Effects of Cyclodextrins on Drug Delivery Through Biological Membranes

Comparative Analysis of γ-Cyclodextrin, Perilla Oil, and Their Inclusion Complexes on Liver Injury and Dyslipidemia Associated with Elevated Gastrointestinal 12-Hydroxylated Bile Acid Levels

Our previous study demonstrated that γ-cyclodextrin (γ-CD)-perilla oil inclusion complexes increase plasma α-linolenic acid and eicosapentaenoic acid levels in healthy rats without adverse effects. The present study examined the effects of perilla oil, γ-CD, and their inclusion complexes on rats fed cholic acid (CA) to mimic the elevated gastrointestinal 12-hydroxylated (12OH) bile acid levels in high-fat diet-fed rats. Rats fed CA (CA group) tended to have higher AST, ALT, plasma total cholesterol (T-CHO), and triglyceride (TG) levels compared to controls fed a standard diet without CA. Rats fed CA and perilla oil (CA+LP group) showed a tendency for lower AST and plasma TG levels than those in the CA group. Rats fed CA and γ-CD (CA+CD group) had significantly higher AST, ALT, plasma T-CHO, and TG levels than the controls, indicating severe liver injury and dyslipidemia. Rats fed CA and the γ-CD-perilla oil inclusion complex (CA+IC group) had significantly lower AST and ALT levels than the CA+CD rats, with a trend towards lower plasma T-CHO and TG levels. Plasma α-linolenic acid and eicosapentaenoic acid levels were significantly higher in the CA+LP and CA+IC groups than in the controls and CA+CD groups. However, the CA+IC group tended to have lower α-linolenic acid levels and significantly lower eicosapentaenoic acid levels than the CA+LP group. This suggests an accelerated conversion of α-linolenic acid to eicosapentaenoic acid in the CA+IC group, which may contribute to the attenuation of liver injury and dyslipidemia. These findings suggest that γ-CD may exacerbate liver injury and dyslipidemia caused by elevated gastrointestinal 12OH bile acid levels, whereas γ-CD-perilla oil inclusion complexes may ameliorate these effects by altering fatty acid metabolism. Furthermore, we recommend evaluating γ-CD safety in both healthy and pathological models and carefully selecting compounds co-ingested with γ-CD.

Advancements in cyclodextrin-based controlled drug delivery: Insights into pharmacokinetic and pharmacodynamic profiles

This article discusses and summarizes some fascinating outcomes and applications of cyclodextrins (CDs) and their derivatives in drug delivery. These applications include the administration of protein, peptide medications, and gene delivery. Several innovative drug delivery systems, including NPs, microspheres, microcapsules, and liposomes, are designed with the help of CD, which is highlighted in this article. The use of these compounds as excipients in medicine formulation is reviewed, in addition to their well-known effects on drug solubility and dissolution, as well as their bioavailability, safety, and stability. Furthermore, the article focuses on many factors that influence the development of inclusion complexes, as having this information is necessary to manage these diverse materials effectively. An overview of the commercial availability, regulatory status, and patent status of CDs for pharmaceutical formulation is also presented. Due to the fact that CDs can discover new uses in drug delivery consistently, it is predicted that they will solve a wide range of issues related to the distribution of a variety of unique medications through various delivery channels.

Multifunctionality of cyclodextrin-based polymeric nanoparticulate delivery systems for chemotherapeutics, combination therapy, and theranostics

As cancer being the most difficult disease to treat, different kinds of medications and therapeutic approaches have been prominently developed by scientists. For certain families of drugs, such as immuno-therapeutics or antibody-drug conjugates, efficient delivery systems are required during administration to protect the drugs from chemical degradation or biological inactivation. Delivery systems with the ability to carry different therapeutics or diagnostic agents or both, hold promising potential to tackle the abnormalities behind cancer. In this context, this review provides updated insights on how cyclodextrin-based polymeric nanosystems have become an effective treatment approach against cancer. Cyclodextrins (CDs) are natural oligosaccharides that are famously exploited in pharmaceutical research due to their exceptional quality of entrapping water-insoluble molecules inside their hydrophobic core and providing enhanced solubility with the help of their hydrophilic exterior. Combining the properties of CDs with polymeric nanoparticles (PNPs) brings out excellent versatile and tunable profiles, thanks to the submicron-sized PNPs. By introducing the significance of CD as a delivery system, a collective discussion on different binding approaches and release mechanisms of CD-drug complexation, followed by their characterization studies has been done in this review. Further, in light of recent studies, the article majorly focuses on conveying how promoting CD to a polymeric and nanoscale elevates the multifunctional advantages against cancer that can be successfully applied in combination therapy and theranostics. Moreover, CD-based delivery systems including CALAA-01, CRLX101, and CRLX301, have demonstrated improved tumor targeting, reduced side effects, and prolonged drug release in preclinical studies and clinical trials.

Mechanistic Insight in Permeability through Different Membranes in the Presence of Pharmaceutical Excipients: A Case of Model Hydrophobic Carbamazepine

The present study reports the effects of two pharmaceutical excipients of differing natures-non-ionic surfactant pluronic F127 (F127) and anionic sulfobutylether-β-cyclodextrin (SBE-β-CD)-on the permeation of the model compound, carbamazepine (CBZ). The permeability coefficients of CBZ at three concentrations of the excipients were measured through two different artificial barriers: hydrophilic cellulose membrane (RC) and lipophilic polydimethylsiloxane-polycarbonate membrane (PDS). The equilibrium solubility of CBZ in F127 and SBE-β-CD solutions was determined. The micellization, complexation, and aggregation tendencies were investigated. Systemically increasing the solubility and the reduction of permeation upon the excipients' concentration growth was revealed. The quantitative evaluation of the permeability tendencies was carried out using a Pratio parameter, a quasi-equilibrium mathematical mass transport model, and a correction of permeability coefficients for the free drug concentration ("true" permeability values). The results revealed the mutual influence of the excipient properties and the membrane nature on the permeability variations.

Solubility-enabling formulations for oral delivery of lipophilic drugs: considering the solubility-permeability interplay for accelerated formulation development

INTRODUCTION

Tackling low water solubility of drug candidates is a major challenge in today's pharmaceutics/biopharmaceutics, especially by means of modern solubility-enabling formulations. However, drug absorption from these formulations oftentimes remains unchanged or even decreases, despite substantial solubility enhancement.

