Rheo-dissolution: A new platform for the simultaneous measurement of rheology and drug release

Experimental Advances in the Real-Time Recording of Cross-Linking Alginate In Situ Gelation: A Review

Alginate-based hydrogels are promising smart materials widely employed in the food, bioengineering, and energy sectors. The development and optimization of their production require a thorough knowledge of gelation. In recent years, advanced experimental procedures have been developed for real-time cross-linking alginate reaction monitoring. Novel methods, such as customized rheometric setups, enable the recording of mechanical properties and morphological changes during hydrogel formation. These innovative techniques provide important insights into the gelation stages, the reaction rate, the diffusion of cross-linker to polymer chains, and the homogeneity of the gelling structures. Based on real-time experimental data, kinetic models are developed to enhance comprehension of the reaction mechanism and, eventually, to predict the gelation progress. The aim is to enable better control of the characterization of both the complex gelation and the propagated structures. This review aspires to present a comprehensive overview and evaluation of the breakthrough innovations of the real-time in situ recording of cross-linking alginate hydrogels and bead formation. A detailed analysis of the pioneering experimental developments provides a deep comprehension of the alginate gelation, including the parameters controlling the reaction.

Rheological and textural analysis as tools for investigation of drug-polymer and polymer-polymer interactions on the example of low-acyl gellan gum and mesalazine

PURPOSE

In the performed study, the rheological and textural parameters of gellan-based hydrogels were investigated and their dependence on three factors was taken into consideration: (i) The presence of the model drug, (ii) The presence and type of the ionic crosslinking agent, and (iii) the composition of the polymer network. The objective was to compare two analytical methods, regarded as complementary, and define to what extent the obtained results correlate with each other.

METHODS

The hydrogels contained low-acyl gellan gum or its mixtures with hydroxyethyl cellulose or κ-carrageenan. CaCl₂ and MgCl₂ were used as gelling agents. Mesalazine was used as a model drug. The rheological analysis included oscillatory stress and frequency sweeping. The texture profile analysis was performed to calculate texture parameters.

RESULTS

Placebo gels without the addition of gelling agents had the weakest structure. The drug had the strongest ability to increase the stiffness of the polymer network. The weakest structure revealed the placebo samples without the addition of gelling agents. Texture analysis revealed no significant influence of the drug on the strength of the gels, while rheological measurements indicated clear differences.

CONCLUSIONS

It can be concluded that in the case of some parameters methods correlate, that is, the effect related to gelling ions. However, the rheological analysis seems to be more precise and sensitive to some changes in the mechanical properties of the gels.

Development of novel functional snacks containing nano-encapsulated resveratrol with anti-diabetic, anti-obesity and antioxidant properties

In this study, functional snacks with addition of nanoenapsuated resveratrol were prepared to evaluate the nutraceutical and physical properties. The nanoencapsulated resveratrol was prepared from horse-chestnut (HRP), water-chestnut (WRP) and lotus-stem starch particles (LRP) and added to the wheat flour at the level of 0.4% for preparation of snacks by extrusing process. After extrusion, 43-53% and 5.42% of resveratrol was retained in snacks containing encapsulated and free resveratrol (FRP), respectively. The HRP, WRP and LRP showed significantly less peak viscosities and less elastic behaviour than native product (NP) which can influence the human sensory perception. The shift of few peaks towards higher wavelength and presence of additional peaks at 1384, 1229, 1513 and 1613 cm^-1 depicts change in molecular pattern and presence of resveratrol in functional snacks. The functional snacks containing encapsulated resveratrol showed significantly higher antioxidant, anti-diabetic and anti-obesity properties than snacks containing no or free resveratrol.

Personalised 3D Printed Fast-Dissolving Tablets for Managing Hypertensive Crisis: In-Vitro/In-Vivo Studies

Hypertensive crisis (HC) is an emergency health condition which requires an effective management strategy. Over the years, various researchers have developed captopril based fast-dissolving formulations to manage HC; however, primarily, the question of personalisation remains unaddressed. Moreover, commercially these formulations are available as in fixed-dose combinations or strengths, so the titration of dose according to patient's prerequisite is challenging to achieve. The recent emergence of 3D printing technologies has given pharmaceutical scientists a way forward to develop personalised medicines keeping in view patients individual needs. The current project, therefore, is aimed at addressing the limitations as mentioned above by developing fast-dissolving captopril tablets using 3D printing approach. Captopril unloaded (F1) and loaded (F2-F4) filaments were successfully produced with an acceptable drug loading and mechanical properties. Various captopril formulations (F2-F4) were successfully printed using fused deposition modelling technique. The results revealed that the formulations (F2 and F3) containing superdisintegrant had a faster extent of dissolution and in-vivo findings were endorsing these results. The present study has successfully exhibited the utilisation of additive manufacturing approach to mend the gap of personalisation and manufacturing fast-dissolving captopril 3D printed tablets. The procedure adopted in the present study may be used for the development of fused deposition modelling (FDM) based fast-dissolving 3D printed tablets.

Optimizing ophthalmic delivery of a poorly water soluble drug from an aqueous in situ gelling system

Poorly soluble drugs are often unsuitable to incorporate in ocular in situ gelling systems due to the aqueous based gelling formulations and low volumes administered. For such formulations to be successful, the administered drug must have sufficient solubility to diffuse from the formulation to the eye and should not affect the gelation of the in situ gelling material. Drug salt forms can improve the solubility of poorly soluble drugs, however, as in situ gel forming formulations are often designed to be crosslinked by salts (present the lacrimal fluid) it can make salt forms difficult to formulate. The aim of this study was to develop an in situ gel forming ophthalmic formulation of a poorly soluble drug flurbiprofen (FBP) through cyclodextrin complex formation and to analyse the impact on gelation, release and permeation through the cornea. Hydroxypropyl-beta-cyclodextrin (HβCD) was used as a complexing agent and low acyl gellan gum was added to the FBP- HβCD complex as a water soluble in situ gelling polymer. Measurements were performed using rheo-dissolution, which utilises a rheometer with a modified lower plate that has the unique ability to allow rheological measurement and analysis of drug release simultaneously. An ex-vivo permeation study was also performed using porcine cornea. Rheological measurements in terms of elastic (G') and viscous (G″) modulus showed rapid gelation of the formulation upon contact with simulated lacrimal fluid (SLF). Approximately, 97% FBP was released when 10% HβCD was used and release was decreased to 79% when the amount of HβCD was increased to 20%. The percentage of drug permeation through the cornea was 55% in 300 min whereas the marketed non gelling eye drop formulation containing FBP sodium showed only 37% permeation. The data presented here, revealed that not only could a poorly soluble drug be complexed with cyclodextrin and loaded into an in situ gelling system without interfering with the gelation, but also permeability the of the drug improved.