Cyclodextrin complexes: Perspective from drug delivery and formulation

Docetaxel/dimethyl-β-cyclodextrin inclusion complexes: preparation, in vitro evaluation and physicochemical characterization

Despite the development in novel drug delivery techniques and synthesis of multifunctional excipients, oral delivery of hydrophobic drug like docetaxel (DTX) is still challenging. The present work investigates the inclusion complexation of DTX, and dimethyl-β-cyclodextrin (DM-β-CD) to improve the solubility, dissolution and permeability of the drug. Amongst the native and modified β-cyclodextrins, DM-β-CD showed the highest solubility of DTX. Solid binary inclusion complex (IC) of DTX with DM-β-CD was prepared by solvent evaporation technique and thoroughly characterized for solubility, dissolution, permeability, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (¹H NMR). The aqueous solubility and in vitro dissolution rate of DTX/DM-β-CD IC were markedly increased by 76.04- and 3.55-fold compared to free DTX powder. The permeability of DTX/DM-β-CD IC showed similar absorptive permeability but decreased efflux from the absorbed DTX, compared to pure DTX. Further, physicochemical studies of IC revealed the change of crystalline state DTX to its amorphous form. Moreover, FT-IR and ¹H NMR results indicate the formation of true inclusion complex between DTX and DM-β-CD at 1:1 molar ratio. Collectively, solid inclusion complexes prepared by spray drying method can be an effective strategy to enhance the biopharmaceutical performance of a highly hydrophobic drug DTX.

Strategies to prolong the residence time of drug delivery systems on ocular surface

Ocular diseases may be treated via different routes of administration, such as topical, intracameral, intravitreal, oral and parenteral. Among them the topical route is most accepted by patients, although it provides in many cases the lowest bioavailability. Indeed, when a topical formulation reaches the precorneal area, i.e., the drug absorption and/or action site, it is rapidly eliminated due to eye protection mechanisms such as blinking, basal and reflex tearing, and naso-lacrimal draining. To avoid this and to reduce the frequency of dosing, various strategies have been developed to prolong drug residence time after topical administration. These strategies include the use of viscosity increasing and mucoadhesive excipients as well as combinations thereof. From the drug delivery system point of view, liquid and semisolid formulations are preferred over solid formulations such as ocular inserts and contact lenses. Furthermore, liquid and semisolid formulations can contain nano- and microcarrier systems that contribute to a prolonged residence time. Within this review an overview about the different types of excipients and formulations as well as their performance in valid animal models and clinical trials is provided.

Diffusivity of α-, β-, γ-cyclodextrin and the inclusion complex of β-cyclodextrin: Ibuprofen in aqueous solutions; A molecular dynamics simulation study

Cyclodextrins (CDs) are widely used in drug delivery, catalysis, food and separation processes. In this work, a comprehensive simulation study on the diffusion of the native α-, β- and γ-CDs in aqueous solutions is carried out using Molecular Dynamics simulations. The effect of the system size on the computed self-diffusivity is investigated and it is found that the required correction can be as much as 75% of the final value. The effect of the water force field is examined and it is shown that the q4md-CD/TIP4P/2005 force field combination predicts the experimentally measured self-diffusion coefficients of CDs very accurately. The self-diffusion coefficients of the three native CDs were also computed in aqueous-NaCl solutions using the Joung and Cheatham (JC) and the Madrid-2019 force fields. It is found that Na+ ions have higher affinity towards the CDs when the JC force field is used and for this reason the predicted diffusivity of CDs is lower compared to simulations using the Madrid-2019 force field. As a model system for drug delivery and waste-water treatment applications, the diffusion of the β-CD:Ibuprofen inclusion complex in water is studied. In agreement with experiments for similar components, it is shown that the inclusion complex and the free β-CD have almost equal self-diffusion coefficients. Our analysis revealed that this is most likely caused by the almost full inclusion of the ibuprofen in the cavity of the β-CD. Our findings show that Molecular Dynamics simulation can be used to provide reasonable diffusivity predictions, and to obtain molecular-level understanding useful for industrial applications of CDs.

Synthesis and biological analysis of anti-addiction effect and hepatotoxicity of tow baclofen analogues complexed with β-Cyclodextrin

AIM AND OBJECTIVE

The excessive consumption of alcohol and the installation of a dependence is, in most cases, facilitated by favorable psychological factors which trigger and maintain the behavior of consumption. Examples more frequently encountered in individuals having difficulty with alcohol are in particular: one or more anxiety disorders, deficits in the capacities to manage stress and anxiety. The main objective of this work was study in vivo the anti-addiction effect and hepatotoxicity of tow baclofen analogues complexed with β-Cyclodextrin (βCD) on an alcohol-dependent rat model.