AREAS COVERED

In this article, we overview the simultaneous effects of the formulation on the solubility and the apparent permeability of the drug, and analyze the contribution of this solubility-permeability interplay to the success/failure of the formulation to increase the overall absorption and bioavailability. Three different patterns of interplay were identified: (1) solubility-permeability tradeoff in which every solubility gain comes with a price of concomitant permeability loss; (2) an advantageous interplay pattern in which the permeability remains unchanged alongside the solubility gain; and (3) an optimal interplay pattern in which the formulation increases both the solubility and the permeability. Passive vs. active intestinal permeability considerations in the context of the solubility-permeability interplay are also thoroughly discussed.

EXPERT OPINION

The solubility-permeability interplay pattern of a given formulation has a critical effect on its overall success/failure, and hence, taking into account both parameters in solubility-enabling formulation development is prudent and highly recommended.

Spray-Dried Powder Containing Cannabigerol: A New Extemporaneous Emulgel for Topical Administration

Cannabigerol (CBG), a cannabinoid from Cannabis sativa L., recently attracted noteworthy attention for its dermatological applications, mainly due to its anti-inflammatory, antioxidant, and antimicrobial effectiveness similar to those of cannabidiol (CBD). In this work, based on results from studies of in vitro permeation through biomimetic membranes performed with CBG and CBD in the presence and in the absence of a randomly substituted methyl-β-cyclodextrin (MβCD), a new CBG extemporaneous emulgel (oil-in-gel emulsion) formulation was developed by spray-drying. The powder (SDE) can be easily reconstituted with purified water, leading to a product with chemical-physical and technological characteristics that are comparable to those of the starting emulgels (E). Thermogravimetric analysis (TGA), attenuated total reflection-Fourier transformed infrared spectroscopy (ATR-FTIR), x-ray powder diffraction (XRPD), and high-performance liquid chromatography (HPLC) analyses demonstrated that the spray-drying treatment did not alter the chemical properties of CBG. This product can represent a metered-dosage form for the localized treatment of cutaneous afflictions such as acne and psoriasis.

Fast disintegrating dosage forms of mucoadhesive-based nanoparticles for oral insulin delivery: Optimization to in vivo evaluation

The aim of this work was to develop fast disintegrating dosage forms, including fast disintegrating tablets (FDTs) and films (FDFs), for oral insulin delivery incorporating mucoadhesive thiolated chitosan (TCS)-based nanoparticles (NPs). Cyclodextrin (CD)-insulin complexes were formed to prevent insulin from degradation and further optimally prepared NPs in order to improve the mucoadhesive properties. After that, these NPs were incorporated into the dosage forms and then evaluated for their morphology as well as physical and mechanical properties. The disintegration time, insulin content, mucoadhesive properties, insulin release, cytotoxicity, in vivo hypoglycemic effect, and stability of dosage forms were studied. Results showed that the CD-insulin complexes were successfully encapsulated into the mucoadhesive NPs. The 15 %w/w CD-insulin complex-loaded NPs, which were probably dispersed and/or fused into the dosage forms, showed promising characteristics, including rapid disintegration as well as good physical and mechanical properties to withstand erosion during handling and storage. The porous structure of the FDTs promoted liquid flow and induced rapid disintegration. The dosage forms provided buccal mucoadhesion before, during, and/or after the disintegration. The FDFs containing hydroxypropyl β-cyclodextrin (HPβCD)-insulin complex-loaded NPs increased mucoadhesion, increasing insulin release. Furthermore, these dosage forms provided excellent in vivo hypoglycemic response with a prolonged effect in diabetic mice and had no cytotoxicity toward the gingival fibroblast cells. In addition, they were stable at temperatures between 2 and 8 °C for three months. The results indicate that these formulations could be applied as promising dosage forms for use in oral insulin delivery.

Development of Innovative Electrospun Nepafenac-Loaded Nanofibers-based Ophthalmic Inserts

Electrospun nanofibers can be utilized to develop patient-centric ophthalmic formulations with reasonable bioavailability at the targeted site. The current study aimed to develop 0.1% w/w of nepafenac-loaded electrospun nanofibrous webs as potential candidates for ocular delivery of nepafenac with improved solubility and stability. Nine different formulations were prepared by electrospinning and investigated for morphology, physicochemical properties, drug release, cytocompatibility, and in vitro and ex vivo permeability. The scanning electron microscopy images showed fibrous samples. Fourier transform infrared spectroscopy and X-ray diffraction confirmed the polymer cross-linking and the formation of amorphous solid dispersion. All formulations showed complete and fast release of nepafenac (≤ 60 minutes), and the release followed first-order kinetics (β values for all formulations were <1). The formulations (F3, F6, and F9) showed considerable in vitro and ex vivo permeability. The Raman studies revealed comparable corneal distributions of F3 and the commercial Nevanac® suspension at 60 min (p value = 0.6433). The fibrous composition remains stable under stress conditions (40 ± 2 °C, 75 ± 5% relative humidity). The formulation composition showed good cytocompatibility with hen eggs tested on the chorioallantoic membrane of chick embryos. The developed nanofiber webs could be a promising candidate for nepafenac-loaded ophthalmic inserts. Chemical compounds studied in this article Nepafenac (PubChem CID151075); Polyvinyl alcohol (PubChem CID 11199); Poloxamer 407 (PubChem CID 24751); Chloroform (PubChem CID 6212); Methanol (PubChem CID 887); L-α-phosphatidylcholine (PubChem CID 10425706); Ethylenediaminetetraacetic acid (PubChem CID 6049).

Colon targeted releases and uptakes of paclitaxel loaded in modified porous starch

Hyaluronic acid can modify porous starch through cross-linking and hydrogen bonding, effectively achieving a paclitaxel entrapment efficiency of ∼92 % and drug loading of ∼23 %. In this study, the pores and intergranular gaps of porous starch were filled with paclitaxel under solvent volatilization, and the enrichment process and its characteristics were recorded using a microscope. The paclitaxel-loaded particles were coated with chitosan-phytic acid to target the colon. In vivo imaging in mice showed that the capsule released paclitaxel in the colon rather than in the upper digestive tract, and the paclitaxel distribution in the main organs at 24 h was significantly lower than that of raw paclitaxel. Hyaluronic acid-modified porous starch can target cancer cells. Cell internalization of paclitaxel mediated by hyaluronic acid was approximately 1.97 times that of raw paclitaxel, higher than that of receptor-shielded cells and cells incubated with unmodified carriers, as evidenced by the accumulation of fluorescent paclitaxel in the nucleus and marked cell apoptosis. The hyaluronic acid-modified porous starch system is an effective method for the high-load and targeted release of hydrophobic anticancer drugs.

