Inclusion Complexation of Etodolac with Hydroxypropyl-beta-cyclodextrin and Auxiliary Agents: Formulation Characterization and Molecular Modeling Studies

A QbD-Navigated Approach to the Development and Evaluation of Etodolac-Phospholipid Complex Containing Polymeric Films for Improved Anti-Inflammatory Effect

The current study focuses on development of phospholipid complex-loaded films of etodolac for enhanced transdermal permeation and anti-inflammatory effect. An etodolac-phospholipid complex was developed using the solvent evaporation method and was characterized by DSC, XRD, FTIR, and 1H-NMR studies. The formation of the complex led to conversion of a crystalline drug to an amorphous form. A stoichiometric ratio of 1:1 (drug-phospholipid) was selected as the optimized ratio. Further, the developed complex was incorporated into films and systematic optimization using a central composite design was carried out using a response surface methodological approach. The desirable design space based on minimum contact angle and maximum tensile strength was selected, while the water vapour transmission rate and swelling index were set within limits. The results for swelling index, contact angle, tensile strength, and water vapour transmission rate were 60.14 ± 1.01%, 31.6 ± 0.03, 2.44 ± 0.39 kg/cm2, and 15.38 g/hm2, respectively. These values exhibited a good correlation with the model-predicted values. The optimized formulation exhibited improved diffusion and permeation across skin. In vivo studies revealed enhanced anti-inflammatory potential of the developed films in comparison to the un-complexed drug. Hence, the study demonstrated that etodolac-phospholipid complex-loaded films improve the transdermal permeation and provided enhanced anti-inflammatory effect.

QbD Assisted Systematic Review for Optimizing the Selection of PVP as a Ternary Substance in Enhancing the Complexation Efficiency of Cyclodextrins: a Pilot Study

Inclusion complexes require higher concentration of Beta cyclodextrins (βCD) resulting in increased formulation bulk, toxicity, and production costs. This systematic review offers a comprehensive analysis using Quality by design (QbD) as a tool to predict potential applications of Polyvinylpyrrolidone (PVP) as a ternary substance to address issues of inclusion complexes. We reviewed 623 documents from 2013 to 2023 and Eighteen (18) research papers were selected for statistical and meta-analysis using the QbD concept to identify the most critical factors for selecting drugs and effect of PVP on inclusion complexes. The QbD analysis revealed that Molecular weight (MW), Partition coefficient (Log P), and the auxiliary substance ratio directly affected complexation efficiency (CE), thermodynamic stability in terms of Gibbs free energy (ΔG), and percent drug release. However, Stability constant (Ks) remained unaffected by any of these parameters. The results showed that low MW (250), median Log P (6), and a βCD: PVP ratio of 2:3 would result in higher CE, lower G, and improved drug release. PVP improves drug solubility, enhances delivery and therapeutic outcomes, and counteracts increased drug ionization due to decreased pH. In certain cases, its bulky nature and hydrogen bonding with CD molecules can form non-inclusion complexes. The findings of the study shows that there is potential molecular interaction between PVP and β-cyclodextrins, which possibly enhances the stability of inclusion complexes for drug with low MW and log P values less than 9. The systematic review shows a comprehensive methodology based on QbD offers a replicable template for future investigations into drug formulation research.

Molecular dynamics simulation techniques and their application to aroma compounds/cyclodextrin inclusion complexes: A review

Homeostatic technologies play a crucial role in maintaining the quality and extending the service life of aroma compounds (ACs). Commercial cyclodextrins (CDs) are commonly used to form inclusion complexes (ICs) with ACs to enhance their solubility, stability, and morphology. The selection of suitable CDs and ACs is of paramount importance in this process. Molecular dynamics (MD) simulations provide an in-depth understanding of the interactions between ACs and CDs, aiding researchers in optimising the properties and effects of ICs. This review offers a systematic discussion of the application of MD simulations in ACs/CDs ICs, covering the establishment of the simulation process, parameter selection, model evaluation, and various application cases, along with their advantages and disadvantages. Additionally, this review summarises the major achievements and challenges of this method while identifying areas that require further exploration. These findings may contribute to a comprehensive understanding of the formation and stabilization mechanisms of ACs/CDs ICs and offer guidance for the selection and computational characterisation of CDs in the AC steady state.

Formulation of silymarin binary and ternary solid dispersions: Characterization, simulation study and cell viability assessment against lung cancer cell line

Silymarin (SL) is a water-insoluble flavonoid used in the treatment of different diseases, but its therapeutic activity is limited due to its low solubility. So, in the present study, SL solid dispersions (SDs) were developed using different carriers like Kollidone VA64 (KL), Soluplus (SP), and Poloxamer 188 (PL) by solvent evaporation (SE), microwave irradiation (MI), and freeze-drying (FD) methods. The phase solubility and saturation solubility studies were assessed to estimate the stability constant as well as the carrier effect. The dissolution studies were performed for prepared SL-SDs (binary and ternary) to select the optimum SL-SDs. The selected SL-SDs (F5, F9) were further characterized for infrared spectroscopy (IR), nuclear magnetic resonance (NMR), differential scanning calorimeter (DSC), scanning electron microscope (SEM), and X-ray diffraction (XRD). Finally, the comparative cell viability assay (lung cancer cell line) was performed to evaluate the change in activity after the formulation of SDs. The phase solubility and solubility study results displayed marked enhancements in solubility. The dissolution study findings showed significant enhancement in drug release from ternary solid dispersions (F7-F9) > ternary physical mixture (PM3) > binary solid dispersions (F1-F6) > binary physical mixture (PM1, PM2) in comparison to free SL. A greater release was observed from ternary SDs due to the addition of PL in the formulation, which had a synergistic effect on increasing the solubility. IR and NMR spectra revealed no chemical interaction between SL, KL, and PL. DSC, XRD, and SEM all confirmed the transformation of crystalline SL into amorphous SL. The cell viability assay demonstrated significantly enhanced results from ternary solid dispersion (F9) compared to free SL. Based on the study results, it can be said that SL-SDs are an alternative way to deliver drugs orally that can improve solubility and have anti-cancer activity.