MATERIALS AND METHODS

The synthesis of two analogues ABF1 and ABF2 close to baclofen was reported. The structural determination of the two compounds was confirmed by NMR and IR analysis. The complexation of analogues with βCyclodextrin (βCD) was performed in water at room temperature (25 °C). The interactions of ABF with β-Cyclodextrin, and the stability constant (Ka) of the inclusion complex formed between them were investigated by using UV-visible spectroscopy. The biological effects of baclofen and the two analogues on alcohol dependence were studied in wistar rats. The anti-addiction effect of the analogues was tested by measuring the alcohol intake and the variation of the animal behaviour. The toxicity of the compounds was also analysed on liver injury markers.

RESULTS

The amino-3-phenylbutanoic acid (ABF1) and 3,4,5-trihydroxy-N-(methyl-2-acetate) benzamide (ABF2) were synthesized. The complexation of both analogues of baclofen (BF) with β-cyclodextrin (βCD) (ABF- βCD) was realized and confirmed by the stability constant of the inclusion complex (Ka) and Job's method. The evaluation of anti-addiction activity in vivo showed that ABF1-βCD inhibits the consumption of alcohol at the doses equivalent to those of baclofen. Both baclofen analogues have shown an anxiolytic effect. Regarding the toxicity of the two compounds, our results showed that ABF1-βCD has less toxic effect than baclofen, it reduces the activity of ALT and AST enzymes. Histologically ABF1-βCD has no effect on structure of the liver in addition and has a protective effect against lesions alcohol-induced liver disease.

CONCLUSION

Therefore, it can be suggested that ABF1 analogue combined with β-Cyclodextrin can be used as a treatment for alcohol dependence. Further clinical works are needed to confirm its effectiveness.

Mucoadhesive nanocrystal-in-microspheres with high drug loading capacity for bioavailability enhancement of silybin

Nanocrystals, due to high drug loading efficiency, have drawn large attention as nanotechnology to enhance solubility and bioavailability of poorly soluble drugs. However, most nanocrystals still encountered low oral absorption percentage due to its insufficient retention time in the gastrointestinal tract (GI). In this work, silybin (SB) as model drug was fabricated to nanocrystals, and further loaded into a mucoadhesive microsphere to increase the GI retention. Such mucoadhesive microspheres were prepared with a wet media milling technique followed by coagulation and film coating. Nanocrystals and microspheres were thoroughly characterized by diverse complementary techniques. As results, such delivery system displayed an encapsulation efficiency of approximately 100 % and a drug loading capacity of up to 35.41 ± 0.31 %. In addition, mucoadhesiveness test ex vivo conducted with rat intestine showed that film-coated microspheres were retained for more than 1 h. Benefiting from nanocrystals technology, the drug cumulative release percentage of the microspheres was remarkable improved compared to unprocessed one in vitro. Finally, pharmacokinetics studies in rats showed a significant 3-fold increase of drug oral bioavailability compared to unprocessed SB. The current study demonstrates that the developed delivery vehicle can enhance the bioavailability of SB by increasing its dissolution percentage as well as through extending retention time in the GI tract, and achieve high drug loading capacity.

Physical formulation approaches for improving aqueous solubility and bioavailability of ellagic acid: A review

Ellagic acid (EA) is a polyphenolic active compound with antimalarial and other promising therapeutic activities. However, its solubility and its permeability are both low (BCS IV). These properties greatly compromise its oral bioavailability and clinical utilizations. To overcome these limitations of the physicochemical parameters, several formulation approaches, including particle size reduction, amorphization and lipid-based formulations, have been used. Although these strategies have not yet led to a clinical application, some of them have resulted in significant improvements in the solubility and bioavailability of EA. This critical review reports and analyses the different formulation approaches used by scientists to improve both the biopharmaceutical properties and the clinical use of EA.