A promising synthetic citric crosslinked β-cyclodextrin derivative for antifungal drugs: Solubilization, cytotoxicity, and antifungal activity

Effective antifungal therapy for the treatment of fungal keratitis requires a high drug concentration at the corneal surface. However, the use of natural β-cyclodextrin (βCD) in the preparation of aqueous eye drop formulations for treating fungal keratitis is limited by its low aqueous solubility. Here, we synthesized water-soluble anionic βCD derivatives capable of forming water-soluble complexes and evaluated the solubility, cytotoxicity, and antifungal efficacy of drug prepared using the βCD derivative. To achieve this, a citric acid crosslinked βCD (polyCTR-βCD) was successfully synthesized, and the aqueous solubilities of selected antifungal drugs, including voriconazole, miconazole (MCZ), itraconazole, and amphotericin B, in polyCTR-βCD and analogous βCD solutions were evaluated. Among the drugs tested, complexation of MCZ with polyCTR-βCD (MCZ/polyCTR-βCD) increased MCZ aqueous solubility by 95-fold compared with that of MCZ/βCD. The inclusion complex formation of MCZ/βCD and MCZ/polyCTR-βCD was confirmed by spectroscopic techniques. Additionally, the nanoaggregates of saturated MCZ/polyCTR-βCD and MCZ/βCD solutions were observed using dynamic light scattering and transmission electron microscopy. Moreover, MCZ/polyCTR-βCD solution exhibited good mucoadhesion, sustained drug release, and high drug permeation of porcine cornea ex vivo. Hen's Egg test-chorioallantoic membrane assay and cell viability study using Statens Seruminstitut Rabbit Cornea cell line showed that both MCZ/polyCTR-βCD and MCZ/βCD exhibited no sign of irritation and non-toxic to cell line. Additionally, antifungal activity evaluation demonstrated that all isolated fungi, including Candida albicans, Aspergillus flavus, and Fusarium solani, were susceptible to MCZ/polyCTR-βCD. Overall, the results showed that polyCTR-βCD could be a promising nanocarrier for the ocular delivery of MCZ.

Bioresponsive and multifunctional cyclodextrin-based non-viral nanocomplexes in cancer therapy: Building foundations for gene and drug delivery, immunotherapy and bioimaging

The interest towards application of nanomaterials in field of cancer therapy is that the drawbacks of conventional therapies including chemoresistance, radio-resistance and lack of specific targeting of tumor cells can be solved by nanotechnology. Cyclodextrins (CDs) are amphiphilic cyclic oligosaccharides that can be present in three forms of α-, β- and γ-CDs, and they can be synthesized from natural sources. The application of CDs in cancer shows an increasing trend due to benefits of these nanocomplexes in improving solubility and bioavailability of current bioactives and therapeutics for cancer. CDs are widely utilized in delivery of drugs and genes in cancer therapy, and by targeted delivery of these therapeutics into target site, they improve anti-proliferative and anti-cancer potential. The blood circulation time and tumor site accumulation of therapeutics can be improved using CD-based nanostructures. More importantly, the stimuli-responsive types of CDs including pH-, redox- and light-sensitive types can accelerate release of bioactive compound at tumor site. Interestingly, the CDs are able to mediate photothermal and photodynamic impact in impairing tumorigenesis in cancer, enhancing cell death and improving response to chemotherapy. In improving the targeting ability of CDs, their surface functionalization with ligands has been conducted. Moreover, CDs can be modified with green products such as chitosan and fucoidan, and they can be embedded in green-based nanostructures to suppress tumorigenesis. The internalization of CDs into tumor cells can occur through endocytosis and this can be clethrin-, caveolae- or receptor-mediated endocytosis. Furthermore, CDs are promising candidates in bioimaging, cancer cell and organelle imaging as well as isolating tumor cells. The main benefits of using CDs in cancer therapy including sustained and low release of drugs and genes, targeted delivery, bioresponsive release of cargo, ease of surface functionalization and complexation with other nanostructures. The application of CDs in overcoming drug resistance requires more investigation.

Cyclodextrins for the Delivery of Bioactive Compounds from Natural Sources: Medicinal, Food and Cosmetics Applications

Cyclodextrins have gained significant and established attention as versatile carriers for the delivery of bioactive compounds derived from natural sources in various applications, including medicine, food and cosmetics. Their toroidal structure and hydrophobic cavity render them ideal candidates for encapsulating and solubilizing hydrophobic and poorly soluble compounds. Most medicinal, food and cosmetic ingredients share the challenges of hydrophobicity and degradation that can be effectively addressed by various cyclodextrin types. Though not new or novel-their first applications appeared in the market in the 1970s-their versatility has inspired numerous developments, either on the academic or industrial level. This review article provides an overview of the ever-growing applications of cyclodextrins in the delivery of bioactive compounds from natural sources and their potential application benefits.

Cyclodextrin-enabled nepafenac eye drops with improved absorption open a new therapeutic window

Nepafenac is a highly effective NSAID used for treating postoperative ocular inflammation and pain after cataract surgery and its advantage over conventional topical NSAIDs has been proved many times. However, Nevanac® is a suspension eye drop, which clearly lacks patient compliance causing irritation, blurred vision, foreign body sensation along with problematic dosage due to its sticky, inhomogeneous consistence. In this study, nepafenac containing eye drops were prepared using hydroxypropyl-β-cyclodextrin to ensure complete dissolution of nepafenac, sodium hyaluronate to provide mucoadhesion and adequate viscosity and a preservative-free officinal formula, Oculogutta Carbomerae containing carbomer (just like Nevanac®), therefore providing a similar base for the new formulations. According to an experimental design, 11 formulations were tested in vitro including two reference formulations by measuring their viscosity, mucoadhesion, drug release and corneal permeability. Finally, two formulations were found promising and investigated further on porcine eyes ex vivo and corneal distribution of nepafenac was determined by RAMAN mapping. The results showed that one formulation possessed better bioavailability ex vivo than Nevanac® 0.1 % suspension, while the other formulation containing only 60 % of the original dose were ex vivo equivalent with Nevanac® opening the way to nepafenac-containing eye drops with better patient compliance in the future.