Cyclodextrin-based nanosponges as promising carriers for active pharmaceutical ingredient

Effective drug distribution at the intended or particular location is a critical issue that researchers are now dealing. Nanosponges have significantly increased in importance in medication delivery using nanotechnology in recent years. An important step toward solving these problems has been the development of nanosponges. Recently created and proposed for use in drug delivery, nanosponge is a unique type of hyper-crosslinked polymer-based colloidal structures made up of solid nanoparticles with colloidal carriers. Nanosponges are solid porous particles that may hold pharmaceuticals and other actives in their nanocavities. They can be made into dosage forms for oral, parenteral, topical, or inhalation use. The targeted distribution of drugs in a regulated manner is greatly aided by nanosponge. The utilization of nanosponges, their benefits, their production processes, the polymers they are made of, and their characterization have all been covered in this review article.

Formulation of multicomponent inclusion complex of cyclodextrin-amino acid with Chrysin: Physicochemical characterization, cell viability and apoptosis assessment in human primary glioblastoma cell line

Chrysin (CR) is a water-insoluble drug reported for different therapeutic effects. The microwave irradiation method was used in this study to create a multicomponent inclusion complex (CR-MC) containing CR (drug) and carrier hydroxyl propyl beta cyclodextrin (HP β CD) and L-arginine (LA). The prepared inclusion complex (CR-MC) was evaluated for dissolution study and results were compared with chrysin physical mixture (CR-PM). Further, the samples were assessed for infra-red (IR), nuclear magnetic resonance (NMR), differential scanning calorimeter (DSC), scanning electron microscope (SEM) and molecular docking. Finally, the cell viability, reactive oxygen species and flow cytometer studies were also assessed to check the potential of the prepared inclusion complex on the human primary glioblastoma cell line (U87-MG cell). The phase solubility findings revealed a stability constant (773 mol L-1) as well as a complexation efficiency of 0.027. The dissolution study displayed a significant increase in CR release from CR-MC (99.03 ± 0.39%) > CR-PM (70.58 ± 1.16%) > pure CR (35.29 ± 1.55%). NMR and IR spectral data revealed no interaction between CR and carriers. SEM and DSC study results revealed the conversion into amorphous form. The molecular docking results illustrated a high docking score, which supports the findings of complex formation. The cell viability, reactive oxygen species, and flow cytometry studies results showed enhanced activity from CR-MC against the tested human primary glioblastoma cell line. From the results it has been observed that chrysin solubility significantly increased after complexation and there in vitro activity also enhanced against cancer cell line.

Development of canagliflozin nanocrystals sublingual tablets in the presence of sodium caprate permeability enhancer: formulation optimization, characterization, in-vitro, in silico, and in-vivo study

Canagliflozin (CFZ) is a sodium-glucose cotransporter-2 inhibitor (SGLT2) that lowers albuminuria in type-2 diabetic patients, cardiovascular, kidney, and liver disease. CFZ is classified as class IV in the Biopharmaceutical Classification System (BCS) and is characterized by low permeability, solubility, and bioavailability, most likely attributed to hepatic first-pass metabolism. Nanocrystal-based sublingual formulations were developed in the presence of sodium caprate, as a wetting agent, and as a permeability enhancer. This formulation is suitable for children and adults and could enhance solubility, permeability, and avoid enterohepatic circulation due to absorption through the sublingual mucosa. In the present study, formulations containing various surfactants (P237, P338, PVA, and PVP K30) were prepared by the Sono-homo-assisted precipitation ion technique. The optimized formula prepared with PVP-K30 showed the smallest particle size (157 ± 0.32 nm), Zeta-potential (-18 ± 0.01), and morphology by TEM analysis. The optimized formula was subsequently formulated into a sublingual tablet containing Pharma burst-V® with a shorter disintegration time (51s) for the in-vivo study. The selected sublingual tablet improved histological and biochemical markers (blood glucose, liver, and kidney function), AMP-activated protein kinase (AMPK), and protein kinase B (AKT) pathway compared to the market formula, increased CFZ's antidiabetic potency in diabetic rabbits, boosted bioavailability by five-fold, and produced faster onset of action. These findings suggest successful treatment of diabetes with CFZ nanocrystal-sublingual tablets.

Nanoemulsions as a Promising Carrier for Topical Delivery of Etodolac: Formulation Development and Characterization

This research primarily focuses on the development of innovative topical nanoemulsions for etodolac, aimed at surmounting its inherent limitations. The preparation of etodolac nanoemulsions is accomplished through a combination of high shear homogenization and ultrasonication methods. The optimization of the formulation components is systematically conducted using the design of experiments methodology. The droplet size (DS), polydispersity index (PDI), and zeta potential (ZP) of the optimized formulation were assessed using the differential light scattering (DLS) technique. Surface morphology examinations were conducted using electron microscopy, while interactions between excipients and the drug were analyzed through FTIR analysis. Additionally, in vitro release and ex vivo permeability studies were carried out. Furthermore, anti-inflammatory activity was evaluated in the context of a carrageenan-induced paw edema model in rats. The DS, PDI, and ZP of the optimal formulation were 163.5 nm, 0.141, and -33.1 mV, respectively. The in vitro release profile was assessed as a sustained release by following a non-Fickian drug transport. The flux of etodolac nanoemulsions and coarse dispersions were 165.7 ± 11.7 µg/cm2 h and 59.7 ± 15.2 µg/cm2 h, respectively. Enhanced edema inhibition was observed at 13.4%, 36.5%, and 50.65% for the 6th, 8th, and 24th hours, respectively. Taken together, these results confirmed that nanoemulsions are promising carriers for the topical delivery of etodolac.