Unveiling the Thermodynamic Aspects of Drug-Cyclodextrin Interactions Through Isothermal Titration Calorimetry

Due to their low toxicity and high aqueous solubility, cyclodextrins have emerged as a distinctive class of supramolecules with wide application in the pharmaceutical and food industry. Their ability to improve the water solubility, stability and pharmacokinetic profile of small molecules has established them as a rich toolkit for drug formulation. In order to improve the physicochemical characteristics and the pharmacokinetic profile of a drug through cyclodextrin inclusion, the proper cyclodextrin type has to be selected among the existing great variety consisting of both natural and synthetic variants. The selection of the most proper cyclodextrin variant comes after drug-cyclodextrin screening studies targeting the characterization of the complex formation and evaluation of the affinity and interaction forces participating in the complexation. Numerous analytical, spectroscopic, separation and electrochemical techniques have been applied to elucidate the interaction profile in a cyclodextrin-drug complex. Herein, we describe the application of Isothermal Titration Calorimetry (ITC) on cyclodextrin-drug complexes that enables the charting of the binding affinity and the thermodynamic profile of the inclusion complexes. We focus on the experimental design and present technical tips of the ITC application. To better illustrate the technique's rationale, the interaction between 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) and the antihypertensive drug losartan is investigated.

Application of Neutralization and Freeze-Drying Technique for the Preparation of the Beneficial in Drug Delivery 2-Hydroxypropyl-β-Cyclodextrin Complexes with Bioactive Molecules

Bioavailability of active substances is of great importance for the formulation of a drug product, as it actually reflects drug absorption and achievement of the optimum pharmacological effect. A great number of chemical compounds with excellent pharmacological properties possess low solubility and permeability values, ending in low bioavailability in the human body after administration (especially after per os administration). CDs are oligosaccharides that possess biological properties similar to their linear counterparts, but some of their physicochemical properties differ. They are enhancing bioavailability and solving problems of absorption for poorly soluble lipophilic drugs by forming water-soluble inclusion complexes. For this reason, they are widely used in drug delivery systems (Carrier et al. J Control Release 123:78-99, 2007; Kurkov and Loftsson, Int J Pharm 453:167-80, 2013). The main purpose of this chapter is to show a protocol for the preparation of drug:CD_complex delivery systems.

Development of HPLC Method for Quantification of Sinigrin from Raphanus sativus Roots and Evaluation of Its Anticancer Potential

Sinigrin, a precursor of allyl isothiocyanate, present in the Raphanus sativus exhibits diverse biological activities, and has an immense role against cancer proliferation. Therefore, the objective of this study was to quantify the sinigrin in the R. sativus roots using developed and validated RP-HPLC method and further evaluated its’ anticancer activity. To achieve the objective, the roots of R. sativus were lyophilized to obtain a stable powder, which were extracted and passed through an ion-exchange column to obtain sinigrin-rich fraction. The RP-HPLC method using C18 analytical column was used for chromatographic separation and quantification of sinigrin in the prepared fraction, which was attained using the mobile phase consisting of 20 mM tetrabutylammonium: acetonitrile (80:20%, v/v at pH 7.0) at a flow rate of 0.5 mL/min. The chromatographic peak for sinigrin was showed at 3.592 min for pure sinigrin, where a good linearity was achieved within the concentration range of 50 to 800 µg/mL (R² > 0.99), with an excellent accuracy (−1.37% and −1.29%) and precision (1.43% and 0.94%), for intra and inter-day, respectively. Finally, the MTT assay was performed for the sinigrin-rich fraction using three different human cancer cell lines, viz. prostate cancer (DU-145), colon adenocarcinoma (HCT-15), and melanoma (A-375). The cell-based assays were extended to conduct apoptotic and caspase-3 activities, to determine the mechanism of action of sinigrin in the treatment of cancer. MTT assay showed IC₅₀ values of 15.88, 21.42, and 24.58 µg/mL for DU-145, HCT-15, and A-375 cell lines, respectively. Increased cellular apoptosis and caspase-3 expression were observed with sinigrin-rich fraction, indicating significant increase in overexpression of caspase-3 in DU-145 cells. In conclusion, a simple, sensitive, fast, and accurate RP-HPLC method was developed for the estimation of sinigrin in the prepared fraction. The data observed here indicate that sinigrin can be beneficial in treating prostate cancer possibly by inducing apoptosis.

Enhanced Oral Bioavailability of Etodolac by the Liquisolid Compact Technique: Optimisation, In-Vitro and In-Vivo Evaluation

BACKGROUND

Poor dissolution of Etodolac is one of the major challenges in achieving the desired therapeutic effect in oral therapy.

OBJECTIVE

This study aimed to assess the potential of the liquisolid compact technique in increasing the rate of dissolution of Etodolac and thus its bioavailability.

