A comparative study of complexation methods for cefdinir-hydroxypropyl-β-cyclodextrin system

Enhancement of Valsartan Oral Bioavailability by Preparing a Microwave-Irradiated Inclusion Complex with Sulfobutyl Ether β-Cyclodextrin Using a Central Composite Face Design for Optimising Process Parameters

The purpose of the study is to investigate the influence of sulfobutyl ether β-cyclodextrin (SBE₇-β-CD) on the bioavailability of valsartan. Phase solubility investigations showed an A_L type curve. The estimated apparent stability constant for valsartan SBE₇-β-CD is 427 ± 0.32 M^-1. Inclusion complexes of valsartan SBE₇-β-CD in equal molar ratio were prepared by microwave irradiation technique. The process parameters were optimised with a central composite face design. Response surface graphs and contour plots showed how process factors affected drug content. The inclusion complexes prepared by optimising process variables are characterised. The DSC and X-ray diffraction confirm the formation of inclusion complexes and the drug's transition from a crystalline to an amorphous state. FTIR suggests hydrogen bonding between valsartan and SBE₇-β-CD. SEM showed changes in drug morphology and shape. The dissolution rate of the prepared SBE₇-β-CD complex using microwave irradiation was 2.85 times that of pure valsartan. The inclusion complex was formulated into tablet dosage forms F₁ to F₄. Furthermore, oral bioavailability studies in rats with tablet formulation F₃ were carried out and compared to the marketed Diovan® tablet as a reference standard. The F₃ tablet formulation exhibited significantly higher values of AUC_0-∞ and C_max than the reference. Finally, the microwave-irradiated valsartan SBE₇-β-CD inclusion complex converted into tablet dosage form may be a promising approach to increasing valsartan oral bioavailability.

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

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

Physico-Chemical, In Vitro and Ex Vivo Characterization of Meloxicam Potassium-Cyclodextrin Nanospheres

Nasal drug delivery has many beneficial properties, such as avoiding the first pass metabolism and rapid onset of action. However, the limited residence time on the mucosa and limited absorption of certain molecules make the use of various excipients necessary to achieve high bioavailability. The application of mucoadhesive polymers can increase the contact time with the nasal mucosa, and permeation enhancers can enhance the absorption of the drug. We aimed to produce nanoparticles containing meloxicam potassium (MEL-P) by spray drying intended for nasal application. Various cyclodextrins (hydroxypropyl-β-cyclodextrin, α-cyclodextrin) and biocompatible polymers (hyaluronic acid, poly(vinylalcohol)) were used as excipients to increase the permeation of the drug and to prepare mucoadhesive products. Physico-chemical, in vitro and ex vivo biopharmaceutical characterization of the formulations were performed. As a result of spray drying, mucoadhesive nanospheres (average particle size <1 µm) were prepared which contained amorphous MEL-P. Cyclodextrin-MEL-P complexes were formed and the applied excipients increased the in vitro and ex vivo permeability of MEL-P. The highest amount of MEL-P permeated from the α-cyclodextrin-based poly(vinylalcohol)-containing samples in vitro (209 μg/cm²) and ex vivo (1.47 μg/mm²) as well. After further optimization, the resulting formulations may be promising for eliciting a rapid analgesic effect through the nasal route.

Thorough characterization and stability of HP-β-cyclodextrin thymol inclusion complexes prepared by microwave technology: A required approach to a successful application in food industry

BACKGROUND

The aims of the present study were to obtain a stable dry powder formulation of cyclodextrins (CDs) encapsulating thymol, for successful use as an ingredient on an industrial scale, and to characterize the thymol-CDs complexes using different techniques.

RESULTS

Thymol was successfully solubilized in aqueous solutions and the Kc value increased with the pH of the media until the pH was neutral, giving the highest values (2583 ± 176 L mol^-1 ) for HP-β-cyclodextrins (HP-β-CDs). The best encapsulation efficiency of thymol in solid complexes was obtained using the microwave (MWI) encapsulation method. The different characterization techniques have demonstrated the affinity of HP-β-CDs for thymol molecules, forming stable complexes.