Formulation of Silymarin-β Cyclodextrin-TPGS Inclusion Complex: Physicochemical Characterization, Molecular Docking, and Cell Viability Assessment against Breast Cancer Cell Lines

Silymarin (SIL) is a poorly water-soluble flavonoid reported for different pharmacological properties. Its therapeutic applications are limited due to poor water solubility. In this study, the solubility of silymarin has been enhanced by preparing freeze-dried binary and ternary complexes using beta cyclodextrin (βCD) and d-α-tocopherol polyethylene glycol 1000 succinate (TPGS). The stoichiometry of the drug and the carrier was selected from the phase solubility study. The dissolution study was performed to assess the effect of complexation on the release pattern of SIL. The formation of inclusion complexes was confirmed by different physicochemical studies. Finally, a cell viability assay (MCF 7; breast cancer cell line) was performed to compare the activity with free SIL. The phase solubilization results revealed the formation of a stable complex (binary) with a stability constant and complexation efficiency (CE) value of 288 mol L-1 and 0.045%. The ternary sample depicted a significantly enhanced stability constant and CE value (890 mol L-1 and 0.14%). The release study results showed a marked increase in the release pattern after addition of βCD (alone) in the binary mixture (49.4 ± 3.1%) as well as inclusion complex (66.2 ± 3.2%) compared to free SIL (32.7 ± 1.85%). Furthermore, with the addition of TPGS in SIL-βCD (ternary), the SIL release was found to be significantly enhanced from the SIL ternary mixture (79.2 ± 2.13%) in 120 min. However, fast SIL release was achieved with 99.2 ± 1.7% in 45 min for the SIL ternary complex. IR and NMR spectral analysis results revealed the formation of a stable complex with no drug-polymer interaction. The formation of complexes was also confirmed by the molecular docking study (docking scores of 4.1 and -6.4 kcal/mol). The in vitro cell viability result showed a concentration-dependent activity. The IC50 value of the SIL ternary complex was found to be significantly lower than that of free SIL. The findings of the study concluded that the prepared SIL inclusion complex can be used as an alternative oral delivery system to enhance solubility, dissolution, and biological activity against the tested cancer cell line.

Cyclodextrin Inclusion Complexes for Improved Drug Bioavailability and Activity: Synthetic and Analytical Aspects

Many active pharmaceutical ingredients show low oral bioavailability due to factors such as poor solubility and physical and chemical instability. The formation of inclusion complexes with cyclodextrins, as well as cyclodextrin-based polymers, nanosponges, and nanofibers, is a valuable tool to improve the oral bioavailability of many drugs. The microencapsulation process modifies key properties of the included drugs including volatility, dissolution rate, bioavailability, and bioactivity. In this context, we present relevant examples of the stabilization of labile drugs through the encapsulation in cyclodextrins. The formation of inclusion complexes with drugs belonging to class IV in the biopharmaceutical classification system as an effective solution to increase their bioavailability is also discussed. The stabilization and improvement in nutraceuticals used as food supplements, which often have low intestinal absorption due to their poor solubility, is also considered. Cyclodextrin-based nanofibers, which are polymer-free and can be generated using environmentally friendly technologies, lead to dramatic bioavailability enhancements. The synthesis of chemically modified cyclodextrins, polymers, and nanosponges based on cyclodextrins is discussed. Analytical techniques that allow the characterization and verification of the formation of true inclusion complexes are also considered, taking into account the differences in the procedures for the formation of inclusion complexes in solution and in the solid state.

Drug complexes: Perspective from Academic Research and Pharmaceutical Market

Despite numerous research efforts, drug delivery through the oral route remains a major challenge to formulation scientists. The oral delivery of drugs poses a significant challenge because more than 40% of new chemical entities are practically insoluble in water. Low aqueous solubility is the main problem encountered during the formulation development of new actives and for generic development. A complexation approach has been widely investigated to address this issue, which subsequently improves the bioavailability of these drugs. This review discusses the various types of complexes such as metal complex (drug-metal ion), organic molecules (drug-caffeine or drug-hydrophilic polymer), inclusion complex (drug-cyclodextrin), and pharmacosomes (drug-phospholipids) that improves the aqueous solubility, dissolution, and permeability of the drug along with the numerous case studies reported in the literature. Besides improving solubility, drug-complexation provides versatile functions like improving stability, reducing the toxicity of drugs, increasing or decreasing the dissolution rate, and enhancing bioavailability and biodistribution. Apart, various methods to predict the stoichiometric ratio of reactants and the stability of the developed complex are discussed.

Assembled Bisphenol A with cyclic oligosaccharide as the controlled release complex to reduce risky effects

Herein, in order to improve the bioavailability of a non-biodegradable pollutant, inclusion complexation procedures had been used to develop better formulations of this pollutant, Bisphenol A (BPA). In our research, an inclusion complex (IC) of β-cyclodextrin (β-CD) with BPA was formed to investigate the effect of β-CD on the water solubility, anti-oxidant, anti-bacterial activity, toxicity, and thermal stability of BPA. UV-Vis and other spectrometric methods such as NMR, FTIR, and XRD indicated the molecular mechanism of interactions between β-CD and BPA, which was further hypothesized using molecular modeling to confirm preliminary results. Studies of TGA and DSC demonstrated that encapsulation boosted the thermal stability of BPA. This research also makes predictions about BPA's release behavior when CT-DNA is present. In vitro testing of the IC's antibacterial activities showed that it outperformed pure BPA. The in silico study was found to have a considerable decrease in toxicity level for IC compared to pure BPA. Therefore, β-CD-encapsulated BPA can lessen toxicity by raising antioxidant levels. Additionally, as its antibacterial activity increases, it may be employed therapeutically. Thus, this discovery of creating BPA formulations with controlled release and/or protective properties allows for a more logical application of BPA by reducing its hazardous effects through boosting its efficacy.