Insights into recent preclinical studies on labelled cyclodextrin-based imaging probes: towards a novel oncological era

As malignancies remain one of the major health concerns worldwide, increasing focus has been centered around the application of cyclodextrins (CDs) in cancer imaging and therapy due to their outstanding inclusion forming capability. Albeit the physicochemical properties of CDs were intensively elucidated, the spread of their clinical application is limited by the relative paucity of knowledge about their pharmacokinetic profile, especially biodistribution. Studies applying fluorescently- CDs, or CD-based MRI contrast agents revealed much about pharmacokinetics and diagnostic applications; however, derivatives labelled with positron emitters seem superior molecular probes in the investigation of the route of CDs in biological niche. In vivo imaging based on preclinical tumor-bearing model systems are well-suited to evaluate the whole-body distribution of the two most frequently assessed CDs: randomly methylated β-cyclodextrin (RAMEB), and hydroxypropyl-β-cyclodextrin (HPBCD). Exploiting the firm signaling interaction between cancer-related cyclooxygenase-2, prostaglandin E2 (PGE2) and RAS oncoprotein, radioconjugated, PGE2-affine CDs project the establishment of novel imaging probes and therapeutic agents. Currently, we provide an overview of the preclinical studies on CD pharmacokinetics highlighting the significance of the integration of translational discoveries into human patient care.

In Vitro and In Vivo Characterization of the Transdermal Gel Formulation of Desloratadine for Prevention of Obesity and Metabolic Syndrome

Chronic use of antihistamines can induce abnormalities in lipid absorption with potential excessive accumulation of lipids in the mesentery that can lead to the development of obesity and a metabolic syndrome. The focus of the present work was to develop a transdermal gel formulation of desloratadine (DES) to prevent/reduce obesity and metabolic syndromes. Nine formulations were prepared to contain hydroxypropyl methylcellulose (2-3%), DES (2.5-5.0%), and Transcutol^® (15-20%). The formulations were evaluated for cohesive and adhesive properties, viscosity, drug diffusion through synthetic and pig ear skin, and pharmacokinetics in New Zealand white rabbits. Drug permeation was faster through the skin compared to synthetic membranes. The drug had good permeation, as indicated by very short lag time (0.08-0.47 h) and high flux (59.3-230.7 μg/cm².h). The maximum plasma concentration (C_max) and area under the curve (AUC) of transdermal gel formulations were 2.4 and 3.2 fold that of the Clarinex tablet formulation. In conclusion, as indicated by the higher bioavailability, transdermal gel formulation of DES may decrease the dose of the drug, compared to commercial formulation. It has the potential to reduce or eliminate metabolic syndromes associated with oral antihistamine therapy.

Anomalous Properties of Cyclodextrins and Their Complexes in Aqueous Solutions

Cyclodextrins (CDs) are cyclic oligosaccharides that emerged as industrial excipients in the early 1970s and are currently found in at least 130 marketed pharmaceutical products, in addition to numerous other consumer products. Although CDs have been the subject of close to 100,000 publications since their discovery, and although their structure and properties appear to be trivial, CDs are constantly surprising investigators by their unique physicochemical properties. In aqueous solutions, CDs are solubilizing complexing agents of poorly soluble drugs while they can also act as organic cosolvents like ethanol. CDs and their complexes self-assemble in aqueous solutions to form both nano- and microparticles. The nanoparticles have diameters that are well below the wavelength of visible light; thus, the solutions appear to be clear. However, the nanoparticles can result in erroneous conclusions and misinterpretations of experimental results. CDs can act as penetration enhancers, increasing drug permeation through lipophilic membranes, but they do so without affecting the membrane barrier. This review is an account of some of the unexpected results the authors have encountered during their studies of CDs as pharmaceutical excipients.

Solid-State Formation of a Potential Melphalan Delivery Nanosystem Based on β-Cyclodextrin and Silver Nanoparticles

Melphalan (Mel) is an antineoplastic widely used in cancer and other diseases. Its low solubility, rapid hydrolysis, and non-specificity limit its therapeutic performance. To overcome these disadvantages, Mel was included in β-cyclodextrin (βCD), which is a macromolecule that increases its aqueous solubility and stability, among other properties. Additionally, the βCD-Mel complex has been used as a substrate to deposit silver nanoparticles (AgNPs) through magnetron sputtering, forming the βCD-Mel-AgNPs crystalline system. Different techniques showed that the complex (stoichiometric ratio 1:1) has a loading capacity of 27%, an association constant of 625 M^-1, and a degree of solubilization of 0.034. Added to this, Mel is partially included, exposing the NH₂ and COOH groups that stabilize AgNPs in the solid state, with an average size of 15 ± 3 nm. Its dissolution results in a colloidal solution of AgNPs covered by multiple layers of the βCD-Mel complex, with a hydrodynamic diameter of 116 nm, a PDI of 0.4, and a surface charge of 19 mV. The in vitro permeability assays show that the effective permeability of Mel increased using βCD and AgNPs. This novel nanosystem based on βCD and AgNPs is a promising candidate as a Mel nanocarrier for cancer therapy.

Permeability of New Antifungal Fluconazole Derivatives through a Lipophilic Membrane: Experiment and Modeling

Relationships between the structures of molecules and their properties form the basis of modern chemistry and lay the foundation for structure-based drug design. Being the main two determinants of bioavailability, solubility and permeability of drugs are widely investigated experimentally and predicted from physicochemical parameters and structural descriptors. In the present study, we measure the passive diffusion permeability of a series of new fluconazole derivatives with triazole and thiazolo-pyrimidine moieties connected by different linker bridges through the PermeaPad barrier-a relatively new biomimetic lipophilic membrane that has been increasingly used in recent years. The permeability coefficients of new derivatives are shown to be dependent both on the structure of the linker fragment and on the substituent in the phenyl ring of the thiazolo-pyrimidine moiety. The impact of the compound ionization state on the permeability is revealed. Reliable correlations of the permeability with the antifungal activity and distribution coefficient are found. In addition, the solubility-diffusion approach is shown to be able to successfully predict the permeability of the studied derivatives. The obtained results can be considered another step in the development of permeability databases and design of schemes for in vitro permeability prediction.

Cyclodextrin-Based Delivery Systems and Hydroxycinnamic Acids: Interactions and Effects on Crucial Parameters Influencing Oral Bioavailability-A Review

Hydroxycinnamic acids (HCAs) are a subclass of phenolic acids presenting caffeic acid (CA), chlorogenic acid (CGA), coumaric acid (COA) isomers, ferulic acid (FA), and rosmarinic acid (RA) as the major representants, being broadly distributed into vegetal species and showing a range of biological potentials. Due to the low oral bioavailability of the HCAs, the development of delivery systems to promote better administration by the oral route is demanding. Among the systems, cyclodextrin (CD)-based delivery systems emerge as an important technology to solve this issue. Regarding these aspects, in this review, CD-based delivery systems containing HCAs are displayed, described, and discussed concerning the degree of interaction and their effects on crucial parameters that affect the oral bioavailability of HCAs.