CONCLUSIONS

The results support the use of the MWI method in the preparation of solid HP-β-CD-thymol complexes, due to greater encapsulation efficiency and technological and economic advantages for industrial applications. © 2018 Society of Chemical Industry.

Grinding as Solvent-Free Green Chemistry Approach for Cyclodextrin Inclusion Complex Preparation in the Solid State

Among the different techniques proposed for preparing cyclodextrin inclusion complex in the solid state, mechanochemical activation by grinding appears as a fast, highly efficient, convenient, versatile, sustainable, and eco-friendly solvent-free method. This review is intended to give a systematic overview of the currently available data in this field, highlighting both the advantages as well as the shortcomings of such an approach. The possible mechanisms involved in the inclusion complex formation in the solid state, by grinding, have been illustrated. For each type of applied milling device, the respective process variables have been examined and discussed, together with the characteristics of the obtained products, also in relation with the physicochemical characteristics of both the drug and cyclodextrin subjected to grinding. The critical process parameters were evidenced in order to provide a useful guide for a rational selection of the most suitable conditions for an efficient inclusion complex preparation by grinding, with the final purpose of promoting a wider use of this effective solvent-free cyclodextrin inclusion complex preparation method in the solid state.

Optimization of a method for preparing solid complexes of essential clove oil with β-cyclodextrins

BACKGROUND

Clove oil (CO) is an aromatic oily liquid used in the food, cosmetics and pharmaceutical industries for its functional properties. However, its disadvantages of pungent taste, volatility, light sensitivity and poor water solubility can be solved by applying microencapsulation or complexation techniques.

RESULTS

Essential CO was successfully solubilized in aqueous solution by forming inclusion complexes with β-cyclodextrins (β-CDs). Moreover, phase solubility studies demonstrated that essential CO also forms insoluble complexes with β-CDs. Based on these results, essential CO-β-CD solid complexes were prepared by the novel approach of microwave irradiation (MWI), followed by three different drying methods: vacuum oven drying (VO), freeze-drying (FD) or spray-drying (SD). FD was the best option for drying the CO-β-CD solid complexes, followed by VO and SD.

CONCLUSION

MWI can be used efficiently to prepare essential CO-β-CD complexes with good yield on an industrial scale. © 2016 Society of Chemical Industry.

Effect of preparation processes and structural insight into the supermolecular system: Bisacodyl and β-cyclodextrin inclusion complex

In this study, β-cyclodextrin (β-CD) and bisacodyl were chosen as model host and guest molecule to explore the effect of preparation processes on the physicochemical properties of inclusion complexes (ICs) and to gain an insight into the structure of ICs. The influence of temperature and pH on complexation was studied by multiple temperature-pH phase solubility analysis. The most favorable conformation was predicted by molecular modeling using AutoDock. (1)H nuclear magnetic resonance and rotating frame nuclear Overhauser effect spectroscopy further confirmed the structure. Moreover, bisacodyl · β-CD ICs in solid state were successfully prepared via three different procedures (co-crystallization, co-evaporation, and co-grinding) and fully characterized by several solid-state techniques, namely, Fourier transform infrared spectroscopy, X-ray powder diffraction, thermogravimetric analysis, differential scanning calorimetry, solid-state NMR spectroscopy, and scanning electron microscopy. It was found that acid solution and low temperature were unfavorable for formation of bisacodyl · β-CD. The pyridine moiety was suggested to be enclosed in the hydrophobic cavity of β-CD. The complexes prepared using co-crystallization showed properties similar to those prepared using co-evaporation. Moreover, ICs obtained by co-evaporation and co-grinding had higher loading efficiency, water solubility, and dissolution rate than ICs obtained by co-crystallization.