METHODS

Liquisolid compacts were prepared using PEG 400, Avicel PH-200 and Aerosil 200 as non-volatile liquid, carrier and coating material, respectively. The optimisation was carried out by applying a 32 full factorial design using Design expert software 11.0.3.0 to examine the effects of independent variables (load factor and carrier: coating ratio) on dependent variables (angle of repose and % cumulative drug release at 30 min [Q <sub>30 min]). Assessment of bioavailability was based on a pharmacokinetic study on rabbits and pharmacodynamics evaluation on rats, respectively.

RESULTS

The formulation M3 was identified as the optimised formulation based on the better flow (lower angle of repose) and a higher rate of dissolution (Q ₃₀ min >95%). The higher dissolution rate could be due to conversion of Etodolac into an amorphous molecularly dispersed state, availability of larger surface area, enhancement of aqueous solubility and enhanced wetting of drug particles. Studies with DSC, XRD, and SEM verified the transformation of Etodolac from crystalline to amorphous state, a key factor responsible for improving the dissolution rate. The pharmacokinetic profile of M3 was prominent, demonstrating higher absorption of Etodolac in comparison to oral suspension and immediate-release conventional tablets in rabbits. Liquisolid formulation exhibited a 27% increment in paw thickness as compared to 57% and 46% increments for oral suspension and immediate-release conventional tablets, respectively, after 7 hrs in the carrageenan-induced paw model in rats.

CONCLUSION

The results indicated the liquisolid compact technique to be a promising strategy to enhance the bioavailability of Etodolac.

Development and Optimization of Naringenin-Loaded Chitosan-Coated Nanoemulsion for Topical Therapy in Wound Healing

The potential role of naringenin (NAR), a natural flavonoid, in the treatment of chronic wound has prompted the present research to deliver the drug in nanoemulsion (NE) form, where synergistic role of chitosan was achieved through development of chitosan-coated NAR NE (CNNE). The NE consisted of Capryol 90, Tween 20 and Transcutol P, which was fabricated by low-energy emulsification method to encapsulate NAR within the oil core. The optimization of the formulated NEs was performed using Box-Behnken statistical design to obtain crucial variable parameters that influence globule size, size distribution and surface charge. Finally, the optimized formulation was coated with different concentrations of chitosan and subsequently characterized in vitro. The size of the CNNE was found to be increased when the drug-loaded formulation was coated with chitosan. Controlled release characteristics depicted 67-81% release of NAR from the CNNE, compared to 89% from the NE formulation. Cytotoxicity study of the formulation was performed in vitro using fibroblast cell line (NIH-3T3), where no inhibition in proliferation of the cells was observed with CNNE. Finally, the wound healing potential of the CNNE was evaluated in an abrasion-created wound model in experimental animals where the animals were treated and compared histologically at 0 and 14 days. Significant improvement in construction of the abrasion wound was observed when the animals were treated with formulated CNNE, whereas stimulation of skin regeneration was depicted in the histological examination. Therefore, it could be summarized that the chitosan coating of the developed NAR NE is a potential platform to accelerate healing of wounds.

Rocuronium Has a Suppressive Effect on Platelet Function via the P2Y12 Receptor Pathway In Vitro That Is Not Reversed by Sugammadex

Rocuronium is an aminosteroid nondepolarizing neuromuscular blocker that is widely used for anesthesia and intensive care. In this study, we investigated the effect of rocuronium on human platelet functions in vitro. The effects of rocuronium on platelet aggregation, P-selectin expression, and cyclic adenosine monophosphate (cAMP) levels in platelets were measured using an aggregometer, an enzyme immunoassay, and flow cytometry, respectively. Rocuronium inhibited ADP-induced platelet aggregation, P-selectin expression and suppression of cAMP production. These effects were not antagonized by equimolar sugammadex, a synthetic γ-cyclodextrin derivative that antagonizes rocuronium-induced muscle relaxation by encapsulating the rocuronium molecule. Morpholine, which constitutes a part of the rocuronium molecule but is not encapsulated by sugammadex, inhibited ADP-induced platelet aggregation. Vecuronium, which has a molecular structure similar to that of rocuronium but does not possess a morpholine ring, had no significant effect on ADP-induced platelet aggregation. These results indicate that rocuronium has a suppressive effect on platelet functions in vitro that is not reversed by sugammadex and suggest that this effect is mediated by blockade of the P2Y12 receptor signaling pathway via the morpholine ring of rocuronium.