Exploring inclusion complex of an anti-cancer drug (6-MP) with β-cyclodextrin and its binding with CT-DNA for innovative applications in anti-bacterial activity and photostability optimized by computational study

The co-evaporation approach was used to examine the host-guest interaction and to explore the cytotoxic and antibacterial properties of an important anti-cancer medication, 6-mercaptopurine monohydrate (6-MP) with β-cyclodextrin (β-CD). The UV-Vis investigation confirmed the inclusion complex's (IC) 1 : 1 stoichiometry and was also utilized to oversee the viability of this inclusion process. FTIR, NMR, and XRD, among other spectrometric techniques, revealed the mechanism of molecular interactions between β-CD and 6-MP which was further hypothesized by DFT to verify tentative outcomes. TGA and DSC studies revealed that 6-MP's thermal stability increased after encapsulation. Because of the protection of drug 6-MP by β-CD, the formed IC was found to have higher photostability. This work also predicts the release behavior of 6-MP in the presence of CT-DNA without any chemical changes. An evaluation of the complex's antibacterial activity in vitro revealed that it was more effective than pure 6-MP. The in vitro cytotoxic activity against the human kidney cancer cell line (ACHN) was also found to be significant for the IC (IC50 = 4.18 μM) compared to that of pure 6-MP (IC50 = 5.49 μM). These findings suggest that 6-MP incorporation via β-CD may result in 6-MP stability and effective presentation of its solubility, cytotoxic and antibacterial properties.

Modelling drug diffusion through unstirred water layers allows real-time quantification of free/loaded drug fractions and release kinetics from colloidal-based formulations

The correlation between in vivo and in vitro data is yet not sufficiently optimized to allow a significant reduction and replacement of animal testing in pharmaceutical development. One of the main reasons for this lies in the poor mechanistic understanding and interpretation of the physical mechanisms enabling formulation rely on for deploying the drug. One mechanism that still lacks a proper interpretation is the kinetics of drug release from nanocarriers. In this work, we investigate two different types of classical enabling formulations - i) cyclodextrin solutions and ii) liposomal dispersions - by a combination of an experimental method (i.e. UV-Vis localized spectroscopy) and mathematical modelling/numerical data fitting. With this approach, we are able to discriminate precisely between the amount of drug bound to nanocarriers or freely dissolved at any time point; in addition, we can precisely estimate the binding and diffusivity constants of all chemical species (free drug/bound drug). The results obtained should serve as the first milestone for the further development of reliable in vitro/in silico models for the prediction of in vivo drug bioavailability when enabling formulations are used.

Progress and prospects of modified starch-based carriers in anticancer drug delivery

Recently, the role of starch-based carrier systems in anticancer drug delivery has gained considerable attention. Although there are same anticancer drugs, difference in their formulations account for unique therapeutic effects. However, the exploration on the effect-enhancing of anticancer drugs and their loading system by modified starch from the perspective of carrier regulation is still limited. Moreover, research on the reduced toxicity of the anticancer drugs due to modified starch as the drug carrier mediated by the intestinal microenvironment is lacking, but worth exploring. In this review, we examined the effect of modified starch on the loading and release properties of anticancer drugs, and the effect of resistant starch and its metabolites on intestinal microecology during inflammation. Particularly, the interactions between modified starch and drugs, and the effect of resistant starch on gene expression, protein secretion, and inflammatory factors were discussed. The findings of this review could serve as reference for the development of anticancer drug carriers in the future.

Cyclodextrin Inclusion Complexes with Antibiotics and Antibacterial Agents as Drug-Delivery Systems—A Pharmaceutical Perspective

Cyclodextrins (CDs) are a family of cyclic oligosaccharides, consisting of a macrocyclic ring of glucose subunits linked by α-1,4 glycosidic bonds. The shape of CD molecules is similar to a truncated cone with a hydrophobic inner cavity and a hydrophilic surface, which allows the formation of inclusion complexes with various molecules. This review article summarises over 200 reports published by the end of 2021 that discuss the complexation of CDs with antibiotics and antibacterial agents, including beta-lactams, tetracyclines, quinolones, macrolides, aminoglycosides, glycopeptides, polypeptides, nitroimidazoles, and oxazolidinones. The review focuses on drug-delivery applications such as improving solubility, modifying the drug-release profile, slowing down the degradation of the drug, improving biological membrane permeability, and enhancing antimicrobial activity. In addition to simple drug/CD combinations, ternary systems with additional auxiliary substances have been described, as well as more sophisticated drug-delivery systems including nanosponges, nanofibres, nanoparticles, microparticles, liposomes, hydrogels, and macromolecules. Depending on the desired properties of the drug product, an accelerated or prolonged dissolution profile can be achieved when combining CD with antibiotics or antimicrobial agents.

Supersaturation-Based Drug Delivery Systems: Strategy for Bioavailability Enhancement of Poorly Water-Soluble Drugs

At present, the majority of APIs synthesized today remain challenging tasks for formulation development. Many technologies are being utilized or explored for enhancing solubility, such as chemical modification, novel drug delivery systems (microemulsions, nanoparticles, liposomes, etc.), salt formation, and many more. One promising avenue attaining attention presently is supersaturated drug delivery systems. When exposed to gastrointestinal fluids, drug concentration exceeds equilibrium solubility and a supersaturation state is maintained long enough to be absorbed, enhancing bioavailability. In this review, the latest developments in supersaturated drug delivery systems are addressed in depth.

Cyclodextrins and drug membrane permeation: Thermodynamic considerations

Cyclodextrins are hydrophilic oligosaccharides that can increase aqueous solubility of lipophilic drugs through formation of water-soluble drug/cyclodextrin complexes. Although the complexes are hydrophilic, and as such do not permeate biological membranes, the complexes are known to enhance drug permeation through lipophilic membranes and improve drug bioavailability after, for example, oral administration. However, it is not clear how cyclodextrins enhance the permeation. An artificial biomembrane (PermeaPad®) was used to study the effect of donor medium composition on drug permeation. It was observed that in aqueous solutions the hydrophilic cyclodextrins behave not like disperse systems but rather like organic cosolvents such as ethanol, increasing the solubility without having significant effect on the molecular mobility and ability of lipophilic drug molecules to partition into the lipophilic membrane. Also, that partition of dissolved drug molecules from the aqueous exterior into the membrane is at its maximum when their thermodynamic activity is at its maximum. In other words, that drug flux from aqueous cyclodextrin solutions through lipophilic membranes depends on both the concentration and the thermodynamic activity of dissolved drug. Maximum flux is obtained when both the drug concentration and thermodynamic activity of the dissolved drug molecules are at their maximum value.

