API-IL formulations to improve membrane permeability of poorly bioavailable APIs.

Enhanced transdermal delivery of insulin by choline-based ionic liquids

Ionic liquids (ILs) show promises as chemical penetration enhancers (CPEs) for transdermal delivery of macromolecular drugs. However, their high viscosity and strong drug-IL affinity may limit drug diffusion and release from the drug-loaded IL (one-step strategy). Herein, a two-step strategy was used by applying choline-based ILs as pretreatment agents followed by insulin solution to improve penetration. Insulin remained stable in the ILs and are released slowly from the IL matrices. In vitro and in vivo studies showed that two-step treatment enhanced insulin penetration compared to one-step treatment, with choline citrate ([Ch][Ci]) and choline geranate ([Ch][Ge]) performing the best. In a diabetic rat model, two-step treatment with [Ch][Ge] reduced blood glucose levels to below 80% within 8 h, while one-step treatment only maintained for 12 h. Trans-epidermal water loss and molecular dynamics simulations suggested that variations in release rates and skin condition accounted for the differences between the two strategies. Physical characterization confirmed that ILs enhanced transdermal delivery of insulin by permeabilizing stratum corneum and opening tight junctions. Preliminary safety assessment indicated mild irritation by [Ch][Ge], whereas [Ch][Ci] showed good biocompatibility. It is concluded that ILs hold potential in enhancing transdermal delivery of insulin.

Ionic co-aggregates based intravenous drug delivery: Evaluation on kinetics and distribution of the drug payloads and nanocarriers

Surfactants are crucial in formulating poorly soluble drugs but lead to serious side effects due to PEG chains. Novel supra-amphiphiles consisting of fatty acids and choline are developed, which spontaneously form ionic co-aggregates (ICAs) in water and exhibit strong solubilizing capacity. Paclitaxel (PTX) is adopted as a model drug here to evaluate the feasibility of choline oleate-based ICAs in the intravenous delivery of poorly soluble drugs by comparing the kinetics and distribution of payloads and nanocarriers. Choline oleate presents a maximum 10-fold enhancement in solubilizing capacity to PTX than Cremophor EL (CreEL), enabling a one-tenth use level in the formulation. Aggregation-caused quenching probes are utilized to evaluate the kinetics and biodistribution of ICAs or CreEL-based micelles (MCs). A huge gap is found between the pharmacokinetic and particokinetic curves of either nanocarrier, indicating fast leakage. ICAs lead to faster PTX leakage in blood circulation but higher PTX distribution to organs than MCs. MCs present a longer circulation in blood but a slower distribution to organs than ICAs. ICAs do not arise adverse reactions in rats following repeated injections, while MCs cause pathological changes in varying degrees. In conclusion, choline oleate-based ICAs provide an alternative to surfactants in formulating poorly soluble drugs.

Next-generation aluminum adjuvants: Immunomodulatory layered double hydroxide NanoAlum reengineered from first-line drugs

Aluminum adjuvants (Alum), approved by the US Food and Drug Administration, have been extensively used in vaccines containing recombinant antigens, subunits of pathogens, or toxins for almost a century. While Alums typically elicit strong humoral immune responses, their ability to induce cellular and mucosal immunity is limited. As an alternative, layered double hydroxide (LDH), a widely used antacid, has emerged as a novel class of potent nano-aluminum adjuvants (NanoAlum), demonstrating advantageous physicochemical properties, biocompatibility and adjuvanticity in both humoral and cellular immune responses. In this review, we summarize and compare the advantages and disadvantages of Alum and NanoAlum in these properties and their performance as adjuvants. Moreover, we propose the key features for ideal adjuvants and demonstrate that LDH NanoAlum is a promising candidate by summarizing its current progress in immunotherapeutic cancer treatments. Finally, we conclude the review by offering our integrated perspectives about the remaining challenges and future directions for NanoAlum's application in preclinical/clinical settings.

Enteral Route Nanomedicine for Cancer Therapy

With the in-depth knowledge of the pathological and physiological characteristics of the intestinal barrier-portal vein/intestinal lymphatic vessels-systemic circulation axis, oral targeted drug delivery is frequently being renewed. With many advantages, such as high safety, convenient administration, and good patient compliance, many researchers have begun to explore targeted drug delivery from intravenous injections to oral administration. Over the past few decades, the fields of materials science and nanomedicine have produced various drug delivery platforms that hold great potential in overcoming the multiple barriers associated with oral drug delivery. However, the oral transport of particles into the systemic circulation is extremely difficult due to immune rejection and biochemical invasion in the intestine, which limits absorption and entry into the bloodstream. The feasibility of the oral delivery of targeted drugs to sites outside the gastrointestinal tract (GIT) is unknown. This article reviews the biological barriers to drug absorption, the in vivo fate and transport mechanisms of drug carriers, the theoretical basis for oral administration, and the impact of carrier structural evolution on oral administration to achieve this goal. Finally, this article reviews the characteristics of different nano-delivery systems that can enhance the bioavailability of oral therapeutics and highlights their applications in the efficient creation of oral anticancer nanomedicines.