Developments of Smart Drug-Delivery Systems Based on Magnetic Molecularly Imprinted Polymers for Targeted Cancer Therapy: A Short Review

Cancer therapy is still a huge challenge, as especially chemotherapy shows several drawbacks like low specificity to tumor cells, rapid elimination of drugs, high toxicity and lack of aqueous solubility. The combination of molecular imprinting technology with magnetic nanoparticles provides a new class of smart hybrids, i.e., magnetic molecularly imprinted polymers (MMIPs) to overcome limitations in current cancer therapy. The application of these complexes is gaining more interest in therapy, due to their favorable properties, namely, the ability to be guided and to generate slight hyperthermia with an appropriate external magnetic field, alongside the high selectivity and loading capacity of imprinted polymers toward a template molecule. In cancer therapy, using the MMIPs as smart-drug-delivery robots can be a promising alternative to conventional direct administered chemotherapy, aiming to enhance drug accumulation/penetration into the tumors while fewer side effects on the other organs. Overview: In this review, we state the necessity of further studies to translate the anticancer drug-delivery systems into clinical applications with high efficiency. This work relates to the latest state of MMIPs as smart-drug-delivery systems aiming to be used in chemotherapy. The application of computational modeling toward selecting the optimum imprinting interaction partners is stated. The preparation methods employed in these works are summarized and their attainment in drug-loading capacity, release behavior and cytotoxicity toward cancer cells in the manner of in vitro and in vivo studies are stated. As an essential issue toward the development of a body-friendly system, the biocompatibility and toxicity of the developed drug-delivery systems are discussed. We conclude with the promising perspectives in this emerging field. Areas covered: Last ten years of publications (till June 2020) in magnetic molecularly imprinted polymeric nanoparticles for application as smart-drug-delivery systems in chemotherapy.

Characterization of β-cyclodextrin/myrtenol complex and its protective effect against nociceptive behavior and cognitive impairment in a chronic musculoskeletal pain model

Myrtenol has gained wide interest because of its pharmacological profiles, mainly for treatment of chronic diseases. To improve the solubility of myrtenol, the formation of inclusion complexes with β-cyclodextrin was performed by physical mixture, kneading process or slurry complexation (SC) methods and characterized using thermal analysis, XRD, SEM and NMR. From these results, myrtenol complexed by SC was successfully complexed into β-cyclodextrin cavity. The interaction between myrtenol and β-cyclodextrin was confirmed by molecular docking. Hence, the SC β-cyclodextrin-myrtenol complex was evaluate for its anti-hyperalgesic, anxiolytic and antioxidant activity in a fibromyalgia model. Results show that myrtenol and β-cyclodextrin form a stable complex and have anti-hyperalgesic effect, improve the cognitive impairment caused and have an anxiolytic-like effect. Furthermore, the β-cyclodextrin/myrtenol complex decrease lipoperoxidation, increased catalase activity and a reduce SOD/CAT ratio. Therefore, β-cyclodextrin/myrtenol complex reduce painful behavior, improves motor skills and emotional behavior and decreases oxidative stress in a fibromyalgia model.

Cyclodextrin-based delivery systems for in vivo-tested anticancer therapies

Cyclodextrins (CDs) are naturally occurring macromolecules widely used as excipients on pharmaceutical formulations, evidencing a large spectrum of applications in the pharmaceutical industry. Their unique ability to act as molecular containers by entrapping a wide range of guest molecules in their internal cavity makes them a remarkable excipient to improve drug apparent solubility, stability, and bioavailability, and a valuable tool for the assembly of new drug delivery systems. These features are especially useful when it comes to chemotherapy, as most of the anticancer drugs present both low permeability and reduced water solubility. Therefore, guest-host inclusion complexes offer several potential advantages not only regarding the improvement of pharmaceutical formulations characteristics but also considering the reduction of drug toxic side effects. The combination of CDs with additional technologies and materials constitutes a potential strategy towards the development of advanced and multifunctional CD-based delivery systems. Paclitaxel, curcumin, camptothecin, doxorubicin, and cisplatin are among the most studied molecules with anticancer activities and have been successfully incorporated in such nanosystems. Exciting results using CDs and CD-based delivery systems have been obtained so far, paving the way towards the attainment of intelligent delivery systems to possibly address cancer therapeutics' unmet needs. In this review, a comprehensive exposition concerning in vivo-tested CD and CD-based delivery systems for anticancer therapy is undertaken. Additionally, the authors address the multivalent functionalities of CD-based delivery systems, namely the incorporation of active target ligands, stimuli-responsiveness components, surface functionalization, or further associations with other delivery systems, aiming at improved in vivo anticancer therapies. Graphical abstract.