Liquid antisolvent crystallization of pharmaceutical compounds: current status and future perspectives

The present work reviews the liquid antisolvent crystallization (LASC) to prepare the nanoparticle of pharmaceutical compounds to enhance their solubility, dissolution rate, and bioavailability. The application of ultrasound and additives is discussed to prepare the particles with narrow size distribution. The use of ionic liquid as an alternative to conventional organic solvent is presented. Herbal compounds, also known for low aqueous solubility and limited clinical application, have been crystalized by LASC and discussed here. The particle characteristics such as particle size and particle size distribution are interpreted in terms of supersaturation, nucleation, and growth phenomena. To overcome the disadvantage of batch crystallization, the scientific literature on continuous flow reactors is also reviewed. LASC in a microfluidic device is emerging as a promising technique. The different design of the microfluidic device and their application in LASC are discussed. The combination of the LASC technique with traditional techniques such as high-pressure homogenization and spray drying is presented. A comparison of product characteristics prepared by LASC and the supercritical CO₂ antisolvent method is discussed to show that LASC is an attractive and inexpensive alternative for nanoparticle preparation. One of the major strengths of this paper is a discussion on less-explored applications of LASC in pharmaceutical research to attract the attention of future researchers.

Solvent Free Twin Screw Processed Silybin Nanophytophospholipid: In Silico, In Vitro and In Vivo Insights

Silybin (SIL) is a polyphenolic phytoconstituent that is commonly used to treat liver disorders. It is difficult to fabricate an orally delivered SIL product due to its low oral bioavailability (0.95%). Therefore, the current research focusses on the development of a novel composition of a phospholipid complex, termed as nanophytophospholipid, of SIL by employing a unique, solvent-free Twin Screw Process (TSP), with the goal of augmenting the solubility and bioavailability of SIL. The optimised SIL-nanophytophospholipid (H6-SNP) was subjected to physicochemical interactions by spectrometry, thermal, X-ray and electron microscopy. The mechanism of drug and phospholipid interaction was confirmed by molecular docking and dynamics studies. Saturation solubility, in vitro dissolution, ex vivo permeation and preclinical pharmacokinetic studies were also conducted. H6-SNP showed good complexation efficiency, with a high practical yield (80%). The low particle size (334.7 ± 3.0 nm) and positively charged zeta potential (30.21 ± 0.3 mV) indicated the immediate dispersive nature of H6-SNP into nanometric dimensions, with good physical stability. Further high solubility and high drug release from the H6-SNP was also observed. The superiority of the H6-SNP was demonstrated in the ex vivo and preclinical pharmacokinetic studies, displaying enhanced apparent permeability (2.45-fold) and enhanced bioavailability (1.28-fold). Overall, these findings indicate that not only can phospholipid complexes be formed using solvent-free TSP, but also that nanophytophospholipids can be formed by using a specific quantity of lipid, drug, surfactant, superdisintegrant and diluent. This amalgamation of technology and unique composition can improve the oral bioavailability of poorly soluble and permeable phytoconstituents or drugs.

Ternary system of sultamicillin tosylate with hydroxypropyl-β-cyclodextrin and L-arginine: susceptibility against methicillin-resistant Staphylococcus aureus

Aim: This study investigated the effect of complex formation between sultamicillin tosylate (ST), hydroxypropyl-β cyclodextrin (HP-βCD) and L-arginine (ARG). Materials & methods: The kneading method was used to prepare the complexes, which were then characterized using SEM, DSC, FT-IR, HPLC, saturation solubility and dissolution studies. The complexes' antibacterial activity against MRSA (ATCC^®-43300TM) was evaluated using ZOI and MIC. Results: Solubility was enhanced in the binary and ternary complexes compared with ST (p < 0.001). MIC and ZOI showed that both complexes have increased antibacterial activity compared with ST (p < 0.001) against MRSA. Conclusion: As a result, the inclusion complex of ST with HP-βCD and ARG can be used to improve the physicochemical properties of ST while also improving antibacterial efficacy against MRSA infections.

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.

Application of ionic liquid to enhance the nose-to-brain delivery of etodolac

The purpose of this study was to enhance the delivery of Etodolac (ETD) to the brain through intranasal administration using an ionic liquid (IL) consisting of ETD and proline ethyl ester. The IL of ETD was prepared by mixing ETD with proline ethyl ester as a counterion in a molar ratio of 1:2.The formation of the IL was confirmed by differential scanning calorimetry (DSC), infrared spectroscopy (IR) and proton nuclear magnetic resonance (¹H-NMR).The solubility of ETD in simulated nasal fluids was improved by approximately 200-fold due to the formation of IL. The intranasal administration of ETD-containing IL, which is viscous, increased the nose-to-brain delivery by approximately 7-fold 30 min after an administration of the ETD solution alone. The enhancement of ETD delivery to the brain from the nose was attributed to the enhanced retention of ETD in the nasal mucosal surface due to the viscosity of IL. The induction of prostaglandin E2 in the brain inflammation that was induced by lipopolysaccharides was significantly suppressed by up to 40% in the IL-treated group compared with the drug-untreated group. Therefore, ETD-containing IL were suggested to be useful in designing intranasal formulations for the nasal delivery of ETDs to the brain.

Enhanced Antioxidant, Antiviral, and Anticancer Activities of the Extract of Fermented Egyptian Rice Bran Complexed with Hydroxypropyl-β-cyclodextrin

Egyptian rice bran was fermented with baker's yeast, and released phenolics were extracted with aqueous methanol to give fermented rice bran extract (FRBE). The analysis of the FRBE with ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry revealed 21 compounds, mainly phenolic acids and flavonoids. The FRBE was then complexed with (2-hydroxypropyl)-β-cyclodextrin (HPβCD) via noncovalent host-guest inclusion complexation using the thin-film hydration technique to improve the hydrophilicity and bioactivity of the FRBE. The formation of the inclusion complex was confirmed using HPLC, ¹H NMR, FT-IR, and a phase solubility study. In addition, the biological activities of the complex were investigated. The FRBE/HPβCD inclusion complex had more pronounced antioxidant, antiviral, and anticancer activities compared to free FRBE. These findings warrant the future investigation of potential medical applications of FRBE.