In vivo fluorescence imaging of nanocarriers in near-infrared window II based on aggregation-caused quenching

Accurate fluorescence imaging of nanocarriers in vivo remains a challenge owing to interference derived mainly from biological tissues and free probes. To address both issues, the current study explored fluorophores in the near-infrared (NIR)-II window with aggregation-caused quenching (ACQ) properties to improve imaging accuracy. Candidate fluorophores with NIR-II emission, ACQ984 (λem = 984 nm) and IR-1060 (λem = 1060 nm), from the aza-BODIPY and cyanine families, respectively, were compared with the commercial fluorophore ICG with NIR-II tail emission and the NIR-I fluorophore P2 from the aza-BODIPY family. ACQ984 demonstrates high water sensitivity with complete fluorescence quenching at a water fraction greater than 50%. Physically embedding the fluorophores illuminates various nanocarriers, while free fluorophores cause negligible interference owing to the ACQ effect. Imaging based on ACQ984 revealed fine structures in the vascular system at high resolution. Moreover, good in vivo and ex vivo correlations in the monitoring of blood nanocarriers can be established, enabling real-time noninvasive in situ investigation of blood pharmacokinetics and dynamic distribution in various tissues. IR-1060 also has a good ACQ effect, but the lack of sufficient photostability and steady post-labeling fluorescence undermines its potential for nanocarrier bioimaging. P2 has an excellent ACQ effect, but its NIR-I emission only provides nondiscriminative ambiguous images. The failure of the non-ACQ probe ICG to display the biodistribution details serves as counterevidence for the improved imaging accuracy by NIR-II ACQ probes. Taken together, it is concluded that fluorescence imaging of nanocarriers based on NIR-II ACQ probes enables accurate in vivo bioimaging and real-time in situ pharmacokinetic analysis.

Oral targeted drug delivery to post-gastrointestinal sites

As an essential branch of targeted drug delivery, oral targeted delivery is attracting growing attention in recent years. In addition to site-specific delivery for the treatment of locoregional diseases in the gastrointestinal tract (GIT), oral targeted delivery to remote sites beyond the GIT emerges as a cutting-edge research topic. This review aims to provide an overview of the fundamental concepts and most recent advances in this field. Owing to the physiological barriers existing in the GIT, carrier systems should be transported across the enteric epithelia to target remote sites. Recently, pioneer investigations have validated the transport of intact micro- or nanocarriers across gastrointestinal barriers and subsequently to various distal organs and tissues. The microfold (M) cell pathway is the leading mechanism underlying the oral absorption of particulates, but the contribution of the transcellular and paracellular pathways should not be neglected either. In addition to well-acknowledged physicochemical and biological factors, the formation of a protein corona may also influence the biological fate of carrier systems. Although in an early stage of conceptualization, oral targeted delivery to remote diseases has demonstrated promising potential for the treatment of inflammation, tumors, and diseases inflicting the lymphatic and mononuclear phagocytosis systems.

Characterization of herpetrione amorphous nanoparticles stabilized by hydroxypropylmethyl cellulose and its absorption mechanism in vitro

Herpetrione(HPE) is an effective compound that has been used in the treatment of liver diseases. To improve its dissolution and absorption, herpetrione nanosuspensions was prepared. Nanosuspensions were proved to achieve intact absorption in vivo. However, the transport mechanisms are not fully understood, especially lack of direct evidence of translocation of particulates. In this study, an environment-responsive dye, P4, was loaded into herpetrione amorphous nanoparticles (HPE-ANPs) to elucidate the absorption and transport mechanism of the nanoparticles. And the amount of HPE and nanoparticles in the samples were quantified using HPLC/LC-MS/MS and IVIS with the model of Caco-2 and Caco-2/HT29-MTX. Results demonstrated that HPE is mainly taken up by passive diffusion in the form of free drugs, while HPE-ANPs are internalized by an energy dependent active transport pathway or intracellular endocytosis. It is speculated that HPE-ANPs may change the original entry pathway of drug molecules. Furthermore, the presence of mucus layer and the use of HPMC E15 may contribute to drug absorption to some extent. Transcellular transport study indicates that HPE-ANPs has a poor absorption. In conclusion, the differences in the absorption behavior trends of HPE-ANPs are caused by the difference in particle properties and the form of existence of the drug.