Cyclodextrin as a magic switch in covalent and non-covalent anticancer drug release systems

Cancer has been a threat to human health, so its treatment is a huge challenge to the present medical field. One of commonly used methods is the controlled release of anticancer drug to reduce the dose for patients, increase the stability of drug treatment and minimize side effects. Cyclodextrin is a kind of cyclic oligosaccharide produced by amylase hydrolysis. Because cyclodextrin contains a cavity structure and active hydroxyl groups, it has a positive effect on the study of the controlled release of anticancer drugs. This article reviews the controlled release of current anticancer drugs based on cyclodextrins as a "flexible switch", and discusses the classification of different types of release systems, highlighting their role in cancer treatment. Moreover, the opportunities and challenges of cyclodextrin as a magic switch in the controlled release of anticancer drugs are discussed.

Amphiphilic Block Copolymers: A Novel Substance for Bitter-Masking in Aqueous Solutions

It is a challenging task to suppress the bitterness of liquid preparations, especially for children. Bitter molecules are highly dispersible in liquids, leading to a strong and instant stimulation of the bitter receptors. At present, there is no effective way to correct this issue except for adding sweeteners, resulting in an unsatisfying taste. Based on the three-point contact theory, which is a universally accepted mechanism of bitterness formation, a new idea and application of amphiphilic block copolymers (ABCs) for bitterness suppression was proposed for the first time. We found that ABCs could widely inhibit the bitterness of four typical bitter substances. The mechanism is that ABCs self-assemble to form association colloids, which attract bitter components and reduce their distribution in the molecular form in solution. The bitter components were demonstrated to automatically embed in the spiral hydrophobic cavity of the hydrophobic chain of the ABCs, and their special interaction dispersed the positive electrostatic potential of bitter groups. The combination did not affect the pharmacokinetic parameters and pharmacodynamics of bitter drugs. These findings highlight the novel application of ABCs for the inhibition of bitterness and illuminate the underlying inhibition mechanisms.

Inclusion of the Phytoalexin trans-Resveratrol in Native Cyclodextrins: A Thermal, Spectroscopic, and X-Ray Structural Study

The aim of the study was to determine the feasibility of complexation between the antioxidant trans-resveratrol (RSV) and underivatized cyclodextrins (CDs) using a variety of preparative methods, including physical mixing, kneading, microwave irradiation, co-evaporation, and co-precipitation techniques. Products were characterized using differential scanning calorimetry (DSC), simultaneous thermogravimetric/DSC analysis (TGA/DSC), Fourier transform infrared (FT-IR) spectroscopy, and powder X-ray diffraction (PXRD). With α-CD and RSV, sample amorphization was revealed by PXRD and FT-IR, but no definitive inclusion complexation was evident. Similar results were obtained in attempts to complex RSV with β-CD. However, complex formation between γ-CD and RSV was evident from observation of an endo-/exothermic effect appearing in the DSC trace of the product from kneading and was further corroborated by FT-IR and PXRD methods. The latter technique indicated complexation unequivocally as the diffraction peak profile for the product matched that for known isostructural γ-CD complexes. Single crystal X-ray analysis followed, confirming the predicted complex between γ-CD and RSV. A combination of ¹H NMR and TGA data yielded the complex formula (γ-CD)₃·(RSV)₄·(H₂O)₆₂. However, severe disorder of the RSV molecules prevented their modeling. In contrast, our previous studies of the inclusion of RSV in methylated CDs yielded crystals with only minor guest disorder.

Nanocarriers: more than tour de force for thymoquinone

Introduction: Thymoquinone (TQ), 2-isopropyl-5-methylbenzo-1, 4-quinone, the main active constituent of Nigella sativa (NS) plant, has been proven to be of great therapeutic aid in various in vitro and in vivo conditions. Despite the promising therapeutic activities of TQ, this molecule is not yet in the clinical trials, restricted by its poor biopharmaceutical properties including photo-instability.Area covered: This review compiles the different types of polymeric and lipidic nanocarriers (NCs), encapsulating TQ for their improved oral bioavailability, and augmented in vitro and in vivo efficacy, evidenced on various pathologies. Furthermore, we provide a comprehensive overview of TQ in relation to its encapsulation approaches advancing the delivery and improving the efficacy of TQ.Expert opinion: TQ was first identified in the essential oil of Nigella sativa L. black seed. TQ has not been used in formulations because it is a highly hydrophobic drug having poor aqueous solubility. To deal with the poor physicochemical problems associated with TQ, various NCs encapsulating TQ have been tried in the past. Nevertheless, these NCs could be impending in bringing forth this potential molecule to clinical reality. This will also be beneficial for a large research community including pharmaceutical & biological sciences and translational researchers.