Molecular docking assisted exploration on solubilization of poorly soluble drug remdesivir in sulfobutyl ether-tycyclodextrin

Objective

To study structure-specific solubilization effect of Sulfobutyl ether-β-cyclodextrin (SBE-β-CD) on Remdesivir (RDV) and to understand the experimental clathration with the aid of quantum mechanics (QM), molecular docking and molecular dynamics (MD) calculations.

Methods

The experiment was carried out by phase solubility method at various pH and temperatures, while the concentration of Remdesivir in the solution was determined by HPLC. The complexation mechanism and the pH dependence of drug loading were investigated following a novel procedure combining QM, MD and molecular docking, based on accurate pKa predictions.

Results

The phase solubility and solubilization effect of RDV in SBE-β-CD were explored kinetically and thermodynamically for each assessed condition. An optimal drug / SBE-β-CD feeding molar ratio was determined stoichiometrically for RDV solubility in pH1.7 solution. The supersaturated solubility was examined over time after pH of the solution was adjusted from 1.7 to 3.5. A possible hypothesis was raised to elucidate the experimentally observed stabilization of supersaturation based on the proposed RDV Cation A /SBE-β-CD pocket conformations.

Conclusion

The computational explorations conformed to the experimentally determined phase solubilization and well elucidated the mechanism of macroscopic clathration between RDV and SBE-β-CD from the perspective of microscopic molecular calculations.

Graphical Abstract

Transfersome Hydrogel Containing 5-Fluorouracil and Etodolac Combination for Synergistic Oral Cancer Treatment

Oral cancer is one of the most common malignancies with an increased rate of incidence. 5-Fluorouracil (5FU) is an effective chemotherapeutic indicated for oral cancer treatment. Etodolac (Et), a cyclooxygenase-2 inhibitor, can be used as an adjuvant agent to sensitize cancer cells to chemotherapy. The aim of this work was to prepare and characterize 5FU and Et dual drug-loaded transfersomes to treat oral cancer. Transfersomes were prepared by thin-film hydration method and characterized for the average particle size and zeta-potential using dynamic light scattering and scanning electron microscopy techniques. The prepared transfersomes were further characterized for their drug loading, entrapment efficiencies using amicon centrifuge tubes and drug release behavior using cellulose membrane. The synergistic activity of dual drug-loaded transfersomes was studied in FaDu oral cancer cells. Results showed that the average particle size, polydispersity index, and zeta potential were 91±6.4 nm, 0.28±0.03, and (-)46.9±9.5 mV, respectively, for 5FU- and Et (1:1)-loaded transfersomes. The highest encapsulation efficiency achieved was 36.9±3.8% and 79.8±6.4% for 5FU and Et (1:1), respectively. Growth inhibition studies in FaDu cells using different concentrations of 5FU and Et showed a combination index of 0.36, indicating a synergistic effect. The FaDu cell uptake of drug-loaded transfersomes was significantly (p<0.05) greater than that of free drugs. The transfersome hydrogel made of HPMC (2% w/w) showed similar flux, lag time, and permeation coefficient as that of drug-loaded transfersomes across excised porcine buccal tissue. In conclusion, 5FU and Et transfersome hydrogel can be developed for localized delivery to treat oral cancer.

Voriconazole-Cyclodextrin Supramolecular Ternary Complex-Loaded Ocular Films for Management of Fungal Keratitis

Fungal keratitis is one of the leading causes of ophthalmic mycosis affecting the vision due to corneal scarring. Voriconazole (VRC) is the most preferred azole antifungal agent for treating ocular mycotic infections. Ocular drug delivery is challenging due to the shorter corneal residence time of the formulation requiring frequent administration, leading to poor patient compliance. The present study aimed at improving the solubility, transcorneal permeation, and efficacy of voriconazole via the formation of cyclodextrin-based ternary complexes and incorporation of the complex into mucoadhesive films. A phase solubility study suggested a ∼14-fold improvement in VRC solubility, whereas physicochemical characterization confirmed the inclusion of VRC in the cyclodextrin inner cavity. In silico docking studies were performed to predict the docking conformation and stability of the inclusion complex. Complex-loaded films showed sustained release of voriconazole from the films and improved transcorneal permeation by ∼4-fold with an improved flux of 8.36 μg/(cm² h) for ternary complex-loaded films compared to 1.86 μg/(cm² h) for the pure VRC film. The 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and hen's egg-chorioallantoic membrane test (HET-CAM) assays confirmed that the complexes and ocular films were nonirritant and safe for ocular administration. The antifungal study performed using Aspergillus fumigatus and Fusarium oxysporum suggested improved antifungal activity compared to the pure drug film. In conclusion, the supramolecular cyclodextrin ternary complex proved to be a promising strategy for enhancing the solubility and permeability and augmenting the antifungal activity of voriconazole in the management of fungal keratitis.

Inclusion complexes of triblock L35 copolymer and hydroxyl propyl cyclodextrins: a physico-chemical study

Polypseudorotaxanes based on triblock L35 copolymer and hydroxyl propyl-modified cyclodextrins (HP-α-CD and HP-β-CD) have been characterized. Their physico-chemical properties have been correlated to the threading process.