A smart and responsive crystalline porous organic cage membrane with switchable pore apertures for graded molecular sieving

Membranes with high selectivity offer an attractive route to molecular separations, where technologies such as distillation and chromatography are energy intensive. However, it remains challenging to fine tune the structure and porosity in membranes, particularly to separate molecules of similar size. Here, we report a process for producing composite membranes that comprise crystalline porous organic cage films fabricated by interfacial synthesis on a polyacrylonitrile support. These membranes exhibit ultrafast solvent permeance and high rejection of organic dyes with molecular weights over 600 g mol^-1. The crystalline cage film is dynamic, and its pore aperture can be switched in methanol to generate larger pores that provide increased methanol permeance and higher molecular weight cut-offs (1,400 g mol^-1). By varying the water/methanol ratio, the film can be switched between two phases that have different selectivities, such that a single, 'smart' crystalline membrane can perform graded molecular sieving. We exemplify this by separating three organic dyes in a single-stage, single-membrane process.

Synthesis, complex formation and corneal permeation of cyclodextrin-modified, thiolated poly(aspartic acid) as self-gelling formulation of dexamethasone

The present study aimed at developing a potential in situ gellable dexamethasone (DXM) eye drop. Poly(aspartic acid) (PASP) derivatives were synthesized with dual functionality to improve the solubility of DXM, and to achieve in situ gelation. First, amine-modified β-cyclodextrin (CD) was attached to polysuccinimide (PSI), second, thiol functionalities were added by the reaction of cysteamine and succinimide rings. Finally, the PSI derivatives were hydrolysed to the corresponding PASP derivatives to get water-soluble polymers. Phase-solubility studies confirmed the complexation ability of CD-containing PASP derivatives. In situ gelation and the effect of the CD immobilization on this behaviour were characterized by rheological measurements. The solubilizing effect of CD was confirmed by kinetic solubility measurements, whereas in vitro corneal permeability assay (corneal-PAMPA) measurements were performed to determine in vitro permeability and flux values. The effect of the PASP derivatives on permeation strongly depended on chemical composition and polymer concentration.

Computational Methods for the Interaction between Cyclodextrins and Natural Compounds: Technology, Benefits, Limitations, and Trends

Cyclodextrins (CDs) have a hollow structure with a hydrophobic interior and hydrophilic exterior. Forming inclusion complexes with CDs will maximize the bioavailability of natural compounds and enable active components to be processed into functional foods, medicines, additives, and so forth. However, experimental methods cannot explain CD-guest binding at the atomic level. Different models have been recently developed to simulate the interaction between CDs and guests to study the binding conformation and analyze noncovalent forces. This review paper summarizes modeling methods of CD-natural compound complexes. The methods include quantitative structure-activity relationships, molecular docking, molecular dynamics simulations, and quantum-chemical calculations. The applications of these methods to enhance the solubility and bioactivities of guest molecules, assist material transportation, and promote compound extraction are also discussed. The purpose of this review is to explore interaction mechanisms of CDs and guests and to help expand new applications of CDs.

Physicochemical and biopharmaceutical aspects influencing skin permeation and role of SLN and NLC for skin drug delivery

The skin is a complex and multifunctional organ, in which the static versus dynamic balance is responsible for its constant adaptation to variations in the external environment that is continuously exposed. One of the most important functions of the skin is its ability to act as a protective barrier, against the entry of foreign substances and against the excessive loss of endogenous material. Human skin imposes physical, chemical and biological limitations on all types of permeating agents that can cross the epithelial barrier. For a molecule to be passively permeated through the skin, it must have properties, such as dimensions, molecular weight, pKa and hydrophilic-lipophilic gradient, appropriate to the anatomy and physiology of the skin. These requirements have limited the number of commercially available products for dermal and transdermal administration of drugs. To understand the mechanisms involved in the drug permeation process through the skin, the approach should be multidisciplinary in order to overcome biological and pharmacotechnical barriers. The study of the mechanisms involved in the permeation process, and the ways to control it, can make this route of drug administration cease to be a constant promise and become a reality. In this work, we address the physicochemical and biopharmaceutical aspects encountered in the pathway of drugs through the skin, and the potential added value of using solid lipid nanoparticles (SLN) and nanostructured lipid vectors (NLC) to drug permeation/penetration through this route. The technology and architecture for obtaining lipid nanoparticles are described in detail, namely the composition, production methods and the ability to release pharmacologically active substances, as well as the application of these systems in the vectorization of various pharmacologically active substances for dermal and transdermal applications. The characteristics of these systems in terms of dermal application are addressed, such as biocompatibility, occlusion, hydration, emollience and the penetration of pharmacologically active substances. The advantages of using these systems over conventional formulations are described and explored from a pharmaceutical point of view.

Cyclodextrin Complexed Lipid Nanoparticles of Irbesartan for Oral Applications: Design, Development, and In Vitro Characterization

Irbesartan (IR) is an angiotensin II receptor antagonist drug with antihypertensive activity. IR bioavailability is limited due to poor solubility and first-pass metabolism. The current investigation aimed to design, develop, and characterize the cyclodextrin(s) (CD) complexed IR (IR-CD) loaded solid lipid nanoparticles (IR-CD-SLNs) for enhanced solubility, sustained release behavior, and subsequently improved bioavailability through oral administration. Based on phase solubility studies, solid complexes were prepared by the coacervation followed by lyophilization method and characterized for drug content, inclusion efficiency, solubility, and in vitro dissolution. IR-CD inclusion complexes demonstrated enhancement of solubility and dissolution rate of IR. However, the dissolution efficiency was significantly increased with hydroxypropyl-βCD (HP-βCD) inclusion complex than beta-CD (βCD). SLNs were obtained by hot homogenization coupled with the ultrasonication method with IR/HP-βCD inclusion complex loaded into Dynasan 112 and glycerol monostearate (GMS). SLNs were evaluated for physicochemical characteristics, in vitro release, differential scanning calorimetry (DSC), powder X-ray diffractometry (PXRD), and physical stability at room temperature for two months. The optimized SLNs formulation showed particle size, polydispersity index, zeta potential, assay, and entrapment efficiency of 257.6 ± 5.1 nm, 0.21 ± 0.03, -30.5 ± 4.1 mV, 99.8 ± 2.5, and 93.7 ± 2.5%, respectively. IR-CD-SLN and IR-SLN dispersions showed sustained release of IR compared to the IR-CD inclusion complexes. DSC results complimented PXRD results by the absence of IR endothermic peak. Optimized IR-CD complex, IR-SLN, and IR-CD-SLN formulations were stable for two months at room temperature. Thus, the current IR oral formulation may exhibit improved oral bioavailability and prolonged antihypertensive activity, which may improve therapeutic outcomes in the treatment of hypertension and heart failure.