Crystallization tendency of APIs possessing different thermal and glass related properties in amorphous solid dispersions

The correlation between glass forming ability (GFA) and several thermophysical or physicochemical properties of APIs with the formation and the physical stability of amorphous solid dispersions (ASDs) was evaluated in the present study. Eight poorly water-soluble APIs belonging in different GFA classes (i.e. a) GFA Class I: Carbamazepine, CBZ, b) GFA Class II: Agomelatine, AGO, Aprepitant, APT, Rivaroxaban, RIV, and c) GFA Class III: Indomethacin, IND, Pioglitazone, PIO, Piroxixam, PIR, and Simvastatin, SIM) were tested, in addition to six commonly used matrix-carriers (namely povidone, PVP, hydroxypropyl cellulose, HPC-SL, copovidone, coPVP, Soluplus®, SOL, and gelatin) in order to prepared ASDs via film casting approach. Results using polarized light microscopy (PLM) showed a similar drug crystallization tendency from ASDs independently of their GFA classification, glass stability or glass fragility. X-ray diffraction analysis verified the formation and the physical stability of ASD (independently of GFA class) when a suitable matrix-carrier was selected (i.e. SOL for AGO, RIV and SIM, PVP for APT, CBZ and IND, coPVP for PIO and gelatin for PIR). Further attempts to correlate some physicochemical properties (i.e. component's binding affinity and miscibility) with the formation and the crystallization tendency of the prepared ASDs showed no apparent correlation in regards to the different drug GFA classes. Finally, the evaluation of molecular interactions via FTIR analysis also failed to adequately distinguish the differences in regards to the formation and the physical stability of the prepared systems.

Emerging role of nanosuspensions in drug delivery systems

Rapid advancement in drug discovery process is leading to a number of potential new drug candidates having excellent drug efficacy but limited aqueous solubility. By virtue of the submicron particle size and distinct physicochemical properties, nanosuspension has the potential ability to tackle many formulation and drug delivery issues typically associated with poorly water and lipid soluble drugs. Conventional size reduction equipment such as media mill and high-pressure homogenizers and formulation approaches such as precipitation, emulsion-solvent evaporation, solvent diffusion and microemulsion techniques can be successfully implemented to prepare and scale-up nanosuspensions. Maintaining the stability in solution as well as in solid state, resuspendability without aggregation are the key factors to be considered for the successful production and scale-up of nanosuspensions. Due to the considerable enhancement of bioavailability, adaptability for surface modification and mucoadhesion for drug targeting have significantly expanded the scope of this novel formulation strategy. The application of nanosuspensions in different drug delivery systems such as oral, ocular, brain, topical, buccal, nasal and transdermal routes are currently undergoing extensive research. Oral drug delivery of nanosuspension with receptor mediated endocytosis has the promising ability to resolve most permeability limited absorption and hepatic first-pass metabolism related issues adversely affecting bioavailability. Advancement of enabling technologies such as nanosuspension can solve many formulation challenges currently faced among protein and peptide-based pharmaceuticals.

Influence of Composition and Spray-Drying Process Parameters on Carrier-Free DPI Properties and Behaviors in the Lung: A review

Although dry powder inhalers (DPIs) have attracted great interest compared to nebulizers and metered-dose inhalers (MDIs), drug deposition in the deep lung is still insufficient to enhance therapeutic activity. Indeed, it is estimated that only 10–15% of the drug reaches the deep lung while 20% of the drug is lost in the oropharyngeal sphere and 65% is not released from the carrier. The potentiality of the powders to disperse in the air during the patient’s inhalation, the aerosolization, should be optimized. To do so, new strategies, in addition to classical lactose-carrier, have emerged. The lung deposition of carrier-free particles, mainly produced by spray drying, is higher due to non-interparticulate forces between the carrier and drug, as well as better powder uniformity and aerosolization. Moreover, the association of two or three active ingredients within the same powder seems easier. This review is focused on a new type of carrier-free particles which are characterized by a sugar-based core encompassed by a corrugated shell layer produced by spray drying. All excipients used to produce such particles are dissected and their physico-chemical properties (Péclet number, glass transition temperature) are put in relation with the lung deposition ability of powders. The importance of spray-drying parameters on powders’ properties and behaviors is also evaluated. Special attention is given to the relation between the morphology (characterized by a corrugated surface) and lung deposition performance. The understanding of the closed relation between particle material composition and spray-drying process parameters, impacting the final powder properties, could help in the development of promising DPI systems suitable for local or systemic drug delivery.