A supramolecular thermosensitive gel of ketoconazole for ocular applications: In silico, in vitro, and ex vivo studies

The incidence of corneal fungal infections continues to be a growing concern worldwide. Ocular delivery of anti-fungal drugs is challenging due to the anatomical and physiological barriers of the eye. The ocular bioavailability of ketoconazole (KTZ), a widely prescribed antifungal agent, is hampered by its limited aqueous solubility and permeation. In the study, the physicochemical properties of KTZ were improved by complexation with sulfobutylether-β-cyclodextrin (SBE-β-CD).KTZ-SBE-β-CD complex was studied in silico with docking and dynamics simulations, followed by wet-lab experiments.The optimized KTZ-SBE-β-CD complex was loaded into a thermosensitivein situ gel to increase corneal bioavailability. The supramolecular complex increased the solubility of KTZ by 5-folds and exhibited a 10-fold increment in drug release compared to the pure KTZ. Owing to the diffusion, thein situ gel exhibited a more sustained drug release profile. Theex vivocorneal permeation studies showed higher permeation from KTZ-SBE-β-CD in situ gel (flux of ∼19.11 µg/cm²/h) than KTZin situ gel (flux of ∼1.17 µg/cm²/h). The cytotoxicity assays and the hen's egg chorioallantoic membrane assay (HET-CAM) confirmed the formulations' safety and non-irritancy. In silico guided design of KTZ-SBE-β-CD inclusion complexes successfully modified the physicochemical properties of KTZ. In addition, the loading of the KTZ-SBE-β-CD complex into an in situ gel significantly increased the precorneal retention and permeation of KTZ, indicating that the developed formulation is a viable modality to treat fungal keratitis.

Exploration on the drug solubility enhancement in aqueous medium with the help of endo-functionalized molecular tubes: a computational approach

One major problem in the pharmaceutical industry is the aqueous solubility of newly developed orally administered drug candidates. More than 50% of newly developed drug molecules suffer from low aqueous solubility. The therapeutic effects of drug molecules are majorly dependent on the bioavailability and, in essence, on the solubility of the used drug molecules. Thus, enhancement of drug solubility of sparingly soluble drug molecules is a need of modern times. Considering the high importance of drug solubility, we have computationally shown the enhancement of drug solubility for seven class II (poorly water-soluble) drug molecules in a water medium. The uses of supramolecular macrocycles have immense importance in the same field. Thus, we have used two synthetic supramolecular receptors named host-1a and host-1b to enhance the water solubility of fluorouracil, albendazole, camptothecin, clopidogrel, indomethacin, melphalan, and tolfenamic acid drug molecules. Biomedical engagements of a supramolecular receptor commence with the formation of stable host-drug complexes. These complexations enhance the water solubility of drug molecules and sustain the release rate and bioavailability of drug molecules. Thus, in this work, we focus on the formation of stable host-drug complexes in water medium. Molecular dynamics simulation is applied to analyze the structural features and the energetics involved in the host-drug complexation process. The information obtained at the atomistic level helps us gain better insights into the key interactions that operate to produce such highly stable complexes. Thus, we can propose that these two supramolecular receptors may be used as drug solubilizing agents, and patients will benefit from this theragnostic application shortly.

Application of Molecular Dynamics Simulations in the Analysis of Cyclodextrin Complexes

Cyclodextrins (CDs) are highly respected for their ability to form inclusion complexes via host-guest noncovalent interactions and, thus, ensofance other molecular properties. Various molecular modeling methods have found their applications in the analysis of those complexes. However, as showed in this review, molecular dynamics (MD) simulations could provide the information unobtainable by any other means. It is therefore not surprising that published works on MD simulations used in this field have rapidly increased since the early 2010s. This review provides an overview of the successful applications of MD simulations in the studies on CD complexes. Information that is crucial for MD simulations, such as application of force fields, the length of the simulation, or solvent treatment method, are thoroughly discussed. Therefore, this work can serve as a guide to properly set up such calculations and analyze their results.

Cyclodextrin Multicomponent Complexes: Pharmaceutical Applications

Cyclodextrins (CDs) are naturally available water-soluble cyclic oligosaccharides widely used as carriers in the pharmaceutical industry for their ability to modulate several properties of drugs through the formation of drug-CD complexes. The addition of an auxiliary substance when forming multicomponent complexes is an adequate strategy to enhance complexation efficiency and to facilitate the therapeutic applicability of different drugs. This review discusses multicomponent complexation using amino acids; organic acids and bases; and water-soluble polymers as auxiliary excipients. Special attention is given to improved properties by including information on the solubility, dissolution, permeation, stability and bioavailability of several relevant drugs. In addition, the use of multicomponent CD complexes to enhance therapeutic drug effects is summarized.

Solubility enhancement of mefenamic acid by inclusion complex with β-cyclodextrin: in silico modelling, formulation, characterisation, and in vitro studies

The aim of this study was to prepare and characterise inclusion complexes of a low water-soluble drug, mefenamic acid (MA), with β-cyclodextrin (β-CD). First, the phase solubility diagram of MA in β-CD was drawn from 0 to 21 × 10⁻³ M of β-CD concentration. A job’s plot experiment was used to determine the stoichiometry of the MA:β-CD complex (2:1). The stability of this complex was confirmed by molecular modelling simulation. Three methods, namely solvent co-evaporation (CE), kneading (KN), and physical mixture (PM), were used to prepare the (2:1) MA:β-CD complexes. All complexes were fully characterised. The drug dissolution tests were established in simulated liquid gastric and the MA water solubility at pH 1.2 from complexes was significantly improved. The mechanism of MA released from the β-CD complexes was illustrated through a mathematical treatment. Finally, two in vitro experiments confirmed the interest to use a (2:1) MA:β-CD complex.

Inclusion Complexes of Non-Steroidal Anti-Inflammatory Drugs with Cyclodextrins: A Systematic Review

Non-steroidal anti-inflammatory drugs (NSAIDs) are one of the most widely used classes of medicines in the treatment of inflammation, fever, and pain. However, evidence has demonstrated that these drugs can induce significant toxicity. In the search for innovative strategies to overcome NSAID-related problems, the incorporation of drugs into cyclodextrins (CDs) has demonstrated promising results. This study aims to review the impact of cyclodextrin incorporation on the biopharmaceutical and pharmacological properties of non-steroidal anti-inflammatory drugs. A systematic search for papers published between 2010 and 2020 was carried out using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol and the following search terms: “Complexation”; AND “Cyclodextrin”; AND “non-steroidal anti-inflammatory drug”. A total of 24 different NSAIDs, 12 types of CDs, and 60 distinct inclusion complexes were identified, with meloxicam and β-CD appearing in most studies. The results of the present review suggest that CDs are drug delivery systems capable of improving the pharmacological and biopharmaceutical properties of non-steroidal anti-inflammatory drugs.