Preparation, Characterization, and Anticancer Effects of Capsaicin-Loaded Nanoliposomes

BACKGROUND

Medicinal plants have proven their value as a source of molecules with therapeutic potential, and recent studies have shown that capsaicin has profound anticancer effects in several types of human cancers. However, its clinical use is handicapped due to its poor pharmacokinetics. This study aims to enhance capsaicin's pharmacokinetic properties by loading the molecule into nanoliposomes model and testing its anticancer activity.

METHODS

Nanoliposomes were prepared using the thin-film method, and characteristics were examined followed by qualitative and quantitative analyses of encapsulation efficiency and drug loading using HPLC at different lipid/capsaicin ratios. Cell viability assay (MTT) was used to determine IC50.

RESULTS

Capsaicin-loaded nanoliposomes showed optimum characteristics of morphology, particle size, zeta potential, and stability. In vitro anticancer activity of capsaicin and capsaicin-loaded nanoliposomes were compared against MCF7, MDA-MB-231, K562, PANC1, and A375 cell lines. Capsaicin-loaded nanoliposomes showed significant improvement in anticancer activity against cancers cell lines studied (p < 0.001), with increased selectivity against cancer cells compared to capsaicin.

CONCLUSION

The encapsulated capsaicin nanoliposomes produced an improvement in pharmacokinetics properties, enhancing the anticancer activity and selectivity compared with capsaicin. This model seems to offer a potential for developing capsaicin formulations for the prevention and treatment of cancer.

New Antifungal Compound: Impact of Cosolvency, Micellization and Complexation on Solubility and Permeability Processes

Poor solubility of new antifungal of 1,2,4-triazole class (S-119)—a structural analogue of fluconazole in aqueous media was estimated. The solubility improvement using different excipients: biopolymers (PEGs, PVP), surfactants (Brij S20, pluronic F-127) and cyclodextrins (α-CD, β-CD, 2-HP-β-CD, 6-O-Maltosyl-β-CD) was assessed in buffer solutions pH 2.0 and pH 7.4. Additionally, 2-HP-β-CD and 6-O-Maltosyl-β-CD were proposed as promising solubilizers for S-119. According to the solubilization capacity and micelle/water partition coefficients in buffer pH 7.4 pluronic F-127 was shown to improve S-119 solubility better than Brij S20. Among biopolymers, the greatest increase in solubility was shown in PVP solutions (pH 7.4) at concentrations above 4 w/v%. Complex analysis of the driving forces of solubilization, micellization and complexation processes matched the solubility results and suggested pluronic F-127 and 6-O-Maltosyl-β-CD as the most effective solubilizing agents for S-119. The comparison of S-119 diffusion through the cellulose membrane and lipophilic PermeaPad barrier revealed a considerable effect of the lipid layer on the decrease in the permeability coefficient. According to the PermeaPad, S-119 was classified as a highly permeated substance. The addition of 1.5 w/v% CDs in donor solution moves it to low-medium permeability class.

A New Approach for β-Cyclodextrin Conjugated Drug Delivery System in Cancer Therapy

Natural cyclodextrins (CDs) are macrocyclic starch molecules discovered a decade ago, in which α-, β-, and γ-CD were commonly used. They originally acted as pharmaceutical excipients to enhance the aqueous solubility and alter the physicochemical properties of drugs that fall under class II and IV categories according to the Biopharmaceutics Classification System (BPS). The industrial significance of CDs became apparent during the 1970s as scientists started to discover more of CD's potential in chemical modifications and the formation of inclusion complexes. CDs can help in masking and prolonging the half-life of drugs used in cancer. Multiple optimization techniques were discovered to prepare the derivatives of CDs and increase their complexation and drug delivery efficiency. In recent years, due to the advancement of nanotechnology in pharmaceutical sectors, there has been growing interest in CDs. This review mainly focuses on the formulation of cyclodextrin conjugated nanocarriers using graphenes, carbon nanotubes, nanosponges, hydrogels, dendrimers, and polymers to achieve drug-release characteristics specific to cells. These approaches benefit the discovery of novel anti-cancer treatments, solubilization of new drug compounds, and cell specific drug delivery properties. Due to these unique properties of CDs, they are essential in achieving and enhancing tumor-specific cancer treatment.

Characteristic of Cyclodextrins: Their Role and Use in the Pharmaceutical Technology

About 40% of newly-discovered entities are poorly soluble in water, and this may be an obstacle in the creation of new drugs. To address this problem, the present review article examines the structure and properties of cyclodextrins and the formation and potential uses of drug - cyclodextrin inclusion complexes. Cyclodextrins are cyclic oligosaccharides containing six or more D-(+)- glucopyranose units linked by α-1,4-glycosidic bonds, which are characterized by a favourable toxicological profile, low local toxicity and low mucous and eye irritability; they are virtually non-toxic when administered orally. They can be incorporated in the formulation of new drugs in their natural form (α-, β-, γ-cyclodextrin) or as chemically-modified derivatives. They may also be used as an excipient in drugs delivered by oral, ocular, dermal, nasal and rectal routes, as described in the present paper. Cyclodextrins are promising compounds with many beneficial properties, and their use may be increasingly profitable for pharmaceutical scientists.

Force Field Parameterization for the Description of the Interactions between Hydroxypropyl-β-Cyclodextrin and Proteins

Cyclodextrins are cyclic oligosaccharides, widely used as drug carriers, solubilizers, and excipients. Among cyclodextrins, the functionalized derivative known as hydroxypropyl-β-cyclodextrin (HPβCD) offers several advantages due to its unique structural features. Its optimal use in pharmaceutical and medical applications would benefit from a molecular-level understanding of its behavior, as can be offered by molecular dynamics simulations. Here, we propose a set of parameters for all-atom simulations of HPβCD, based on the ADD force field for sugars developed in our group, and compare it to the original CHARMM36 description. Using Kirkwood-Buff integrals of binary HPβCD-water mixtures as target experimental data, we show that the ADD-based description results in a considerably improved prediction of HPβCD self-association and interaction with water. We then use the new set of parameters to characterize the behavior of HPβCD toward the different amino acids. We observe pronounced interactions of HPβCD with both polar and nonpolar moieties, with a special preference for the aromatic rings of tyrosine, phenylalanine, and tryptophan. Interestingly, our simulations further highlight a preferential orientation of HPβCD's hydrophobic cavity toward the backbone atoms of amino acids, which, coupled with a favorable interaction of HPβCD with the peptide backbone, suggest a propensity for HPβCD to denature proteins.