Oral self-nanoemulsifying drug delivery systems for enhancing bioavailability and anticancer potential of fosfestrol: In vitro and in vivo characterization

PURPOSE

The objective of the current research work was to fabricate a fosfestrol (FST)-loaded self-nanoemulsifying drug delivery system (SNEDDS) to escalate the oral solubility and bioavailability and thereby the effectiveness of FST against prostate cancer.

METHODS

32 full factorial design was employed, and the effect of lipid and surfactant mixtures on percentage transmittance, time required for self-emulsification, and drug release were studied. The optimized solid FST-loaded SNEDDS (FSTNE) was characterized for in vitro anticancer activity and Caco-2 cell permeability, and in vivo pharmacokinetic parameters.

RESULTS

Using different ratios of surfactant and co-surfactant (Km) a pseudo ternary phase diagram was constructed. Thirteen liquid nano emulsion formulations (LNE-1 to LNE-13) were formulated at Km = 3:1. LNE-9 exhibited a higher % transmittance (99.25 ± 1.82 %) and a lower self-emulsification time (24 ± 0.32 s). No incompatibility was observed in FT-IR analysis. Within 20 min the solidified FST loaded LNE-9 (FSTNE) formulation showed almost complete drug release (98.20 ± 1.30 %) when compared to marketed formulation (40.36 ± 2.8 %), and pure FST (32 ± 3.3 %) in 0.1 N HCl. In pH 6.8 phosphate buffer, the release profiles are found moderately higher than in 0.1 N HCl. FSTNE significantly (P < 0.001) inhibited the PC-3 prostate cell proliferation and also caused apoptosis (P < 0.001) compared to FST. The in vitro Caco-2 cell permeability study results revealed 4.68-fold higher cell permeability of FSTNE than FST. Remarkably, 4.5-fold rise in bioavailability was observed after oral administration of FSTNE than plain FST.

CONCLUSIONS

FSTNE remarkably enhanced the in vitro anticancer activity and Caco-2 cell permeability, and in vivo bioavailability of FST. Thus, FST-SNEDDS could be utilized as a potential carrier for effective oral treatment of prostate cancer.

Pickering Emulsions Enhance Oral Bioavailability of Curcumin Nanocrystals: The Effect of Oil Types

Nanocrystals (NCs) have the potential to enhance the oral bioavailability of Class IV drugs in the Biopharmaceutical Classification System (BCS) due to the absorption of the intact crystals. The performance is compromised by the dissolution of NCs. Drug NCs have recently been adopted as solid emulsifiers to prepare nanocrystal self-stabilized Pickering emulsions (NCSSPEs). They are advantageous in high drug loading and low side effects due to the specific drug loading mode and the absence of chemical surfactants. More importantly, NCSSPEs may further enhance the oral bioavailability of drug NCs by impeding their dissolution. This is especially true for BCS IV drugs. In this study, curcumin (CUR), a typical BCS IV drug, was adopted to prepare CUR-NCs stabilized Pickering emulsions using either indigestible (isopropyl palmitate, IPP) or digestible (soybean oil, SO) oils, i.e., IPP-PEs and SO-PEs. The optimized formulations were spheric with CUR-NCs adsorbed on the water/oil interface. The CUR concentration in the formulation reached 20 mg/mL, which was far beyond the solubility of CUR in IPP (158.06 ± 3.44 μg/g) or SO (124.19 ± 2.40 μg/g). Moreover, the Pickering emulsions enhanced the oral bioavailability of CUR-NCs, being 172.85% for IPP-PEs and 152.07% for SO-PEs. The digestibility of the oil phase affected the amounts of CUR-NCs that remained intact in lipolysis and, thus, the oral bioavailability. In conclusion, converting NCs into Pickering emulsions provides a novel strategy to enhance the oral bioavailability of CUR and BCS IV drugs.