Development of a Highly Water-Soluble Lycopene Cyclodextrin Ternary Formulation by the Integrated Experimental and Modeling Techniques

Lycopene, the aliphatic hydrocarbon carotenoid with abundant bioactivities, has instability, extremely poor water solubility, and low oral bioavailability. The study aimed to develop a highly water-soluble and practical lycopene formulation to improve the oral bioavailability and efficiency of lycopene. Environment-friendly hot-melt extrusion (HME) technique was applied to fabricate lycopene-cyclodextrin-polyethylene glycol 6000 (PEG 6000) ternary systems, which possessed highly aqueous solubility (897.665 μg mL^-1), almost 32-fold higher than that of the reported lycopene binary inclusion (27.1 ± 3.2 μg mL^-1). The dissolution rate was significantly accelerated compared to pure lycopene. The molecular mechanism was further investigated by the integrated experimental and modeling tools. Molecular dynamics (MD) simulation revealed lycopene molecule was wrapped within the aggregates of hydroxypropyl-beta-cyclodextrin (HP-β-CD) and PEG 6000 through extensive hydrogen bond interactions, which was experimentally validated by DSC, XRD, and FTIR spectrum analysis. The third component PEG 6000 facilitated the process of HME and augmented hydrogen bond interactions with HP-β-CD. Moreover, lycopene inclusions exhibited significant antitumor activity via inhibiting cell proliferation and inducing apoptosis. The pharmacokinetic studies showed the relative bioavailability of lycopene ternary preparation was up to 313.08% and the C_max was 4.9-fold higher than that of the marketed tablet. In conclusion, the lycopene cyclodextrin ternary formulation developed by the modified HME techniques is suitable for industrial production, while PEG 6000 plays a vital part in the multicomponent systems to increase solubility, dissolution rate, and oral bioavailability of lycopene. The combination of experimental and computational tools is able to benefit the development of multicomponent formulations accurately and effectively.

Anti-Inflammatory and Physicochemical Characterization of the Croton Rhamnifolioides Essential Oil Inclusion Complex in β-Cyclodextrin

Croton rhamnifolioides is used in popular medicine for the treatment of inflammatory diseases. The objective of this study was to characterize and evaluate the anti-inflammatory effect of C. rhamnifolioides essential oil complexed in β-cyclodextrin (COEFC). The physicochemical characterization of the complexes was performed using different physical methods. The anti-inflammatory activity was evaluated in vivo by ear edema, paw edema, cotton pellet-induced granuloma, and vascular permeability by Evans blue extravasation. The mechanism of action was validated by molecular docking of the major constituent into the cyclooxygenase-2 (COX-2 enzyme). All doses of the COEFC reduced acute paw edema induced by carrageenan and dextran, as well as vascular permeability. Our results suggest the lowest effective dose of all samples inhibited the response induced by histamine or arachidonic acid as well as the granuloma formation. The complexation process showed that the pharmacological effects were maintained, however, showing similar results using much lower doses. The results demonstrated an involvement of the inhibition of pathways dependent on eicosanoids and histamine. Complexation of β-cyclodextrin/Essential oil (β-CD/EO) may present an important tool in the study of new compounds for the development of anti-inflammatory drugs.

Stimulatory Effects of Soluplus® on Flufenamic Acid β-Cyclodextrin Supramolecular Complex: Physicochemical Characterization and Pre-clinical Anti-inflammatory Assessment

The present study demonstrates the solubility and dissolution of flufenamic acid (FLF)/β-cyclodextrin (β-CD)/Soluplus® supramolecular ternary inclusion complex. The binary and ternary inclusion complexes were prepared using solvent evaporation and the microwave irradiation method. The prepared inclusion complexes were evaluated for physicochemical characterization and anti-inflammatory activity using a murine paw edema mol. The phase solubility studies demonstrated 4.59-fold and 17.54-fold enhancements in FLF solubility with β-CD alone and β-CD:Soluplus® combination compared with pure FLF, respectively. The in vitro drug release results revealed a significant improvement (P < 0.05) in the release pattern compared with pure FLF. Maximum release was found with flufenamic acid binary and ternary complexes prepared using the microwave irradiation method, i.e., 75.23 ± 3.12% and 95.36 ± 3.23% in 60 min, respectively. The physicochemical characterization results showed complex formation and conversion of the crystalline form of FLF to an amorphous form. The SEM study revealed the presence of a more agglomerated and amorphous structure of the solid particles, which confirmed the formation of complexes. The anti-inflammatory effect of the complex was higher than pure FLF. Therefore, the FLF:β-CD:Soluplus® inclusion complex may be a very valuable formulation with improved solubility, dissolution, and anti-inflammatory effect.

Multiple approaches for achieving drug solubility: an in silico perspective

Discovering new therapeutically active molecules is the ultimate destination in pharmaceutical research and development. Most drugs discovered are lipophilic and, hence, exhibit poor aqueous solubility, resulting in low bioavailability. Thus, there is a need to use various solubility enhancement techniques. Computational approaches enable the analysis of drug-carrier interactions or the numerous conformational changes in the carrier matrix that might establish an appropriate balance between cohesive and adhesive stability in a formulation. In this review, we discuss research approaches that provided molecular insight into drugs and their modifiers to unravel their solubility, stability, and bioavailability.

Study of the complexation of structurally modified curcumin with hydroxypropyl beta cyclodextrin and its effect on anticancer activity

This study aims at modifying curcumin to curcumin pyrazole and complexing it with HPβCD employing a simple protocol to improve curcumin's chemical–physical properties and biological activities.