Ultrasound Triggered Drug Release from Affinity-Based β-Cyclodextrin Polymers for Infection Control

This work demonstrates a slow, sustained drug delivery system that provides on-demand delivery bursts through the application of pulsed therapeutic ultrasound (TUS). Insoluble β-cyclodextrin-polymer (pCD) disks were loaded with a saturated antibiotic solution of rifampicin (RIF) and used for drug delivery studies. To obtain on-demand release from the implants, TUS was applied at an intensity of 1.8 W/cm². The therapeutic efficacy of the combination treatment was assessed in bacterial culture via an in vitro Staphylococcus aureus bioluminescence assay. The results demonstrated that the application of pulsed TUS at 3 MHz and 1.8 W/cm² to pCD implants leads to a significantly higher short-term burst in the drug release rate compared to samples not treated with TUS. The addition of TUS increased the drug release by 100% within 4 days. The pCD disk + RIF stimulated with TUS showed a comparatively higher bacterial eradication with CFU/mL of 4.277E+09, and 8.00E+08 at 1 and 24 h compared with control treated bacteria at 1.48E+10. Overall, these results suggest that the addition of pulsed TUS could be an effective technology to noninvasively expedite antibiotic release on demand at desired intervals.

Cardiovascular effects of farnesol and its β-cyclodextrin complex in normotensive and hypertensive rats

Farnesol (FAR) is a sesquiterpene alcohol with a range of reported biological effects including cardioprotective, antioxidant and antiarrhythmic properties. However, due to its volatility, the use of drug incorporation systems, such as cyclodextrins, have been proposed to improve its pharmacological properties. Thus, the aim of this study was to evaluate and characterize the cardiovascular effects of FAR alone, and to investigate the antihypertensive effects of FAR complexed with β-cyclodextrin (βCD) in rats. Mean arterial pressure (MAP) and heart rate (HR) were measured before and after intravenous administration of FAR (0,5; 2,5; 5 and 7,5 mg/kg) in normotensive rats, and after oral acute administration (200 mg/kg) of FAR and FAR/βCD complex in NG-nitro-L-arginine-methyl-ester (L-NAME) hypertensive rats. In normotensive animals, FAR induced dose-dependent hypotension associated with bradycardia. These effects were not affected by pre-treatment with L-NAME or indomethacin (INDO), but were partially attenuated by atropine. Pre-treatment with hexamethonium (HEXA) only affected hypotension. In the hypertensive rats, FAR/βCD potentialized the antihypertensive effect when compared to FAR alone. Molecular docking experiments demonstrated for the first time that FAR has affinity to bind to the M₃ and M₂ muscarinic, and nicotinic receptors through hydrogen bonds in the same residues as known ligands. In conclusion, our results demonstrated that FAR induced hypotension associated with bradycardia, possibly through the muscarinic and nicotinic receptors. The inclusion complex with βCD improved the antihypertensive effects of FAR, which can be relevant to improve current cardiovascular therapy using volatile natural components.

Study of supramolecular complex of nifedipine with arabinogalactan on Wistar and ISIAH rats

Aim: Physicochemical and pharmacological study of the supramolecular inclusion complexes of the hypotensive drug nifedipine (NF) with the larch polysaccharide arabinogalactan (AG). Materials & methods: The NF:AG complexes were obtained and their physicochemical properties were studied. Their hypotensive action and pharmacokinetic profiles were evaluated in rats with normal and elevated arterial blood pressure. Results: In both rat lines the NF:AG complex decreased the arterial blood pressure at a lower dose than free NF (1.75 mg/kg of NF in complex compared with 3.5 mg/kg of free NF) and has a better pharmacokinetic profile than free NF. Conclusion: The use of the NF:AG complex is an effective way to sufficiently enhance and hasten NF's hypotensive action.

Topical drug delivery to the posterior segment of the eye: Thermodynamic considerations

Almost all studies on non-invasive topical drug delivery to the eye have emphasized the importance of biological barriers, static membrane barriers such as the cornea and the conjunctiva/sclera and dynamic barriers such as the lacrimal drainage. Hardly any have discussed the importance of the thermodynamic activity of the permeating drug molecules. Most drugs permeate from the eye surface into the eye by passive diffusion where, according to Fick's first law, the drug concentration gradient over the various permeation barriers (e.g., the tear fluid and the lipophilic membrane barriers) is the driving force. At the barrier interphases the dissolved drug molecules must partition from one barrier to another. For example, at the tear-cornea interphase the drug molecules must partition from the aqueous exterior into the lipophilic membrane. The drug partition coefficient between two phases is commonly defined as the equilibrium concentration ratio. However, these are only approximations. The actual driving force in Fick's first law is the gradient of the chemical potential and the equilibrium between two phases is attained when the chemical potential of the drug in one phase is equal to that in the other phase. Here the importance of thermodynamic considerations in topical drug delivery to the eye is reviewed.

Aerosolization Performance, Antitussive Effect and Local Toxicity of Naringenin-Hydroxypropyl-β-Cyclodextrin Inhalation Solution for Pulmonary Delivery

The aim of present study was to evaluate the feasibility of a naringenin-hydroxypropyl-β-cyclodextrin (naringenin-HPβCD) inhalation solution for pulmonary delivery. Naringenin, a flavanone derived from citrus fruits, has been proven to exhibit excellent peripheral antitussive effect. To address the limitation of its poor oral bioavailability and low local concentration in the lung, a naringenin-HPβCD inhalation solution was prepared for pulmonary delivery. The aerosolization performance of formulation was evaluated by next generation impactor (NGI). Both dose-dependent and time-dependent antitussive effects of naringenin-HPβCD inhalation solution on acute cough induced by citric acid in guinea pigs were investigated. In vitro toxicity of naringenin-HPβCD inhalation solution in pulmonary Calu-3 cells was evaluated by MTS assay, and in vivo local toxicity investigation was achieved by assessing bronchoalveolar lavage (BALF) and lung histology after a 7-day inhalation treatment in guinea pigs. Fine particle fraction (FPF) of the formulation was determined as 53.09%. After inhalation treatment of 15 min, naringenin-HPβCD inhalation solution within the studied range of 0.2-3.6 mg/kg could dose-dependently reduce the cough frequency with the antitussive rate of 29.42-39.42%. Naringenin-HPβCD inhalation solution in concentration range of 100-400 μM did not decrease cell viability of Calu-3 cells, and the maximum effective dose (3.6 mg/kg) was non-toxic during the short-term inhalation treatment for guinea pigs. In conclusion, naringenin-HPβCD inhalation solution was capable for nebulization and could provide rapid response with reduced dose for the treatment of cough.