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- MakaleYalnız künye2023Scopus SJRQ2Three-Dimensional Printing of Repaglinide Tablets: Effect of Perforations on Hypromellose-Based Drug Release
Wadi, Ahmed; Rauf, Muhammed Abdur
Purpose: Drug release from hypromellose-based tablets involves the formation of characteristic dry cores surrounded by outer gel layers in aqueous media. The aim of this study was to investigate the effect of perforation sizes on the dissolution of repaglinide from three-dimensionally (3D) printed tablets with two viscosity grades of hypromellose as rate-controlling polymer. Methods: Printing pastes of appropriate consistency were developed and fed into a bioplotter cartridge to extrude strands/filaments. Tablets were printed in a crisscross pattern with 1.0, 1.3, and 1.6 mm of inter-strand distances. Printed tablets were characterized and repaglinide dissolution data were evaluated mathematically. Results: Scanning electron microscopy images confirmed the sealing of the defect-free strands. Differential scanning calorimetry studies indicated potential interaction of ingredients above 150 °C which suggested that the formulation, printing, and drying of tablets should be performed at room temperature. All of the tablets possessed acceptable size, shape, and mechanical strength. Repaglinide dissolution data were evaluated by similarity factor (f2), dissolution efficiency, and two-way analysis of variance (ANOVA) which revealed that drug release rate and extent could be gradually increased by increasing the perforation sizes inside the tablets. Korsmeyer-Peppas modeling of dissolution data showed that the drug release rate approached zero-order kinetics and the release mechanism was Super Case II. This mechanism implies that an outer layer of HPMC gel limits the swelling of the characteristic HPMC tablet cores. Conclusion: The cores in HPMC tablets usually remain dry for long time in aqueous media. Higher perforation sizes enhanced repaglinide dissolution rate from such tablets. This led us to conclude that different perforation sizes in the tablets must have caused differences in the structural consistency of the core. Perforation sizes played the dominant role over HPMC viscosity grades in determining repaglinide release.
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İncele - Kitap BölümüYalnız künye2022Stability and release of bioactives from liposomes
Rauf, Muhammed Abdur
The health benefits of bioactive compounds have been proved beyond doubt, but their instabilities and poor bioavailabilities most often limit their full potential. Encapsulating them in vesicular carrier systems, such as liposomes or emulsions, protects the sensitive compounds against damaging factors and offers an opportunity to achieve controlled release, which in turn aims to enhance their bioavailabilities and efficacies. Liposomes and emulsions are regularly used to tackle the stability issues of bioactives, however, they themselves are susceptible to various chemical, physical, and biological instabilities. Different factors related to lipids, bioactives, and liposome size and lamellarity are known to affect both the stabilities and release behavior of liposomes. Liposomes show biphasic or triphasic release patterns with an initial burst release which is brought under control to achieve better release properties. Optimizing release-affecting factors, utilization of the bioactive–cyclodextrin complex, polymeric coating of liposomes, or encapsulation of liposomes into another polymeric matrix are reported to control the liposomal release behavior. Moreover, liposomes are designed to hold (slow or no release) their content until stimulated/triggered by some release-triggering mechanism like pH, temperature, ultrasound, etc. In comparison, double/multiple emulsion and polyelectrolyte coated multilayer emulsions can also offer controlled release of their payload. Liposomes, being made of natural ingredients, are an attractive choice as carriers for bioactives, although some challenges remain. The first is the destruction of liposomes by bile and lipases in the gastrointestinal tract, the most plausible route of administration for bioactives. In addition, they do not permeate through the gastrointestinal epithelial layers. A large amount (often 20%–30%) of cholesterol, a common ingredient required for liposome rigidity, also remains a concern for hypercholesterolemic people. However, our intense interest in bioactive substances can be expected to overcome these challenges in the near future.
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