Optimization of reaction parameters for synthesis of Cyclodextrin nanosponges in controlled nanoscopic size dimensions

Optimisation of a Greener-Approach for the Synthesis of Cyclodextrin-Based Nanosponges for the Solubility Enhancement of Domperidone, a BCS Class II Drug

BCS class II molecules suffer from low oral bioavailability because of their poor permeability and sub-optimal aqueous solubility. One of the approaches to enhance their bioavailability is using cyclodextrin-based nanosponges. This study aimed to optimise and evaluate the feasibility of a microwave-assisted approach to synthesise nanosponges and improve domperidone's solubility and drug delivery potential. In the production process, microwave power level, response speed, and stirring speed were optimised using the Box-Behnken approach. Ultimately, the batch with the smallest particle size and highest yield was chosen. The optimised method of synthesis of the nanosponges resulted in a product yield of 77.4% and a particle size of 195.68 ± 2.16 nm. The nanocarriers had a drug entrapment capacity of 84 ± 4.2% and a zeta potential of -9.17± 0.43 mV. The similarity and the difference factors demonstrated proof-of-concept, showing that the drug release from the loaded nanosponges is significantly greater than the plain drug. Additionally, spectral and thermal characterisations, such as FTIR, DSC, and XRD, confirmed the entrapment of the drug within the nanocarrier. SEM scans revealed the porous nature of the nanocarriers. Microwave-assisted synthesis could be used as a better and greener approach to synthesise these nanocarriers. It could then be utilised to load drugs and improve their solubility, as seen in the case of domperidone.

Comparative evaluation of dithranol-loaded nanosponges fabricated by solvent evaporation technique and melt method

Background

Dithranol, a standard drug for psoriasis, has lured keen attention by virtue of its antioxidant, anti-proliferative and anti-inflammatory activities. However, its poor stability and solubility critically impair the formulation design, evaluation and administration. To improve these issues, dithranol was encased in β-cyclodextrin nanosponges using solvent evaporation technique. Previously, nanosponges containing dithranol were developed in our laboratory using melt technique. Herein, a comparison of nanosponges prepared by both techniques was also included.

Results

Different nanosponge batches were engineered using diphenyl carbonate as cross-linker with β-cyclodextrin as polymer employing solvent evaporation technique. Dithranol was loaded in nanosponges via lyophilization. Fourier transform infrared spectroscopy, differential scanning colorimeter and powdered X-ray diffraction studies confirmed successful encapsulation and complexation of this drug in β-cyclodextrin nanosponges. The effect of a variable amount of cross-linker on the solubility, encapsulation efficiency, zeta potential, particle size and polydispersity index was evaluated in fabricated nanocarriers. Further, β-cyclodextrin nanosponge batches were subjected to solubility studies, photostability examination and antioxidant activity analysis and compared with previously prepared dithranol-loaded nanosponges. From the present studies results, it was concluded that dithranol-loaded nanosponges using solvent evaporation technique not only improved solubility and photostability but also preserved the antioxidant efficacy of the chosen drug.

Conclusion

The overall results emphasized moral guidance concerning encapsulation, evaluation and characterization and accredited dithranol solubilization, photostability and antioxidant potential. However, solvent evaporation and melt method are easy and promising methods to fabricate nanosponges for dithranol. This comparative study demonstrated the parameters which were affected by chosen techniques. Further, from the results of present studies, it was concluded that the formulation scientists should select the preparation technique based on the objective of their research work and requirement of desired features.

Graphical abstract

Preparation and Optimization of Ibrutinib-Loaded Nanoliposomes Using Response Surface Methodology