Synthesis, Characterization, and Drug Delivery Application of Self-assembling Amphiphilic Cyclodextrin

The main aim of the research was to synthesize amphiphilic cyclodextrin (AMCD) by substituting C12 alkyl chain to a β-cyclodextrin (βCD) in a single step and to study its self-assembly in an aqueous medium. The drug delivery application of the AMCD was also evaluated by encapsulating tamoxifen citrate as a model hydrophobic drug. AMCD was able to self-assemble in aqueous media, forming nanovesicles of size < 200 nm, capable of encapsulating tamoxifen citrate (TMX). Molecular docking and MD simulation studies revealed the interaction between TMX and AMCD which formed a stable complex. TEM and AFM studies showed that nanovesicles were perfectly spherical having a smooth surface and a theoretical AMCD bilayer thickness of ~ 7.2 nm as observed from SANS studies. XRD and DSC studies revealed that TMX was amorphized and molecularly dispersed in AMCD bilayer which was released slowly following Fickian diffusion. AMCD has excellent hemocompatibility as opposed to βCD and no genotoxicity. IC₅₀ of TMX against MCF-7 cell lines was significantly reduced from 11.43 to 7.96 μg/ml after encapsulation in nanovesicle because of nanovesicles being endocytosed by the MCF-7 cells. AMCD was well tolerated by IV route at a dose of > 2000 mg/kg in rats. Pharmacokinetic profile of TMX after encapsulation was improved giving 3-fold higher AUC; extended mean residence time is improving chances of nanovesicle to extravasate in tumor via EPR effect.

Predicting complexation performance between cyclodextrins and guest molecules by integrated machine learning and molecular modeling techniques

Most pharmaceutical formulation developments are complex and ideal formulations are generally obtained after extensive experimentation. Machine learning is increasingly advancing many aspects in modern society and has achieved significant success in multiple subjects. Current research demonstrated that machine learning can be adopted to build up high-accurate predictive models in drugs/cyclodextrins (CDs) systems. Molecular descriptors of compounds and experimental conditions were employed as inputs, while complexation free energy as outputs. Results showed that the light gradient boosting machine provided significantly improved predictive performance over random forest and deep learning. The mean absolute error was 1.38 kJ/mol and squared correlation coefficient was 0.86. The evaluation of relative importance of molecular descriptors further demonstrated the key factors affecting molecular interactions in drugs/CD systems. In the specific ketoprofen-CD systems, machine learning model showed better predictive performance than molecular modeling calculation, while molecular simulation could provide structural, dynamic and energetic information. The integration of machine learning and molecular simulation could produce synergistic effect for interpreting and predicting pharmaceutical formulations. In conclusion, the developed predictive models were able to quickly and accurately predict the solubilizing capacity of CD systems. Current research has taken an important step toward the application of machine learning in pharmaceutical formulation design.

Multicomponent cyclodextrin system for improvement of solubility and dissolution rate of poorly water soluble drug

The purpose of the present study was to investigate the interaction of Cinnarizine (CIN) with Hydroxypropyl-β-Cyclodextrin (HPβCD) in the presence of Hydroxy Acids (HA). Various binary and ternary systems of CIN with HPβCD and HA were prepared by kneading and coevaporation methods. For the ternary systems, HA were tried in three different concentrations. The interaction in solution phase was studied in detail by the phase solubility method, and the solid phase interactions were characterized by Fourier Transform Infrared (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC), X-Ray Diffractometry (XRD), Scanning Electron Microscopy (SEM) and Proton Nuclear Magnetic Resonance (1H-NMR). Phase solubility revealed the positive effect of HA on the complexation of CIN with HPβCD. Solid phase characterization confirmed the formation of inclusion complex in the ternary systems. Solubility and dissolution studies illustrated that out of three different concentrations tried, HA were most effective at the 1 M concentration level. Ternary systems were very effective in improving the solubility as well as dissolution profile of CIN than the CIN-HPβCD binary systems. FTIR, 1H-NMR and Molecular docking studies gave some insight at molecular level that actually which part of CIN was interacting with the HPβCD. Molecular docking and free energy calculation even enlighten the role of tartaric acid in increasing solubility of CIN in the ternary system.

β-Cyclodextrin-based inclusion complexes and nanocomposites of rivaroxaban for solubility enhancement

Rivaroxaban (RIV) is an oral anticoagulant used in the prevention of venous thromboembolism in adult patients after total hip replacement or total knee replacement surgery. It is practically insoluble in water and buffer systems (pH 3-9). The present study was aimed to investigate the β-CD-based inclusion complexes and nanocomposites of rivaroxaban (RIV) for solubility and dissolution enhancement. A novel solubility enhancement approach of inclusion complexation of RIV with β-CD using spray drying method combined with high pressure homogenization as a particle engineering method was used. Change in crystallinity of RIV nanocomposites was assessed by DSC and PXRD. The interaction of drug with β-CD was projected through ¹H-NMR and FT-IR studies. Saturation solubility and in vitro dissolution study revealed a dramatic increase in solubility and dissolution of RIV, respectively. Thus, spray-dried β-CD-based nanocomposites could be an innovative approach for solubility and dissolution enhancement of RIV.

Thermodynamic compatibility between cyclodextrin supramolecular complexes and surfactant

Supramolecular structures based on cyclodextrins have been extensively used for drug delivery systems over decades. However, combining host and guest molecules in a pharmaceutical formulation is not a trivial process, being one of the majors concern the inclusion complex compatibility with other excipients presented in the final formulation. Herein, experimental and theoretical calculations were used to investigate the competition of sodium dodecyl sulfate (SDS) with atenolol (ATE) or losartan (LOS), antihypertensive drugs widely used in the treatment of hypertension. Our findings, using nuclear magnetic resonance and isothermal titrations calorimetry experiments and molecular dynamic simulations demonstrated that LOS remain included into CD cavity after excipient (SDS) addition, which was not verified for ATE ternary system, being the drug displaced by SDS molecule.