Recent Advances in Biocompatible Ionic Liquids in Drug Formulation and Delivery

The development of effective drug formulations and delivery systems for newly developed or marketed drug molecules remains a significant challenge. These drugs can exhibit polymorphic conversion, poor bioavailability, and systemic toxicity, and can be difficult to formulate with traditional organic solvents due to acute toxicity. Ionic liquids (ILs) are recognized as solvents that can improve the pharmacokinetic and pharmacodynamic properties of drugs. ILs can address the operational/functional challenges associated with traditional organic solvents. However, many ILs are non-biodegradable and inherently toxic, which is the most significant challenge in developing IL-based drug formulations and delivery systems. Biocompatible ILs comprising biocompatible cations and anions mainly derived from bio-renewable sources are considered a green alternative to both conventional ILs and organic/inorganic solvents. This review covers the technologies and strategies developed to design biocompatible ILs, focusing on the design of biocompatible IL-based drug formulations and delivery systems, and discusses the advantages of these ILs in pharmaceutical and biomedical applications. Furthermore, this review will provide guidance on transitioning to biocompatible ILs rather than commonly used toxic ILs and organic solvents in fields ranging from chemical synthesis to pharmaceutics.

Transcellular Transport Behavior of the Intact Polymeric Mixed Micelles with Different Polymeric Ratios

In order to better promote the application of the polymeric mixed micelles (PMMs) in oral delivery, in addition to focusing on the improvement of micellar structural stability, it is necessary to obtain the absorption characteristics of the intact micellar particles. In this work, the transport behavior across Caco-2 cells of FS/PMMs composed of Pluronic F127 and Solutol HS15 was tracked by encapsulating an environment-responsive probe into the particles. The specific property of the probe is the water-initiated aggregation-caused quenching (ACQ) ability, by which integral particles can be identified accurately. The influence of polymeric ratios (FS) on the transcellular behavior of FS/PMMs was explored and the single pass intestinal perfusion experiment was used to further illustrate it. Moreover, pharmacokinetics parameters were detected to analyze the relationship among FS ratios, transport behavior, and pharmacokinetic parameters. FS ratios were found to hardly affect the endocytosis pathways and intracellular itinerary of FS/PMMs, but do affect the proportion of each path. FS/PMMs with high HS15 content, namely System-I, were found to primarily undergo receptor-mediated endocytosis pathway and be less susceptible to lysosomal degradation, which would lead to more absorption and higher Cmax and AUC than drug suspension. In contrast, despite System-II with high F127 content cannot contribute to drug plasma concentration, it can prolong the in vivo retention time. These findings provided evidence for the role of polymeric ratios in modulating the transcellular absorption and pharmacokinetic parameters of the drug-loaded PMMs, and would be a step forward in helping PMMs' design to enhance oral drug delivery.

Engineered organic nanoparticles to combat biofilms

Biofilms are colonies of microorganisms that are embedded in autocrine extracellular polymeric substances (EPS), imparting antibiotic resistance and recalcitrant bacterial infection. Nanoparticles (NPs) can enhance the biofilm inhibition and eradication of delivered antibiotics. This is mainly because of enhanced EPS penetration and a high local drug concentration. As we discuss here, novel strategies are being developed to further enhance the antibiofilm capacity of NPs, including size optimization, surface modification, stimuli-triggered release, and combined strategies. Thus, NPs represent an effective and promising approach to combat biofilms.

Enhanced oral bioavailability from food protein nanoparticles: A mini review

The oral route is the most desirable drug administration path. The oral bioavailability is always compromised from the poor physicochemical and/or biopharmaceutical properties of the active pharmaceutical ingredients. Food protein nanoparticles show promise for oral drug delivery, with improved biosafety and cost-effectiveness compared to polymeric nanoparticles. More importantly, diverse food proteins provide "choice and variety" to meet the challenges faced by different drugs in oral delivery resulting from low solubility, poor permeability, and gastrointestinal stability. The abundance of hydroxyl, amino, and carboxyl groups in food proteins allows easy surface modification of the nanoparticles to impart unique functions. Albeit being in its infancy, food protein nanoparticles exhibit high capability to enhance oral bioavailability of a wide range of drugs from small molecules to biomacromolecules. Considering the rapid growth of the field, the achievements and mechanisms of food protein nanoparticles in enhancing oral bioavailability are reviewed. Factors affecting the performance of food protein nanoparticles are discussed with the purpose to inspire the development of food protein nanoparticle-based oral drug delivery systems.

Ionic Liquids-Based Drug Delivery: a Perspective

Ionic liquids (ILs) recently draw attention for addressing unmet needs in biomedicines. By converting solids into liquids, ILs are emerging as novel platforms to overcome some critical drawbacks associated with the application of solid or crystalline active pharmaceutical ingredients (APIs). ILs have shown promise in liquidizing or solubilizing APIs, or as green solvents, novel permeation enhancers or active ingredients, alone or synergistically with APIs. Meanwhile, challenges turn up in company with the deepening understanding of ILs as drug delivery carrier systems. This perspective aims to provide a sketchy overview on the status quo with specific attention paid to new problems arising from the utilization of ILs-based technologies in drug delivery.