Orodispersible Carbamazepine/Hydroxypropyl-β-Cyclodextrin Tablets Obtained by Direct Compression with Five-in-One Co-processed Excipients

The development of orodispersible tablets (ODTs) for poorly soluble and poorly flowable drugs via direct compression is still a challenge. This work aimed to develop ODTs of poorly soluble drugs by combining cyclodextrins that form inclusion complexes to improve wetting and release properties, and directly compressible co-processed excipients able to promote rapid disintegration and solve the poor flowability typical of inclusion complexes. Carbamazepine (CBZ) and hydroxypropyl-β-cyclodextrin (HPβCD) were used, respectively, as a model of a poorly soluble drug with poor flowability and as a solubilizing agent. Specifically, CBZ-an antiepileptic and anticonvulsant drug-may benefit from the studied formulation approach, since some patients have swallowing difficulties or fear of choking and are non-cooperative. Prosolv® ODT G2 and F-Melt® type C were the studied five-in-one co-processed excipients. The complex was prepared by kneading. Flow properties of all materials and main properties of the tablets were characterized. The obtained results showed that ODTs containing CBZ/HPβCD complex can be prepared by direct compression through the addition of co-processed excipients. The simultaneous use of co-processing and cyclodextrin technologies rendered ODTs with an in vitro disintegration time in accordance with the European Pharmacopoeia requirement and with a fast and complete drug dissolution. In conclusion, the combination of five-in-one co-processed excipients and hydrophilic cyclodextrins may help addressing the ODT formulation of poorly soluble drugs with poor flowability, by direct compression and with desired release properties.

Current Approaches to Use Cyclodextrins and Mucoadhesive Polymers in Ocular Drug Delivery—A Mini-Review

Ocular drug delivery provides a challenging opportunity to develop optimal formulations with proper therapeutic effects and acceptable patient compliance because there are many restricting factors involved, such as complex anatomical structures, defensive mechanisms, rapid drainage, and applicability issues. Fortunately, recent advances in the field mean that these problems can be overcome through the formulation of innovative ophthalmic products. Through the addition of solubility enhancer cyclodextrin derivatives and mucoadhesive polymers, the permeability of active ingredients is improved, and retention time is increased in the ocular surface. Therefore, preferable efficacy and bioavailability can be achieved. In this short review, the authors describe the theoretical background, technological possibilities, and the current approaches in the field of ophthalmology.

Nanoparticles Functionalized with Venom-Derived Peptides and Toxins for Pharmaceutical Applications

Venom-derived peptides display diverse biological and pharmacological activities, making them useful in drug discovery platforms and for a wide range of applications in medicine and pharmaceutical biotechnology. Due to their target specificities, venom peptides have the potential to be developed into biopharmaceuticals to treat various health conditions such as diabetes mellitus, hypertension, and chronic pain. Despite the high potential for drug development, several limitations preclude the direct use of peptides as therapeutics and hamper the process of converting venom peptides into pharmaceuticals. These limitations include, for instance, chemical instability, poor oral absorption, short halflife, and off-target cytotoxicity. One strategy to overcome these disadvantages relies on the formulation of bioactive peptides with nanocarriers. A range of biocompatible materials are now available that can serve as nanocarriers and can improve the bioavailability of therapeutic and venom-derived peptides for clinical and diagnostic application. Examples of isolated venom peptides and crude animal venoms that have been encapsulated and formulated with different types of nanomaterials with promising results are increasingly reported. Based on the current data, a wealth of information can be collected regarding the utilization of nanocarriers to encapsulate venom peptides and render them bioavailable for pharmaceutical use. Overall, nanomaterials arise as essential components in the preparation of biopharmaceuticals that are based on biological and pharmacological active venom-derived peptides.

Fluorescence solvatochromism and modulated anticholinergic activity of novel coumarin compounds sequestered in human serum albumin nanocavities

The antagonistic effect of the HSA matrix towards the acetylcholinesterase inhibition potencies of novel coumarin compounds is probed by multi-spectroscopic techniques.