The main aim of this study was to optimize the formulation and process variables for the preparation of ibrutinib nanoliposomes and to evaluate the stability of nanoliposomes. The influence of four formulations and process parameters, namely, the phosphatidylcholine-to-cholesterol ratio (A), conc. of ibrutinib (B), sonication time (C), and stirring time (D) on the drug encapsulation efficiency (Y₁) and particle size (Y₂) of ibrutinib nanoliposomes were investigated by using response surface methodology. Reverse-phase evaporation was used to prepare ibrutinib nanoliposomes. Twenty-nine trial experiments were performed as per the design and the response parameters were noted. Multiple linear regression analysis was used to assess each response parameter. The effect of each factor on the response parameters was depicted using perturbation, response surface, and contour plots. A numerical optimization technique was used to estimate the optimum process parameters to obtain the desired responses. Ibrutinib nanoliposomes prepared under optimal conditions were evaluated for stability at a different temperature, pH, and sonication time. It is evident from the results that the phosphatidylcholine-to-cholesterol ratio (A) was the major factor influencing the encapsulation efficiency. All the factors were found to have noteworthy influences on particle size. A statistical evaluation provided the information about the individual and interactive effects of independent factors on the response parameters in order to obtain optimum experimental conditions that lead to preparing nanoliposomes with improved characteristics. The optimum level of the independent variables was phosphatidylcholine:cholesterol (6.76:1), ibrutinib concentration (2 mg/mL), sonication time (15.13 min), and stirring time (45 min). At optimal conditions, Y₁ and Y₂ were found to be 90.76 ± 1.56% and 208.24 ± 3.16 nm, respectively. The ibrutinib nanoliposomes were found to be stable both in simulated gastric and intestinal fluids at 37 °C for 6 h. At elevated conditions of temperature and pH, the prepared nanoliposomes were found to be unstable. Sonication for shorter periods resulted in decreased particle size, whereas longer periods can be helpful for ultrasound-assisted drug delivery. The closeness between the obtained results and predicted results indicates the reliability of the optimization technique for the preparation of ibrutinib nanoliposomes.

Design and formulation of polymeric nanosponge tablets with enhanced solubility for combination therapy

Three drugs namely caffeine, paracetamol, and aceclofenac are commonly used for treating various acute and chronic pain related ailments. These 3 drugs have varied solubility profiles, and formulating them into a single tablet did not have the desired dissolution profile for drug absorption. The objective of the present research was to tailor the drug release profile by altering drug solubility. This was achieved by loading the drug into nanosponges. Here, three-dimensional colloidal nanosponges were prepared using β-cyclodextrin with dimethyl carbonate as a cross-linker using the hot-melt compression method. The prepared nanosponges were characterized by FTIR, ¹H NMR spectroscopy, DSC, XRPD studies and SEM. The FTIR and DSC results obtained indicated polymer-drug compatibility. The ¹H NMR spectroscopy results obtained indicated the drug entrapment within nanosponges with the formation of the inclusion complex. XRPD studies showed that the loaded drug had changed crystalline properties altering drug solubility. SEM photographs revealed the porous and spongy texture on the surface of the nanosponge. Box–Behnken experimental design was adopted for the optimization of nanosponge synthesis. Among the synthesized nanosponges containing paracetamol, aceclofenac and caffeine, batch F3–P31, F3–A31 and F3–C31 were considered optimized. Their particle size was 185, 181 and 199 nm with an entrapment efficiency of 81.53, 84.96, and 89.28% respectively. These optimized nanosponges were directly compressed into tablets and were studied for both pre and post-compression properties including in vitro drug release. The prepared tablet showed desired drug dissolution properties compared to the pure drug. The above outcomes indicated the applicability of nanosponges in modulating the drug release with varied solubility for combination therapy.

Polymeric nanosponges as potential carriers for successful combination therapy of poorly soluble drugs (paracetamol, aceclofenac, caffeine).

History of Cyclodextrin Nanosponges

Nowadays, research in the field of nanotechnology and nanomedicine has become increasingly predominant, focusing on the manipulation and development of materials on a nanometer scale. Polysaccharides have often been used as they are safe, non-toxic, hydrophilic, biodegradable and are low cost. Among them, starch derivatives and, in particular, cyclodextrin-based nanosponges (CD NSs) have recently emerged due to the outstanding properties attributable to their peculiar structure. In fact, alongside the common polysaccharide features, such as the presence of tunable functional groups and their ability to interact with biological tissues, thus giving rise to bioadhesion, which is particularly useful in drug delivery, what makes CD NSs unique is their three-dimensional network made up of crosslinked cyclodextrin units. The name “nanosponge” appeared for the first time in the 1990s due to their nanoporous, sponge-like structure and responded to the need to overcome the limitations of native cyclodextrins (CDs), particularly their water solubility and inability to encapsulate charged and large molecules efficiently. Since CD NSs were introduced, efforts have been made over the years to understand their mechanism of action and their capability to host molecules with low or high molecular weight, charged, hydrophobic or hydrophilic by changing the type of cyclodextrin, crosslinker and degree of crosslinking used. They enabled great advances to be made in various fields such as agroscience, pharmaceutical, biomedical and biotechnological sectors, and NS research is far from reaching its conclusion. This review gives an overview of CD NS research, focusing on the origin and key points of the historical development in the last 50 years, progressing from relatively simple crosslinked networks in the 1960s to today’s multifunctional polymers. The approach adopted in writing the present study consisted in exploring the historical evolution of NSs in order to understand their role today, and imagine their future.